And there are more?
It seems that I've opened a can of worms. Just when I had resigned myself to there being 10 planets, I happened upon this article from the BBC : -
"Today, the world knows that Pluto is not unique. There are other Plutos, just farther out in the Solar System where they are a little harder to find," says David Rabinowitz of Yale University, who was among the astronomers who discovered 2003 UB313 two years ago.
His point is echoed by Professor Mark Bailey, director of Armagh Observatory in Northern Ireland. "Increasingly, objects are far away and there are objects which are of comparable size to Pluto, so if you think of Pluto as a planet then you should refer to those objects as planets," he says.
He estimates that there could be tens of thousands of objects beyond Neptune in the Solar System region known as the Kuiper belt, many of which may be larger than Pluto.
The discovery of 2003 UB313 comes soon after it was announced that 2003 EL61 had been found.
A number of distant objects around the same size of Pluto have been found in recent years, including Quaoar (found in 2002) and Sedna (detected in 2004).
It is widely accepted that the struggle to provide an adequate definition of a planet is the crux of the problem.
"Originally a planet was a wandering star. Then it was something that moved across the sky. Then it was something that revolved around the Sun. The criterion about when it should be called a planet is something that is changing over time," says Prof Bailey.
Read more here
"Today, the world knows that Pluto is not unique. There are other Plutos, just farther out in the Solar System where they are a little harder to find," says David Rabinowitz of Yale University, who was among the astronomers who discovered 2003 UB313 two years ago.
His point is echoed by Professor Mark Bailey, director of Armagh Observatory in Northern Ireland. "Increasingly, objects are far away and there are objects which are of comparable size to Pluto, so if you think of Pluto as a planet then you should refer to those objects as planets," he says.
He estimates that there could be tens of thousands of objects beyond Neptune in the Solar System region known as the Kuiper belt, many of which may be larger than Pluto.
The discovery of 2003 UB313 comes soon after it was announced that 2003 EL61 had been found.
A number of distant objects around the same size of Pluto have been found in recent years, including Quaoar (found in 2002) and Sedna (detected in 2004).
It is widely accepted that the struggle to provide an adequate definition of a planet is the crux of the problem.
"Originally a planet was a wandering star. Then it was something that moved across the sky. Then it was something that revolved around the Sun. The criterion about when it should be called a planet is something that is changing over time," says Prof Bailey.
Read more here
posted by chris at 5:22 am
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