Comets Go Way Back to Solar System's Birth

Comets are pristine remnants left over from the solar system's formation 4.6 billion years ago, rather than younger fragments created by collisions between larger bodies, a new study suggests. "Comets really are the treasure troves of the solar system," Matt Taylor, project scientist for the European Space Agency's comet-hunting Rosetta mission, said in a statement. "They give us unparalleled insight into the processes that were important in the planetary construction yard at these early times a