The comet looked different than scientists had anticipated, with two bodies rather than one. Officials said the two-and-a-half-mile-wide comet resembled a rubber duck. Holger Sierks, principal investigator for Rosetta's high-resolution camera, noted cliffs, shadows, and flat areas with boulders on G-G's surface.
The C-G comet.
In July, C-G's average surface temperature was minus 94 degrees Fahrenheit, indicating that the surface was not exclusively ice. Some parts of the comet are dusty and darker, after absorbing heat from the sun. Additionally, water vapor is steaming off the comet at about two cups a second which will eventually grow into a torrent a hundred or a thousand times that size, contributing to the comet's long tail.
"An unsolved mystery of Earth is where the water in the oceans came from; some suggest it came from comets. The water in comets from the distant Oort Cloud, far beyond Pluto, does not match the water on Earth, but the water in nearer comets may," The New York Times reported.