Why have scientist renamed pluto as a dawrf planet?

Question

Why have scientist renamed pluto as a dawrf planet?

Answer 1

Scientists named pluto as a dwarf planet because pluto is very small.But plutois no longer a planet

Answer 2

cause it doesnt suites to the characteristics of a planet

Answer 3

The International Astronomical Union, at their convention a year ago, debated this topic pretty heavily.

There are a couple of problems with Pluto that make it unlike most other planets:

a) It has an eccentric orbit -- the ellipse is tighter than any other planet in our solar system --  and is sometimes closer to the sun than Uranus, while at other times farther than Uranus.

b) It has such a low mass that its own gravity does not pull it into a spherical shape

c) There are asteroids in the belt between Mars and Jupiter that are as large, or larger, than Pluto, and they are not classified as planets.

So these characteristics caused a conundrum.  The solution was to reclassify Pluto as a Dwarf Planet -- but this has caused its own set of problems.

Answer 4

Here's the explanation:

http://www.space.com/scienceastronomy/06...

Answer 5

If we call every body as large or larger than pluto in our solar system a planet, we would and up with 100's of planets. Sadly my kids homework and textbook still require them to call pluto a planet.

Answer 6

I'll just add a note no one else did:

Previously. the definition of a planet wasn't very specific. Based on the old definition, some asteroids could have qualified. So that raised all sorts of questions.  Pluto was always considered a planet but as we learned more about the solar system, it appears that Pluto may be more like the other kieper belt objects. So that spurred the astronomer's organization to decide to clearly and specifically define exactly what a planet is.

Of coarse, Pluto is still a lovable and playful Disney  character.  

Answer 7

In 2006 the IAU decided to demote Pluto because of its position in the asteroid belt. One of the criteria for a celestial body to be considered a planet is that it has to be outside of an asteroid belt. There are probably hundreds of objects like Pluto, some maybe even bigger, but we don't consider those planets. Pluto is now a "plutoid" which is a more concise type of dwarf planet.

Answer 8

Because it just doesn't match the definition of a planet!