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APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Ganymede: The Largest Moon in the Solar System
Explanation: If Ganymede orbited the Sun, it would be considered a planet. The reason is that Jupiter 's moon Ganymede is not only the largest moon in the Solar System , it is larger than planets Mercury and Pluto . The robot spacecraft Galileo currently orbiting Jupiter has been able to zoom by Ganymede several times and snap many close-up pictures. Ganymede, shown above in its natural colors, sports a large oval dark region known as Galileo Regio . In general, the dark regions on Ganymede are heavily cratered, implying they are very old, while the light regions are younger and dominated by unusual grooves . The origin of the grooves is still under investigation .
| Date | June 20, 2000 |
|---|---|
| Credit | Credit: Galileo Project , JPL , NASA |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |