Like Pluto-gate, are there any other planets that could be found not to be planets?

Question

http://au.news.yahoo.com/060824/2/109sg.html

Please explain your answer as well, thanks.

Answer 1

Nice, Pluto-gate. First I've heard that, but the "gate" reference always seems to pop up with an contraversy. I don't think there are any other planets in question, at least of the eight remaining in our Solar System. All were discovered well before Pluto, in the 1700s (Pluto wasn't found until 1930) and are much larger than Pluto, so there would be no basis for demoting other planets.

Answer 2

No the others were all formed around the same time, and amoung the two groups already named (inner/terrestrial planets and outer/gaseous planets) the composition is similar. They all fit well into the new definition as well.

Controversy can arise however when dealing with extrasolar planets. Now we are having trouble making a definate line between brown dwarfs and large gaseous planets, and are making guesses based on size when what we really need to know are their origins. When we are able to detect smaller planets this argument will come up again and perhaps not be solved for some time since it is nearly impossible to figure out the origins of distant objects and is difficult to find their composition.

Answer 3

First it would be a good idea to look at the new "definition" of what is considered a planet.

The IAU has defined a planet to be:
"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 neighborhood around its orbit."

Pluto is disqualified due to the third clause as its orbit overlaps with the orbits of other ice bodies in the Kuiper Belt, not to mention that of another (unquestioned) planet....Neptune.

Under this new definition, no other former planets (the ones we all knew and loved) are in danger of loosing their status.

The main point of controversy for many people over Pluto's status as a planet is due to its size. Many people cited evidence that even our own moon (AKA "the moon") was larger than Pluto.

Pluto's equatorial radius: 1151 km
Pluto's Mass: 1.3 E22 kg

By comparison,
Our own moon's equatorial radius: 1737.4 km
Our own moon's mass: 7.3483 E22 kg

Mercury's radius: 2439.7 km
Mercury's mass: 3.3022 E23 kg

Jupiter's radius: 71492 km
Jupiter's Mass: 1.8987 E27 kg

So you can see, Pluto really was pretty small by comparison.

Answer 4

Well, now that you ask...

Mercury is kinda small, much smaller than many moons around other planets... so I say we scratch Mercury from the list.

Uranus and Neptune? Well they aren't even visible in the night sky to the unaided sky. And besides planet means 'wanderer' because they wander across the sky. Since the ancients defined planets and didn't know about Uranus and Neptune, perhaps we should scratch them off the list too.

Jupiter, you know it's kinda big, in fact, I'm thinking it might be a proto-star. So scratch that one off the list too.

So what do we have left? Mars and Venus, hmm, yeah, 3 sounds like a good number. So now we have: Earth, Mars and Venus in the solar system.

How's that?

Oh, how silly of me, I forgot Saturn. Hmm, well maybe we should keep Saturn on the list too, I guess 4 is a nice round number...

Answer 5

Nope. They specifically wrote the definition so that the other 8 would be official planets, and so that the number will (probably) never grow again. Personally I think the whole thing is just silly - it's all just semantics.

Answer 6

I agree with wcivils. The whole controversy really only pertains to the scientific community. So much speculation about a frozen far off celestial body, and so little attention to the millions of problems facing the burgening population of earth.

Answer 7

well now that the world is being politically correct now-awadays you dont know what to expect..like one day, the moon may actually be made of cheese...and jupiter is just gas so i dont think that counts either, cause people are stupid and have stupied reasoning to make everyone happy about everythigna dnt they cant do that no can they? umm no