Einstein’s Planetoid is a novelet by C.M. Kornbluth (as by Paul Dennis Lavond), Robert A. W. Lowndes and Frederik Pohl. Originally published in Science Fiction Quarterly, No. 6, Spring 1942.
Their quest lay outside the usual spacelanes, and it led them to the strangest world men had ever found. And they found, when they landed, that a grim cosmic joke had been played upon them, for their most powerful rockets were helpless to fling them off the little world. Caught in the brilliant arms was a flattish thing that looked more like a centipede than anything else.