106 meters = 1 megameter


Gravity is an extremely weak force when compared to the electromagnetic, weak, and strong forces. As a consequence, a large mass is required for a body's self gravity to become dominant over other forces. Hyperion is a moon of Jupiter and is the largest known nonspherical object. It measures roughly 410 km x 260 km x 220 km. It does not contain enough mass to overcome its own rigidity. The electromagnetic forces that determine the structure of the rocks and minerals making up Hyperion are too strong for gravity to overcome.

A moon of Neptune named Proteus is nearly spherical, measuring 436 km x 416 km x 402 km. The point is that an object with a radius of 500 km would necessarily be spherical because of its own mass. It is at this scale that gravity finally wins out over electromagnetism.