First Known Moon of an Asteroid
Posted in Astronomy at 12:00 on 23 November 2025
From Astronomy Picture of the Day (APOD) for 17/10/25. I’ve only just caught uop with this as the APOD website was down during the recent US government shutdown.
This is the asteroid 243 Ida. To its right in the picture can be seen its moon Dactyl. Ida was the first asteroid to have a moon to be discovered.

