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Moon of Saturn

Rhea

Open in OuranosCompare its size

Saturn's second-largest moon.

At Saturn.

Measured

Mean radius
764 km
From the Earth today
8.7 AU (1.3 billion km)
Goes round once every
4.52 days

How far, from the Earth

8.7 AU. To cross it:

  • Light1 hour 12 minutes
  • Voyager 1's speed2.44 years
  • Driving at 100 km/h1,480 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.