By Ron Cowen
When comets pass close to the sun, solar radiation can bake and chemically alter their outer layers. Yet new observations of fragments of a comet that broke apart almost in front of astronomers’ eyes suggest that its interior was remarkably similar to its exterior.
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For comets, breaking up isn’t hard to do. Relics of the solar system’s formation, these fragile amalgams of ice, rock, and dust can burst into fragments when the sun’s heat vaporizes some of their icy material.