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.
Ida and Dactyl: Asteroid and Moon
Explanation: This asteroid has a moon. The robot spacecraft Galileo on route to Jupiter in 1993 encountered and photographed two asteroids during its long interplanetary voyage. The second minor planet it photographed, 243 Ida , was unexpectedly discovered to have a moon. The tiny moon, Dactyl , is only about 1.6 kilometers across and seen as a small dot on the right of the sharpened featured image . In contrast, the potato-shaped Ida is much larger, measuring about 60 kilometers long and 25 km wide. Dactyl is the first moon of an asteroid ever discovered -- now many asteroids are known to have moons . The names Ida and Dactyl are from Greek mythology .
| Date | May 28, 2023 |
|---|---|
| Credit | Image Credit: NASA , JPL , Galileo Mission |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |