Is there a tenth planet?
#56374. Asked by TheuntouchablE. (Apr 02 05 4:11 PM)
Yes, Sedna, but some people don't consider it a planet.|
SEDNA: the tenth planet in our solar system?
Sedna, which was very recently discovered at the outer limits of our solar system, seems hardly any different from Pluto. It is a massive, spherical body that revolves around the Sun and may even have its own satellite. But does this really mean that Sedna is a planet?
For more than two years, Michael E. Brown and his team of scientists at the California Institute of Technology (Pasadena) have been scanning the sky looking for any celestial body moving within our solar system. Their efforts paid off: on November 14th 2003*, using the Samuel Oschin Telescope at Mount Palomar Observatory (California), the scientists made out a small, faintly bright point moving very slowly in the Whale constellation...
Scrutinised from every angle with various instruments on Earth and in space (particularly the Spitzer Infrared Space Telescope), the object, officially christened 2003 VB12, seems to beat all records.
With a diameter of between 1,300 and 1,700 km, it is the largest celestial body to be discovered in the solar system since Pluto in 1930 (2,300 km in diameter). It is also the furthest ever to be observed, as it is currently at a distance of 90 AU*.
Because of this great distance from the Sun, it is also the coldest: its temperature probably never exceeds -240°C! This is one of the reasons its discoverers nicknamed the body Sedna, in homage to an Inuit goddess who lives in the glacial depths of the ocean.
*AU: astronomical unit (the average distance between the Earth and the Sun, about 150 million kilometres)
[Added reference - McG]
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