Since the year 2000, a number of

Kuiper belt The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

objects (KBOs) with diameters of between 500 and 1500 km (more than half that of Pluto) have been discovered.

50000 Quaoar Quaoar (50000 Quaoar), provisional designation , is a dwarf planet in the Kuiper belt, a region of icy planetesimals beyond Neptune. A non-resonant object (cubewano), it measures approximately in diameter, about half the diameter of Pluto. The ...

, a classical KBO discovered in 2002, is over 1000 km across. and , both announced on 29 July 2005, are larger still. Other objects, such as

28978 Ixion 28978 Ixion (, provisional designation ) is a large trans-Neptunian object and a possible dwarf planet. It is located in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. Ixion is classified as a plu ...

(discovered in 2001) and

20000 Varuna 20000 Varuna, provisional designation , is a large trans-Neptunian object in the Kuiper belt. It was discovered in November 2000 by American astronomer Robert McMillan during a Spacewatch survey at the Kitt Peak National Observatory. It is na ...

(discovered in 2000) measure roughly 500 km across. This has led gradually to the acceptance of

Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the S ...

as the largest member of the Kuiper belt. The brightest known

dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to p ...

s and other KBOs (with

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

s < 4.0) are:

References

{{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System *List of the brightest KBOs Lists of trans-Neptunian objects Kuiper belt objects, brightest

See also

References