The Kuiper Belt extends from about 30 to 55 AU and is probably populated with hundreds of thousands of icy bodies larger than 100 kilometers (62 miles) across and an estimated trillion or more comets. The Oort Cloud occupies space at a distance between 5,000 and 100,000 astronomical units. No objects residing within the Oort Cloud have ever been directly observed.
Note: This lithograph was revised in September 2013.
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