2006-09-04 13:04:05 · 5 answers · asked by bluesparkles4 2 in Science & Mathematics ➔ Astronomy & Space
the international astronomical union defined three terms "planet", "dwarf planet", and "small solar system body". this does not change anything about the solar system or pluto. it just corrects the mistake of classifying pluto as a planet initially. i have been waiting for this since i was about twelve. i feel somewhat satisfied. this was the right thing to do, believe me.
because pluto orbits the sun, is round, does not have an isolated orbit (a bunch of other similar bodies that have similar orbits.), and is not a satellite it is a dwarf planet.
(1) A "planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.
(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighborhood around its orbit, and (d) is not a satellite.
(3) All other objects orbiting the Sun shall be referred to collectively as "small solar system bodies".
look here:
http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html
http://en.wikipedia.org/wiki/Kuiper_belt
2006-09-04 13:08:21 · answer #1 · answered by warm soapy water 5 · 2⤊ 0⤋
You can get all the info at space.com. Basically it comes town to size and orbit. Pluto is too small and doesn't have a circular orbit. The other proposal was to designate Charon (Pluto's partner), Ceres (an asteroid between Mars and Jupiter) and UB313 (larger than Pluto and farther out) as planets which would have made twelve planets. The problem is that if those qualify as planets there are about 500 to several thousand other "planets" within the Kupier belt. So they went the other way and designated them "minor planets" bringing the number of "planets" in the solar system to 8.
2006-09-04 13:13:33 · answer #2 · answered by Perry L 5 · 0⤊ 0⤋
See Resolution 5A and 6A in this article
http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html
This is from the International Astronomical Union - the ones who made the decision.
2006-09-04 13:07:19 · answer #3 · answered by goodlittlegirl11 4 · 0⤊ 0⤋
I like this essay/explanation by Mike Brown, the astronomer who discovered 2003 UB313 ("Xena"): http://www.gps.caltech.edu/~mbrown/eightplanets/
2006-09-04 13:12:35 · answer #4 · answered by kris 6 · 0⤊ 0⤋
it's still one of our planets, but they changed its classification from "planet" to "dwarf planet"
2006-09-04 23:54:18 · answer #5 · answered by jhstha 4 · 0⤊ 1⤋