Why Comet 67P Looks Like a Rubber Ducky
The cosmic visitor owes its bizarre shape to a collision that welded two smaller objects together 4.6 billion years ago.
In the year and change since the European Space Agency’s Rosetta mission became the first spacecraft to orbit a comet, the probe has made all sorts of discoveries about the object known as Comet 67P/Churyumov-Gerasimenko—for instance, that it’s bumpy, not smooth as expected, and is covered in dark, carbon-rich compounds with surprisingly little ice.
What scientists haven’t been able to figure out is how the comet got its strange, rubber-duck-like appearance. It has two bulbous lobes—a larger “body” about two miles across, and a smaller “head,” about a mile in diameter. Was it originally a single lump that was carved into its present shape by erosion, or did it form when two smaller comets banged together and remained stuck.