Wikipedia:Today's featured article/May 12, 2017
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The Kuiper belt is a circumstellar disc in the Solar System extending beyond the orbit of Neptune, at 30 to 50 astronomical units from the Sun. It is similar to the asteroid belt between Mars and Jupiter, but far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies that are remnants from the Solar System's formation. Many asteroids are composed primarily of rock and metal, but most Kuiper belt objects are composed largely of frozen volatiles such as methane, ammonia and water. The disc was named after Dutch-American astronomer Gerard Kuiper, though he did not predict its existence. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, are thought to have originated in the region. It is home to three officially recognized dwarf planets: Haumea, Makemake, and Pluto, the largest and most massive member of the Kuiper belt. Originally considered a planet, Pluto was reclassified as a dwarf planet in 2006. (Full article...)
Part of the Solar System featured topic.