Kuiper Belt
A huge ring of icy bodies beyond Neptune, including the dwarf planet Pluto.
Past the orbit of Neptune, roughly 30 to 50 times as far from the Sun as Earth, lies the Kuiper Belt. It is like the asteroid belt but far bigger and colder, and its members are mostly ice mixed with rock. Pluto is one of the largest. The belt is named after the astronomer Gerard Kuiper, though the first object beyond Pluto was not found until 1992.
Kuiper Belt objects are thought to be leftover building blocks of the outer planets, kept deep-frozen for over 4.5 billion years. Some get nudged inwards by the giant planets and become short-period comets. NASA's New Horizons spacecraft flew past Pluto in July 2015 and then, on 1 January 2019, past Arrokoth, a small double-lobed body about 36 kilometres long that looks almost untouched since it formed.
No meteorite is known to come from the Kuiper Belt. Its objects are so far away that pieces knocked off them very rarely reach Earth, and icy material would not survive the fall as a rock. Some of the finest interplanetary dust collected in the stratosphere, however, may come from comets that began there. Kuiper Belt objects are visible only with large telescopes.
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Level: Explorer Ages 10 and up