# Deimos

*In the Solar System*

The smaller and farther of Mars's moons, about 15 by 12 by 11 kilometres and smoothed by a blanket of dust that fills its craters. It goes round in thirty hours, only a little slower than Mars turns, so it creeps across the Martian sky and stays up for more than two days at a time; from the surface it is a bright star rather than a disc. Where both moons came from - captured asteroids, or debris from an impact on Mars - is still argued.

| | |
| --- | --- |
| Radius | 6 km |
| Around the equator | 39 km |
| From the Sun | 234,743,968 km (+204,941 km/d) |
| From the Earth | 239,681,513 km (-1,074,919 km/d) |
| A signal takes | 13 min |
| Goes round | Mars |
| Placed to within | 39 km |

Distances and speed are computed from JPL Horizons trajectories and are true of 2026-10-09, 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=deimos
- This object as a page: https://www.orbitalmap.space/o/deimos/
- Every object: https://www.orbitalmap.space/o/
- What this site is and what it reads: https://www.orbitalmap.space/llms.txt