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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.
Iapetus: Saturn's Disappearing Moon
Explanation: Iapetus has an unusual surface, one half of which is very dark, the other half very light. This caused it's discoverer Cassini to remark that Iapetus could only be seen when on one side of Saturn but not the other. The reason for the difference between hemispheres is presently unknown. Iapetus is the third largest of Saturn 's moon behind Titan and Rhea . Iapetus is composed predominantly of water ice.
| Date | October 15, 1995 |
|---|---|
| Credit | Credit: NASA, Voyager, Copyright Calvin J. Hamilton |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |