Novo otkriveni Solarni Sistem ima Mesec

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Novotkriveni sistem(petak),koji orbitira van solarnog sistema(mlecnog puta),po svemu sudeci ima Mesec.

But although initial calculations suggested the Kuiper Belt object could be up to twice as big as Pluto, the new data indicates it is about 70% the diameter of that planet. This makes its size second only to Pluto itself among objects beyond Neptune.

The new object has been temporarily named 2003 EL61 by the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics in Massachusetts, US, and was first spotted by Jose-Luis Ortiz at the Sierra Nevada Observatory in Spain in 2003. Ortiz's group uncovered observations as far back as 1955, and after additional observations reported its orbit to the Minor Planet Center.

When he first saw how bright the object was, Gareth Williams of the Minor Planet Center could not believe it was as far from the Sun as Ortiz claimed - 51 times further away than the Earth. However, he quickly found two images of the object in the online Digital Sky Survey, and posted it on a confirmation page on the Minor Planet Center's website. Half an hour later, German amateur astronomers announced they had found it where predicted.

But more was to come. After Williams put out a notice of the new object and its orbit the evening of 28 July, Mike Brown of Caltech in California, US, said his group had discovered the same object in 2004 - and in January 2005 had spotted a moon orbiting it using the Keck Observatory in Hawaii.
Mass by moon

The moon is not the first discovered around a Kuiper Belt object, but it is the smallest, only about 1% the mass of 2003 EL61. More importantly, observations of the satellite's 49-day orbit allowed Brown to precisely calculate the masses of both 2003 EL61 and its moon.

Brown's results - posted on his website - show the object is about 32% as massive as Pluto. Assuming its composition is similar, that implies its diameter is about 70% of Pluto's, or about 1600 kilometres. That would probably make it larger than Sedna, an object beyond the Kuiper Belt discovered earlier by Brown's group.

Brown had not made his findings public because he was waiting for infrared data from the Spitzer Space Telescope, which he could use to calculate how much visible light 2003 EL61 reflected. That would allow him to calculate its size more precisely.
Taking a chance

He finally received that data on 22 July, and is still in process of analysing it. "We could have announced the object earlier, but we took a chance that no one else would find it while we were awaiting our observations" from Spitzer, Brown writes on his web site. "We were wrong," so the Spanish group earned credit for the discovery.

Williams is surprised the object had not been spotted earlier. Although its motion in the sky is very slow: "It's bloody bright," he told New Scientist.

If it was in the main asteroid belt, it would be visible to the unaided eye in a dark sky, one to two magnitudes brighter than Vesta, the brightest object in the main belt. Even far beyond Neptune, it is bright enough for amateur astronomers to have captured images of it without recognising its motion.

http://www.newscientistspace.com/article.ns?id=dn7758

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'New planet' found in solar system

American astronomers funded by NASA have announced the discovery of a new planet in the outer reaches of our solar system.

California Institute of Technology astronomer Michael Brown says the new body is the most distant object ever detected orbiting the sun and ranks as the solar system's 10th planet.

The body of rock and ice orbits the sun every 560 years.

If confirmed, the discovery would be the first of a planet since Pluto was identified in 1930.

The possible new planet is at least the size of Pluto and was discovered orbiting about 14.5 billion kilometres from the sun.

Dr Brown says the object is a typical member of the Kuiper belt - which extends from the orbit of Neptune out through the solar system for about 3,000 million kilometres - but its sheer size in relation to the nine known planets means it can only be classified as a planet.

However, Dr Brown conceded that the discovery would likely rekindle debate over the definition of a 'planet' and whether Pluto should still be regarded as one.

Dr Brown says the new object was detected in January by the Samuel Oschin Telescope at the Palomar Observatory near San Diego.

He says the planet went undiscovered for so long because its orbit is tilted at a 45-degree angle to the orbital plane of the other planets.

Dr Brown says the team has a name in mind for the planet but wants to formally propose it before releasing it to the public.

Officially, the new planet is known as 2003UB313, though the New York Times reports that astronomers have been calling it Xena, after the television character named for a Greek warrior princess.

On his website, Dr Brown writes that the new planet is at least as large as Pluto.

"Usually when we find these we don't know their size for certain, only lower limits," he wrote.

"The lower limit to this object is the size of Pluto. This object is at least the size of Pluto and likely a bit larger."

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