insects are animals.

I assume that the sentence was written this way to emphasize the large number of insect species separately from other animal species. (The majority of animal species are insects.)

Should Earth be capitalized?

only in the context of celestial bodies

Aren't we in this context here?

No. It's only because this would look weird: Alpha Centauri, Betelgeuse, Rigel, earth, Milky Way

Huh? I'm not saying to put Earth the planet in lowercase.

I'm saying that it should be capitalized here. It's the Earth and its surface. You're not talking about the earth in your garden.

I don't see how this is any different from the uses here: http://en.wikipedia.org/wiki/Earth (which all have Earth capitalized).

e.g.:

The atmospheric pressure on the surface of the Earth averages 101.325 kPa, with a scale height of about 8.5 km.

The Kármán line, defined as 100 km above the Earth's surface, is a working definition for the boundary between atmosphere and space.

Large areas of the Earth's surface are subject to extreme weather such as tropical cyclones, hurricanes, or typhoons that dominate life in those areas.

Furthermore, I think it should be "rainforests" (but I can't prove that writing it as two words is not acceptable).

Sorry, I should have been more clear.

"Capitalize earth only when using it in association with the names of other astronomical bodies that are capitalized.
The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus…
The sun warms the earth."

http://www.wwu.edu/journalism/s...7labmanual.htm

Styles vary, but this is what I've always been told in school, and it seems to be the most common style.

Can't say I much like that convention. Seems ambiguous.

Hey sc, wanna bash on English with me for a bit? I can probably take your side of the argument here.

I don't particularly like it either (from a logical standpoint; I think it looks nicer), but I'm not in the business of telling people how their language should work.

But you agree that, by that convention, the entire Wiki article is riddled with improper capitalizations, right?

>but I'm not in the business of telling people how their language should work.

A language is not some sacred God's creation ...

>But you agree that, by that convention, the entire Wiki article is riddled with improper capitalizations, right?

Not that article: The whole site...

> But you agree that, by that convention, the entire Wiki article is riddled with improper capitalizations, right?

By that convention, sure, but conventions are not universal.

> Not that article: The whole site...

Wikipedia has a style guide. See:

http://en.wikipedia.org/wiki/Wi...lestial_bodies

Wikipedia doesn't always follow this guide.

Oh, okay. I didn't know they had such a detailed guide. I see they're a bit more liberal with the rules than the aforementioned convention.