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Spacetech's Orrery: Comets Visitors From Afar
This site provides a report on comets, with many links to more detailed information. Content includes a focus on Halley's Comet, Hale Bopp, and Shoemaker-Levy 9.
Australian Broadcasting Corporation
Australian Broadcasting Corporation: News in Science: Mars as You've Never Seen It Before
From ABC News in Science, this article charts findings of the Rosetta ("Europe's comet-chasing spacecraft") as it took photographs of Mars from a close-up perspective.