What Are Kuiper Belt Objects?
There is an architecture to our Solar System – four small, rocky planets on circular orbits close to the Sun (Mercury, Venus, Earth, and Mars) followed by four giant, hydrogen-rich planets on circular orbits farther from the Sun (Jupiter, Saturn, Uranus, and Neptune). Pluto’s small size, icy nature, and eccentric orbit about the Sun do not fit into the planetary architecture of our Solar System. We now know why Pluto is an oddball among planets. It is the first known and among the largest members of an ancient debris disk of icy objects orbiting the Sun at and beyond Neptune. Because of Neptune’s disruptive gravitational influence, these icy objects did not accrete into the core of a Jupiter-like planet. The Kuiper belt at and beyond Neptune. Figure By Dan Boone and NAU Bilby Research Center The icy debris disk is commonly called the Kuiper belt in honor of Dutch-American astronomer Gerard P. Kuiper, who postulated its existence in 1950. The icy objects are known as Kuiper belt objects
