Why was Pluto downgraded from its Planet status, and what makes a planet a planet?

Question

Why was Pluto downgraded from its Planet status, and what makes a planet a planet?

Answer 1

size is everything.

Answer 2

too small

Answer 3

I have heard there is a twin "planet" to Pluto, both so close that you can't say who is who. According to my ill-working memory, the new found planet should have been named 'Eris' (Greek mythology, see there). Astronomers had a meeting in Austria last year or the year before, where the original intention was to stop Space from taking more space without asking them. But some bright spark guy with new looking- glasses had just found this new thing and whatever else what might have come out of this come together, Pluto made the headlines.

Pluto is still there and will remain for the rest of Earth's life.

Lars.

Answer 4

The researchers said Pluto failed to dominate its orbit around the Sun in the same way as the other planets.

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

Answer 5

a planet is

1. The object must be in orbit around the Sun.

2. The object must be massive enough to be a sphere by its own gravitational force. More specifically, its own gravity should pull it into a shape of hydrostatic equilibrium (this occurs when compression due to gravity is balanced by a pressure gradient which creates a pressure gradient force in the opposite direction.

3. It must have cleared the neighbourhood around its orbit.

Answer 6

The size of Pluto was one of the reason because its diameter is only about 1300 miles I think. which  is only about a third of the way across the U.S. Another reason is because its orbit is so elliptical and so far off the plane that the rest of the planets are on that it seems more like a giant comet  than a planet. So it is called a dwarf planet.

Answer 7

It was downgraded, because there had been an inflation of objects, which had all been similar to Pluto or even much larger. The definition of a planet was never really formally defined, until 2006:

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 neighbourhood around its orbit.

This is of course not without opposition, but an improvement to earlier times.

Pluto is now a dwarf planet, because there are many asteroids and other objects in his orbital path:

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 neighbourhood around its orbit, and (d) is not a satellite.

Answer 8

it is found that pluto croses neptune's orbit & goes far away without revolving around the sun.....so they r considering it as an asteroid or sumthing else!!!!!!!.....it can be a satellite for neptune & other plannet in other solar system

Answer 9

a new class called dwarf planets have been defined my the IAU.

for a planet to be a planet it has to be

1. in orbit around the sun

2. it shud have enuf mass so tht it is a nearly spherical shape

Originally classified as a planet, Pluto is now considered the largest member of a distinct region called the Kuiper belt.

it is the 2nd largest dwarf planet...

check out wikipedia for more info...

Answer 10

dunno i think its too small....stupid really dont you think? i mean its still bloody massive and i think it should be called a planet...if it has gravity it should be a planet in my opinion