# Ida

*In the Solar System*

A main-belt asteroid, here because Galileo flew past it in August 1993 on the way to Jupiter - and found the first moon ever seen round an asteroid, a kilometre-wide rock now called Dactyl. Until that picture it was an open question whether such a thing could exist; the moon's orbit also gave the first direct measurement of an asteroid's mass.

| | |
| --- | --- |
| Radius | 16 km |
| Around the equator | 99 km |
| From the Sun | 421,680,212 km (+67,324 km/d) |
| From the Earth | 569,438,395 km (-323,185 km/d) |
| A signal takes | 32 min |

Distances and speed are computed from JPL Horizons trajectories and are true of 2026-09-05, changing at the rate given beside each. The interpolation itself is good to a few kilometres; what ages these figures is the date, not the arithmetic.

## Elsewhere

- On the live map: https://www.orbitalmap.space/?world=solar-system&focus=ida
- This object as a page: https://www.orbitalmap.space/o/ida/
- Every object: https://www.orbitalmap.space/o/
- What this site is and what it reads: https://www.orbitalmap.space/llms.txt