Post by Eternal Sailor Moon on Dec 6, 2006 20:13:52 GMT -5
About 2,500 scientists meeting in Prague have adopted historic new guidelines that see the small, distant world demoted to a secondary category.
The researchers said Pluto failed to dominate its orbit around the Sun in the same way as the other planets.
The International Astronomical Union's (IAU) decision means textbooks will now have to describe a Solar System with just eight major planetary bodies.
See the new Solar System
Pluto, which was discovered in 1930 by the American Clyde Tombaugh, will be referred to as a "dwarf planet".
There is a recognition that the demotion is likely to upset the public, who have become accustomed to a particular view of the Solar System.
Teary-eyed
"I have a slight tear in my eye today, yes; but at the end of the day we have to describe the Solar System as it really is, not as we would like it to be," said Professor Iwan Williams, chair of the IAU panel that has been working over recent months to define the term "planet".
The meeting had seen some fierce arguments before final voting
The need for a strict definition was deemed necessary after new telescope technologies began to reveal far-off objects that rivalled Pluto in size.
Without a new nomenclature, these discoveries raised the prospect that textbooks could soon be talking about 50 or more planets in the Solar System.
Amid dramatic scenes in the Czech capital which saw astronomers waving yellow ballot papers in the air, the IAU voted to block this possibility - and in the process took the historic decision to relegate Pluto.
The scientists agreed that for a celestial body to qualify as a planet:
it must be in orbit around the Sun
it must be large enough that it takes on a nearly round shape
it has cleared its orbit of other objects
Pluto was automatically disqualified because its highly elliptical orbit overlaps with that of Neptune. It will now join a new category of dwarf planets.
Icy reaches
Pluto's status has been contested for many years. It is further away and considerably smaller than the eight other "traditional" planets in our Solar System. At just 2,360km (1,467 miles) across, Pluto is smaller even than some moons in the Solar System.
The nerve of some people, I can't believe this!
The researchers said Pluto failed to dominate its orbit around the Sun in the same way as the other planets.
The International Astronomical Union's (IAU) decision means textbooks will now have to describe a Solar System with just eight major planetary bodies.
See the new Solar System
Pluto, which was discovered in 1930 by the American Clyde Tombaugh, will be referred to as a "dwarf planet".
There is a recognition that the demotion is likely to upset the public, who have become accustomed to a particular view of the Solar System.
Teary-eyed
"I have a slight tear in my eye today, yes; but at the end of the day we have to describe the Solar System as it really is, not as we would like it to be," said Professor Iwan Williams, chair of the IAU panel that has been working over recent months to define the term "planet".
The meeting had seen some fierce arguments before final voting
The need for a strict definition was deemed necessary after new telescope technologies began to reveal far-off objects that rivalled Pluto in size.
Without a new nomenclature, these discoveries raised the prospect that textbooks could soon be talking about 50 or more planets in the Solar System.
Amid dramatic scenes in the Czech capital which saw astronomers waving yellow ballot papers in the air, the IAU voted to block this possibility - and in the process took the historic decision to relegate Pluto.
The scientists agreed that for a celestial body to qualify as a planet:
it must be in orbit around the Sun
it must be large enough that it takes on a nearly round shape
it has cleared its orbit of other objects
Pluto was automatically disqualified because its highly elliptical orbit overlaps with that of Neptune. It will now join a new category of dwarf planets.
Icy reaches
Pluto's status has been contested for many years. It is further away and considerably smaller than the eight other "traditional" planets in our Solar System. At just 2,360km (1,467 miles) across, Pluto is smaller even than some moons in the Solar System.
The nerve of some people, I can't believe this!
