Why hasn’t gravity rounded off Miranda’s jagged surface?
Gravity gives celestial bodies their rounded shape, so why does Miranda look so rough?
Moon of Uranus, Miranda (second from the front), has a breathtaking landscape of large ice canyons, rifts and ridges
Asked by Tony Huntingdon
Uranus’ moon, Miranda, is too small for gravity to have rounded off the jagged surface. It is believed that Miranda is an ice moon, with 1,000 times less mass than the Earth’s Moon. In its past, tidal heating due to the extremes of its orbit allowed the interior ice to melt, and behave in a similar geological way to the crust and mantle on the Earth. This produced the breathtaking landscape of large ice canyons, rifts and ridges leaving a jagged icy surface. However, with such a low mass, gravitational heating is not enough to melt and round off these edges, so they remain as they are, a legacy of Miranda’s more violent past.
Answered by Sophie Allen from the National Space Centre