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79,433 pages · 13,741 images · since 1994 Browse A–Z Today in space history
Encyclopedia Astronautica The full story of spaceflight

Deep Space

Stars, galaxies, black holes and worlds around other suns. Stories from the far edges of the universe, and the telescopes and signals that brought them within reach.

A comet’s tail doesn’t stream out behind it like smoke from a moving car, because it always points away from the Sun, which means that as a comet heads back out of the solar system, its tail actually flies out in front of it