Quaoar

Quaoar is a Trans-Neptunian object orbiting the Sun in the Edgeworth-Kuiper belt. It was discovered on June 4, 2002 by astronomers Chad Trujillo and Michael Brown at the California Institute of Technology in Pasadena, California from images acquired at the Samuel Oschin Telescope at Palomar Observatory. This discovery was announced on October 7, 2002, at a meeting of the American Astronomical Society. The earliest precovery turned out to be a May 25, 1954 plate from Palomar Observatory.

Quaoar is estimated to have a diameter of about 1,200 kilometres, which at the time of discovery made it the largest object found in the solar system since Pluto and, indeed, then the largest known minor planet (it was later supplanted by Sedna and Template:2003 UB313). Quaoar's volume is somewhat more than all of the asteroids put together, it is about one tenth the diameter of Earth or one third the diameter of the Moon. It is about one-third the size of Pluto. It orbits at about 6 thousand million kilometres from the Sun with an orbital period of 286 years.

The planetoid's name follows International Astronomical Union rules by naming all planetoids after creation deities (see planetary nomenclature). "Quaoar" is the name of a creation deity of the Native American Tongva people, native to the area around Los Angeles, where the discovery was named. The IAU approved the name Quaoar, making it the official name; it also has the provisional designation Template:mp.

Quaoar has a more typical planetary orbit than Pluto does -- a near-circular orbit with a radius of somewhat over 40 AU, unlike Pluto's highly eccentric one. Like Neptune, Quaoar's orbit lies between Pluto's perihelion and aphelion, so that Pluto is closer to the Sun than Quaoar at some times of its year, and farther at others.

Quaoar is believed to be a mixture of rock and ice, like other Kuiper Belt Objects; however its extremely low albedo (estimated at 0.1) indicates that the ice has disappeared from its outer layers. If the New Horizons mission visits several Kuiper Belt Objects after visiting Pluto in 2015, our knowledge of such things may greatly improve.

In 2004, scientists were surprised to find signs of crystalline ice on Quaoar, indicating that the temperature rose to at least −160 Â°C (110 K or −260 Â°F) sometime in the last ten million years. Speculation began as to what could have caused Quaoar to heat up from its natural temperature of −220 Â°C (55 K or −360 Â°F). Some have theorized that a barrage of mini-meteors may have raised the temperature, but the most discussed theory speculates that cryovolcanism may be occurring, spurred by the decay of radioactive elements within Quaoar's core. (Jewitt & Luu, 2004)

References

• Template:Journal reference PMID 15592406

External links

• Quaoar discoverers' webpage
• Orbit simulation from NASA JPL site
• Astronomers Contemplate Icy Volcanoes in Far Places - New York Times article
• Quaoar, the newest planet . . . or is it? - article in an Australian science magazine
• New Planet-Shaped Body Found in Our Solar System - article in National Geographic
• Volcanism possible on planet-like Quaoar - CNN.com
• Chilly Quaoar had a warmer past - Nature.com article
• Crystalline Ice on Kuiper Belt Object (50000) Quaoar - article about crystalline ice on Quaoar

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