scoperto il decimo "pianeta" :>

[eriol]

fonte: ansa

[Coyote74]

2000 Km di diametro, più piccolo di Plutone. Più che un pianeta è un asteroide

[eriol]

va beh accontentati no?

[GioFX]

se ne parlava già qui:

http://forum.hwupgrade.it/showthread...21#post3420521

cmq la mia opinione, anche se devo leggere di più su querto asteroide, è che se plutone è considerato un pianeta, anche questo lo può essere, a patto che ci si decida una volta per tutte sulla definizione di pianeta, e che l'asteroide in oggetto sia stato catturato dalla forza gravitazionale del sole.

[GioFX]

Da Space.com:

Scientists Find Another Huge Mini-World in Outer Solar System

By Andrew Bridges
Associated Press
posted: 09:00 am ET
15 March 2004

LOS ANGELES (AP) -- It is a frozen world more than 8 billion miles from Earth and believed to be the farthest known object within our solar system.

NASA planned a Monday press conference to offer more details about Sedna, a planetoid between 800 miles and 1,100 miles in diameter, or about three-quarters the size of Pluto.

Named for the Inuit goddess who created the sea creatures of the Arctic, Sedna lies more than three times farther from the sun than Pluto. It was discovered in November.

"The sun appears so small from that distance that you could completely block it out with the head of a pin," said Mike Brown, an astronomer at the California Institute of Technology who led the NASA-funded team that found Sedna.

That makes Sedna the largest object found orbiting the sun since the discovery of Pluto, the ninth planet, in 1930. It trumps in size another world, called Quaoar, discovered by the same team in 2002.

Brown and his colleagues estimate the temperature on Sedna never rises above 400 degrees below zero Fahrenheit, making it the coldest known body in the solar system.

Sedna follows a highly elliptical path around the sun, a circuit that it takes 10,500 years to complete. Its orbit loops out as far as 84 billion miles from the sun, or 900 times the distance between the Earth and our star.

Brown and Chad Trujillo, of the Gemini Observatory in Hawaii, and David Rabinowitz, of Yale University, discovered Sedna on Nov. 14, 2003, using a 48-inch telescope at Caltech's Palomar Observatory east of San Diego.

Within days, other astronomers around the world trained their telescopes, including the recently launched Spitzer Space Telescope, on the object.

The team also have indirect evidence a tiny moon may trail Sedna, which is redder than all other known solar system bodies except Mars.