How many planets are in the Solar System?

[Crono]

The Ennead are upset we took out a planet.

 

[dennilfloss]

Good discussion of the detailed points from both sides in the comments under this blog piece.

http://astroversity.blogspot.ca/2007/07/explained-why-pluto-is-not-planet.html

 

[Puppies04]

I don't think the definition of a planet matters. At the specific level we commonly think of, all we need to know is whether something orbits the sun and not something orbiting something orbiting the sun.

Then we can pair it up with the earth. The moon wouldn't meet this definition.

But billions of asteroids in the belt between mars and jupiter would.

 

[sao123]

What does the dude from Exosquad have to do with anything?

Who? What?

Phaeton is the broken planet between mars and Jupiter... you probably know it by its lesser name... the inner Asteroid Belt

 

[SphinxnihpS]

Personally, I'd define a planet as an object big enough to retain an atmosphere, but not so big it starts nuclear fusion in its core.

So retains an atmosphere, but is not a star?

 

[SphinxnihpS]

Who? What?

Phaeton is the broken planet between mars and Jupiter... you probably know it by its lesser name... the inner Asteroid Belt

The asteroid belt was never ever a planet. Phaeton is an asteroid in the belt.

 

[TechBoyJK]

yeah a small planet which is actually smaller than our moon and over half of its mass its ice so that if it were closer to the sun it will melt away and create a tail

doesnt sound like a planet to me

yea and there's probably 100's of more plutos right behind in the keplar belt. Its a giant ice overed asteroid, not a planet. Titan (a moon) is by far more a planet than pluto and would be right up there with earth and mars if it hadn't fallen into Saturn's orbit.

 

[thedarkwolf]

Who? What?

Phaeton is the broken planet between mars and Jupiter... you probably know it by its lesser name... the inner Asteroid Belt

No. Phaeton is the leader of the Neosapiens.

 

[AstroManLuca]

If .99999999=1 then Pluto is a planet.

.99999999 is not equal to 1. .99999999..., however, is. You have to get the repeating in there.

The problem with designating Pluto as a real planet is that you have to add a few more, like Eris and Ceres. It makes a lot more sense to just remove Pluto.

Bingo. And now Pluto is a big fish (but not the biggest fish) in a small pond rather than a tiny afterthought in a huge solar system. It also makes the solar system much more balanced and predictable - there are four rocky planets on the inside, and four gas giants on the outside.

If Pluto is a planet then so are Ceres (in the asteroid belt), Pluto, Haumea, Makemake, Eris, 2007 OR10, Sedna, Quaoar, Orcus, and probably many other undiscovered "dwarf planets".

Personally, I'd define a planet as an object big enough to retain an atmosphere, but not so big it starts nuclear fusion in its core. Which would rule out Mercury as well. :sneaky:

Posted from the second planet in a system of seven.

But Mercury does have an atmosphere (a very tenuous one). Even the moon does. And Ceres.

 

[sao123]

The asteroid belt was never ever a planet. Phaeton is an asteroid in the belt.

Negative... The greeks have evidence it was a planet and Plato himself said its destruction resulted in the sinking of atlantis.

 

[SphinxnihpS]

Negative... The greeks have evidence it was a planet and Plato himself said its destruction resulted in the sinking of atlantis.

Fucking Greeks.

 

[Childs]

Negative... The greeks have evidence it was a planet and Plato himself said its destruction resulted in the sinking of atlantis.

Nice, I did't know this theory. Interesting that one site I looked at says the Greeks reported that they actually saw it disappear.

 

[Squisher]

Pluto is a friend of mine.