I need a good explination.
Thank you!
2007-07-26 04:18:53 · 12 answers · asked by Love. 5 in Science & Mathematics ➔ Astronomy & Space
quite simply because there are so many objects out in space related in size to pluto that we do not consider any of them planets. Also, partly because it has a very eccentric orbit and doesn't lie on the same plane as the rest of the planets.
2007-07-26 04:27:48 · answer #1 · answered by justask23 5 · 4⤊ 1⤋
Even as a small boy in the late 70's and early 80's, I remember thinking that Pluto shouldn't be called a planet. I even annoyed a few teachers by arguing with them. I didn't have the resources or knowledge to check back then, but I can guarantee if I felt that way that a lot of scientists had the same nagging doubts. In part, my more definite doubting was probably based on the fact that it hadn't yet been engrained into me to accept what "the experts" teach us. :)
* Pluto has always had an orbit that wasn't even close to the same as the orbits of other planets. Other planet's orbits are almost circular, and they're all more or less in the same plane. Pluto's orbit is very eliptical, and it is tilted over 17 degrees relative to the plane that the other planets orbit in.
* Pluto is small; it's about 1/5 the mass of our Moon. And our Moon is only 2000 miles across, or 6000 miles around.
* much further out than all other planets. 50 times the distance that Earth is from the Sun. Neptune (8th planet) is 30 times as far from the Sun as is the Earth.
* A lot of other objects similar to Pluto were discovered, which made it easier for us to start thinking of it as something other than a planet. (We know about the Asteroid Belt, as a similar example, but we don't call each Asteroid in it a Planet). The Kuiper Belt, which Pluto is a part of, can be thought of in a similar manner.
* On August 24, 2006, the IAU defined the term "planet" for the first time, and they intentionally did it in such a way that Pluto is not a planet. It is not a planet because they defined "planet" in a way that exludes Pluto.
Be sure to read the bottom part of the page on Pluto, as well as the definiton of planet page.
2007-07-26 04:49:45 · answer #2 · answered by silverlock1974 4 · 1⤊ 0⤋
When it was found, it was "assumed" to be a planet, but its orbit was weird (40 degrees off the avg solar plane). There were ALWAYS questions about what it really was. Later discoveries (many within the last 5-10 years) have found that our solar system is actually composed of three regions - the planetary disc, the Kuyper belt, and the Ort cloud.
These findings indicate that Pluto is really a member of the Kuyper belt beyond the planets (there have been found objects found in the Kuyper belt that are larger than Pluto). So we finally got around to reclassifying it.
It's original classification as a planet was not accurate according to the latest information. It is really an object in the Keyper belt, and it has been reclassified as a "sub-planet" Eventually it shall be reclassified as just another Kuyper belt object...
Ron.
2007-07-26 04:30:22 · answer #3 · answered by Anonymous · 3⤊ 0⤋
Because, after being a planet for over seventy years, the powers that be in the scientific community, have now decided to 'demoted' Pluto to a dwarf planet! Get this, it still has its own orbit around the Sun. It even has its own moon called Charon, and if it should be called anything else, in my book, besides a planet, it should be called a 'double-planet' instead of a dwarf planet!!! Clyde Tombaugh, the discoverer of Pluto back in 1930, must be turning over in his grave by now!
2007-07-26 05:14:26 · answer #4 · answered by Old Truth Traveler 3 · 1⤊ 0⤋
There are several solar objects in orbit around the sun of a roughly similar size, and several moons in orbit around planets larger.
Thus many other objects have been promoted to the rank of planetoid, while Pluto was demoted to planetoid. However, nobody has had the heart to tell Pluto yet. Apparently he's still broken up over Mickey's death.
2007-07-26 04:27:03 · answer #5 · answered by Anonymous · 1⤊ 0⤋
Because if Pluto was to be closer to the sun it would grow a tail like a comet, That alone would exclude Pluto from being a planet.
2007-07-26 04:22:56 · answer #6 · answered by M Series 3 · 0⤊ 1⤋
The truth is, there are other planetoids out there *larger* than Pluto (up to 50, estimated), and it was either allow ALL those to be planets, and learn the new ones as they were spotted, or call them something else, and keep the names we've known.
2007-07-26 05:00:55 · answer #7 · answered by quantumclaustrophobe 7 · 1⤊ 0⤋
pluto is not a planet anymore because the people who decided it was one changed their mind and said it doesn't meet all of the qualifacations (sorry i don't know how to spell that!) to be a planet. it's too small to be a planet is the main thing!!!!
2007-07-26 04:24:31 · answer #8 · answered by Anonymous · 1⤊ 0⤋
Cause a committe of scientists got together made up some rules and regulations and Pluto violated those, so it got demoted.
Not every scientist agrees with them.
2007-07-26 07:17:54 · answer #9 · answered by Anonymous · 1⤊ 0⤋
It's basically too small and it's a misfit: it doesn't fit into the category of the terrestrial (inner) planets or the Jovian/gas giants (outer) planets.
2007-07-26 04:29:54 · answer #10 · answered by Karen 5 · 1⤊ 0⤋