A Moon of One's Own.

Asteroid Ida is a little more than 50 kilometers long and 20 kilometers wide - bigger than a mountain, smaller than a mountain range. Its gravity is not strong enough to pull irregularities into itself as happens for the Earth, where the attraction of matter to matter will not tolerate much departure from the spherical. Here, mountains sink under their own weight and the peaks of the Rockies and the Himalayas cannot be higher than they are, but the shape of the little asteroid is not so constrained. [ABSTRACT FROM AUTHOR]