Astronomy Picture of the Day
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June 30, 1995
Ida and Dactyl: Asteroid and Moon
Picture Credit: NASA, JPL, Galileo Project
An asteroid with a moon! The robot spacecraft
whose primary mission is to explore the Jupiter system, has encountered
and photographed two asteroids during its long journey to Jupiter.
The second asteroid it photographed, called Ida, was discovered to have a moon
which appears as a small dot to the right of Ida in this picture.
The tiny moon, named Dactyl, is about one mile
across, while the potato shaped Ida measures about 36 miles long and
14 miles wide. Dactyl is the first moon of an asteroid ever discovered.
The names Ida and Dactyl are based on characters in Greek mythology.
For more information see
NASA, Jet Propulsion Laboratory press release.
The Hooker Telescope
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