Bruce Murray Space Image Library

Three half-megameter moons

Three half-megameter moons
Three half-megameter moons Large objects in the solar system are round; small objects are lumpy. Where does round transition to lumpy? In the outer solar system, the transition happens at roughly 500 kilometers, give or take. Enceladus (512 kilometers) is geologically active and very round, while Miranda (472 kilometers) and Mimas (397 kilometers) have noticeable departures from roundness. NASA / JPL-Caltech / SSI / processing by Gordan Ugarkovic (Enceladus, Mimas) and Ted Stryk (Miranda). Montage by Emily Lakdawalla.

"We're changing the world. Are you in?"
- CEO Bill Nye

Sign up for email updates