How would you define a planet?

Question

no dictionary answers

Answer 1

big balls of gas and matter..some having cores others not..some dense others less dense

Answer 2

I would say that the following are minimum characteristics of planets.

1 & 2 below are arbitrary, you may prefer other variables.

1. Minimum Mass. 10^20 Kg. (about 1/100th the mass of Pluto).

2. Minimum Diameter. 1,500 Km (about 900 miles)

3. Orbit. Must be in orbit around a sun, and not a planet (therefore, Luna is not a planet, even though it's larger than Pluto).

4. Distance from sun. Not relevant, as long as it is clearly in orbit around the sun. Therefore, a massive sun may have planets dozen's of light-years away.

5. Is not itself a sun. That would be a binary or higher system.

6. Must not be in interstellar space, not associated with a sun or suns.

7. Not in a field of other bodies with the same approximate orbit. That would leave out anything in the Asteroid Belt and Oort Cloud.So,

I say that Pluto is a planet. Now, how about "Xena" (aka, 2003 UB313)? To Hades (Greek God of the underworld) with conventions for naming planets. Xena is perfect. And Gabrielle for the moon.

Ceres shares it's orbit with thousands of other asteroids, it doesn't dominate the orbital belt like other planets. So, not a planet.

Charon orbits a much larger body (Pluto), so it's a moon.

Answer 3

any of the nine large celestial bodies in the solar system that revolve around the sun and shine by reflected light; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto in order of their proximity to the sun; viewed from the constellation Hercules, all the planets rotate around the sun in a counterclockwise direction

example of a satellite: a person who follows or serves another
any celestial body (other than comets or satellites) that revolves around a star .

A planet (from the Greek πλανήτης, planētēs which means "wanderer" ) is an object in orbit around a star that is not a star in its own right. Much like "continent," "planet" is a word without a precise definition, with history and culture playing as much of a role as geology and astrophysics !!

Planetology rocks!

Answer 4

That is being debated currently. Some say Pluto should not be considered a planet as it is smaller than our moon. Others have found other objects beyond Pluto that are much larger and could raise the count of planets in our system as high as 14 of what is currently known.

Answer 5

The new proposed definition of a planet is: a celestial body with sufficient mass to assume a nearly spherical shape that orbits a star without being another star or a satellite of another planet

Answer 6

A spherical object of above a certain size that orbits a star within a certain distance. If it is big enough, but orbits it's star at a huge distance, is it really a planet? What about 'planets' that don't orbit stars?

Answer 7

I think it should have to orbit the a sun and be within a certain size. I was reading the news about the new planets and I'm not even sure if they actually orbit a sun or not.

Answer 8

Starr Jones

Answer 9

well this is basically what the IAU has stated recently

1. must be orbiting a star but not be a star
2.bust have enough mass where the gravity pushes it inward to make it round
3.mustn't be an asteroid/comet/meteor but bigger than one

Answer 10

planets are the essential thing of sun family