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Encyclopedia > Mercury (planet)
Note: This article contains special characters.
Mercury   Astronomical symbol of mercury
Mercury
Mariner 10 photomosaic of Mercury
Orbital characteristics[1]
Epoch J2000
Aphelion 69,816,927 km
0.46669733 AU
Perihelion: 46,001,210 km
0.30749909 AU
Semi-major axis: 57,909,068 km
0.38709821 AU
Eccentricity: 0.205 30294
Orbital period: 87.969 098 d
(0.240846264 a)
Synodic period: 115.88 d[2]
Avg. orbital speed: 47.87 km/s[2]
Mean anomaly: 174.795884°
Inclination: 7.005015818°
3.38° to Sun’s equator
Longitude of ascending node: 48.330541°
Argument of perihelion: 29.124279°
Satellites: None
Physical characteristics
Mean radius: 2439.7 ± 1.0 km[3][4]
0.3829 Earths
Flattening: < 0.0006 [4]
Surface area: 7.48×107 km²
0.108 Earths[3]
Volume: 6.083×1010 km³
0.054 Earths[3]
Mass: 3.3022×1023 kg
0.055 Earths[3]
Mean density: 5.427 g/cm³[3]
Equatorial surface gravity: 3.7 m/s²
0.38 g[3]
Escape velocity: 4.25 km/s[3]
Sidereal rotation period: 58.646 day (58 d 15.5 h)[3]
Rotation velocity at equator: 10.892 km/h
Axial tilt: 0.01°[2]
Right ascension of North pole: 18 h 44 min 2 s
281.01°[2]
Declination of North pole: 61.45°[2]
Albedo: 0.119 (bond)
0.106 (geom.)[2]
Surface temp.:
   0°N, 0°W
   85°N, 0°W
min mean max
100 K 340 K 700 K
80 K 200 K 380 K
Apparent magnitude: up to -1.9[2]
Angular diameter: 4.5" — 13"[2]
Adjectives: Mercurian
Atmosphere
Surface pressure: trace
Composition: [citation needed]
31.7% Potassium
24.9% Sodium
9.5% Atomic Oxygen
7.0% Argon
5.9% Helium
5.6% Molecular Oxygen
5.2% Nitrogen
3.6% Carbon dioxide
3.4% Water
3.2% Hydrogen

Mercury (pronounced /ˈmɝkjʊəri/) is the innermost and smallest planet in the solar system, orbiting the Sun once every 88 days. It ranges in brightness from about −2.0 to 5.5 in apparent magnitude, but is not easily seen as its greatest angular separation from the Sun (greatest elongation) is only 28.3°. It can only be seen in morning or evening twilight. Comparatively little is known about the planet: the only spacecraft to approach Mercury was Mariner 10 from 1974 to 1975, which mapped only 40%–45% of the planet’s surface. Look up Mercury in Wiktionary, the free dictionary. ... Image File history File links Mercury_symbol. ... Image File history File links No higher resolution available. ... In the field of photographic imaging, a photomosaic is a picture (usually a photograph) that has been divided into (usually equal sized) rectangular sections, each of which is replaced with another photograph of appropriate average color. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... The J2000. ... A diagram of Keplerian orbital elements. ... The astronomical unit (AU or au or a. ... A diagram of Keplerian orbital elements. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... To help compare different distances this page lists lengths starting at 1010 metres (10 million kilometres, 0. ... (This page refers to eccitricity in astrodynamics. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... To help compare orders of magnitude of different times this page lists times between 106 seconds (a megasecond) and 107 seconds (11. ... Look up day in Wiktionary, the free dictionary. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... 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. ... In the study of orbital dynamics the mean anomaly is a measure of time, specific to the orbiting body p, which is a multiple of 2&#960; radians at and only at periapsis. ... For the science fiction novella by William Shunn, see Inclination (novella). ... The Longitude of the ascending node (☊, also noted Ω) is one of the orbital elements used to specify the orbit of an object in space. ... The argument of periapsis (ω) is the orbital element describing the angle between an orbiting bodys ascending node (the point where the body crosses the plane of reference from South to North) and its periapsis (the point of closest approach to the central body), measured in the orbital plane and... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... The flattening, ellipticity, or oblateness of an oblate spheroid is the relative difference between its equatorial radius a and its polar radius b: The flattening of the Earth is 1:298. ... In mathematics, a spheroid is a quadric surface in three dimensions obtained by rotating an ellipse about one of its principal axes. ... To help compare sizes of different areas, here is a list of areas between 10 million km² and 100 million km². See also areas of other orders of magnitude. ... For other uses, see Volume (disambiguation). ... For other uses, see Mass (disambiguation). ... For other uses, see Density (disambiguation). ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Acceleration is the time rate of change of velocity and/or direction, and at any point on a velocity-time graph, it is given by the slope of the tangent to the curve at that point. ... 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. ... On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ... The hour (symbol: h) is a unit of time. ... In astronomy, axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ... Equatorial Coordinates Right ascension (abbrev. ... In astronomy, declination (abbrev. ... For other uses, see Albedo (disambiguation). ... The Bond albedo is the fraction of power in the total electromagnetic radiation incident on an astronomical body that is scattered back out into space. ... The geometric albedo of an astronomical body is the ratio of its total brightness at zero phase angle to that of an idealised fully reflecting, diffusively scattering (Lambertian) disk with the same cross-section. ... For other uses, see Temperature (disambiguation). ... 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. ... The angular diameter of an object as seen from a given position is the diameter measured as an angle. ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... For sodium in the diet, see Edible salt. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colourless (gas) colourless (liquid) Standard atomic weight 15. ... General Name, symbol, number argon, Ar, 18 Chemical series noble gases Group, period, block 18, 3, p Appearance colorless Standard atomic weight 39. ... 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 colourless (gas) colourless (liquid) Standard atomic weight 15. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... This article is about the chemistry of hydrogen. ... This article is about the astronomical term. ... This article is about the Solar System. ... Sol 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. ... This diagram shows the elongations (or angle) of the Earths position from the Sun. ... For other uses, see Twilight (disambiguation). ... The Space Shuttle Discovery as seen from the International Space Station. ... The Mariner 10 probe. ... Year 1974 (MCMLXXIV) was a common year starting on Tuesday (link will display full calendar) of the 1974 Gregorian calendar. ... Year 1975 (MCMLXXV) was a common year starting on Wednesday (link will display full calendar) of the Gregorian calendar. ...


Physically, Mercury is similar in appearance to the Moon as it is heavily cratered. It has no natural satellites and no substantial atmosphere. The planet has a large iron core which generates a magnetic field about 0.1% as strong as that of the Earth.[5] Surface temperatures on Mercury range from about 90 to 700 K (−180 to 430 °C), with the subsolar point being the hottest and the bottoms of craters near the poles being the coldest. This article is about Earths moon. ... Tycho crater on Earths moon. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ... For other uses, see Iron (disambiguation). ... The planetary core consists of the innermost layer(s) of a planet. ... Magnetic field lines shown by iron filings Magnetostatics Electrodynamics Electrical Network Tensors in Relativity This box:      In physics, the magnetic field is a field that permeates space and which exerts a magnetic force on moving electric charges and magnetic dipoles. ... This article is about Earth as a planet. ... For other uses, see Kelvin (disambiguation). ... The subsolar point on earth is where the sun is perceived to be directly overhead. ...


Recorded observations of Mercury date back to the time of the Sumerians, in the third millennium BC. The Romans named the planet after the Roman god Mercurius, equated to the Greek Hermes and the Babylonian Nabu. The astronomical symbol for Mercury is a stylized version of the god’s head and winged hat atop his caduceus, an ancient astrological symbol. The Greeks of Hesiod's time called it Στίλβων Stilbon (“the gleaming”) and Hermaon. Before the 5th century BC, Greek astronomers believed the planet to be two separate objects: one visible only at sunrise, the other only at sunset. In India, the planet was named Budha (बुध), after the son of Chandra (the Moon). The Chinese, Korean, Japanese, and Vietnamese cultures refer to the planet as the water star (水星), based on the Five Elements. The Hebrews named it Kokhav Hamah (כוכב חמה), “the star of the hot one” (“the hot one” being the Sun). Mercury is smaller (though still having a greater mass) than two of the natural satellites in our solar system, Ganymede and Titan. Sumer (or Å umer; Sumerian: KI-EN-GIR [1]) was the earliest known civilization of the ancient Near East, located in lower Mesopotamia (modern Iraq), from the time of the earliest records in the mid 4th millennium BC until the rise of Babylonia in the late 3rd millennium BC. The term... Ancient Rome was a civilization that grew from a small agricultural community founded on the Italian Peninsula circa the 9th century BC to a massive empire straddling the Mediterranean Sea. ... A head of Minerva found in the ruins of the Roman baths in Bath Roman mythology, the mythological beliefs of the people of Ancient Rome, can be considered as having two parts. ... A sculpture of the Roman god Mercury by 17th-century Flemish artist Artus Quellinus. ... For other uses, see Hermes (disambiguation). ... It has been suggested that Nebo (god) be merged into this article or section. ... Chinese Celestial symbols on an antique bronze mirror Astronomical symbols are symbols used to represent various celestial objects, theoretical constructs and observational events. ... For the medical symbol often mistakenly referred to as a caduceus, see Rod of Asclepius. ... ... Roman bronze bust, the so-called Pseudo-Seneca, now identified by some as possibly Hesiod Hesiod (Hesiodos, ) was an early Greek poet and rhapsode, who presumably lived around 700 BC. Hesiod and Homer, with whom Hesiod is often paired, have been considered the earliest Greek poets whose work has survived... In Hindu mythology, Budha (not to be confused with Buddha) is the name for the planet Mercury, a son of Chandra (the moon) with either Tara or Rohini. ... This article is about the Hindu moon deity. ... Chinese Wood (木) | Fire (火) Earth (土) | Metal (金) | Water (æ°´) Japanese Earth (地) | Water (æ°´) | Fire (火) | Air / Wind (風) | Void / Sky / Heaven (空) Hinduism and Buddhism Vayu / Pavan — Air / Wind Agni / Tejas — Fire Akasha — Aether Prithvi / Bhumi — Earth Ap / Jala — Water In traditional Chinese philosophy, natural phenomena can be classified into the Five Elements (Chinese: ; Pinyin: ): wood, fire... This article is about the Hebrew people. ... It has been suggested that Planetary-size comparison be merged into this article or section. ... This article is about the natural satellite of Jupiter. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the only moon known to have a dense atmosphere. ...

Contents

Internal structure

Mercury is one of the four terrestrial planets, being a rocky body like the Earth. It is the smallest of the four, with a diameter of 4879 km at its equator. Mercury consists of approximately 70% metallic and 30% silicate material. The density of the planet is the second highest in the solar system at 5.43 g/cm³, only slightly less than Earth’s density. If the effect of gravitational compression were to be factored out, the materials of which Mercury is made would be denser, with an uncompressed density of 5.3 g/cm³ versus Earth’s 4.4 g/cm³.[6] The inner planets, Mercury, Venus, Earth, and Mars, their sizes to scale. ... 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 metallic materials. ... In chemistry, a silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. ...

1. Crust - 100–200 km thick 2. Mantle - 600 km thick 3. Core - 1,800 km radius
1. Crust - 100–200 km thick
2. Mantle - 600 km thick
3. Core - 1,800 km radius

Mercury’s density can be used to infer details of its inner structure. While the Earth’s high density results appreciably from gravitational compression, particularly at the core, Mercury is much smaller and its inner regions are not nearly as strongly compressed. Therefore, for it to have such a high density, its core must be large and rich in iron.[7] Geologists estimate that Mercury’s core occupies about 42% of its volume. (For Earth this proportion is 17%.) Recent research strongly suggests Mercury has a molten core.[8] Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... The planetary core consists of the innermost layer(s) of a planet. ...


Surrounding the core is a 600 km mantle. It is generally thought that early in Mercury’s history, a giant impact with a body several hundred kilometers across stripped the planet of much of its original mantle material, resulting in the relatively thin mantle compared to the sizable core.[9] (alternative theories are discussed below) Earth cutaway from core to exosphere. ...


Mercury’s crust is thought to be 100–200 km thick. One distinctive feature of Mercury’s surface are numerous narrow ridges, some extending over several hundred kilometers. It is believed that these were formed as Mercury’s core and mantle cooled and contracted at a time when the crust had already solidified.[10] Earth cutaway from core to exosphere. ...


Mercury has a higher iron content than any other major planet in our solar system, and several theories have been proposed to explain this. The most widely accepted theory is that Mercury originally had a metal-silicate ratio similar to common chondrite meteors (thought to be typical of average solar system rocky matter) and a mass approximately 2.25 times its current mass. However, early in the solar system’s history, Mercury was struck by a planetesimal of approximately 1/6 that mass. The impact would have stripped away much of the original crust and mantle, leaving the core behind as a relatively major component.[9] A similar process has been proposed to explain the formation of Earth’s Moon (see giant impact theory). A specimen of the NWA 869 chondrite (type L4-6), showing chondrules and metal flakes Chondrites are stony meteorites that have not been modified due to melting or differentiation of the parent body. ... Planetesimals are solid objects thought to exist in protoplanetary disks and in debris disks. ... This article is about Earths moon. ... The Big Splash The giant impact theory (or Big Splash or Big Whack; cf. ...


Alternatively, Mercury may have formed from the solar nebula before the Sun’s energy output had stabilized. The planet would initially have had twice its present mass. But as the protosun contracted, temperatures near Mercury could have been between 2500 and 3500 K, and possibly even as high as 10000 K. Much of Mercury’s surface rock could have been vaporized at such temperatures, forming an atmosphere of “rock vapor” which could have been carried away by the solar wind.[11] This article or section does not cite any references or sources. ... A Protostar is an object that forms by contraction out of the gas of a giant molecular cloud in the interstellar medium. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ...


A third theory proposes that the solar nebula caused drag on the particles from which Mercury was accreting, which meant that lighter particles were lost from the accreting material.[12] Each of these theories predicts a different surface composition, and two upcoming space missions MESSENGER and BepiColombo both aim to take observations that will allow the theories to be tested. This article or section does not cite any references or sources. ... An object falling through a gas or liquid experiences a force in direction opposite to its motion. ... See also: Accretion (finance) Accretion is increase in size by gradual addition of smaller parts. ... This article is about the NASA space mission. ... BepiColombo is a joint Cornerstone mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. ...


Surface geology

Main article: Geology of Mercury

Mercury’s surface is overall very similar in appearance to that of the Moon, showing extensive mare-like plains and heavy cratering, indicating that it has been geologically inactive for billions of years. Since our knowledge of Mercury's geology is based on only a single spacecraft flyby, it is the least well understood of the terrestrial planets. Surface features are given the following names: Of all the terrestrial planets in the Solar System, the geology of Mercury is the least understood. ... Lunar nearside with major maria and craters labeled A global albedo map of the Moon obtained from the Clementine missionThe dark regions are the lunar maria, whereas the lighter regions are the highlands. ... Of all the terrestrial planets in the Solar System, the geology of Mercury is the least understood. ...

Mercury was heavily bombarded by comets and asteroids during and shortly following its formation 4.6 billion years ago, as well as during a possibly separate subsequent episode called the late heavy bombardment that came to an end 3.8 billion years ago. During this period of intense crater formation, the planet received impacts over its entire surface, facilitated by the lack of any atmosphere to slow impactors down. During this time the planet was volcanically active; basins such as the Caloris Basin were filled by magma from within the planet, which produced smooth plains similar to the maria found on the Moon. For other uses, see Albedo (disambiguation). ... Dorsum (pl. ... This article is about the use of the term in geography and physical geology. ... This is a list of geological features on Mercury. ... For other uses, see Mountain (disambiguation). ... This is a list of geological features on Mercury. ... Planitia is the Latin word for plain. ... In geography, a plain is a large area of land with relatively low relief. ... This is a list of geological features on Mercury. ... Rupes is the Latin word for cliff. It is used in planetary geology to refer to escarpments on other planets and moons. ... In geology, an escarpment is a transition zone between different physiogeographic provinces that involves an elevation differential, often involving high cliffs. ... This is a list of geological features on Mercury. ... Vallis (plural valles) is the Latin word for valley. ... Fljótsdalur in East Iceland, a rather flat valley In geology, a valley (also called a vale or dale) is a depression with predominant extent in one direction. ... This is a list of geological features on Mercury. ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... For other uses, see Asteroid (disambiguation). ... The Late Heavy Bombardment (LHB) was a period approximately 3. ... Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ... Cleveland Volcano in the Aleutian Islands of Alaska photographed from the International Space Station For other uses, see Volcano (disambiguation). ... The Caloris Basin, also called Caloris Planitia, is an impact crater, on Mercury, which is ~1350km in diameter. ... Magma is molten rock located beneath the surface of the Earth (or any other terrestrial planet), and which often collects in a magma chamber. ... Lunar nearside with major maria and craters labeled A global albedo map of the Moon obtained from the Clementine missionThe dark regions are the lunar maria, whereas the lighter regions are the highlands. ...

Mercury’s Caloris Basin is one of the largest impact features in the Solar System.
Mercury’s Caloris Basin is one of the largest impact features in the Solar System.

Craters on Mercury range in diameter from a few meters to hundreds of kilometers across. The largest known craters are the enormous Caloris Basin, with a diameter of 1300 km, and the Skinakas Basin with a diameter of 1600 km, but known only from low resolution Earth-based imaging of the non-Mariner-imaged hemisphere. The impact which created the Caloris Basin was so powerful that it caused lava eruptions and left a concentric ring over 2 km tall surrounding the impact crater. At the antipode of the Caloris Basin is a large region of unusual, hilly terrain known as the “Weird Terrain”. One hypothesis for the origin of this geomorphological unit is that shock waves generated during the impact traveled around the planet, and when they converged at the basin’s antipode (180 degrees away) the high stresses were capable of fracturing the surface.[13] Alternatively, it has been suggested that this terrain formed as a result of the convergence of ejecta at this basin’s antipode. Image File history File links Mercury_Caloris_Basin2. ... Image File history File links Mercury_Caloris_Basin2. ... The Caloris Basin, also called Caloris Planitia, is an impact crater, on Mercury, which is ~1350km in diameter. ... The Skinakas Basin is the informal name given to a structure on Mercury that appears to be an extremely large impact basin. ... Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ... Tycho crater on Earths moon. ... This map shows the antipodes of each point on the Earths surface – the points where the blue and pink overlap are land antipodes. ...

The so-called “Weird Terrain” was formed by the Caloris Basin impact at its antipodal point.
The so-called “Weird Terrain” was formed by the Caloris Basin impact at its antipodal point.

The plains of Mercury have two distinct ages: the younger plains are less heavily cratered and probably formed when lava flows buried earlier terrain. One unusual feature of the planet’s surface is the numerous compression folds which crisscross the plains. It is thought that as the planet’s interior cooled, it contracted and its surface began to deform. The folds can be seen on top of other features, such as craters and smoother plains, indicating that they are more recent.[14] Mercury’s surface is also flexed by significant tidal bulges raised by the Sun—the Sun’s tides on Mercury are about 17% stronger than the Moon’s on Earth.[15] Image File history File links Mercury's_'Weird_Terrain'.jpg The so-called Weird terrain on Mercury, at the antipodal point of the Caloris Basin. ... Image File history File links Mercury's_'Weird_Terrain'.jpg The so-called Weird terrain on Mercury, at the antipodal point of the Caloris Basin. ... The Caloris Basin, also called Caloris Planitia, is an impact crater, on Mercury, which is ~1350km in diameter. ... The tidal force is a secondary effect of the force of gravity and is responsible for the tides. ... Sol redirects here. ...


Like the Moon, the surface of Mercury has likely incurred the effects of space weathering processes. Solar wind and micrometeorite impacts can darken the albedo and alter the reflectance properties of the surface. This article is about Earths moon. ... Please wikify (format) this article as suggested in the Guide to layout and the Manual of Style. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... A Micrometeoroid (also micrometeorite, micrometeor) is a tiny meteoroid; a small particle of rock from space, usually weighing less than a gram, that poses a threat to space exploration. ... For other uses, see Albedo (disambiguation). ...


The mean surface temperature of Mercury is 452 K (179 °C), but it ranges from 90 K (−183 °C) to 700 K (427 °C), due to the absence of an atmosphere; by comparison, the temperature on Earth varies by only about 80 K. The sunlight on Mercury’s surface is 6.5 times as intense as it is on Earth, with a solar constant value of 9.13 kW/m². This article is about mathematical mean. ... For other uses, see Temperature (disambiguation). ... For other uses, see Kelvin (disambiguation). ... 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. ... Solar irradiance spectrum at top of atmosphere. ...

Radar image of Mercury's north pole
Radar image of Mercury's north pole

Despite the generally extremely high temperature of its surface, observations strongly suggest that ice exists on Mercury. The floors of some deep craters near the poles are never exposed to direct sunlight, and temperatures there remain far lower than the global average. Water ice strongly reflects radar, and observations reveal that there are patches of very high radar reflection near the poles.[16] While ice is not the only possible cause of these reflective regions, astronomers believe it is the most likely. Image File history File links Merc_fig2sm. ... Image File history File links Merc_fig2sm. ... This article is about water ice. ... For other uses, see Radar (disambiguation). ... Look up reflection in Wiktionary, the free dictionary. ...


The icy regions are believed to be covered to a depth of only a few meters, and contain about 1014–1015 kg of ice. By comparison, the Antarctic ice sheet on Earth has a mass of about 4×1018 kg, and Mars’ south polar cap contains about 1016 kg of water. The origin of the ice on Mercury is not yet known, but the two most likely sources are from outgassing of water from the planet’s interior or deposition by impacts of comets.[17] For other uses, see Antarctica (disambiguation). ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Outgassing (sometimes called Offgassing, particularly when in reference to indoor air quality) is the slow release of a gas that was trapped, frozen, absorbed or adsorbed in some material. ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ...


Atmosphere

Main article: Atmosphere of Mercury
Size comparison of terrestrial planets (left to right): Mercury, Venus, Earth, and Mars
Size comparison of terrestrial planets (left to right): Mercury, Venus, Earth, and Mars

Mercury is too small for its gravity to retain any significant atmosphere over long periods of time; however, it does have a tenuous atmosphere containing hydrogen, helium, oxygen, sodium, calcium and potassium. This atmosphere is not stable—atoms are continuously lost and replenished from a variety of sources. Hydrogen and helium atoms probably come from the solar wind, diffusing into Mercury’s magnetosphere before later escaping back into space. Radioactive decay of elements within Mercury’s crust is another source of helium, as well as sodium and potassium. Water vapor is probably present, being brought to Mercury by comets impacting on its surface.[18] Mercurys primordial atmosphere dissipated shortly after the planets formation because of both the low level of gravity on the planet, the high temperature,and the effects of the solar wind. ... Image File history File linksMetadata Download high resolution version (1500x653, 488 KB)Terrestrial planet size comparisons. ... Image File history File linksMetadata Download high resolution version (1500x653, 488 KB)Terrestrial planet size comparisons. ... For other uses, see Venus (disambiguation). ... This article is about Earth as a planet. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Gravity is a force of attraction that acts between bodies that have mass. ... This article is about the chemistry of hydrogen. ... 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 colourless (gas) colourless (liquid) Standard atomic weight 15. ... For sodium in the diet, see Edible salt. ... For other uses, see Calcium (disambiguation). ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... diffusion (disambiguation). ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ...


Magnetosphere

Despite its slow 59-day-long rotation, Mercury has a relatively strong, and apparently global, magnetic field. It is about 1.1% as strong as the Earth’s.[19][20] It is likely that this magnetic field is generated in a manner similar to Earth’s, by a dynamo of circulating liquid core material.[21] A mechanism that has been suggested for keeping it liquid are particularly strong tidal effects during periods of high orbital eccentricity. Magnetic field lines shown by iron filings Magnetostatics Electrodynamics Electrical Network Tensors in Relativity This box:      In physics, the magnetic field is a field that permeates space and which exerts a magnetic force on moving electric charges and magnetic dipoles. ... Dynamo, or Dinamo, may refer to: Dynamo, an electrical generator Dynamo (sports society) of the Soviet Union Operation Dynamo, the 1940 mass evacuation at Dunkirk Dynamo, the rock band based in Belfast Dynamo theory, a theory relating to magnetic fields of celestial bodies Dynamo Open Air, annual heavy metal music...


Mercury’s magnetic field is strong enough to deflect the solar wind around the planet, creating a magnetosphere inside which the solar wind does not penetrate. This is in contrast to the situation on the Moon, which has a magnetic field too weak to stop the solar wind impacting on its surface and so lacks a magnetosphere. The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ...


Orbit and rotation

Orbit of Mercury (yellow). Orbit of Mercury as seen from the ascending node (bottom) and from 10° above (top). Image File history File links ThePlanets_Orbits_Mercury_PolarView. ... Image File history File links ThePlanets_Orbits_Mercury_EclipticView. ...

The orbit of Mercury is the most eccentric of the major planets, with the planet’s distance from the Sun ranging from 46,000,000 to 70,000,000 kilometers. It takes 88 days to complete an orbit. The diagram on the left illustrates the effects of the eccentricity, showing Mercury’s orbit overlain with a circular orbit having the same semi-major axis. The higher velocity of the planet when it is near perihelion is clear from the greater distance it covers in each 5-day interval. The size of the spheres, inversely proportional to their distance from the Sun, is used to illustrate the varying heliocentric distance. This varying distance to the Sun, combined with a 3:2 spin-orbit resonance of the planet’s rotation around its axis, result in complex variations of the surface temperature. In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... This article is about the planet. ...


Mercury’s orbit is inclined by 7° to the plane of Earth’s orbit (the ecliptic), as shown in the diagram on the left. As a result, transits of Mercury across the face of the Sun can only occur when the planet is crossing the plane of the ecliptic at the time it lies between the Earth and the Sun. This occurs about every seven years on average. The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... Transit of Mercury (time lapse showing entire event) Transit of Mercury 11-8-06 - Photographed by Eric S. Kounce of the West Texas Astronomers (www. ...


Mercury’s axial tilt is only 0.01 degrees. This is over 300 times smaller than that of Jupiter, which is the second smallest axial tilt of all planets at 3.1 degrees. This means an observer at Mercury’s equator during local noon would never see the Sun more than 1/100 of one degree north or south of the zenith. Conversely, at the poles the Sun never rises more than 0.01° above the horizon. In astronomy, axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ... In broad terms, the zenith is the direction pointing directly above a particular location (perpendicular, orthogonal). ...


At certain points on Mercury’s surface, an observer would be able to see the Sun rise about halfway, then reverse and set before rising again, all within the same Mercurian day. This is because approximately four days prior to perihelion, Mercury’s angular orbital velocity exactly equals its angular rotational velocity so that the Sun’s apparent motion ceases; at perihelion, Mercury’s angular orbital velocity then exceeds the angular rotational velocity. Thus, the Sun appears to move in a retrograde direction. Four days after perihelion, the Sun’s normal apparent motion resumes at these points. This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... 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. ... Rotational speed (sometimes called speed of revolution) indicates, for example, how fast a motor is running. ... Apparent motion is used in at least two senses. ... This article is about retrograde motion. ...


Advance of perihelion

Main articles: Tests of general relativity#Perihelion_precession_of_Mercury and Perihelion precession of Mercury

It was noticed in the 19th century that the slow precession of Mercury’s orbit around the Sun could not be completely explained by Newtonian mechanics and perturbations by the known planets (notably by the French mathematician Le Verrier). It was hypothesized that another planet might exist in an orbit even closer to the Sun to account for this perturbation (other explanations considered included a slight oblateness of the Sun). The success of the search for Neptune based on its perturbations of the orbit of Uranus led astronomers to place great faith in this explanation, and the hypothetical planet was even named Vulcan. However, in the early 20th century, Albert Einstein’s General Theory of Relativity provided the explanation for the observed precession. The effect is very small: the Mercurian relativistic perihelion advance excess is just 42.98 arcseconds per century, therefore it requires a little over twelve million orbits for a full excess turn. Similar, but much smaller effects, operate for other planets, being 8.62 arcseconds per century for Venus, 3.84 for Earth, 1.35 for Mars, and 10.05 for 1566 Icarus.[22][23] Tests of Einsteins general theory of relativity did not provide an experimental foundation for the theory until well after it was introduced in 1915. ... Precession redirects here. ... It has been suggested that this article or section be merged with Classical mechanics. ... Leonhard Euler, considered one of the greatest mathematicians of all time A mathematician is a person whose primary area of study and research is the field of mathematics. ... Urbain Le Verrier. ... For other uses, see Neptune (disambiguation). ... For other uses, see Uranus (disambiguation). ... Vulcan was the name given to a small planet proposed to exist in an orbit between Mercury and the Sun in a 19th-century hypothesis. ... “Einstein” redirects here. ... For a less technical and generally accessible introduction to the topic, see Introduction to general relativity. ... A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7. ... 1566 Icarus is an Apollo asteroid (a sub-class of near-Earth asteroid) whose unusual characteristic is that at perihelion it is closer to the Sun than Mercury; it is said to be a Mercury-crosser asteroid. ...


Spin–orbit resonance

After one orbit, Mercury has rotated 1.5 times, so after two complete orbits the same hemisphere is again illuminated.
After one orbit, Mercury has rotated 1.5 times, so after two complete orbits the same hemisphere is again illuminated.

For many years it was thought that Mercury was synchronously tidally locked with the Sun, rotating once for each orbit and keeping the same face directed towards the Sun at all times, in the same way that the same side of the Moon always faces the Earth. However, radar observations in 1965 proved that the planet has a 3:2 spin–orbit resonance, rotating three times for every two revolutions around the Sun; the eccentricity of Mercury’s orbit makes this resonance stable—at perihelion, when the solar tide is strongest, the Sun is nearly still in Mercury’s sky. The original reason astronomers thought it was synchronously locked was because whenever Mercury was best placed for observation, it was always at the same point in its 3:2 resonance, hence showing the same face. Due to Mercury’s 3:2 spin–orbit resonance, a solar day (the length between two meridian transits of the Sun) lasts about 176 Earth days. A sidereal day (the period of rotation) lasts about 58.7 Earth days. Image File history File links Download high resolution version (528x648, 7 KB) Summary Diagram showing how Mercurys orbital period and rotational period are locked in a 3:2 resonance. ... Image File history File links Download high resolution version (528x648, 7 KB) Summary Diagram showing how Mercurys orbital period and rotational period are locked in a 3:2 resonance. ... Tidal locking makes one side of an astronomical body always face another, like the Moon facing the Earth. ... This article is about rotation as a movement of a physical body. ... For other uses, see Radar (disambiguation). ... Solar time is based on the idea that, when the sun reaches its highest point in the sky, it is noon. ... This article is about the astronomical concept. ... 2003 Transit of Mercury The term transit or astronomical transit has two meanings in astronomy: A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, as seen by an observer at some particular vantage point. ... On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ...


Orbital simulations indicate that the eccentricity of Mercury’s orbit varies chaotically from 0 (circular) to a very high 0.47 over millions of years. This is thought to explain Mercury’s 3:2 spin-orbit resonance (rather than the more usual 1:1), since this state is more likely to arise during a period of high eccentricity.[24] For other uses, see Chaos Theory (disambiguation). ...


Observation

Mercury’s apparent magnitude varies between about −2.0 — brighter than Sirius — and 5.5.[25] Observation of Mercury is complicated by its proximity to the Sun, as it is lost in the Sun’s glare for much of the time. Mercury can be observed for only a brief period during either morning or evening twilight. The Hubble Space Telescope cannot observe Mercury at all, due to safety procedures which prevent its pointing too close to the Sun. Image File history File links Size of this preview: 600 × 600 pixelsFull resolution (2000 × 2000 pixel, file size: 1. ... Image File history File links Size of this preview: 600 × 600 pixelsFull resolution (2000 × 2000 pixel, file size: 1. ... Transit of Mercury (time lapse showing entire event) Transit of Mercury 11-8-06 - Photographed by Eric S. Kounce of the West Texas Astronomers (www. ... 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. ... For other uses, see Sirius (disambiguation). ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ...


Like the Moon, Mercury exhibits phases as seen from Earth, being “new” at inferior conjunction and “full” at superior conjunction. The planet is rendered invisible on both of these occasions by virtue of its rising and setting in concert with the Sun in each case. The first and last quarter phases occur at greatest elongation east and west, respectively, when Mercury's separation from the Sun ranges anywhere from 18.5° at perihelion to 28.3° at aphelion. At greatest elongation west, Mercury rises earliest before the Sun, and at greatest elongation east, it sets latest after the Sun. Lunar phase refers to the appearance of the illuminated portion of the Moon as seen by an observer, usually on Earth. ... Conjunction is a term used in positional astronomy and astrology. ... Conjunction is a term used in positional astronomy and astrology. ... 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. ...


Mercury attains inferior conjunction every 116 days on average, but this interval can range from 111 days to 121 days due to the planet’s eccentric orbit. Its period of retrograde motion as seen from Earth can vary from 8 to 15 days on either side of inferior conjunction. This large range also arises from the planet’s high orbital eccentricity. This article is about retrograde motion. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ...


Mercury is more often easily visible from Earth’s Southern Hemisphere than from its Northern Hemisphere; this is because its maximum possible elongations west of the Sun always occur when it is early autumn in the Southern Hemisphere, while its maximum possible eastern elongations happen when the Southern Hemisphere is having its late winter season. In both of these cases, the angle Mercury strikes with the ecliptic is maximized, allowing it to rise several hours before the Sun in the former instance and not set until several hours after sundown in the latter in countries located at southern temperate zone latitudes, such as Argentina and New Zealand. By contrast, at northern temperate latitudes, Mercury is never above the horizon of a more-or-less fully dark night sky. southern hemisphere highlighted in yellow (Antarctica not depicted). ... Northern hemisphere highlighted in yellow. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ...


Mercury can, like several other planets and the brightest stars, be seen during a total solar eclipse. Photo taken during the 1999 eclipse. ...


Mercury is brightest as seen from Earth when it is at a gibbous phase, between either quarter phase and full. Although the planet is further away from Earth when it is gibbous than when it is a crescent, the greater illuminated area visible more than compensates for the greater distance. The opposite is true for Venus, which appears brightest when it is a thin crescent, because it is much closer to Earth than when gibbous. In astronomy, a phase of the Moon is any of the aspects or appearances presented by the Moon as seen from Earth, determined by the portion of the Moon that is visibly illuminated by the Sun. ...


Studies of Mercury

Ancient astronomers

The earliest mentions of Mercury come from the 3rd millennium BC, when it was known to the Sumerians of Mesopotamia as Ubu-idim-gud-ud, among other names. The Babylonians (2000–500 BC) succeeded the Sumerians, and early Babylonians may have recorded observations of the planet: although these have not survived, later Babylonian records from the 7th century BC refer to much earlier records. The Babylonians called the planet Nabu or Nebu after the messenger to the Gods in their mythology.[26] Sumer (or Å umer; Sumerian: KI-EN-GIR [1]) was the earliest known civilization of the ancient Near East, located in lower Mesopotamia (modern Iraq), from the time of the earliest records in the mid 4th millennium BC until the rise of Babylonia in the late 3rd millennium BC. The term... Mesopotamia was a cradle of civilization geographically located between the Tigris and Euphrates rivers, largely corresponding to modern-day Iraq. ... Babylonia was a state in southern Mesopotamia, in modern Iraq, combining the territories of Sumer and Akkad. ... For other uses, see Mythology (disambiguation). ...


The ancient Greeks gave the planet two names: Apollo when it was visible in the morning sky and Hermes when visible in the evening. However, Greek astronomers came to understand that the two names referred to the same body, with Pythagoras being the first Greek to propose the idea.[27] The term ancient Greece refers to the periods of Greek history in Classical Antiquity, lasting ca. ... For other uses, see Apollo (disambiguation). ... For other uses, see Hermes (disambiguation). ... Pythagoras of Samos (Greek: ; between 580 and 572 BC–between 500 and 490 BC) was an Ionian (Greek) philosopher[1] and founder of the religious movement called Pythagoreanism. ...


Ground-based telescopic research

This Mariner 10 view from 4.3 million km is similar to the very best views that can be achieved telescopically from Earth
This Mariner 10 view from 4.3 million km is similar to the very best views that can be achieved telescopically from Earth

The first telescopic observations of Mercury were made by Galileo in the early 17th century. Although he observed phases when he looked at Venus, his telescope was not powerful enough to see the phases of Mercury. In 1631 Pierre Gassendi made the first observations of the transit of a planet across the Sun when he saw a transit of Mercury predicted by Johannes Kepler. In 1639 Giovanni Zupi used a telescope to discover that the planet had orbital phases similar to Venus and the Moon. The observation demonstrated conclusively that Mercury orbited around the Sun. Image File history File links Distant_view_of_Mercury_from_Mariner_10. ... Image File history File links Distant_view_of_Mercury_from_Mariner_10. ... This article does not cite any references or sources. ... 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... Planetary phase is the term used to describe the appearance of the illuminated section of a planet. ... Pierre Gassendi (January 22, 1592 – October 24, 1655) was a French philosopher, scientist and mathematician, best known for attempting to reconcile Epicurean atomism with Christianity and for publishing the first official observations of the Transit of Mercury in 1631. ... Transit commonly refers to: Public transport, transportation systems in which the passengers do not travel in their own vehicles Astronomical transit, when one celestial body appears to move across the face of another celestial body, as seen by an observer at some particular vantage point Navigational transit, when a navigator... Kepler redirects here. ... Giovanni Battista Zupi or Zupus (circa 1590–1650) was an Italian astronomer, mathematician, and Jesuit priest. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ...


A very rare event in astronomy is the passage of one planet in front of another (occultation), as seen from Earth. Mercury and Venus occult each other every few centuries, and the event of May 28, 1737 is the only one historically observed, having been seen by John Bevis at the Royal Greenwich Observatory.[28] The next occultation of Mercury by Venus will be in 2133. In this July, 1997 still frame captured from video, the bright star Aldebaran has just reappeared on the dark limb of the waning crescent moon in this predawn occultation. ... is the 148th day of the year (149th in leap years) in the Gregorian calendar. ... Events 12 February — The San Carlo, the oldest working opera house in Europe, is inaugurated. ... John Bevis (October 31, 1693 – November 6, 1771) was an English doctor and astronomer. ... Royal Observatory, Greenwich The original site of the Royal Greenwich Observatory (RGO), which was built as a workplace for the Astronomer Royal, was on a hill in Greenwich Park in Greenwich, London, overlooking the River Thames. ...


The difficulties inherent in observing Mercury mean that it has been far less studied than the other planets. In 1800 Johann Schröter made observations of surface features, but erroneously estimated the planet’s rotational period at about 24 hours. In the 1880s Giovanni Schiaparelli mapped the planet more accurately, and suggested that Mercury’s rotational period was 88 days, the same as its orbital period due to tidal locking.[29] This phenomenon is known as synchronous rotation and is also shown by Earth’s Moon. Johann Hieronymus Schröter (August 30, 1745 – August 29, 1816) was a German astronomer. ... Giovanni Virginio Schiaparelli (March 14, 1835 – July 4, 1910) was an Italian astronomer. ... Tidal locking makes one side of an astronomical body always face another, like the Moon facing the Earth. ... Due to synchronous rotation of their moon, the inhabitants of the central body will never be able to see its green side. ...


The theory that Mercury’s rotation was synchronous became widely held, and it was a significant shock to astronomers when radio observations made in the 1960s questioned this. If Mercury were tidally locked, its dark face would be extremely cold, but measurements of radio emission revealed that it was much hotter than expected. Astronomers were reluctant to drop the synchronous rotation theory and proposed alternative mechanisms such as powerful heat-distributing winds to explain the observations, but in 1965 radar observations showed conclusively that the planet’s rotational period was about 59 days. Italian astronomer Giuseppe Colombo noted that this value was about two-thirds of Mercury’s orbital period, and proposed that a different form of tidal locking had occurred in which the planet’s orbital and rotational periods were locked into a 3:2 rather than a 1:1 resonance.[30] Data from Mariner 10 subsequently confirmed this view.[31] For other uses, see Radar (disambiguation). ... Giuseppe Colombo (October 2, 1920 â€“ February 20, 1984), better known by his nickname Bepi Colombo, was an Italian scientist, mathematician and engineer at the University of Padua, Italy. ...


Ground-based observations did not shed much further light on the innermost planet, and it was not until space probes visited Mercury that many of its most fundamental properties became known. However, recent technological advances have led to improved ground-based observations. In 2000, high-resolution lucky imaging from the Mount Wilson Observatory 1500 mm telescope provided the first views that resolved some surface features on the parts of Mercury which were not imaged in the Mariner missions.[32] Later imaging has shown evidence of a huge double-ringed impact basin even larger than the Caloris Basin in the non-Mariner-imaged hemisphere. It has informally been dubbed the Skinakas Basin.[33] Most of the planet has been mapped by the Arecibo radar telescope, with 5 km resolution, including polar deposits in shadowed craters of what may be water ice.[34] Ground-based telescopes have detected the bright rays around some radar-mapped craters. Lucky image of M15 core Lucky imaging is an astronomical photographic technique using a high-speed camera with exposure times short enough (100 ms or less) so that the changes in the atmosphere during the exposure are minimal. ... The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California. ... The Caloris Basin, also called Caloris Planitia, is an impact crater, on Mercury, which is ~1350km in diameter. ... The Skinakas Basin is the informal name given to a structure on Mercury that appears to be an extremely large impact basin. ...


Research with space probes

The Mariner 10 probe, the only probe that has yet visited the innermost planet
View of Mercury from Mariner 10
View of Mercury from Mariner 10
Mercury as imaged by the Mariner 10 spacecraft

Reaching Mercury from Earth poses significant technical challenges, since the planet orbits so much closer to the Sun than does the Earth. A Mercury-bound spacecraft launched from Earth must travel over 91 million kilometers into the Sun’s gravitational potential well. Starting from the Earth’s orbital speed of 30 km/s, the change in velocity (delta-v) the spacecraft must make to enter into a Hohmann transfer orbit that passes near Mercury is large compared to other planetary missions. The Mariner 10 was a probe sent to Mercury. ... The Mariner 10 was a probe sent to Mercury. ... Image File history File links Mercury_Mariner10. ... Image File history File links Mercury_Mariner10. ... Image File history File links Download high resolution version (704x1206, 143 KB)Original Caption Released with Image: This is a mosaic of images of Mercury taken from 125,000 miles away. ... Image File history File links Download high resolution version (704x1206, 143 KB)Original Caption Released with Image: This is a mosaic of images of Mercury taken from 125,000 miles away. ... The Space Shuttle Discovery as seen from the International Space Station. ... Gravity is a force of attraction that acts between bodies that have mass. ... A potential well is the region surrounding a local minimum of potential energy. ... 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. ... This article is about velocity in physics. ... General In general physics delta-v is simply the change in velocity. ... In astronautics and aerospace engineering, the Hohmann transfer orbit is an orbital maneuver that, under standard assumption, moves a spacecraft from one circular orbit to another using two engine impulses. ...


The potential energy liberated by moving down the Sun’s potential well becomes kinetic energy; requiring another large delta-v to do anything other than rapidly pass by Mercury. In order to land safely or enter a stable orbit the spacecraft must rely entirely on rocket motors since aerobraking is ruled out because the planet has very little atmosphere. A trip to Mercury actually requires more rocket fuel than that required to escape the solar system completely. As a result, only one space probe has visited the planet so far. Potential energy can be thought of as energy stored within a physical system. ... The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. ... An artists conception of a spacecraft aerobraking Aerobraking is a technique used by spacecraft in which it uses drag within a planetary atmosphere to reduce its velocity relative to the planet. ... Space Shuttle Atlantis launches on mission STS-71. ...


Mariner 10

Main article: Mariner 10

The only spacecraft to approach Mercury so far has been NASA’s Mariner 10 (1974–75).[27] The spacecraft used the gravity of Venus to adjust its orbital velocity so that it could approach Mercury—the first spacecraft to use this gravitational “slingshot” effect. Mariner 10 provided the first close-up images of Mercury’s surface, which immediately showed its heavily cratered nature, and also revealed many other types of geological features, such as the giant scarps which were later ascribed to the effect of the planet shrinking slightly as its iron core cools.[35] Unfortunately, because Mariner 10's orbital period was almost exactly 3 sidereal Mercury days, the same face of the planet was lit at each of Mariner 10’s close approaches, resulting in less than 45% of the planet’s surface being mapped. The Mariner 10 probe. ... The National Aeronautics and Space Administration (NASA) (IPA [ˈnæsÉ™]) is an agency of the United States government, responsible for the nations public space program. ... For other uses, see Venus (disambiguation). ... In orbital mechanics and aerospace engineering, a gravitational slingshot or gravity assist is the use of the gravity of a planet or other celestial body to alter the path and speed of a spacecraft. ...


The spacecraft made three close approaches to Mercury, the closest of which took it to within 327 km of the surface. At the first close approach, instruments detected a magnetic field, to the great surprise of planetary geologists—Mercury’s rotation was expected to be much too slow to generate a significant dynamo effect. The second close approach was primarily used for imaging, but at the third approach, extensive magnetic data were obtained. The data revealed that the planet’s magnetic field is much like the Earth’s, which deflects the solar wind around the planet. However, the origin of Mercury’s magnetic field is still the subject of several competing theories. Dynamo, or Dinamo, may refer to: Dynamo, an electrical generator Dynamo (sports society) of the Soviet Union Operation Dynamo, the 1940 mass evacuation at Dunkirk Dynamo, the rock band based in Belfast Dynamo theory, a theory relating to magnetic fields of celestial bodies Dynamo Open Air, annual heavy metal music... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ...


Just a few days after its final close approach, Mariner 10 ran out of fuel; since its orbit could no longer be accurately controlled, mission controllers instructed the probe to shut itself down. Mariner 10 is thought to be still orbiting the Sun, passing close to Mercury every few months.[36]


MESSENGER

Main article: MESSENGER

A second NASA mission to Mercury, named MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging), was launched on August 3, 2004, from the Cape Canaveral Air Force Station aboard a Boeing Delta 2 rocket. The MESSENGER spacecraft will make several close approaches to planets to place it onto the correct trajectory to reach an orbit around Mercury. It made a fly-by of the Earth in August 2005, and of Venus in October 2006 and June 2007. Three fly-bys of Mercury are scheduled, in January 2008, October 2008, and September 2009. Most of the hemisphere not imaged by Mariner 10 will be mapped during the fly-bys. The probe will then enter an elliptical orbit around the planet in March 2011; the nominal mapping mission is one terrestrial year. Orbital perapsis will be over the northern hemisphere. Communications with Earth occur near apoapsis, every 12 hours. This article is about the NASA space mission. ... is the 215th day of the year (216th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... The Bumper V-2 was the first missile launched at Cape Canaveral on July 24, 1950. ... A Delta II rocket launches from Cape Canaveral carrying a GPS satellite The Boeing IDS Delta II family of launch vehicles has been in service since 1989 and has successfully launched 115 projects (through August, 2004) including the last six NASA missions to Mars: Mars Global Surveyor in 1996 Mars...


The mission is designed to shed light on six key issues: Mercury’s high density, its geological history, the nature of its magnetic field, the structure of its core, whether it really has ice at its poles, and where its tenuous atmosphere comes from. To this end, the probe is carrying imaging devices which will gather much higher resolution images of much more of the planet than Mariner 10, assorted spectrometers to determine abundances of elements in the crust, and magnetometers and devices to measure velocities of charged particles. Detailed measurements of tiny changes in the probe’s velocity as it orbits will be used to infer details of the planet’s interior structure.[37] Magnetic field lines shown by iron filings Magnetostatics Electrodynamics Electrical Network Tensors in Relativity This box:      In physics, the magnetic field is a field that permeates space and which exerts a magnetic force on moving electric charges and magnetic dipoles. ... Spectrometer A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. ... A magnetometer is a scientific instrument used to measure the strength and/or direction of the magnetic field in the vicinity of the instrument. ...


BepiColombo

Main article: BepiColombo

Japan is planning a joint mission with the European Space Agency called BepiColombo, which will orbit Mercury with two probes: one to map the planet and the other to study its magnetosphere. An original plan to include a lander has been shelved. A Russian Soyuz rocket will launch the bus carrying the two probes in 2013, from ESA's Guiana Space Center to take advantage of its equatorial location. As with MESSENGER, the BepiColombo bus will make close approaches to other planets en route to Mercury for orbit-changing gravitational assists, passing the Moon and Venus and making several approaches to Mercury before entering orbit. A combination of chemical and ion engines will be used, the latter thrusting continuously for long intervals. The spacecraft bus will reach Mercury in 2019. The bus will release the magnetometer probe into an elliptical orbit, then chemical rockets will fire to deposit the mapper probe into a circular orbit. Both probes will operate for a terrestrial year. BepiColombo is a joint Cornerstone mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. ... ESA redirects here. ... BepiColombo is a joint Cornerstone mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. ... A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ... Soyuz rocket on launch pad. ... The Guiana space centre (French: Centre Spatial Guyanais) is a French/European spaceport near Kourou in French Guiana. ...


The mapper probe will carry an array of spectrometers similar to those on MESSENGER, and will study the planet at many different wavelengths including infrared, ultraviolet, X-ray and gamma ray. Apart from intensively studying the planet itself, mission planners also hope to use the probe's proximity to the Sun to test the predictions of General Relativity theory with improved accuracy. For other uses, see Infrared (disambiguation). ... For other uses, see Ultraviolet (disambiguation). ... 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... This article is about electromagnetic radiation. ... For a less technical and generally accessible introduction to the topic, see Introduction to general relativity. ...


The mission is named after Giuseppe (Bepi) Colombo, the scientist who first determined the nature of Mercury’s spin-orbit resonance and who was also involved in the planning of Mariner 10’s gravity-assisted trajectory to the planet in 1974.[38] Giuseppe Colombo (October 2, 1920 â€“ February 20, 1984), better known by his nickname Bepi Colombo, was an Italian scientist, mathematician and engineer at the University of Padua, Italy. ...


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... A popular setting for science fiction writers, there are many examples of the planet Mercury in fiction. ... Mercury Mercury has been suggested as one possible target for space colonization of the inner solar system, along with Mars, Venus, the Moon and the asteroid belt. ... The exploration of Mercury has taken only a minor role in the space interests of the world. ...

References

  1. ^ JPL HORIZONS System
  2. ^ a b c d e f g h Williams, Dr. David R. (September 1, 2004). Mercury Fact Sheet. NASA. Retrieved on 2007-10-12.
  3. ^ a b c d e f g h NASA: Solar System Exploration: Planets: Mercury: Facts & Figures
  4. ^ a b Seidelmann, P. Kenneth; Archinal, B. A.; A’hearn, M. F.; et.al. (2007). "Report of the IAU/IAGWorking Group on cartographic coordinates and rotational elements: 2006". Celestial Mechanics and Dynamical Astronomy 90: 155–180. doi:10.1007/s10569-007-9072-y. Retrieved on 2007-08-28. 
  5. ^ Mercury magnetic field. C. T. Russell & J. G. Luhmann. Retrieved on 2007-03-16.
  6. ^ Mercury. U.S. Geological Survey. Retrieved on 2006-11-26.
  7. ^ Lyttleton, R. A.; On the Internal Structures of Mercury and Venus, Astrophysics and Space Science, Vol. 5 (1969), p. 18
  8. ^ Cornell University. "Mercury has molten core, Cornell researcher shows", Chronicle Online, May 3, 2007.. 
  9. ^ a b Benz, W.; Slattery, W. L.; Cameron, A. G. W.; Collisional stripping of Mercury’s mantle, Icarus, Vol. 74 (1988), pp. 516–528
  10. ^ Schenk, P.; Melosh, H. J.; Lobate Thrust Scarps and the Thickness of Mercury’s Lithosphere, Abstracts of the 25th Lunar and Planetary Science Conference (1994), 1994LPI....25.1203S
  11. ^ Cameron, A. G. W.; The partial volatilization of Mercury, Icarus, Vol. 64 (1985), pp. 285–294.
  12. ^ Weidenschilling, S. J.; Iron/silicate fractionation and the origin of Mercury, Icarus, Vol. 35 (1987), pp. 99–111
  13. ^ Schultz, P. H.; Gault, D. E.; Seismic effects from major basin formations on the moon and Mercury, The Moon, Vol. 12 (February 1975), pp. 159–177
  14. ^ Dzurisin, D.; The tectonic and volcanic history of Mercury as inferred from studies of scarps, ridges, troughs, and other lineaments, Journal of Geophysical Research, Vol. 83 (1978), pp. 4883–4906
  15. ^ Van Hoolst, T.; Jacobs, C.; Mercury’s tides and interior structure, Journal of Geophysical Research, Vol. 108 (2003), p. 7.
  16. ^ Slade, M. A.; Butler, B. J.; Muhleman, D. O.; Mercury radar imaging — Evidence for polar ice, Science, Vol. 258 (1992), pp. 635–640.
  17. ^ Rawlins, K.; Moses, J. I.; Zahnle, K. J.; Exogenic Sources of Water for Mercury’s Polar Ice, DPS, Vol. 27 (1995), p. 2112
  18. ^ Hunten, D. M.; Shemansky, D. E.; Morgan, T. H.; The Mercury atmosphere, In: Mercury (A89-43751 19-91). University of Arizona Press (1988), pp. 562–612
  19. ^ Seeds, Michael A. (2004). Astronomy: The Solar System and Beyond, 4th, Brooks Cole. ISBN 0534421113. 
  20. ^ http://nssdc.gsfc.nasa.gov/planetary/planetfact.html
  21. ^ Gold, Lauren. "Mercury has molten core, Cornell researcher shows", Cornell University, 3 May 2007. Retrieved 11 July 2007.
  22. ^ Gilvarry, J. J.; Relativity Precession of the Asteroid Icarus, Physical Review, Vol. 89, No. 5 (March 1953), p. 1046
  23. ^ Iorio, L.; Solar System planetary motions and modified gravity, arXiv:gr-qc/0511138 v1 25 Nov 2005 (table 4)
  24. ^ Correia, A. C. M.; Laskar, J.; Mercury’s capture into the 3/2 spin–orbit resonance as a result of its chaotic dynamics, Nature, Vol. 429 (2004), pp. 848–850.
  25. ^ Espenak, F.; Twelve Year Planetary Ephemeris: 1995–2006, NASA Reference Publication 1349
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  27. ^ a b Dunne, J. A.; and Burgess, E.; The Voyage of Mariner 10 — Mission to Venus and Mercury, NASA History Office publication SP-424 (1978)
  28. ^ Sinnott, R. W.; Meeus, J.; John Bevis and a Rare Occultation, Sky and Telescope, Vol. 72 (1986), p. 220
  29. ^ Holden, E. S.; Announcement of the Discovery of the Rotation Period of Mercury [by Professor Schiaparelli], Publications of the Astronomical Society of the Pacific, Vol. 2 (1890), p. 79
  30. ^ Colombo, G., Rotational Period of the Planet Mercury, Nature, Vol. 208 (1965), p. 575
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  33. ^ Ksanfomality, L. V. (2006). "Earth-based optical imaging of Mercury". Advances in Space Research 38: 594. 
  34. ^ Harmon, J. K. et al (2007). "Mercury: Radar images of the equatorial and midlatitude zones". Icarus 187: 374. 
  35. ^ NASA - 2006 Transit of Mercury. Retrieved on March 28, 2007.
  36. ^ NSSDC Master Catalog Display: Mariner 10. Retrieved on October 20, 2005.
  37. ^ Johns Hopkins University’s MESSENGER mission web pages. Retrieved on 27 April 2006.
  38. ^ ESA Science & Technology: BepiColombo. Retrieved on 27 April 2006.

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 285th day of the year (286th in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 240th day of the year (241st 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 in the 21st century. ... is the 75th day of the year (76th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 330th day of the year (331st in leap years) in the Gregorian calendar. ... Cornell redirects here. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 68th day of the year (69th in leap years) in the Gregorian calendar. ... is the 87th day of the year (88th 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 in the 21st century. ... is the 293rd day of the year (294th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 117th day of the year (118th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 117th day of the year (118th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

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The Sun Mercury Venus The Moon Earth Phobos and Deimos Mars Ceres The asteroid belt Jupiter Moons of Jupiter Saturn Moons of Saturn Uranus Moons of Uranus Moons of Neptune Neptune Moons of Pluto 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. ... Animation showing atmosphere and shading effects in v1. ... For other uses, see Celestia (disambiguation). ... This article is about the Solar System. ... Sol redirects here. ... For other uses, see Venus (disambiguation). ... 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). ... This article is about the planet. ... For other uses, see Uranus (disambiguation). ... For other uses, see Neptune (disambiguation). ... For other uses, see Pluto (disambiguation). ... Absolute magnitude: −1. ... This article is about the astronomical term. ... 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 : Phobos (top) and Deimos (bottom). ... Jupiters 4 Galilean moons, in a composite image comparing their sizes and the size of Jupiter (Great Red Spot visible). ... The Saturnian system (photographic montage) Moons of Saturn (photographic montage) Saturn has 60 confirmed natural satellites, plus three hypothetical moons. ... Uranus has twenty-seven known moons. ... Neptune (top) and Triton (bottom), 3 days after the Voyager 2 flyby. ... Hubble image of the Plutonian system 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. ... For other uses, see Asteroid (disambiguation). ... 243 Ida and its moon Dactyl An asteroid moon is an asteroid that orbits another asteroid. ... For other uses, see Asteroid (disambiguation). ... 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. ... Eris, the largest known scattered disc object (center), and its moon Dysnomia (left of center). ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... 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. ... Mercurys primordial atmosphere dissipated shortly after the planets formation because of both the low level of gravity on the planet, the high temperature,and the effects of the solar wind. ... This is a list of geological features on Mercury. ... This is a list of the albedo features of the planet Mercury as seen by early telescopic observation. ... The Caloris Basin, also called Caloris Planitia, is an impact crater, on Mercury, which is ~1350km in diameter. ... Chao Meng-Fu is a crater (167km in diameter) on Mercury. ... This is a list of named craters on Mercury. ... Discovery Rupes Discovery Rupes is an escarpment on Mercury approximately 650 kilometers long and 2 kilometers high, located at latitude -56. ... Of all the terrestrial planets in the Solar System, the geology of Mercury is the least understood. ... A moon orbiting Mercury was, for a short time, believed to exist. ... The Skinakas Basin is the informal name given to a structure on Mercury that appears to be an extremely large impact basin. ... Image File history File links Mercury_Mariner10. ... The exploration of Mercury has taken only a minor role in the space interests of the world. ... BepiColombo is a joint Cornerstone mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. ... This article is about the NASA space mission. ... The Mariner 10 probe. ... Launch of Mariner 1 (NASA) The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes designed to investigate Mars, Venus and Mercury. ... A popular setting for science fiction writers, there are many examples of the planet Mercury in fiction. ... Mercury Mercury has been suggested as one possible target for space colonization of the inner solar system, along with Mars, Venus, the Moon and the asteroid belt. ... A Mercury-crosser asteroid is an asteroid whose orbit crosses that of Mercury. ... Transit of Mercury (time lapse showing entire event) Transit of Mercury 11-8-06 - Photographed by Eric S. Kounce of the West Texas Astronomers (www. ...


  Results from FactBites:
 
Mercury (planet) - MSN Encarta (2155 words)
The observation of these changes in Mercury’s perihelion was one of the first confirmations of Einstein’s general theory of relativity, which predicted such variation due to the curvature of space caused by the enormous mass of the Sun.
Mercury’s axis is almost perfectly vertical, unlike Earth’s axis, which is tilted 23.5 degrees.
Mercury’s high density indicates that the relatively dense and abundant element iron accounts for a large proportion of the planet’s composition.
Mercury (planet) - Wikipedia, the free encyclopedia (4630 words)
Mercury's surface is very similar in appearance to that of the Moon, showing extensive mare-like plains and heavy cratering, indicating that it has been geologically inactive for billions of years.
Mercury's orbit is inclined by 7° to the plane of Earth's orbit (the ecliptic), as shown in the diagram on the left.
Mercury's precession showed the effects of mass dilation, providing a crucial observational confirmation of one of Einstein's theories—Mercury is slightly heavier at perihelion than it is at aphelion because it is moving faster, and so it slightly "overshoots" the perihelion position predicted by Newtonian gravity.
  More results at FactBites »

 
 

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