Deimos

Measured

Mean radius

6 km

From the Earth today

1.31 AU (196 million km)

Goes round once every

1.26 days

How far, from the Earth

1.31 AU. To cross it:

• Light11 minutes
• Voyager 1's speed4.41 months
• Driving at 100 km/h223 years

Voyager 1 at the speed it moved outward over the year to 2026-10-25 (JPL Horizons). Driving: nonstop, never refuelling.

Facts

• Within 1° of where JPL Horizons has it round its planet, 2024-2031. Further from those years it is less sure.
• Its map is turned by the rule for a moon that keeps one face to its planet: longitude 0 towards the planet, on the planet's pole. Which way it really faces can differ by a few degrees, and the published rotation formulas differ from this by as much (Titan 5° now and 16° by 2050, Enceladus 6°).

Where this comes from

• Planets, Pluto, the Moon and Jupiter's big moons: astronomy-engine (Don Cross, MIT). Other moons: JPL Planetary Satellite Mean Elements. Ceres, Eris, Haumea, Makemake: JPL Small-Body Database. NASA/JPL-Caltech.

Every catalogue Ouranos draws is credited on the credits page.