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Encyclopedia > James W. Christy

James Walter Christy (born 1938) is an American astronomer. 1938 (MCMXXXVIII) was a common year starting on Saturday (link will take you to calendar). ... An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ...

Working at the United States Naval Observatory, he discovered in 1978 that Pluto had a moon, which he named Charon. Aerial view of USNO. The United States Naval Observatory (USNO) is one of the oldest scientific agencies in the United States. ... 1978 (MCMLXXVIII) was a common year starting on Sunday (the link is to a full 1978 calendar). ... Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ... Moons of solar system scaled to Earths Moon A natural satellite is a moon (not capitalized), that is, any natural object that orbits a planet. ... Media:Example. ...

The discovery was made by carefully examining an enlargement of a photographic plate of Pluto and noticing it had a very slight bulge on one side. By examining images taken over several successive days, he was able to convince himself that it was a moon. The photographic evidence was considered convincing but not conclusive; however, based on the orbit determined, a series of mutual eclipses of Pluto and Charon was predicted and observed, which provided confirmation. The French 1999 eclipse An eclipse (Greek verb: ekleipô, to vanish) is an astronomical event that occurs when one celestial object moves into the shadow of another. ...

In more modern telescopes, such as the Hubble Space Telescope or ground-based telescopes using adaptive optics, separate images of Pluto and Charon can very easily be resolved. The Hubble Space Telescope (HST) is a telescope in orbit around the Earth. ... A deformable mirror can be used to correct wavefront errors in an astronomical telescope. ...

External links

  • Pluto's Companion from the website "Pluto: The Discovery of Planet X," by Brad Mager
  • 25th Anniversary of the Discovery of Pluto's moon CHARON from U.S. Naval Observatory website

  Results from FactBites:
Charon (656 words)
It was discovered by astronomer James Christy on June 22, 1978 by carefully examining highly magnified images of Pluto on photographic plates taken a couple of months before and noticing that a slight bulge appeared periodically.
It is not to be confused with the similarly named 2060 Chiron, another object in the outer solar system with an orbit between those of Saturn and Uranus.
In Greek mythology, Charon was the ferryman of the dead, a figure with close ties to the god Pluto.
  More results at FactBites »



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