THE KUIPER BELT

Beyond the orbit of Neptune are a large number of icy objects making up the Kuiper Belt which extends from 30 AU to about 50 AU. Belts of this nature appear to be a normal product of star (and possibly planet) formation as Kuiper Belts have been photographed around other stars.

DIAGRAM : © Matthew Wallace 2006

Note how the orbit of Pluto crosses inside the orbit of Neptune and extends near the outer edge of the Kuiper Belt.

The Hubble Space Telescope photo at the right shows a disk of material around the star Beta Pictoris and is the equivalent of the Kuiper Belt around the Sun.

A large number of Kuiper Belt objects are known and an up-to-date list can be found here >>

Kuiper Belt Objects are often known as Trans Neptunian Objects or TNOs as most are found beyond the orbit of Neptune.

A number of notable Kuiper Belt Objects

Quaoar was discovered in 2002 at a distance of 6 billion kilometres from the Sun with an orbital period of 287 years. It has a diameter of about 1300 kilometres, about half of that of Pluto and is made up of rock and ice.

CREDIT: NASA

Sedna has a highly elliptical orbit varying in distance from the Sun from 76 AU to 975 AU. One orbit around the Sun takes 12050 years and has an estimated diameter of about 1500 kilometres.

CREDIT: NASA/JPL/Caltech

In 2003 a Kuiper Belt object larger than Pluto was discovered. It is designated 2003 UB313. It is similar to Pluto in many ways, even possessing a moon. Its distance from the Sun varies from 37.8 AU to 97 AU taking 557 years to complete one orbit. The fact that it is larger than Pluto has again raised questions about whether Pluto should be considered a planet or a Kuiper Belt object.

Pluto and the mysterious Kuiper belt beyond are the only parts of the solar system not yet explored close-up by space craft. Because of the small size and great distance of these objects even our best telescopes are unable to gather much information. It is becoming clear that these distant objects could tell us a lot about the formation of the solar system.

The New Horizons mission intends to send a space craft to the outer solar system to study Pluto and its moons and then continue on into the Kuiper Belt to give us a close look at a number of Kuiper Belt objects.

Exploring the Kuiper Belt

Background information on the New Horizons mission here >>>