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The Sun
The Sun
Observation data
Mean distance
from Earth
1.496×1011 m
(8.31 min at light speed)
Visual brightness (V) −26.74m [54]
Absolute magnitude 4.83m [54]
Spectral classification G2V
Orbital characteristics
Mean distance
from Milky Way core
~2.5×1020 m
(26,000 light-years)
Galactic period 2.25–2.50×108 a
Velocity 2.17×105 m/s(orbit around the center of the Galaxy)
2×104 m/s
(relative to average velocity of other stars in stellar neighborhood)
Physical characteristics
Mean diameter 1.392×109 m [54]
(109 Earths)
Equatorial radius 6.955×108 m [55]
Equatorial circumference 4.379×109 m [55]
Oblateness 9×10−6
Surface area 6.088×1018  [55]
(11,900 Earths)
Volume 1.4122×1027  [55]
(1,300,000 Earths)
Mass 1.9891 ×1030 kg[54]
(332,946 Earths)
Average density 1,409 kg/m³ [55]
Equatorial surface gravity 274.0 m s-2 [54]
(27.94 g)
Escape velocity
(from the surface)
617.7 km/s [55]
(55 Earths)
Temperature
of surface (effective)
5,778 K [54]
Temperature
of corona
5 MK
Temperature
of core
~15.71 MK [54]
Luminosity (Lsol) 3.846×1026 W [54]
~3.75×1028 lm
(~98 lm/W efficacy)
Mean Intensity (Isol) 2.009×107 W m-2 sr-1
Rotation characteristics
Obliquity 7.25° [54]
(to the ecliptic)
67.23°
(to the galactic plane)
Right ascension
of North pole[56]
286.13°
(19 h 4 min 30 s)
Declination
of North pole
+63.87°
(63°52' North)
Sidereal Rotation period
(at 16° latitude)
25.38 days [54]
(25 d 9 h 7 min 13 s)[56]
(at equator) 25.05 days [54]
(at poles) 34.3 days [54]
Rotation velocity
(at equator)
7,284 km/h
Photospheric composition (by mass)
Hydrogen 73.46 %
Helium 24.85 %
Oxygen 0.77 %
Carbon 0.29 %
Iron 0.16 %
Sulfur 0.12 %
Neon 0.12 %
Nitrogen 0.09 %
Silicon 0.07 %
Magnesium 0.05 %
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The Sun (Latin: Sol) is the star at the center of the Solar System. The Earth and other matter (including other planets, asteroids, meteoroids, comets and dust) orbit the Sun, which by itself accounts for about 99.8% of the solar system's mass. Energy from the Sun—in the form of sunlight—supports almost all life on Earth via photosynthesis, and drives the Earth's climate and weather. It has been suggested that this article or section be merged with SOL. (Discuss) Look up Sol in Wiktionary, the free dictionary. ... Look up sun in Wiktionary, the free dictionary. ... Image File history File links Sun_symbol. ... Image File history File links Sun920607. ... This article is about Earth as a planet. ... To help compare distances at different orders of magnitude this page lists lengths starting at 1011 metres (100 Gm or 100 million kilometres or 0. ... ‹ The template below (Unit of length) is being considered for deletion. ... “Lightspeed” redirects here. ... The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... This article refers to the Milky Way galaxy, for the Milky Way as the hazy band of white light visible from Earths surface, see Milky Way (astronomy) For other uses, see Milky Way (disambiguation). ... A light-year, symbol ly, is the distance light travels in one year: exactly 9. ... NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 17,000 parsecs in diameter and approximately 20 million parsecs distant. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... Look up second in Wiktionary, the free dictionary. ... To help compare different distances this page lists lengths starting at 109 m (1 million km). ... To help compare different distances this page lists lengths starting at 109 m (1 million km). ... Oblate also refers to a member of the Roman Catholic religious order of the Missionary Oblates of Mary Immaculate, or in some cases to a lay or religious person who has officially associated himself (or herself) with a monastic community such as the Benedictines for reasons of personal enrichment without... To help compare sizes of different surface areas, we list here areas of the order of 1018 square metres, i. ... A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ... To help compare different orders of magnitudes this page lists volumes between one and one thousand cubic gigametre ( to cubic metres). ... A cubic kilometre (symbol km³) is an SI derived unit of volume. ... The kilogram or kilogramme (symbol: kg) is the SI base unit of mass. ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ... Space Shuttle Atlantis launches on mission STS-71. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... A corona is a type of plasma atmosphere of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ... Mega (symbol M) is a SI prefix in the SI system of units denoting a factor of 106, i. ... This article does not cite any references or sources. ... For other uses, see Watt (disambiguation). ... The lumen (symbol: lm) is the SI unit of luminous flux. ... Luminous efficacy is a property of light sources, which indicates what portion of the emitted electromagnetic radiation is usable for human vision. ... Radiance and spectral radiance are radiometric measures that describe the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle in a specified direction. ... A sphere rotating around its axis. ... Axial tilt is an astronomical term regarding the inclination angle of a planets rotational axis in relation to its orbital plane. ... This article describes the unit of angle. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... This article refers to the Milky Way galaxy, for the Milky Way as the hazy band of white light visible from Earths surface, see Milky Way (astronomy) For other uses, see Milky Way (disambiguation). ... Equatorial Coordinates Right ascension (abbrev. ... In astronomy, declination (abbrev. ... Since the sun is composed of a gaseous plasma, it does not have a fixed rotation rate. ... The hour (symbol: h) is a unit of time. ... The photosphere of an astronomical object is the region at which the optical depth becomes one for a photon of wavelength equal to 5000 angstroms. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... General Name, symbol, number carbon, C, 6 Chemical series nonmetals Group, period, block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ... General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Standard atomic weight 32. ... For other uses, see Neon (disambiguation). ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance as coarse powder, dark grey with bluish tinge Standard atomic weight 28. ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... For other uses, see Latin (disambiguation). ... STAR is an acronym for: Organizations Society of Ticket Agents and Retailers], the self-regulatory body for the entertainment ticket industry in the UK. Society for Telescopy, Astronomy, and Radio, a non-profit New Jersey astronomy club. ... This article is about the Solar System. ... This article is about Earth as a planet. ... The eight planets and three dwarf planets of the Solar System. ... 253 Mathilde, a C-type asteroid. ... “Meteor” redirects here. ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... Porous chondrite interplanetary dust particle. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... This article is about the Solar System. ... This article or section is in need of attention from an expert on the subject. ... The leaf is the primary site of photosynthesis in plants. ...


The Sun is composed of hydrogen (about 74% of its mass, or 92% of its volume), helium (about 25% of mass, 7% of volume), and trace quantities of other elements. The Sun has a spectral class of G2V. G2 implies that it has a surface temperature of approximately 5,780 K (or approximately 5,515 degrees Celsius / 9,940 Fahrenheit), giving it a white color which, because of atmospheric scattering, appears yellow as seen from the surface of the Earth. This is a subtractive effect, as the preferential scattering of blue photons (causing the sky color) removes enough blue light to leave a residual reddishness that is perceived as yellow. (When low enough in the sky, the Sun appears orange or red, due to this scattering.) General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... Color temperature is a characteristic of visible light that has important applications in photography, videography, publishing and other fields. ... Scattering is a general physical process whereby some forms of radiation, such as light, sound or moving particles, for example, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which it passes. ... Rayleigh scattering causing the blue hue of the sky and the reddening at sunset Rayleigh scattering (named after Lord Rayleigh) is the scattering of light, or other electromagnetic radiation, by particles much smaller than the wavelength of the light. ...


Its spectrum contains lines of ionized and neutral metals as well as very weak hydrogen lines. The V (Roman five) suffix indicates that the Sun, like most stars, is a main sequence star. This means that it generates its energy by nuclear fusion of hydrogen nuclei into helium and is in a state of hydrostatic equilibrium, neither contracting nor expanding over time. There are more than 100 million G2 class stars in our galaxy. Because of logarithmic size distribution, the Sun is actually brighter than 85% of the stars in the galaxy, most of which are red dwarfs.[1] A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... Roman numerals are a numeral system originating in ancient Rome, adapted from Etruscan numerals. ... Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... Hydrostatic equilibrium occurs when compression due to gravity is balanced by a pressure gradient which creates a pressure gradient force in the opposite direction. ... This article refers to the Milky Way galaxy, for the Milky Way as the hazy band of white light visible from Earths surface, see Milky Way (astronomy) For other uses, see Milky Way (disambiguation). ... For the type of star, see Red dwarf. ...


The Sun orbits the center of the Milky Way galaxy at a distance of approximately 26,000 light-years from the galactic center, completing one revolution in about 225–250 million years. The orbital speed is 217 km/s (135 mi/s), equivalent to one light-year every 1,400 years, and one AU every 8 days.[2] This article refers to the Milky Way galaxy, for the Milky Way as the hazy band of white light visible from Earths surface, see Milky Way (astronomy) For other uses, see Milky Way (disambiguation). ... NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 17,000 parsecs in diameter and approximately 20 million parsecs distant. ... A light-year, symbol ly, is the distance light travels in one year: exactly 9. ... The Galactic Center is the rotational center of the Milky Way galaxy. ... The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ... The astronomical unit (AU or au or a. ...


It is currently travelling through the Local Interstellar Cloud in the low-density Local Bubble zone of diffuse high-temperature gas, in the inner rim of the Orion Arm of the Milky Way Galaxy, between the larger Perseus and Sagittarius arms of the galaxy. Of the 50 nearest stellar systems within 17 light years from the Earth, the sun ranks 4th in absolute magnitude as a fourth magnitude star (M=4.83). The Local Interstellar Cloud is the interstellar cloud that our solar system is currently moving through. ... The Local Bubble is a cavity in the local interstellar medium (ISM) at least 300 light years across containing a neutral hydrogen density that is approximately one tenth of that of the average ISM in the Milky Way (approximately 0. ... Observed structure of the Milky Ways spiral arms The Orion Arm or Local Arm (labeled 0) is a minor, spiral arm of the Milky Way galaxy. ... The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Galaxia Kuklos; or simply the Galaxy) is a barred spiral galaxy in the Local Group, and has special significance to humanity as the location of the solar system, which is located near the Orion... The Perseus Arm (labeled +I) is a spiral arm of the Milky Way galaxy with a radius of 10. ... The Sagittarius Arm or Sagittarius-Carina Arm (labeled -I) is one of two major spiral arms of the Milky Way galaxy, along with the Cygnus Arm. ... This list of the nearest stars to Earth is ordered by increasing distance. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ...

Contents

Overview

The Sun is a Population I, or third generation, star whose formation may have been triggered by shockwaves from one or more nearby supernovae.[3] This is suggested by a high abundance of heavy elements such as gold and uranium in the solar system. These elements could most plausibly have been produced by endergonic nuclear reactions during a supernova, or by transmutation via neutron absorption inside a massive second-generation star. Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... Abundance is the state in which there is more than enough. ... A heavy metal is any of a number of higher atomic weight elements, which has the properties of a metallic substance at room temperature. ... GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... General Name, symbol, number uranium, U, 92 Chemical series actinides Group, period, block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... Endergonic means absorbing energy in the form of work. ... // Transmutation is the conversion of one object into another. ... This article or section does not adequately cite its references or sources. ...


Sunlight is the primary source of energy to Earth. The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,370 watts per square meter of area at a distance of one AU from the Sun (that is, on or near Earth). Sunlight on the surface of Earth is attenuated by the Earth's atmosphere so that less power arrives at the surface—closer to 1,000 watts per directly exposed square meter in clear conditions when the Sun is near the zenith. This energy can be harnessed via a variety of natural and synthetic processes—photosynthesis by plants captures the energy of sunlight and converts it to chemical form (oxygen and reduced carbon compounds), while direct heating or electrical conversion by solar cells are used by solar power equipment to generate electricity or to do other useful work. The energy stored in petroleum and other fossil fuels was originally converted from sunlight by photosynthesis in the distant past. Solar irradiance spectrum at top of atmosphere. ... For other uses, see Watt (disambiguation). ... The astronomical unit (AU or au or a. ... Attenuation is the decrease in intensity of electromagnetic radiation due to absorption or scattering of photons. ... In broad terms, the zenith is the direction pointing directly above a particular location (perpendicular, orthogonal). ... The leaf is the primary site of photosynthesis in plants. ... A solar cell, a form of photovoltaic cell, is a device that uses the photoelectric effect to generate electricity from light, thus generating solar power (energy). ... Solar power describes a number of methods of harnessing energy from the light of the sun. ... Pumpjack pumping an oil well near Lubbock, Texas Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... Fossil fuels are hydrocarbons, primarily coal and petroleum (fuel oil or natural gas), formed from the fossilized remains of dead plants and animals[1] by exposure to heat and pressure in the Earths crust over hundreds of millions of years[2]. The theory that hydrocarbons were formed from these... The leaf is the primary site of photosynthesis in plants. ...


Ultraviolet light from the Sun has antiseptic properties and can be used to sanitize tools and water. It also causes sunburn, and has other medical effects such as the production of Vitamin D. Ultraviolet light is strongly attenuated by Earth's ozone layer, so that the amount of UV varied greatly with latitude. The angle that the Sun makes with Zenith at noon has been responsible for many biological adaptations, including variations in human skin color in different regions of the globe.[4] For other uses, see Ultraviolet (disambiguation). ... An antiseptic solution of Povidone-iodine applied to an abrasion Antiseptics (Greek αντί, against, and σηπτικός, putrefactive) are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. ... Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. ... The ozone layer is the part of the Earths atmosphere which contains relatively high concentrations of ozone (O3). ... Latitude,usually denoted symbolically by the Greek letter phi, , gives the location of a place on Earth north or south of the equator. ... Historical data for native populations collected by R. Biasutti prior to 1940. ...


Observed from Earth, the Sun's path across the sky varies throughout the year. The shape described by the Sun's position, considered at the same time each day for a complete year, is called the analemma and resembles a figure 8 aligned along a north/south axis. While the most obvious variation in the Sun's apparent position through the year is a north/south swing over 47 degrees of angle (because of the 23.5-degree tilt of the Earth with respect to the Sun), there is an east/west component as well, caused by the acceleration of the Earth as it approaches its perihelion with the sun, and the reduction in the Earth's speed as it moves away to approach its aphelion. The north/south swing in apparent angle is the main source of seasons on Earth. The analemma photographed, looking east in the northern hemisphere. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about divisions of a year. ...


The Sun is a magnetically active star. It supports a strong, changing magnetic field that varies year-to-year and reverses direction about every eleven years around solar maximum. The Sun's magnetic field gives rise to many effects that are collectively called solar activity, including sunspots on the surface of the Sun, solar flares, and variations in solar wind that carry material through the Solar System. Effects of solar activity on Earth include auroras at moderate to high latitudes, and the disruption of radio communications and electric power. Solar activity is thought to have played a large role in the formation and evolution of the Solar System. Solar activity changes the structure of Earth's outer atmosphere. Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges and magnetic dipoles, such as those in electric currents and magnets. ... 400 year history of sunspot numbers. ... A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature. ... A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to tens of millions of hydrogen bombs. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... The Aurora Borealis, or Northern Lights, shines above Bear Lake Aurora Borealis as seen over Canada at 11,000m (36,000 feet) Red and green Aurora in Fairbanks, Alaska “Aurora Borealis” redirects here. ... It has been suggested that this article or section be merged into electricity. ... This article or section does not cite any references or sources. ... This article is about the Solar System. ... Relationship of the atmosphere and ionosphere The ionosphere is the uppermost part of the atmosphere, distinguished because it is ionized by solar radiation. ...


Although it is the nearest star to Earth and has been intensively studied by scientists, many questions about the Sun remain unanswered, such as why its outer atmosphere has a temperature of over 1 million K while its visible surface (the photosphere) has a temperature of less than 6,000 K. Current topics of scientific inquiry include the Sun's regular cycle of sunspot activity, the physics and origin of flaress and prominences, the magnetic interaction between the chromosphere and the corona, and the origin (propulsion source) of solar wind. The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... The photosphere of an astronomical object is the region at which the optical depth becomes one for a photon of wavelength equal to 5000 angstroms. ... A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature. ... A Solar Flare and CME, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to a billion megatons, traveling normally at about 1 million km per hour (about 0. ... Filaments surrounding a solar flare, caused by the interaction of the plasma in the Suns atmosphere with its magnetic field. ... The chromosphere (literally, color sphere) is a thin layer of the Suns atmosphere just above the photosphere, roughly 10,000 kilometers deep (approximating to, if a little less than, the diameter of the Earth). ... A corona is a type of plasma atmosphere of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ...


Life cycle

The Sun's current main sequence age, determined using computer models of stellar evolution and nucleocosmochronology, is thought to be about 4.57 billion years.[5] The theories concerning the formation and evolution of the Solar System are complex and varied, interweaving various scientific disciplines, from astronomy and physics to geology and planetary science. ... In astronomy, stellar evolution is the sequence of radical changes that a star undergoes during its lifetime (the time in which it emits light and heat). ... Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... It has been suggested that simulation software be merged into this article or section. ... In astronomy, stellar evolution is the sequence of radical changes that a star undergoes during its lifetime (the time in which it emits light and heat). ... Nucleocosmochronology is the study of the evolution of the Universe with respect to the four fundamental processes of Nucleosynthesis. ...


It is thought that about 4592.1 million years ago, the rapid collapse of a hydrogen molecular cloud led to the formation of a third generation T Tauri Population I star, the Sun, in a region of the Galactic Habitable Zone (GHZ). The nascent star assumed a nearly circular orbit about 26,000 light-years from the centre of the Milky Way Galaxy [6]. General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... A molecular cloud is a type of interstellar cloud whose density and size permits the formation of molecules, most commonly molecular hydrogen (H2). ... Drawing of a T-Tauri star with a circumstellar accretion disk T Tauri stars are a class of variable stars named after their prototype - T Tauri. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In astronomy a habitable zone (HZ) is a region of space where conditions are favorable for the creation of life. ... The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Galaxia Kuklos; or simply the Galaxy) is a barred spiral galaxy in the Local Group, and has special significance to humanity as the location of the solar system, which is located near the Orion...


The Sun is about halfway through its main-sequence evolution, during which nuclear fusion reactions in its core fuse hydrogen into helium. Each second, more than 4 million tonnes of matter are converted into energy within the Sun's core, producing neutrinos and solar radiation; at this rate, the Sun will have so far converted around 100 Earth-masses of matter into energy. The Sun will spend a total of approximately 10 billion years as a main sequence star. Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... In astronomy, stellar evolution is the sequence of radical changes that a star undergoes during its lifetime (the time in which it emits light and heat). ... Cross section of a red giant showing nucleosynthesis and elements formed Stellar nucleosynthesis is the collective term for the nuclear reactions taking place in stars to build the nuclei of the heavier elements. ... A tonne or metric ton (symbol t), sometimes referred to as a metric tonne, is a measurement of mass equal to 1,000 kilograms. ... Neutrinos are elementary particles denoted by the symbol ν. Travelling close to the speed of light, lacking electric charge and able to pass through ordinary matter almost undisturbed, they are extremely difficult to detect. ... Solar irradiance spectrum at top of atmosphere. ... One thousand million (1,000,000,000) is the natural number following 999,999,999 and preceding 1,000,000,001. ...


The Sun does not have enough mass to explode as a supernova. Instead, in 4–5 billion years, it will enter a red giant phase, its outer layers expanding as the hydrogen fuel in the core is consumed and the core contracts and heats up. Helium fusion will begin when the core temperature reaches around 100 MK, and will produce carbon and oxygen, entering the asymptotic giant branch of a planetary nebula phase in about 7.8 billion years, during which instabilities in interior temperature lead the surface of the sun to shed mass. While it is likely that the expansion of the outer layers of the Sun will reach the current position of Earth's orbit, recent research suggests that mass lost from the Sun earlier in its red giant phase will cause the Earth's orbit to move further out, preventing it from being engulfed.[7] However, Earth's water will be boiled away and most of its atmosphere will escape into space. The increase in solar temperatures over this period is sufficient that by about 500-700 million years into the future, the surface of the Earth will become too hot for the survival of life as we know it. Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... According to the Hertzsprung-Russell diagram, a red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giant stars. ... A period of Stellar evolution undertaken by all low to intermediate mass stars (0. ... NGC 6543, The Cats Eye Nebula NGC 6853, The Dumbbell Nebula A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. ...

Life-cycle of the Sun
Life-cycle of the Sun

Following the red giant phase, intense thermal pulsations will cause the Sun to throw off its outer layers, forming a planetary nebula. The only object that will remain after the outer layers are ejected is the extremely hot stellar core, which will slowly cool and fade as a white dwarf over many billions of years. This stellar evolution scenario is typical of low- to medium-mass stars.[7][8] Image File history File links Download high-resolution version (872x210, 53 KB) Illustration of the life-cycle of the Sun. ... Image File history File links Download high-resolution version (872x210, 53 KB) Illustration of the life-cycle of the Sun. ... NGC 6543, The Cats Eye Nebula NGC 6853, The Dumbbell Nebula A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. ... This article or section does not adequately cite its references or sources. ... In astronomy, stellar evolution is the sequence of radical changes that a star undergoes during its lifetime (the time in which it emits light and heat). ...


Structure

An illustration of the structure of the Sun
An illustration of the structure of the Sun

The Sun is an averaged-sized star. It contains approximately 99% of the total mass of the solar system. The Sun is a near-perfect sphere, with an oblateness estimated at about 9 millionths,[9] which means that its polar diameter differs from its equatorial diameter by only 10 km (6 mi). As the Sun exists in a plasmatic state and is not solid, it undergoes differential rotation as it spins on its axis (i.e. it rotates faster at the equator than at the poles). The period of this actual rotation is approximately 25 days at the equator and 35 days at the poles. However, due to our constantly changing vantage point from the Earth as it orbits the Sun, the apparent rotation of the Sun at its equator is about 28 days. The centrifugal effect of this slow rotation is 18 million times weaker than the surface gravity at the Sun's equator. Also, the tidal effect from the planets does not significantly affect the shape of the Sun. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... A sphere is a symmetrical geometrical object. ... Oblate also refers to a member of the Roman Catholic religious order of the Missionary Oblates of Mary Immaculate, or in some cases to a lay or religious person who has officially associated himself (or herself) with a monastic community such as the Benedictines for reasons of personal enrichment without... Since the sun is composed of a gaseous plasma, it does not have a fixed rotation rate. ... The word axis has several meanings: In mathematics, axis can mean: A straight line around which a geometric figure can be rotated. ... World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe. ... This article is about Earth as a planet. ...


The Sun does not have a definite boundary as rocky planets do; in its outer parts the density of its gases drops approximately exponentially with increasing distance from the center of the Sun. Nevertheless, the Sun has a well-defined interior structure, described below. The Sun's radius is measured from its center to the edge of the photosphere. This is simply the layer above which the gases are too cool or too thin to radiate a significant amount of light; the photosphere is the surface most readily visible to the naked eye. The solar core comprises 10 percent of its total volume, but 40 percent of its total mass.[10] In probability theory and statistics, the exponential distributions are a class of continuous probability distribution. ... The photosphere of an astronomical object is the region at which the optical depth becomes one for a photon of wavelength equal to 5000 angstroms. ... The naked eye is a figure of speech referring to human visual perception that is unaided by enhancing equipment, such as a telescope or binoculars. ...


The solar interior is not directly observable, and the Sun itself is opaque to electromagnetic radiation. However, just as seismology uses waves generated by earthquakes to reveal the interior structure of the Earth, the discipline of helioseismology makes use of pressure waves (infrasound) traversing the Sun's interior to measure and visualize the Sun's inner structure. Computer modeling of the Sun is also used as a theoretical tool to investigate its deeper layers. Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. ... An earthquake is the result of a sudden release of stored energy in the Earths crust that creates seismic waves. ... A computer generated image showing the pattern of a p-mode solar acoustic oscillation both in the interior and on the surface of the sun. ... Infrasound is sound with a frequency too low to be detected by the human ear. ... A computer simulation or a computer model is a computer program which attempts to simulate an abstract model of a particular system. ...


Core

The core of the Sun is considered to extend from the center to about 0.2 solar radii. It has a density of up to 150,000 kg/m³ (150 times the density of water on Earth) and a temperature of close to 13,600,000 kelvins (by contrast, the surface of the Sun is close to 5,785 kelvins (1/2350th of the core). Recent analysis of SOHO mission data favors a faster rotation rate in the core than in the rest of the radiative zone.[11] Through most of the Sun's life, energy is produced by nuclear fusion through a series of steps called the p-p (proton-proton) chain; this process converts hydrogen into helium. The core is the only location in the Sun that produces an appreciable amount of heat via fusion: the rest of the star is heated by energy that is transferred outward from the core. All of the energy produced by fusion in the core must travel through many successive layers to the solar photosphere before it escapes into space as sunlight or kinetic energy of particles. The structure of the Sun The core of the Sun is considered to extend from the center to about 0. ... The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched on an Atlas IIAS launch vehicle on 2 December 1995 to study the Sun, and began normal operations in May 1996. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Overveiw of the proton-proton chain. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ... Prism splitting light High Resolution Solar Spectrum Sunlight in the broad sense is the total spectrum of the electromagnetic radiation given off by the Sun. ... The kinetic energy of an object is the extra energy which it possesses due to its motion. ...


About 3.4×1038 protons (hydrogen nuclei) are converted into helium nuclei every second (out of about ~8.9×1056 total amount of free protons in Sun), releasing energy at the matter-energy conversion rate of 4.26 million tonnes per second, 383 yottawatts (383×1024 W) or 9.15×1010 megatons of TNT per second. This actually corresponds to a surprisingly low rate of energy production in the Sun's core - about 0.3 µW/cm³ (micro-watts per cubic cm), or about 6 µW/kg of matter. For comparison, a candela of light (roughly one candle) produces heat at the rate 1 W/cm³, and the human body at approximately the rate 1.2 W/kg - millions of times more heat production. The use of plasma with similar parameters for energy production on Earth would be completely impractical — even a modest 1 GW fusion power plant would require about 170 billion tonnes of plasma occupying almost one cubic mile. Thus, terrestrial fusion reactors utilize far higher plasma temperatures than those in Sun's interior. In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... For other uses, see Watt (disambiguation). ... A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ... R-phrases S-phrases Related Compounds Related compounds picric acid hexanitrobenzene Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Trinitrotoluene (TNT) is a chemical compound with the formula C6H2(NO2)3CH3. ... Photopic (black) and scotopic [1] (green) luminosity functions. ...


The rate of nuclear fusion depends strongly on density and temperature, so the fusion rate in the core is in a self-correcting equilibrium: a slightly higher rate of fusion would cause the core to heat up more and expand slightly against the weight of the outer layers, reducing the fusion rate and correcting the perturbation; and a slightly lower rate would cause the core to cool and shrink slightly, increasing the fusion rate and again reverting it to its present level. In physics, thermal expansion is the tendency of matter to increase in volume or pressure when heated. ... For other uses, see Weight (disambiguation). ... Look up perturbation in Wiktionary, the free dictionary. ...


The high-energy photons (cosmic, gamma and X-rays) released in fusion reactions are absorbed in only few millimetres of solar plasma and then re-emitted again in random direction (and at slightly lower energy)—so it takes a long time for radiation to reach the Sun's surface. Estimates of the "photon travel time" range from as much as 50 million years[12] to as little as 17,000 years.[13] After a final trip through the convective outer layer to the transparent "surface" of the photosphere, the photons escape as visible light. Each gamma ray in the Sun's core is converted into several million visible light photons before escaping into space. Neutrinos are also released by the fusion reactions in the core, but unlike photons they very rarely interact with matter, so almost all are able to escape the Sun immediately. For many years measurements of the number of neutrinos produced in the Sun were lower than theories predicted by a factor of 3. This discrepancy was recently resolved through the discovery of the effects of neutrino oscillation: the sun in fact emits the number of neutrinos predicted by the theory, but neutrino detectors were missing 2/3 of them because the neutrinos had changed flavor. In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ... Neutrinos are elementary particles denoted by the symbol ν. Travelling close to the speed of light, lacking electric charge and able to pass through ordinary matter almost undisturbed, they are extremely difficult to detect. ... The solar neutrino problem was a major discrepancy between measurements of the neutrinos flowing through the Earth and theoretical models of the solar interior, lasting from the mid-1960s to about 2002. ... Neutrino oscillation is a quantum mechanical phenomenon predicted by Bruno Pontecorvo whereby a neutrino created with a specific lepton flavor (electron, muon or tau) can later be measured to have a different flavor. ...


Radiation zone

From about 0.2 to about 0.7 solar radii, solar material is hot and dense enough that thermal radiation is sufficient to transfer the intense heat of the core outward. In this zone there is no thermal convection; while the material grows cooler as altitude increases, this temperature gradient is slower than the adiabatic lapse rate and hence cannot drive convection. Heat is transferred by radiationions of hydrogen and helium emit photons, which travel a brief distance before being reabsorbed by other ions. In this way energy makes its way very slowly (see above) outward. Hot metalwork from a blacksmith. ... Convection in the most general terms refers to the internal movement of currents within fluids (i. ... For other uses, see Gradient (disambiguation). ... The adiabatic lapse rate is the rate of temperature change that occurs in an atmosphere as a function of elevation, assuming that air behaves adiabatically. ... Radiation as used in physics, is energy in the form of waves or moving subatomic particles. ... ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ...


Convection zone

Structure of the Sun

In the Sun's outer layer (down to approximately 70% of the solar radius), the solar plasma is not dense enough or hot enough to transfer the heat energy of the interior outward via radiation. As a result, thermal convection occurs as thermal columns carry hot material to the surface (photosphere) of the Sun. Once the material cools off at the surface, it plunges back downward to the base of the convection zone, to receive more heat from the top of the radiant zone. Convective overshoot is thought to occur at the base of the convection zone, carrying turbulent downflows into the outer layers of the radiant zone. Image File history File links SunLayers. ... Image File history File links SunLayers. ... Example of a thermal column between the ground and a cumulus This article is about the atmospheric phenomenon. ... Convective overshoot is the phenomenon of convection carrying material beyond an unstable region of convection, into a stratified, stable region. ...


The thermal columns in the convection zone form an imprint on the surface of the Sun, in the form of the solar granulation and supergranulation. The turbulent convection of this outer part of the solar interior gives rise to a "small-scale" dynamo that produces magnetic north and south poles all over the surface of the Sun. Solar photosphere Granules on the photosphere of the Sun are caused by convection currents of plasma within the Suns convective zone. ... Supergranulation is one of the influences on the Sun. ...


Photosphere

The visible surface of the Sun, the photosphere, is the layer below which the Sun becomes opaque to visible light. Above the photosphere visible sunlight is free to propagate into space, and its energy escapes the Sun entirely. The change in opacity is due to the decreasing amount of H- ions, which absorb visible light easily. Conversely, the visible light we see is produced as electrons react with hydrogen atoms to produce H- ions.[14][15] The photosphere is actually tens to hundreds of kilometers thick, being slightly less opaque than air on Earth. Because the upper part of the photosphere is cooler than the lower part, an image of the Sun appears brighter in the center than on the edge or limb of the solar disk, in a phenomenon known as limb darkening. Sunlight has approximately a black-body spectrum that indicates its temperature is about 6,000 K, interspersed with atomic absorption lines from the tenuous layers above the photosphere. The photosphere has a particle density of about 1023 m−3 (this is about 1% of the particle density of Earth's atmosphere at sea level). General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Look up air in Wiktionary, the free dictionary. ... The limb darkened Sun - An image of the Sun in visible light showing the limb darkening effect as a drop in intensity towards the edge or limb of the solar disk. ... WMAP image of the cosmic microwave background radiation anisotropy. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... “Air” redirects here. ...


During early studies of the optical spectrum of the photosphere, some absorption lines were found that did not correspond to any chemical elements then known on Earth. In 1868, Norman Lockyer hypothesized that these absorption lines were because of a new element which he dubbed "helium", after the Greek Sun god Helios. It was not until 25 years later that helium was isolated on Earth.[16] The visible spectrum is the portion of the optical spectrum (light or electromagnetic spectrum) that is visible to the human eye. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... Sir Joseph Norman Lockyer or Norman Lockyer (May 17, 1836 – August 16, 1920) was an English scientist and astronomer. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... In Greek mythology the sun was personified as Helius (Greek Ἥλιος / ἥλιος). Homer often calls him Titan and Hyperion. ...


Atmosphere

During a total solar eclipse, the solar corona can be seen with the naked eye.
During a total solar eclipse, the solar corona can be seen with the naked eye.

The parts of the Sun above the photosphere are referred to collectively as the solar atmosphere. They can be viewed with telescopes operating across the electromagnetic spectrum, from radio through visible light to gamma rays, and comprise five principal zones: the temperature minimum, the chromosphere, the transition region, the corona, and the heliosphere. The heliosphere, which may be considered the tenuous outer atmosphere of the Sun, extends outward past the orbit of Pluto to the heliopause, where it forms a sharp shock front boundary with the interstellar medium. The chromosphere, transition region, and corona are much hotter than the surface of the Sun; the reason why is not yet known. Image File history File linksMetadata Download high-resolution version (3543x3489, 2027 KB) Summary Description: Solar eclipse 1999 in France view 4 Additional noise reduction performed by Diliff. ... Image File history File linksMetadata Download high-resolution version (3543x3489, 2027 KB) Summary Description: Solar eclipse 1999 in France view 4 Additional noise reduction performed by Diliff. ... Photo taken during the 1999 eclipse. ... A corona is a type of plasma atmosphere of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ... This article is about electromagnetic radiation. ... The chromosphere (literally, color sphere) is a thin layer of the Suns atmosphere just above the photosphere, roughly 10,000 kilometers deep (approximating to, if a little less than, the diameter of the Earth). ... TRACE 19. ... A corona is a type of plasma atmosphere of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ... The heliosphere is a bubble in space produced by the solar wind. ... Adjectives: Plutonian Atmosphere Surface pressure: 0. ... The heliopause is the boundary between the heliosphere and the interstellar medium outside the solar system. ... Introduction The shock wave is one of several different ways in which a gas in a supersonic flow can be compressed. ... The interstellar medium (or ISM) is the name astronomers give to the tenuous gas and dust that pervade interstellar space. ...


The coolest layer of the Sun is a temperature minimum region about 500 km (300 mi) above the photosphere, with a temperature of about 4,000 K. This part of the Sun is cool enough to support simple molecules such as carbon monoxide and water, which can be detected by their absorption spectra. The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ...


Above the temperature minimum layer is a thin layer about 2,000 km (1,000 mi) thick, dominated by a spectrum of emission and absorption lines. It is called the chromosphere from the Greek root chroma, meaning color, because the chromosphere is visible as a colored flash at the beginning and end of total eclipses of the Sun. The temperature in the chromosphere increases gradually with altitude, ranging up to around 100,000 K near the top. Photo taken during the 1999 eclipse. ...

Taken by Hinode's Solar Optical Telescope on January 12, 2007, this image of the Sun reveals the filamentary nature of the plasma connecting regions of different magnetic polarity.
Taken by Hinode's Solar Optical Telescope on January 12, 2007, this image of the Sun reveals the filamentary nature of the plasma connecting regions of different magnetic polarity.

Above the chromosphere is a transition region in which the temperature rises rapidly from around 100,000 K to coronal temperatures closer to one million K. The increase is because of a phase transition as helium within the region becomes fully ionized by the high temperatures. The transition region does not occur at a well-defined altitude. Rather, it forms a kind of nimbus around chromospheric features such as spicules and filaments, and is in constant, chaotic motion. The transition region is not easily visible from Earth's surface, but is readily observable from space by instruments sensitive to the far ultraviolet portion of the spectrum. Image File history File links Size of this preview: 800 × 562 pixel Image in higher resolution (1014 × 712 pixel, file size: 497 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Sun ... Image File history File links Size of this preview: 800 × 562 pixel Image in higher resolution (1014 × 712 pixel, file size: 497 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Sun ... SOLAR-B Hinode (ひので, Sunrise in Japanese), formerly known as Solar-B, is a Japan Aerospace Exploration Agency Solar mission with United States and United Kingdom collaboration. ... is the 12th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... The chromosphere (literally, color sphere) is a thin layer of the Suns atmosphere just above the photosphere, roughly 10,000 kilometers deep (approximating to, if a little less than, the diameter of the Earth). ... TRACE 19. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... Ionization is the physical process of converting an atom or molecule into an ion by changing the difference between the number of protons and electrons. ... Nimbus may mean: Halo, light or mist around an object Nimbus program, spacecraft used for weather research Nimbus cloud Nimbus (motorcycle) Nimbus Records is a classical music record company Nimbus, fictional broomsticks from the Harry Potter series Nimbus Land, a fictional location in the Super Mario RPG video game The... A spicule is a dynamic jet of about 500km diameter on the Sun. ... Filaments surrounding a solar flare, caused by the interaction of the plasma in the Suns atmosphere with its magnetic field. ... Layers of Atmosphere - not to scale (NOAA)[1] Outer space, sometimes simply called space, refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. ... For other uses, see Ultraviolet (disambiguation). ... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High...


The corona is the extended outer atmosphere of the Sun, which is much larger in volume than the Sun itself. The corona merges smoothly with the solar wind that fills the solar system and heliosphere. The low corona, which is very near the surface of the Sun, has a particle density of 1014 m−3–1016 m−3. (Earth's atmosphere near sea level has a particle density of about 2×1025 m−3.) The temperature of the corona is several million kelvin. While no complete theory yet exists to account for the temperature of the corona, at least some of its heat is known to be from magnetic reconnection. A corona is a type of plasma atmosphere of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... This article is about the Solar System. ... The heliosphere is a bubble in space produced by the solar wind. ... Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field. ...


The heliosphere extends from approximately 20 solar radii (0.1 AU) to the outer fringes of the solar system. Its inner boundary is defined as the layer in which the flow of the solar wind becomes superalfvénic—that is, where the flow becomes faster than the speed of Alfvén waves. Turbulence and dynamic forces outside this boundary cannot affect the shape of the solar corona within, because the information can only travel at the speed of Alfvén waves. The solar wind travels outward continuously through the heliosphere, forming the solar magnetic field into a spiral shape, until it impacts the heliopause more than 50 AU from the Sun. In December 2004, the Voyager 1 probe passed through a shock front that is thought to be part of the heliopause. Both of the Voyager probes have recorded higher levels of energetic particles as they approach the boundary.[17] The heliosphere is a bubble in space produced by the solar wind. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... An Alfvén wave, named after Hannes Alfvén, is a type of magnetohydrodynamic (or hydromagnetic) wave. ... Heliospheric current sheet, the largest structure in the Solar System, is the three-dimensional form of the Parker spiral, that results from the influence of the Suns rotating magnetic field on the plasma in the interplanetary medium (Solar Wind) [1]. (click to enlarge) The Parker spiral is the shape... The heliopause is the boundary between the heliosphere and the interstellar medium outside the solar system. ... Voyager Project redirects here. ... Shock Front is the first full length album by Converter (music), released November 22, 1999 (see 1999 in music). ...


Solar cycles

Main article: Sunspots

400 year sunspot history A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings, and intense magnetic activity. ...

Sunspots and the sunspot cycle

Measurements of solar cycle variation during the last 30 years.

When observing the Sun with appropriate filtration, the most immediately visible features are usually its sunspots, which are well-defined surface areas that appear darker than their surroundings because of lower temperatures. Sunspots are regions of intense magnetic activity where convection is inhibited by strong magnetic fields, reducing energy transport from the hot interior to the surface. The magnetic field gives rise to strong heating in the corona, forming active regions that are the source of intense solar flares and coronal mass ejections. The largest sunspots can be tens of thousands of kilometers across. Image File history File links Pic of 20 years of solar output data. ... Image File history File links Pic of 20 years of solar output data. ... A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature. ... Convection in the most general terms refers to the internal movement of currents within fluids (i. ... A Solar Flare and CME, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to a billion megatons, traveling normally at about 1 million km per hour (about 0. ... A composite image showing two CMEs (at 2 oclock and 8 oclock), with the sun at center. ...


The number of sunspots visible on the Sun is not constant, but varies over a 11 year cycle known as the Solar cycle. At a typical solar minimum, few sunspots are visible, and occasionally none at all can be seen. Those that do appear are at high solar latitudes. As the sunspot cycle progresses, the number of sunspots increases and they move closer to the equator of the Sun, a phenomenon described by Spörer's law. Sunspots usually exist as pairs with opposite magnetic polarity. The polarity of the leading sunspot alternates every solar cycle, so that it will be a north magnetic pole in one solar cycle and a south magnetic pole in the next. It has been suggested that this article or section be merged with Schwabe-Wolf cycle. ... Spörers law predicts the variation of sunspot latitudes during a solar cycle. ...

History of the number of observed sunspots during the last 250 years, which shows the ~11 year solar cycle.
History of the number of observed sunspots during the last 250 years, which shows the ~11 year solar cycle.

The solar cycle has a great influence on space weather, and is a significant influence on the Earth's climate. Solar activity minima tend to be correlated with colder temperatures, and longer than average solar cycles tend to be correlated with hotter temperatures. In the 17th century, the solar cycle appears to have stopped entirely for several decades; very few sunspots were observed during this period. During this era, which is known as the Maunder minimum or Little Ice Age, Europe experienced very cold temperatures.[18] Earlier extended minima have been discovered through analysis of tree rings and also appear to have coincided with lower-than-average global temperatures. Image File history File links Download high resolution version (1250x875, 189 KB) Description This chart depicts average monthly Sunspot Number variation since 1750. ... Image File history File links Download high resolution version (1250x875, 189 KB) Description This chart depicts average monthly Sunspot Number variation since 1750. ... Aurora australis observed by Discovery, May 1991. ... The Maunder minimum in a 400 year history of sunspot numbers The Maunder Minimum is the name given to the period roughly from 1645 to 1715 A.D., when sunspots became exceedingly rare, as noted by solar observers of the time. ... The Little Ice Age (LIA) was a period of cooling occurring after a warmer era known as the Medieval climate optimum. ... Pinus taeda Cross section showing annual rings Cheraw, South Carolina Dendrochronology or tree-ring dating is the method of scientific dating based on the analysis of tree ring patterns. ...


Possible long term cycle

A recent theory claims that there are magnetic instabilities in the core of the Sun which cause fluctuations with periods of either 41,000 or 100,000 years. These could provide a better explanation of the ice ages than the Milankovitch cycles. Like many theories in astrophysics, this theory cannot be tested directly.[19][20] Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... Milankovitch cycles are the collective effect of changes in the Earths movements upon its climate, named after Serbian civil engineer and mathematician Milutin Milanković. The eccentricity, axial tilt, and precession of the Earths orbit vary in several patterns, resulting in 100,000 year ice age cycles of the...


Theoretical problems

Solar neutrino problem

For many years the number of solar electron neutrinos detected on Earth was one third to one half of the number predicted by the standard solar model. This anomalous result was termed the solar neutrino problem. Theories proposed to resolve the problem either tried to reduce the temperature of the Sun's interior to explain the lower neutrino flux, or posited that electron neutrinos could oscillate—that is, change into undetectable tau and muon neutrinos as they traveled between the Sun and the Earth.[21] Several neutrino observatories were built in the 1980s to measure the solar neutrino flux as accurately as possible, including the Sudbury Neutrino Observatory and Kamiokande. Results from these observatories eventually led to the discovery that neutrinos have a very small rest mass and do indeed oscillate.[22] Moreover, in 2001 the Sudbury Neutrino Observatory was able to detect all three types of neutrinos directly, and found that the Sun's total neutrino emission rate agreed with the Standard Solar Model, although depending on the neutrino energy as few as one-third of the neutrinos seen at Earth are of the electron type. This proportion agrees with that predicted by the Mikheyev-Smirnov-Wolfenstein effect (also known as the matter effect), which describes neutrino oscillation in matter. Hence, the problem is now resolved. The neutrino is an elementary particle. ... The Standard Solar Model (SSM) is the best current physical model of our sun. ... The solar neutrino problem was a major discrepancy between measurements of the neutrinos flowing through the Earth and theoretical models of the solar interior, lasting from the mid-1960s to about 2002. ... Neutrino oscillation is a quantum mechanical phenomenon predicted by Bruno Pontecorvo whereby a neutrino created with a specific lepton flavor (electron, muon or tau) can later be measured to have a different flavor. ... The neutrino is an elementary particle. ... The neutrino is an elementary particle. ... Artists concept of SNOs detector. ... Super-Kamiokande, or Super-K for short, is a neutrino observatory in Japan. ... The term mass in special relativity is used in a couple of different ways, occasionally leading to a great deal of confusion. ... The Mikheyev-Smirnov-Wolfenstein effect is a particle physics process which acts to enhance neutrino oscillations in matter. ...


Coronal heating problem

The optical surface of the Sun (the photosphere) is known to have a temperature of approximately 6,000 K. Above it lies the solar corona at a temperature of 1,000,000 K. The high temperature of the corona shows that it is heated by something other than direct heat conduction from the photosphere. The photosphere of an astronomical object is the region at which the optical depth becomes one for a photon of wavelength equal to 5000 angstroms. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... Heat conduction or thermal conduction is the spontaneous transfer of thermal energy through matter, from a region of higher temperature to a region of lower temperature, and hence acts to even out temperature differences. ...


It is thought that the energy necessary to heat the corona is provided by turbulent motion in the convection zone below the photosphere, and two main mechanisms have been proposed to explain coronal heating. The first is wave heating, in which sound, gravitational and magnetohydrodynamic waves are produced by turbulence in the convection zone. These waves travel upward and dissipate in the corona, depositing their energy in the ambient gas in the form of heat. The other is magnetic heating, in which magnetic energy is continuously built up by photospheric motion and released through magnetic reconnection in the form of large solar flares and myriad similar but smaller events.[23] A wave is a disturbance that propagates through space or spacetime, transferring energy and momentum and sometimes angular momentum. ... Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges and magnetic dipoles, such as those in electric currents and magnets. ... Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field. ... A Solar Flare and CME, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to a billion megatons, traveling normally at about 1 million km per hour (about 0. ...


Currently, it is unclear whether waves are an efficient heating mechanism. All waves except Alfvén waves have been found to dissipate or refract before reaching the corona.[24] In addition, Alfvén waves do not easily dissipate in the corona. Current research focus has therefore shifted towards flare heating mechanisms. One possible candidate to explain coronal heating is continuous flaring at small scales,[25] but this remains an open topic of investigation. A cluster of double layers forming in an Alfvén wave, about a sixth of the distance from the left. ...


Faint young Sun problem

Theoretical models of the Sun's development suggest that 3.8 to 2.5 billion years ago, during the Archean period, the Sun was only about 75% as bright as it is today. Such a weak star would not have been able to sustain liquid water on the Earth's surface, and thus life should not have been able to develop. However, the geological record demonstrates that the Earth has remained at a fairly constant temperature throughout its history, and in fact that the young Earth was somewhat warmer than it is today. The consensus among scientists is that the young Earth's atmosphere contained much larger quantities of greenhouse gases (such as carbon dioxide, methane and/or ammonia) than are present today, which trapped enough heat to compensate for the lesser amount of solar energy reaching the planet.[26] The faint young sun paradox describes the apparent contradiction between observations of liquid water early in Earths history and the astrophysical expectation that the suns output would be only 70% as intense during that epoch as it is during the modern epoch. ... The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ... In order to meet Wikipedias quality standards, this article requires cleanup. ... Methane is a chemical compound with the molecular formula CH4. ... Ammonia is a compound with the formula NH3. ...


Magnetic field

See also: Stellar magnetic field
The heliospheric current sheet extends to the outer reaches of the Solar System, and results from the influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium.
The heliospheric current sheet extends to the outer reaches of the Solar System, and results from the influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium.[27]

All matter in the Sun is in the form of gas and plasma because of its high temperatures. This makes it possible for the Sun to rotate faster at its equator (about 25 days) than it does at higher latitudes (about 35 days near its poles). The differential rotation of the Sun's latitudes causes its magnetic field lines to become twisted together over time, causing magnetic field loops to erupt from the Sun's surface and trigger the formation of the Sun's dramatic sunspots and solar prominences (see magnetic reconnection). This twisting action gives rise to the solar dynamo and an 11-year solar cycle of magnetic activity as the Sun's magnetic field reverses itself about every 11 years. The magnetic field of the Sun is driving this massive ejection of plasma. ... Image File history File links Size of this preview: 768 × 600 pixelsFull resolution (866 × 676 pixel, file size: 172 KB, MIME type: image/gif) (All user names refer to en. ... Image File history File links Size of this preview: 768 × 600 pixelsFull resolution (866 × 676 pixel, file size: 172 KB, MIME type: image/gif) (All user names refer to en. ... Heliospheric current sheet The Heliospheric current sheet (HCS) is the surface within the Solar System where the polarity of the Suns magnetic field changes from north to south. ... For other uses, see Plasma. ... Heliospheric current sheet, the largest structure in the Solar System, results from the influence of the Suns rotating magnetic field on the plasma in the interplanetary medium (Solar Wind) [1]. (click to enlarge) The interplanetary medium is the material which fills the solar system and through which all the... In physics, matter is commonly defined as the substance of which physical objects are composed, not counting the contribution of various energy or force-fields, which are not usually considered to be matter per se (though they may contribute to the mass of objects). ... This article does not cite any references or sources. ... For other uses, see Plasma. ... Since the sun is composed of a gaseous plasma, it does not have a fixed rotation rate. ... Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges and magnetic dipoles, such as those in electric currents and magnets. ... Typical coronal loops observed by TRACE Coronal loops form the basic structure of the lower corona and transition region of the Sun. ... A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature. ... Filaments surrounding a solar flare, caused by the interaction of the plasma in the Suns atmosphere with its magnetic field. ... Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field. ... The solar dynamo is the physical process that generates the Suns magnetic field. ... 400 year sunspot history A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings, and intense magnetic activity. ...


The influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium creates the heliospheric current sheet, which separates regions with magnetic fields pointing in different directions. The plasma in the interplanetary medium is also responsible for the strength of the Sun's magnetic field at the orbit of the Earth. If space were a vacuum, then the Sun's 10-4 tesla magnetic dipole field would reduce with the cube of the distance to about 10-11 tesla. But satellite observations show that it is about 100 times greater at around 10-9 tesla. Magnetohydrodynamic (MHD) theory predicts that the motion of a conducting fluid (e.g., the interplanetary medium) in a magnetic field, induces electric currents which in turn generates magnetic fields, and in this respect it behaves like an MHD dynamo. Heliospheric current sheet, the largest structure in the Solar System, results from the influence of the Suns rotating magnetic field on the plasma in the interplanetary medium (Solar Wind) [1]. (click to enlarge) The interplanetary medium is the material which fills the solar system and through which all the... Heliospheric current sheet The Heliospheric current sheet (HCS) is the surface within the Solar System where the polarity of the Suns magnetic field changes from north to south. ... SI unit. ... MHD Simulation of Solar Wind Magnetohydrodynamics (MHD), or magnetofluiddynamics, is the academic discipline which studies the dynamics of electrically-conducting fluids. ... The MHD (magnetohydrodynamic) dynamo is a fluid example of a dynamo, or electrical generator. ...


History of solar observation

Early understanding of the Sun

The Trundholm Sun chariot pulled by a horse is a sculpture believed to be illustrating an important part of Nordic Bronze Age mythology.
The Trundholm Sun chariot pulled by a horse is a sculpture believed to be illustrating an important part of Nordic Bronze Age mythology.

Humanity's most fundamental understanding of the Sun is as the luminous disk in the sky, whose presence above the horizon creates day and whose absence causes night. In many prehistoric and ancient cultures, the Sun was thought to be a solar deity or other supernatural phenomenon, and worship of the Sun was central to civilizations such as the Inca of South America and the Aztecs of what is now Mexico. Many ancient monuments were constructed with solar phenomena in mind; for example, stone megaliths accurately mark the summer solstice (some of the most prominent megaliths are located in Nabta Playa, Egypt, and at Stonehenge in England); the pyramid of El Castillo at Chichén Itzá in Mexico is designed to cast shadows in the shape of serpents climbing the pyramid at the vernal and autumn equinoxes. With respect to the fixed stars, the Sun appears from Earth to revolve once a year along the ecliptic through the zodiac, and so the Sun was considered by Greek astronomers to be one of the seven planets (Greek planetes, "wanderer"), after which the seven days of the week are named in some languages. Image File history File links en: Solvognen (The Sun Carriage) from the Bronze Age, at display at the National Museum (Nationalmuseet) in Denmark da: Solvognen fra bronzealderen, udstillet pÃ¥ Nationalmuseet Date: 29. ... Image File history File links en: Solvognen (The Sun Carriage) from the Bronze Age, at display at the National Museum (Nationalmuseet) in Denmark da: Solvognen fra bronzealderen, udstillet pÃ¥ Nationalmuseet Date: 29. ... The Sun Chariot pulled by a horse is believed to be a sculpture illustrating an important part of Nordic Bronze Age mythology. ... Map of the Nordic Bronze Age culture, ca 1200 BC The Nordic Bronze Age (also Northern Bronze Age) is the name given by Oscar Montelius (1843-1921) to a period and a Bronze Age culture in Scandinavian pre-history, ca 1800 BC - 600 BC, with sites that reached as far... For other uses, see Sky (disambiguation). ... Horizon. ... It has been suggested that Sun cults be merged into this article or section. ... Look up Supernatural in Wiktionary, the free dictionary. ... A solar deity is a deity who represents the Sun. ... For other meanings of Inca, see Inca (disambiguation). ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... It has been suggested that Mexica be merged into this article or section. ... Megalithic tomb, Mane Braz, Brittany Bronze age wedge tomb in the Burren area of Ireland For the record label, see Megalith Records. ... “Summer solstice” redirects here. ... The neutrality and factual accuracy of this article are disputed. ... For other uses, see Stonehenge (disambiguation). ... For other uses, see England (disambiguation). ... El Castillo, Chichen Itza West side of El Castillo Plumed Serpent Ballcourt, from El Castillo El Castillo (Spanish for The Castle) is the nickname of a spectacular Mesoamerican step-pyramid that dominates the center of the Chichen Itza archaeological site in the Mexican state of Yucatán. ... Templo de los Guerreros (Temple of the Warriors) at Chichen Itza. ... Illumination of the Earth by the Sun on the day of equinox, (ignoring twilight). ... A fixed star is a celestial object that does not seem to move (in comparison to the other stars of the night sky). ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... The term zodiac denotes an annual cycle of twelve stations along the ecliptic, the apparent path of the sun across the heavens through constellations that divide the ecliptic into twelve equal zones of celestial longitude. ... The eight planets and three dwarf planets of the Solar System. ... For the TV station in the Peoria-Bloomington, Illinois market, see WEEK-TV. A week is a unit of time longer than a day and shorter than a month. ...


Development of modern scientific understanding

One of the first people to offer a scientific explanation for the Sun was the Greek philosopher Anaxagoras, who reasoned that it was a giant flaming ball of metal even larger than the Peloponnesus, and not the chariot of Helios. For teaching this heresy, he was imprisoned by the authorities and sentenced to death (though later released through the intervention of Pericles). Eratosthenes might have been the first person to have accurately calculated the distance from the Earth to the Sun, in the 3rd century BCE, as 149 million kilometers, roughly the same as the modern accepted figure. A philosopher is a person who thinks deeply regarding people, society, the world, and/or the universe. ... Anaxagoras Anaxagoras (Greek: Αναξαγόρας, c. ... Greece and the Peloponnese The Peloponnese or Peloponnesus (Greek: Πελοπόννησος Peloponnesos; see also List of Greek place names) is a large peninsula in southern Greece, forming the part of the country south of the Gulf of Corinth. ... Hittite chariot (drawing of an Egyptian relief) Approximate historical map of the spread of the chariot, 2000–500 BC. A chariot is a two-wheeled, horse-drawn vehicle. ... In Greek mythology the sun was personified as Helius (Greek Ἥλιος / ἥλιος). Homer often calls him Titan and Hyperion. ... Look up Heresy in Wiktionary, the free dictionary. ... Capital punishment, or the death penalty, is the execution of a convicted criminal by the state as punishment for crimes known as capital crimes or capital offences. ... Pericles or Perikles (ca. ... Eratosthenes (Greek ; 276 BC - 194 BC) was a Greek mathematician, geographer and astronomer. ... “Era Vulgaris” redirects here. ...


The theory that the Sun is the center around which the planets move was apparently proposed by the ancient Greek Aristarchus and Indians (see Heliocentrism). This view was revived in the 16th century by Nicolaus Copernicus. In the early 17th century, the invention of the telescope permitted detailed observations of sunspots by Thomas Harriot, Galileo and other astronomers. Galileo made some of the first known observations of sunspots and posited that they were on the surface of the Sun rather than small objects passing between the Earth and the Sun.[28] In 1672 Giovanni Cassini and Jean Richer determined the distance to Mars and were thereby able to calculate the distance to the Sun. Isaac Newton observed the Sun's light using a prism, and showed that it was made up of light of many colors,[29] while in 1800 William Herschel discovered infrared radiation beyond the red part of the solar spectrum.[30] The 1800s saw spectroscopic studies of the Sun advance, and Joseph von Fraunhofer made the first observations of absorption lines in the spectrum, the strongest of which are still often referred to as Fraunhofer lines. Statue of Aristarchus at Aristoteles University in Thessaloniki, Greece Aristarchus (310 BC - circa 230 BC) was a Greek astronomer and mathematician, born in Samos, Greece. ... Heliocentric Solar System Heliocentrism (lower panel) in comparison to the geocentric model (upper panel) In astronomy, heliocentrism is the theory that the sun is at the centre of the Universe and/or the Solar System. ... (15th century - 16th century - 17th century - more centuries) As a means of recording the passage of time, the 16th century was that century which lasted from 1501 to 1600. ... “Copernicus” redirects here. ... This article does not cite any references or sources. ... Thomas Harriot (ca. ... Galileo can refer to: Galileo Galilei, astronomer, philosopher, and physicist (1564 - 1642) the Galileo spacecraft, a NASA space probe that visited Jupiter and its moons the Galileo positioning system Life of Galileo, a play by Bertolt Brecht Galileo (1975) - screen adaptation of the play Life of Galileo by Bertolt Brecht... Events England, France, Munster and Cologne invade the United Provinces, therefore this name is know as ´het rampjaar´ (the disaster year) in the Netherlands. ... Giovanni Domenico (Jean-Dominique) Cassini Giovanni Domenico Cassini (June 8, 1625 - September 14, 1712) was an Italian-French astronomer and engineer. ... Jean Richer (born 1630; died 1696 in Paris) was a French astronomer and assistant (élève astronome) of Giovanni Domenico Cassini. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Sir Isaac Newton FRS (4 January 1643 – 31 March 1728) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, natural philosopher, and alchemist. ... If a shaft of light entering a prism is sufficiently narrow, a spectrum results. ... William Herschel Sir Frederick William Herschel, FRS KH (15 November 1738-25 August 1822) was a German-born British astronomer and composer who became famous for discovering the planet Uranus. ... Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... Joseph von Fraunhofer Joseph von Fraunhofer (March 6, 1787 – June 7, 1826) was a German physicist. ... ...


In the early years of the modern scientific era, the source of the Sun's energy was a significant puzzle. Lord Kelvin suggested that the Sun was a gradually cooling liquid body that was radiating an internal store of heat.[31] Kelvin and Hermann von Helmholtz then proposed the Kelvin-Helmholtz mechanism to explain the energy output. Unfortunately the resulting age estimate was only 20 million years, well short of the time span of several billion years suggested by geology. In 1890 Joseph Lockyer, who discovered helium in the solar spectrum, proposed a meteoritic hypothesis for the formation and evolution of the Sun.[32] William Thomson, Archbishop of York, has the same name as this man. ... Hermann Ludwig Ferdinand von Helmholtz (August 31, 1821 – September 8, 1894) was a German physician and physicist. ... The Kelvin-Helmholtz mechanism is an astronomical event that occurs when the surface of a star or a planet cools. ... Sir Joseph Norman Lockyer or Norman Lockyer (May 17, 1836 – August 16, 1920) was an English scientist and astronomer. ...


Not until 1904 was a substantiated solution offered. Ernest Rutherford suggested that the Sun's output could be maintained by an internal source of heat, and suggested radioactive decay as the source.[33] However it would be Albert Einstein who would provide the essential clue to the source of the Sun's energy output with his mass-energy equivalence relation E = mc². Ernest Rutherford, 1st Baron Rutherford of Nelson OM PC FRS (30 August 1871 - 19 October 1937), widely referred to as Lord Rutherford, was a nuclear physicist who became known as the father of nuclear physics. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... “Einstein” redirects here. ... 15ft sculpture of Einsteins 1905 E = mc² formula at the 2006 Walk of Ideas, Germany In physics, mass-energy equivalence is the concept that all mass has an energy equivalence, and all energy has a mass equivalence. ...


In 1920 Sir Arthur Eddington proposed that the pressures and temperatures at the core of the Sun could produce a nuclear fusion reaction that merged hydrogen (protons) into helium nuclei, resulting in a production of energy from the net change in mass.[34] The preponderance of hydrogen in the sun was confirmed in 1925 by Cecilia Payne. The theoretical concept of fusion was developed in the 1930s by the astrophysicists Subrahmanyan Chandrasekhar and Hans Bethe. Hans Bethe calculated the details of the two main energy-producing nuclear reactions that power the Sun.[35][36] One of Sir Arthur Stanley Eddingtons papers announced Einsteins theory of general relativity to the English-speaking world. ... Cecilia Payne-Gaposchkin (May 10, 1900 – December 7, 1979) was an English-American astronomer who in 1925 was first to show that the Sun is mainly composed of hydrogen, contradicting accepted wisdom at the time. ... Chandrasekhar redirects here. ... Hans Albrecht Bethe (pronounced bay-tuh; July 2, 1906 – March 6, 2005), was a German-American physicist who won the Nobel Prize in Physics in 1967 for his work on the theory of stellar nucleosynthesis. ...


Finally, a seminal paper was published in 1957 by Margaret Burbidge, entitled "Synthesis of the Elements in Stars".[37] The paper demonstrated convincingly that most of the elements in the universe had been synthesized by nuclear reactions inside stars, some like our Sun. This revelation stands today as one of the great achievements of science. Margaret Burbidge (nee Eleanor Margaret Peachey) (born August 12, 1919) is a British astrophysicist, noted for original research and holding many administrative posts, including director of the Royal Greenwich Observatory. ... Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). ...


Solar space missions

Solar "fireworks" in sequence as recorded in November 2000 by four instruments onboard the SOHO spacecraft.

The first satellites designed to observe the Sun were NASA's Pioneers 5, 6, 7, 8 and 9, which were launched between 1959 and 1968. These probes orbited the Sun at a distance similar to that of the Earth, and made the first detailed measurements of the solar wind and the solar magnetic field. Pioneer 9 operated for a particularly long period of time, transmitting data until 1987.[38] Image File history File linksMetadata I_screenimage_30579. ... Image File history File linksMetadata I_screenimage_30579. ... A composite image showing two CMEs (at 2 oclock and 8 oclock), with the sun at center. ... The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched on an Atlas IIAS launch vehicle on 2 December 1995 to study the Sun, and began normal operations in May 1996. ... This article is about the American space agency. ... The US Pioneer program of unmanned space missions was designed for planetary exploration. ... This article is about Earth as a planet. ... Year 1987 (MCMLXXXVII) was a common year starting on Thursday (link displays 1987 Gregorian calendar). ...


In the 1970s, Helios 1 and the Skylab Apollo Telescope Mount provided scientists with significant new data on solar wind and the solar corona. The Helios 1 satellite was a joint U.S.-German probe that studied the solar wind from an orbit carrying the spacecraft inside Mercury's orbit at perihelion. The Skylab space station, launched by NASA in 1973, included a solar observatory module called the Apollo Telescope Mount that was operated by astronauts resident on the station. Skylab made the first time-resolved observations of the solar transition region and of ultraviolet emissions from the solar corona. Discoveries included the first observations of coronal mass ejections, then called "coronal transients", and of coronal holes, now known to be intimately associated with the solar wind. Prototype of the Helios spacecraft Helios I sitting atop its Titan IIIE Centaur launcher (LC-41, CCAFS, 1974) The Helios deep space probes were launched in the mid 1970s by the Federal Republic of Germany and NASA, using US Air Force launch vehicles. ... Skylab was the first space station the United States launched into orbit. ... The Apollo Telescope Mount, or ATM, is the name of a solar observatory that was attached to Skylab, the first US space station. ... Motto: (Out Of Many, One) (traditional) In God We Trust (1956 to date) Anthem: The Star-Spangled Banner Capital Washington D.C. Largest city New York City None at federal level (English de facto) Government Federal constitutional republic  - President George Walker Bush (R)  - Vice President Dick Cheney (R) Independence from... This article is about the planet. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... MolÄ—tai Astronomical Observatory An observatory is a location used for observing terrestrial and/or celestial events. ... A composite image showing two CMEs (at 2 oclock and 8 oclock), with the sun at center. ... Coronal holes are areas where the Suns corona is darker, colder, and has lower-density plasma than average. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ...


In 1980, the Solar Maximum Mission was launched by NASA. This spacecraft was designed to observe gamma rays, X-rays and UV radiation from solar flares during a time of high solar activity. Just a few months after launch, however, an electronics failure caused the probe to go into standby mode, and it spent the next three years in this inactive state. In 1984 Space Shuttle Challenger mission STS-41C retrieved the satellite and repaired its electronics before re-releasing it into orbit. The Solar Maximum Mission subsequently acquired thousands of images of the solar corona before re-entering the Earth's atmosphere in June 1989.[39] The Solar Maximum Mission satellite (or SolarMax) was designed to investigate solar phenomenon, particularly solar flares. ... This article is about the American space agency. ... This article is about electromagnetic radiation. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... A Solar Flare and CME, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to a billion megatons, traveling normally at about 1 million km per hour (about 0. ... NASAs Space Shuttle, officially called Space Transportation System (STS), is the United States governments current manned launch vehicle. ... Challenger may mean: Space Shuttle Challenger, the American space shuttle which broke up shortly after liftoff on January 28, 1986 Challenger was the name of the Apollo 17 lunar module Canadair Challenger series of business jets manufactured by Bombardier Challenger Equipment, AGCO Corporations division of Agricultural machinery HMS Challenger... Atmospheric entry is the transition from the vacuum of space to the atmosphere of any planet or other celestial body. ...


Japan's Yohkoh (Sunbeam) satellite, launched in 1991, observed solar flares at X-ray wavelengths. Mission data allowed scientists to identify several different types of flares, and also demonstrated that the corona away from regions of peak activity was much more dynamic and active than had previously been supposed. Yohkoh observed an entire solar cycle but went into standby mode when an annular eclipse in 2001 caused it to lose its lock on the Sun. It was destroyed by atmospheric reentry in 2005.[40] Yohkoh (Sunbeam in Japanese), also known as SOLAR-A, was a Japanese Institute of Space and Astronautical Science Solar mission with United States and United Kingdom collaboration. ... Photo taken during the 1999 eclipse. ...


One of the most important solar missions to date has been the Solar and Heliospheric Observatory, jointly built by the European Space Agency and NASA and launched on December 2, 1995. Originally a two-year mission, SOHO has now operated for over ten years (as of 2007). It has proved so useful that a follow-on mission, the Solar Dynamics Observatory, is planned for launch in 2008. Situated at the Lagrangian point between the Earth and the Sun (at which the gravitational pull from both is equal), SOHO has provided a constant view of the Sun at many wavelengths since its launch. In addition to its direct solar observation, SOHO has enabled the discovery of large numbers of comets, mostly very tiny sungrazing comets which incinerate as they pass the Sun.[41] The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched on an Atlas IIAS launch vehicle on 2 December 1995 to study the Sun, and began normal operations in May 1996. ... Paris headquarters The ESA control room in Darmstadt, Germany The European Space Agency (ESA), established in 1974, is an inter-governmental organisation dedicated to the exploration of space, currently with 17 member states. ... This article is about the American space agency. ... is the 336th day of the year (337th in leap years) in the Gregorian calendar. ... Year 1995 (MCMXCV) was a common year starting on Sunday (link will display full 1995 Gregorian calendar). ... 2007 is a common year starting on Monday of the Gregorian calendar. ... The Solar Dynamics Observatory (SDO) is a NASA mission under the Living with a Star (LWS) program. ... A contour plot of the effective potential (the Hills Surfaces) of a two-body system (the Sun and Earth here), showing the five Lagrange points. ... SOHO spots a Kreutz Sungrazer with a prominent tail, plunging towards the Sun A Sungrazing comet is a comet that passes extremely close to the Sun at perihelion - sometimes within a few thousand kilometres of the Suns surface. ...

The Sun's south pole, taken by STEREO solar observation mission. Material can be seen erupting off the Sun in the lower right side of the image.

All these satellites have observed the Sun from the plane of the ecliptic, and so have only observed its equatorial regions in detail. The Ulysses probe was launched in 1990 to study the Sun's polar regions. It first traveled to Jupiter, to 'slingshot' past the planet into an orbit which would take it far above the plane of the ecliptic. Serendipitously, it was well-placed to observe the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994. Once Ulysses was in its scheduled orbit, it began observing the solar wind and magnetic field strength at high solar latitudes, finding that the solar wind from high latitudes was moving at about 750 km/s (450 mi/s—slower than expected), and that there were large magnetic waves emerging from high latitudes which scattered galactic cosmic rays.[42] Image File history File links Size of this preview: 800 × 450 pixels Full resolution (1280 × 720 pixel, file size: 353 KB, MIME type: image/jpeg) The suns South Pole. ... Image File history File links Size of this preview: 800 × 450 pixels Full resolution (1280 × 720 pixel, file size: 353 KB, MIME type: image/jpeg) The suns South Pole. ... This article is about the spacecraft and the mission. ... Ulysses spacecraft Ulysses is an unmanned probe designed to study the Sun at all latitudes. ... For other uses, see Jupiter (disambiguation). ... Hubble Space Telescope image of Comet Shoemaker-Levy 9, taken on May 17, 1994. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ...


Elemental abundances in the photosphere are well known from spectroscopic studies, but the composition of the interior of the Sun is more poorly understood. A solar wind sample return mission, Genesis, was designed to allow astronomers to directly measure the composition of solar material. Genesis returned to Earth in 2004 but was damaged by a crash landing after its parachute failed to deploy on reentry into Earth's atmosphere. Despite severe damage, some usable samples have been recovered from the spacecraft's sample return module and are undergoing analysis. High resolution spectrum of the Sun showing thousands of elemental absorption lines (fraunhofer lines). ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... In its collecting configuration, the Genesis spacecraft exposed collecting wafers to the solar wind. ... The Apollo 15 capsule landed safely despite a parachute failure. ...


The Solar Terrestrial Relations Observatory (STEREO) mission was launched in October 2006. Two identical spacecraft were launched into orbits that cause them to (respectively) pull further ahead of and fall gradually behind the Earth. This enables stereoscopic imaging of the Sun and solar phenomena, such as coronal mass ejections. This article is about the spacecraft and the mission. ... Stereoscopy, stereoscopic imaging or 3-D (three-dimensional) imaging is a technique to create the illusion of depth in a photograph, movie, or other two-dimensional image, by presenting a slightly different image to each eye. ... A solar coronal mass ejection blasts plasma throughout the Solar System. ...


If one were to observe it from Alpha Centauri, the closest star system, the Sun would appear to be in the constellation Cassiopeia. Alpha Centauri (α Cen / α Centauri, also known as Rigil Kentaurus), is the brightest star system in the southern constellation of Centaurus. ... Cassiopeia (IPA: ) is a northern constellation which Greek mythology considered to represent a vain queen who boasted about her unrivaled beauty. ...


Sun observation and eye damage

The Sun as it appears through a camera lens from the surface of Earth
The Sun as it appears through a camera lens from the surface of Earth

Sunlight is very bright, and looking directly at the Sun with the naked eye for brief periods can be painful, but is not particularly hazardous for normal, non-dilated eyes[43][44]. Looking directly at the Sun causes phosphene visual artifacts and temporary partial blindness. It also delivers about 4 milliwatts of sunlight to the retina, slightly heating it and potentially causing damage in eyes that cannot respond properly to the brightness [45][46]. UV exposure gradually yellows the lens of the eye over a period of years and is thought to contribute to the formation of cataracts, but this depends on general exposure to solar UV, not on whether one looks directly at the Sun.[47] Long-duration viewing of the direct Sun with the naked eye can begin to cause UV-induced, sunburn-like lesions on the retina after about 100 seconds, particularly under conditions where the UV light from the Sun is intense and well focused[48][49]; conditions are worsened by young eyes or new lens implants (which admit more UV than aging natural eyes), sun angles near the zenith, and observing locations at high altitude. Image File history File links Download high resolution version (1024x768, 38 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (1024x768, 38 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Photographic lens One of Canons most popular wide angle lenses - 17-40 f/4 L The zoom lens of the Canon Elph A photographic lens (or more correctly, objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images... The naked eye is a figure of speech referring to human visual perception that is unaided by enhancing equipment, such as a telescope or binoculars. ... A phosphene is an entoptic phenomenon characterized by the sensation of seeing light. ... For other uses, see Ultraviolet (disambiguation). ... Cataract is also used to mean a waterfall or where the flow of a river changes dramatically. ...


Viewing the Sun through light-concentrating optics such as binoculars is very hazardous without an attenuating (ND) filter to dim the sunlight. Unfiltered binoculars can deliver over 500 times as much energy to the retina as using the naked eye, killing retinal cells almost instantly. (Even though the power per unit area of image on the retina is the same, the heat cannot dissipate fast enough because the image is larger.) Even brief glances at the midday Sun through unfiltered binoculars can cause permanent blindness.[50] One way to view the Sun safely is by projecting its image onto a screen using telescope and eyepiece without cemented elements. This should only be done with a small refracting telescope (or binoculars) with a clean eyepiece. Other kinds of telescope can be damaged by this procedure. For the book by Sir Isaac Newton, see Opticks. ... Porro-prism binoculars with central focusing Binocular telescopes, or binoculars, (also known as field glasses) are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. ... In photography and optics, a neutral density filter or ND filter is a grey filter;. In theory, a neutral density filter reduces light of all wavelengths or colors equally, much like inexpensive sunglasses. ...


Partial solar eclipses are hazardous to view because the eye's pupil is not adapted to the unusually high visual contrast: the pupil dilates according to the total amount of light in the field of view, not by the brightest object in the field. During partial eclipses most sunlight is blocked by the Moon passing in front of the Sun, but the uncovered parts of the photosphere have the same surface brightness as during a normal day. In the overall gloom, the pupil expands from ~2 mm to ~6 mm, and each retinal cell exposed to the solar image receives about ten times more light than it would looking at the non-eclipsed Sun. This can damage or kill those cells, resulting in small permanent blind spots for the viewer.[51] The hazard is insidious for inexperienced observers and for children, because there is no perception of pain: it is not immediately obvious that one's vision is being destroyed. Photo taken during the 1999 eclipse. ... The human eye The pupil is the central transparent area (showing as black). ... This article is about Earths moon. ... Surface brightness is a concept used in astronomy when describing extended astronomical objects such as galaxies and nebulae. ...


During sunrise and sunset, sunlight is attenuated due to Rayleigh scattering and Mie scattering from a particularly long passage through Earth's atmosphere and the direct Sun is sometimes faint enough to be viewed comfortably with the naked eye or safely with optics (provided there is no risk of bright sunlight suddenly appearing through a break between clouds). Hazy conditions, atmospheric dust, and high humidity contribute to this atmospheric attenuation. A typical sunrise, in New Zealand A sunrise through clouds over Oakland, California. ... A composite image showing the terminator dividing night from day, running across Europe and Africa. ... Rayleigh scattering causing the blue hue of the sky and the reddening at sunset Rayleigh scattering (named after Lord Rayleigh) is the scattering of light, or other electromagnetic radiation, by particles much smaller than the wavelength of the light. ... Mie theory, also called Lorenz-Mie theory or Lorenz-Mie-Debye theory, is a complete analytical solution of Maxwells equations for the scattering of electromagnetic radiation by spherical particles (also called Mie scattering). ...


Attenuating filters to view the Sun should be specifically designed for that use: some improvised filters pass UV or IR rays that can harm the eye at high brightness levels. Filters on telescopes or binoculars should be on the objective lens or aperture, never on the eyepiece, because eyepiece filters can suddenly crack or shatter due to high heat loads from the absorbed sunlight. Welding glass #14 is an acceptable solar filter, but "black" exposed photographic film is not (it passes too much infrared). An objective lens is the lens in a microscope, telescope, camera or other optical instrument, that receives the first light rays from the object being observed. ... a big (1) and a small (2) aperture For other uses, see Aperture (disambiguation). ... A collection of different types of eyepieces. ...


Solar cultural history

Like other natural phenomena, the Sun has been an object of veneration in many cultures throughout human history. Sol (IPA: [sɔl]) was the name of the Sun in Latin. The Latin name is widely known, but not common in general English language usage,[citation needed] although the related adjective solar is more common. 'Sol' is more frequently used in science fiction writing (Star Trek in particular) as a formal name for the specific star, since in many stories the local sun is a different star and thus the generic term "the sun" would be ambiguous. By extension, the Solar System is often referred to in science fiction as the "Sol System". Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... For other uses, see Latin (disambiguation). ... Science fiction is a form of speculative fiction principally dealing with the impact of imagined science and technology, or both, upon society and persons as individuals. ... The current Star Trek franchise logo Star Trek is an American science fiction entertainment series and media franchise. ... STAR is an acronym for: Organizations Society of Ticket Agents and Retailers], the self-regulatory body for the entertainment ticket industry in the UK. Society for Telescopy, Astronomy, and Radio, a non-profit New Jersey astronomy club. ... This article is about the Solar System. ...


The term sol is used by planetary astronomers to refer to the duration of a solar day on Mars.[52] A mean Earth solar day is approximately 24 hours. A mean Martian solar day, or "sol", is 24 hours, 39 minutes, and 35.244 seconds.[53] See also Timekeeping on Mars. Solar time is based on the idea that, when the sun reaches its highest point in the sky, it is noon. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... Various schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars. ...


Sol is also the modern word for "Sun" in Portuguese, Spanish, Icelandic, Danish, Norwegian, Swedish, Catalan and Galician. The Peruvian currency nuevo sol is named after the Sun (in Spanish), like its successor (and predecessor, in use 1985–1991) the Inti (in Quechua). Also "Sol" in Persian means a solar year. Catalan IPA: (català IPA: or []) is a Romance language, the national language of Andorra, and a co-official language in the Spanish autonomous communities of Balearic Islands, Catalonia and Valencia (in the latter with the name of Valencian), and in the city of LAlguer in the Italian island of... Galician (Galician: galego, IPA: ) is a language of the Western Ibero-Romance branch, spoken in Galicia, an autonomous community with the constitutional status of historic nationality, located in northwestern Spain and small bordering zones in neighbouring autonomous communities of Asturias and Castilla y León. ... ISO 4217 Code PEN User(s) Peru Inflation 2. ... The inti was a currency adopted by Peru in mid-1985 during the García presidency, replacing the over-inflated sol. ... It has been suggested that this article or section be merged with Quechuan languages. ... “Farsi” redirects here. ... Solar year The period of time required for the earth to make one complete revolution around the sun, measured from one vernal equinox to the next. ...


See also

Solar System Portal

Image File history File links Download high resolution version (1024x1274, 113 KB) Original caption released with image This is a montage of planetary images taken by spacecraft managed by the Jet Propulsion Laboratory in Pasadena, CA. Included are (from top to bottom) images of Mercury, Venus, Earth (and Moon), Mars... Here is the list of Solar cycles (or sunspot cycles), tracked since 1755: March 1755 - June 1766 June 1766 - June 1775 June 1775 - September 1784 September 1784 - May 1798 May 1798 - December 1810 December 1810 - May 1823 May 1823 - November 1833 November 1833 - July 1843 July 1843 - December 1855 December... The table below lists Solar System bodies formerly considered to be planets: ^ Recently (2006) reclassified as a dwarf planet. ... The theories concerning the formation and evolution of the Solar System are complex and varied, interweaving various scientific disciplines, from astronomy and physics to geology and planetary science. ... Humans have long recognized the Suns role in supporting life on Earth, and as a result many societies throughout history have paid homage to the Sun by giving it prominent roles in their religions and mythologies. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... It has been suggested that Sun cults be merged into this article or section. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... Solar power describes a number of methods of harnessing energy from the light of the sun. ... This article does not cite any references or sources. ... Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition...

References

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Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 213th day of the year (214th in leap years) in the Gregorian calendar. ... Ca-Al-rich inclusions (CAIs) are centimeter-sized light-coloured calcium and aluminium rich inclusions found in carbonaceous chondrites. ... A protoplanetary disc (also protoplanetary disk, proplyd) is an accretion disc surrounding a T Tauri star. ... A protoplanetary disc (also protoplanetary disk, proplyd) is an accretion disc surrounding a T Tauri star. ... A protoplanetary disc (also protoplanetary disk, proplyd) is an accretion disc surrounding a T Tauri star. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 341st day of the year (342nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... May 16 is the 136th day of the year (137th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... New Scientist is a weekly international science magazine covering recent developments in science and technology for a general English-speaking audience. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 213th day of the year (214th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 213th day of the year (214th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 213th day of the year (214th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 213th day of the year (214th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ...

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 v  d  e The Solar System
The Sun Mercury Venus The Moon Earth Phobos and Deimos Mars Ceres The asteroid belt Jupiter Jupiter's natural satellites Saturn Saturn's natural satellites Uranus Uranus' natural satellites Neptune's natural satellites Neptune Charon, Nix, and Hydra Pluto The Kuiper belt Dysnomia Eris The scattered disc The Oort cloud
The Sun · Mercury · Venus · Earth · Mars · Ceres · Jupiter · Saturn · Uranus · Neptune · Pluto · Eris
Planets · Dwarf planets · Moons: Terrestrial · Martian · Jovian · Saturnian · Uranian · Neptunian · Plutonian · Eridian
Small bodies:   Meteoroids · Asteroids/Asteroid moons (Asteroid belt) · Centaurs · TNOs (Kuiper belt/Scattered disc) · Comets (Oort cloud)
See also astronomical objects, the solar system's list of objects, sorted by radius or mass, and the Solar System Portal

Wikipedia does not have an article with this exact name. ... Image File history File links Wikibooks-logo. ... Image File history File links Wikiquote-logo. ... Image File history File links Wikisource-logo. ... Image File history File links Commons-logo. ... Image File history File links WikiNews-Logo. ... Image File history File links Wikiversity-logo-Snorky. ... The Portable Document Format (PDF) is the file format created by Adobe Systems in 1993 for document exchange. ... A kibibyte (a contraction of kilo binary byte) is a unit of information or computer storage, commonly abbreviated KiB (never kiB). 1 kibibyte = 210 bytes = 1,024 bytes The kibibyte is closely related to the kilobyte, which can be used either as a synonym for kibibyte or to refer to... The structure of the Sun The core of the Sun is considered to extend from the center to about 0. ... The radiation zone is the middle zone in the suns interior. ... The convection zone is the outermost layer of the suns interior. ... Image File history File links Sun920607. ... Photo taken during the French 1999 eclipse The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. ... The photosphere of an astronomical object is the region at which the optical depth becomes one for a photon of wavelength equal to 5000 angstroms. ... The chromosphere (literally, color sphere) is a thin layer of the Suns atmosphere just above the photosphere, roughly 10,000 kilometers deep (approximating to, if a little less than, the diameter of the Earth). ... TRACE 19. ... A corona is a type of plasma atmosphere of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ... The locations of Voyagers 1 and 2 as of 2005 In space physics, the termination shock is the boundary marking one of the outer limits of the suns influence. ... The heliosphere is a bubble in space produced by the solar wind. ... The heliopause is the boundary between the heliosphere and the interstellar medium outside the solar system. ... The locations of Voyagers 1 and 2 as of 2005 The heliosheath is the zone between the termination shock and the heliopause at the outer border of the solar system. ... In a planetary magnetosphere, the bow shock is the boundary at which the solar wind abruptly drops as a result of its approach to the magnetopause. ... A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature. ... A facula (plural: faculae) is literally a bright spot. ... Solar photosphere Granules on the photosphere of the Sun are caused by convection currents of plasma within the Suns convective zone. ... Supergranulation is one of the influences on the Sun. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... A spicule is a dynamic jet of about 500km diameter on the Sun. ... Typical coronal loops observed by TRACE Coronal loops form the basic structure of the lower corona and transition region of the Sun. ... A Solar Flare and CME, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to a billion megatons, traveling normally at about 1 million km per hour (about 0. ... Filaments surrounding a solar flare, caused by the interaction of the plasma in the Suns atmosphere with its magnetic field. ... A composite image showing two CMEs (at 2 oclock and 8 oclock), with the sun at center. ... Animation of a Moreton wave which occurred on December 6, 2006 A Moreton wave is a kind of shockwave on the Suns chromosphere. ... Coronal holes are areas where the Suns corona is darker, colder, and has lower-density plasma than average. ... This article is about the Solar System. ... 400 year history of sunspot numbers. ... The solar dynamo is the physical process that generates the Suns magnetic field. ... Heliospheric current sheet The Heliospheric current sheet (HCS) is the surface within the Solar System where the polarity of the Suns magnetic field changes from north to south. ... Solar irradiance spectrum at top of atmosphere. ... Photo taken during the 1999 eclipse. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... Pioneer 6, 7, 8 and 9 were all part of the Pioneer program, and together formed a series of solar-orbiting, spin-stabilized, solar-cell and battery-powered satellites designed to obtain measurements on a continuing basis of interplanetary phenomena from widely separated points in space. ... Prototype of the Helios spacecraft Helios I sitting atop its Titan IIIE Centaur launcher (LC-41, CCAFS, 1974) The Helios deep space probes were launched in the mid 1970s by the Federal Republic of Germany and NASA, using US Air Force launch vehicles. ... Ulysses spacecraft Ulysses is an unmanned probe designed to study the Sun at all latitudes. ... The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched on an Atlas IIAS launch vehicle on 2 December 1995 to study the Sun, and began normal operations in May 1996. ... Reuven Ramaty High Energy Solar Spectroscopic Imager (or RHESSI) is a NASA sixthSmall Explorer, launched on 5 February 2002. ... SOLAR-B Hinode (ひので, Sunrise in Japanese), formerly known as Solar-B, is a Japan Aerospace Exploration Agency Solar mission with United States and United Kingdom collaboration. ... This article is about the spacecraft and the mission. ... Look up Trace in Wiktionary, the free dictionary. ... Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition Explorer Advanced Composition... In its collecting configuration, the Genesis spacecraft exposed collecting wafers to the solar wind. ... The Solar Dynamics Observatory (SDO) is a NASA mission under the Living with a Star (LWS) program. ... The Solar Orbiter is a Sun-observing satellite, in development by the European Space Agency. ... The Solar Sentinels is a space mission to study the Sun during its solar maximum, the last before the beginning of the Orion program. ... Pioneer H is an unlaunched unmanned space mission that was part of the US Pioneer program. ... This article is about the Solar System. ... This article is about the planet. ... Adjectives: Venusian or (rarely) Cytherean Atmosphere Surface pressure: 9. ... This article is about Earth as a planet. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Spectral type: G[8] Absolute magnitude: 3. ... For other uses, see Jupiter (disambiguation). ... Adjectives: Saturnian Atmosphere [3] Scale height: 59. ... For other uses, see Uranus (disambiguation). ... For other uses, see Neptune (disambiguation). ... Adjectives: Plutonian Atmosphere Surface pressure: 0. ... Absolute magnitude: −1. ... The eight planets and three dwarf planets of the Solar System. ... Artists impression of Pluto (background) and Charon (foreground). ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... This article is about Earths moon. ... The relative sizes of and distance between Mars, Phobos, and Deimos, to scale. ... Jupiters outer moons and their highly inclined orbits. ... The Saturnian system (photographic montage) Saturn has 60 confirmed natural satellites, plus three hypothetical moons. ... Uranus has 27 known moons. ... Neptune (top) and Triton (bottom), 3 days after the Voyager 2 flyby. ... The planet Pluto has three known moons. ... Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... A Small Solar System Body (SSSB) is a term defined in 2006 by the International Astronomical Union to describe objects in the Solar System that are neither planets nor dwarf planets: [1] This encompasses: all minor planets apart from the dwarf planets, : the classical asteroids, (except for 1 Ceres, the... “Meteor” redirects here. ... 253 Mathilde, a C-type asteroid. ... 243 Ida and its moon Dactyl An asteroid moon is an asteroid that orbits another asteroid. ... For details on the physical properties of bodies in the asteroid belt see Asteroid and Main-belt comet. ... The centaurs are a class of icy planetoids that orbit the Sun between Jupiter and Neptune, named after the mythical race of centaurs. ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... The Kuiper belt, derived from data from the Minor Planet Center. ... The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... This image is an artists rendering of the Oort cloud and the Kuiper Belt. ... Astronomical objects are significant physical entities, associations or structures which current science has confirmed to exist in space. ... Below is a list of solar system objects with diameter >500km: The Sun, a spectral class G2 star Mercury Venus Earth Moon Mars Jupiter Io Europa Ganymede Callisto complete list of Jupiters natural satellites Saturn Tethys Dione Rhea Titan Iapetus complete list of Saturns natural satellites Uranus Ariel... It has been suggested that Planetary-size comparison be merged into this article or section. ... This is a list of solar system objects by mass, in decreasing order. ...


  Results from FactBites:
 
Sun-Hwa Kwon - Lostpedia (8766 words)
Sun suggested that they escape, together, and leave Seoul so that Jin would not have to be under Paik's control, but he told her that her father would find them and stated that this is what it took to be married to her.
Sun slowly recuperated from her injuries to the point where she was well enough to watch Claire’s baby so Claire could go into the jungle for a vaccine.
Sun has met all of the main characters, except Ben (whom she never spoke to whilst he was a prisoner, but she knows who he is) and Miles.
Sun - MSN Encarta (1256 words)
The Sun is an average star—its size, age, and temperature fall in about the middle of the ranges of these properties for all stars.
The Sun is much closer to Earth than any other star is. The Sun’s nearest stellar neighbor, Proxima Centauri (part of the triple star Alpha Centauri), is 4.3 light-years from our solar system, meaning light from Proxima Centauri takes 4.3 years to reach the Sun.
Within the heliosphere, the Sun provides most of the heat and light that are present, and the particles in the solar wind interact with the planets and satellites in the solar system.
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