Rosetta’s ‘rubber duck’ comet was once two objects

The rubber duck-shaped comet being followed by Europe’s Rosetta probe used to be two separate objects. Scientists say pictures of 67P show its two lobes to have “onion skin” layers that intersect in a way that can only be the result of two different bodies having collided and stuck together. Ever since Rosetta arrived at the comet, the origin of its bizarre form has been one of the major puzzles.