Talk:Terrestrial planet

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So what about Pluto? It's clearly not a gas giant. So is it a terrestrial planet? Or is it a third class? Or do we not know?

Well, it's not listed in the article text but it's present in the image, along with a bunch of other bodies that are mainly ice rather than silicate (and also some that have active hydrospheres, directly contradicting the article text). I don't know the answer myself but we should either find out what the official line is or we should mention that there's ambiguity. Bryan 18:21, 28 Mar 2005 (UTC)

Pluto is, at the moment, considered a planet, and would technically be designated as a terrestial planet. However, there's so much debate over Pluto's status, especially since Sedna was discovered, that I think Bryan's idea of just mentioning an ambiguity is best. Also, I was thinking of maybe adding a list of exo-terrestial-planets, too, if nobody objects? So far, I have:

55 Cancri A e 14 ME

Gliese 777 A c 18 ME

mu Arae d 14 ME

GJ 436 b 21 ME

PSR 1257+12 A .020 ME

PSR 1257+12 B 4.3 ME

PSR 1257+12 C 3.9 ME

Gliese 876 d 6-8 ME.

I'm not sure how complete this list is, as I took these from Wikipedia's "list of extrasolar planets" and then added Gliese 876 d, which despite being mentioned on most exoplanet-related pages as the lowest-mass non-pulsar exoplanet, is not listed on the "list of extrasolar planets page." Whew. Long sentence, that. ZelmersZoetrop

Pluto (and anything that far out) would probably be better classified as a 'Kuiper Object' as technically the Kuiper Belt starts from inside Neptune's orbit. ref-Kuiper_belt.

Although the label 'Minor Planet' is adequate, i would hesitate to call Pluto 'Terrestrial' in the truest sense...

Ambiguity, as you say is probably the best course for now :) Grey Area 08:44, 29 July 2005 (UTC)

[edit] Conflicting data?

I am doing a project in school. We have to design a planet and the planet that my partner and i designed is completly water except for a few scattered volcanoes. Would animals like penguins and walruses be able to survive on a planet like this? Please answer ASAP!!!!!

See planetary habitability to begin with. I think that page will have the most data for you.

If your planet is only going to have volcanic islands then its probably not tectonically active, as this is the main continent building process. This means low biodiversity and a lesser chance that animals like penguins and walruses would arise. But nothing is impossible with a hypothetical planet. Perhaps in shallow pools surrounding your islands multi-cellularity arose, and after that the sky's the limit. Perhaps you can revisit the model and add in some continents? Marskell 13:50, 4 April 2006 (UTC)

[edit] Impact Cratering

What is the role that impact cratering had in history on the formation of terrestrial planets? —The preceding unsigned comment was added by 149.169.207.32 (talk • contribs) on 00:17, 1 September 2006.

I'm not sure I understand the question. Cratering itself doesn't affect the formation much; it's usually just used as a yardstick to measure how active the geology of a planet or moon is (if it's geologically active, it recycles its surface material, reducing the number of visible craters; if it was active but then stopped being so, the crater density can give you a rough idea of how long ago this happened).

The material that's delivered in the process of bombardment is, however, important, as it's how a lot of the volatiles posessed by the inner planets got here as the solar system was forming (how much this changed the amount of volatiles is an open question, though). --Christopher Thomas 05:14, 1 September 2006 (UTC)