This remarkable picture shows the planet's very faint rings, which were discovered in 1977. Extremely dark, they may be made of countless fragments of water ice containing radiation-altered organic material. Uranus was unknown to ancient astronomers. British astronomer William Herschel discovered the planet in 1781 using a homemade 15-centimeter telescope. Voyager, Jan. 24, 1986
Saturn’s tiny moon Mimas in transit across rippling ring shadows on the planet’s northern hemisphere during that hemisphere’s winter. Mimas is only 246 miles in diameter. South is up. Mosaic composite photographs. Cassini, Jan. 18, 2005
For nearly three years, we have been gathering the best, most interesting, most beautiful photographs of space we could find, delivering one of them to you each day. Here are 35 of our favorites among this year's bunch.