Pluto: not a planet?

[danbaron]

(My opinion only.)

To me, a planet is a solid body in space which is large enough so that gravity forces it into a spherical shape. In that case, our moon, and the other moons in
our solar system qualify as planets. And then, so would Pluto. The surface area of Pluto is approximately 6,424,243 square miles. The surface area of Russia is
approximately 6,592,800 square miles. The surface of Pluto is 97% as large as Russia's. The gravity on Pluto is approximately 1/12th of that on Earth. A
spaceship could land on Pluto, and people could get out and walk around.

According to my idea, Jupiter, Saturn, Uranus, and Neptune, would not qualify as planets. They are made of gas. They have no surfaces. No spaceship will ever
land on them. Maybe, they should be called, "gas balls".

Also, I think the definition of a planet should have nothing to do with whether it orbits a star. If not, and an object like the one we live on was found in
deep space, what would you call it?

:twisted:

http://www.space.com/scienceastronomy/dwarf-planet-eris-surprises-101027.html

http://www.space.com/scienceastronomy/060824_planet_definition.html

http://www.space.com/scienceastronomy/solarsystem/pluto-ez.html

http://wiki.answers.com/Q/How_big_is_Russia_in_square_miles

http://www.clarkplanetarium.com/blog/why-are-planets-spherical

http://coolcosmos.ipac.caltech.edu/cosmic_kids/AskKids/pluto_gravity.shtml

[danbaron]

If you had to choose, which one would you rather live on - Jupiter, Saturn, Uranus, Neptune, or Pluto?

http://www.livescience.com/15720-pluto-dwarf-planet-anniversary.html

[kryton9]

Dan, I have thought about this stuff too. I do like having moons though. I agree there could be rogue planets, those without a sun. Probably formed with a sun then got pulled away some how.

From wikipedia
A gas giant is a massive planet with a thick atmosphere and a dense molten core. The "traditional" gas giants, Jupiter and Saturn, are composed primarily of hydrogen and helium. Uranus and Neptune are sometimes called ice giants, as they are mostly composed of water, ammonia, and methane molten ices. Among extrasolar planets, Hot Jupiters are gas giants that orbit very close to their stars and thus have a very high surface temperature. Hot Jupiters are currently the most common form of extrasolar planet known, perhaps due to the relative ease of detecting them.
Gas giants are commonly said to lack solid surfaces, but it is closer to the truth to say that they lack surfaces altogether since the gases that make them up simply become thinner and thinner with increasing distance from the planets' centers, eventually becoming indistinguishable from the interstellar medium. Therefore landing on a gas giant may or may not be possible, depending on the size and composition of its core. If you can't land on it, then it should not be a planet, I agree with that.

But I like the organization of solar systems, suns, planets, moons, gas balls, asteroids, comets... what about planetoids? Perhaps that could be used for rogue planets?

Of the ones you listed Pluto is the one I would like to go to.

[danbaron]

Here is a photo we took of Pluto and Charon, when we camped on Nix for a week. 7441

[kryton9]

That was a great view. Definitely gotta go back for another visit :)