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More than 7, less than 9
Hi Mabsj2,
Rightly or wrongly and without wanting to court a(nother) long and tedious debate on the merits of the issue, in August 2006 the International Astronomical Union (the international body that governs astronomers) finally and formally defined what constitutes a planet.
The up-shot of that decision is that there are 8 planets orbiting the Sun -- the 6 classical planets plus Uranus and Neptune. The wordng of the definition they came up with, on the face of it, excludes Pluto. For abundant clarity, the IAU passed a _specific clause_ as part of the definition that disincluded Pluto from the Sun's family of planets.
Pluto is now designated a "dwarf planet", as is I believe Eris -- 2003 UB 313 (a Kuiper belt object) and 1Ceres (the largest asteroid).
That is "the law" as it was decreed.
Personally, I don't believe we will find any further major planets orbiting the Sun. It is probable that many, many more Kuiper Belt objects will be found in the next 10-20 years. Some will probably approach or even exceed Pluto in size.
Just because Pluto is no longer designated a major planet, does _not_ mean it isn't (a) interesting or (b) scientifically important, it very much is! It just isn't called a planet anymore.
Best,
Les D
Contributing Editor
AS&T
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