Kuiper << KY pur >> belt is a band of objects in the outer regions of our solar system. Kuiper belt objects (KBO’s) probably consist of ice and rock. Astronomers estimate that there may be roughly 100 billion KBO’s larger than 0.6 mile (1 kilometer) in diameter. About 100,000 may measure more than 60 miles (100 kilometers) across. Some KBO’s are large enough to be considered dwarf planets. Scientists believe that KBO’s are “building blocks” left over from the formation of the planets, which occurred about 4.6 billion years ago.
Most KBO’s orbit the sun in circular and oval orbits beyond Neptune. Many of the objects have orbits similar to that of Pluto, a large KBO. Pluto is large enough to be classified as a dwarf planet. Astronomers have also categorized all the dwarf planets beyond Neptune as plutoids. Among KBO’s, the first few to be designated as a plutoid include Eris, Makemake, and Haumea. Eris measures about 1,450 miles (2,350 kilometers) in diameter, roughly the size of Pluto.
Sometimes, a KBO strays so close to Neptune that Neptune’s gravity hurls the object toward the sun. The object may turn into a comet by absorbing enough heat to vaporize some of its ice.
The Kuiper belt is also called the Edgeworth-Kuiper belt or the trans-Neptunian disk. An Irish scientist named Kenneth E. Edgeworth suggested in 1943 that the belt existed. The Dutch-born American astronomer Gerard P. Kuiper described it in more detail in 1951. In 1992, the English-born American astronomer David Jewitt and the Vietnamese-born astronomer Jane Luu discovered the first object to be classified as a KBO at the time of its discovery. In 2003, the American astronomers Michael Brown, Chad Trujillo, and David Rabinowitz discovered Eris.
The United States New Horizons probe was launched in 2006 to explore the Kuiper Belt. It flew by Pluto in 2015. In 2019, the probe made its first close observation of a small KBO named Arrokoth, the Powhatan word for sky. The Powhatan are a Native American group.
See also Comet; Dwarf planet; Kuiper, Gerard Peter.
