What is a planet?

[Gogf]

What do you consider to be defined as a planet?

I consider anything larger than earth's moon orbiting a star to be a planet.

 

[Ultima Dragoon]

Large objects that are orbiting a star with a sufficient amount of gravity to keep them selves in a orbit with the help of a star.

 

[Gogf]

Large objects that are orbiting a star with a sufficient amount of gravity to keep them selves in a orbit with the help of a star.

What does "large" mean? Are all the asteroids, comets and meteors orbiting the sun planets too?

 

[Meleager]

What do you consider to be defined as a planet?

I consider anything larger than earth's moon orbiting a star to be a planet.

So pluto is not a planet?

 

[Bozo Erectus]

Size matters. But when dealing with smaller bodies, any body that has its own native life on it qualifies.

 

[Ultima Dragoon]

"Large" for this subject, i think is anything larger than somethimg the size of plut but smaller than the sun.

@Meleager: It is disputed whether pluto and charon are planets or asteroids caught in neptune's gravity.

 

[Gogf]

So pluto is not a planet?

No.

@Ultima Dragoon: Or the sun's gravity...

 

[Irish Caesar]

Any object with enough mass to be spherical, but not enough to sustain nuclear fusion, with a stable orbit around a star.

Sorry, Pluto...your orbit is way too elliptical and 17 degrees off of the plane of orbit...but I'll consider you a planet for tradition's sake.

 

[Perfection]

Any object with enough mass to be spherical, but not enough to sustain nuclear fusion, with a stable orbit around a star.

Then Ceres should be a planet

My proposal would be a body that is in direct orbit around a star that is not large enough to sustain nuclear fusion but large enough to sweep debris out of its orbital path.

 

[newfangle]

Direct orbit with enough mass to become "spherical."

 

[Meleager]

My definition would probobly be something about the strength of magnetic feilds.

 

[Ultima Dragoon]

No.

@Ultima Dragoon: Or the sun's gravity...

Damn. I though I wrote that.

Yes, anything which has sufficient mass, gravity, magnetic fields, life etc. Make a planet a planet.

 

[Perfection]

Direct orbit with enough mass to become "spherical."

Then the solar system would have over 20 planets

My definition would probobly be something about the strength of magnetic feilds.

Venus isn't a planet?!

 

[Meleager]

Venus isn't a planet?!

Venus does have a magnetic feild. It is just very small for its size.

The new upper limit on the dipole moment obtained from the Pioneer Venus Orbiter wake measurements placed the Venus intrinsic magnetic field at ~ 10-5 times that of Earth.

 

[Perfection]

Venus does have a magnetic feild. It is just very small for its size.

So then what's the cutoff? I think this is a poor definition for a planet. Should a hypothetical fieldless Venus not be considered a planet?

 

[Meleager]

So then what's the cutoff? I think this is a poor definition for a planet. Should a hypothetical fieldless Venus not be considered a planet?

A Hypothetical feildless venus could not exist as every object emmits a magnetic feild.

I would think that the ability to deflect solar wind before making contact with the surface would work. Ofcourse its probobly not the best definition, but it sounds scientific.

 

[Souron]

So pluto is not a planet?

Pluto is not a planet in the technical sence, but still considered a planet anyway becouse the archiologists desided it would be too much trouble to change the standard. As I understand it they had a big meating on this and came to this conclution.

Imagine trying to change the culturally accepted statement that pluto is a planet. So many books to rewrite, people to convince, memory devices to change. . .

 

[Perfection]

A Hypothetical feildless venus could not exist as every object emmits a magnetic feild.

A hypothetical Venus with a magnetic field on par with that of a sack of bricks. (and objects do exist without emmiting a magnetic field)

I would think that the ability to deflect solar wind before making contact with the surface would work. Ofcourse its probobly not the best definition, but it sounds scientific.

If a planet's core were to solidify (which all terrestrial planets' cores will do eventually), it would lose its magnetic field, and thus according to your definition, no longer be a planet.

 

[Meleager]

(and objects do exist without emmiting a magnetic field)

only if they have no atoms. Protons and electrons both emmit magnetic feilds.

 

[Perfection]

Pluto is not a planet in the technical sence, but still considered a planet anyway becouse the archiologists desided it would be too much trouble to change the standard. As I understand it they had a big meating on this and came to this conclution.

Ummm, no. First off, what the heck do Archeaologists have to do with this? You mean astronomers don't you?

The IAU (the authority on such matters), ruled a few years ago that Pluto was still a planet for scientific reasons (size, moon presence, among others). Since then, several large TNOs (which were considered to not be planets) were discovered. With the recent discovery of the TNO UB313 (which is larger then Pluto) and its submission as a Planet the IAU will have to decide Pluto's fate yet again. The IAU claims that it will figure it out by year's end.