When you consider the millions/billions of galaxies each with millions/billions of stars the possibility of Earth [sic--more properly Terra] being unusual becomes a little difficult to believe...the odds are simply against it.
Interestingly non-believers only think about odds when it comes to non-observable assumptions ...
I used to think exactly that; in fact, forty years ago I wrote a long school paper arguing exactly that. Indeed, that was Carl Sagan's argument.
However, it turns out to be a totally fallacious argument. Sagan posited two parameters (you mentioned only one) for the existence of life on even one planet anywhere in the universe. But scientists have been looking into that, and now they have over 200 (and rising rapidly) such parameters, all of which must be exquisitely fine-tuned for life to exist anywhere. The true odds of even one planet being able to support life anywhere in the universe are (very conservatively stated) much less than one in 10 to the 40th.
I'll mention just two examples:
* If earth were just 1% closer to or farther from the sun, the water cycle would break down and life would not exist on earth. (Actually, this is two parameters: not only must earth's orbit be the right distance, but it also must be nearly circular.)
* If earth's mass (i.e., its gravity) were 2% larger or smaller, life would not exist on earth. You've noticed that water vapor (H2O, atomic weight 18) rises as clouds. If the earth were slightly smaller, those clouds would simply keep on going, higher and higher, until they were in space. However, if the earth were slightly larger, then methane gas (CH5, atomic weight 17) would not escape into space as it does, and we would all suffocate. Methane gas is the technical term for flatulence--not a pretty picture, is it?
There are over 200 parameters like that which must be right for life to exist on a planet. These factors work on the extra-galactic level, the galactic level, the solar-system level, and the planetary level.
Don't take my word for it--see for yourself:
http://www.reasons.org/resources/apologetics/index.shtml#design_in_the_universe
Both terms are very old, just different languages, and both mean the same thing--this place here. Earth is not capitalized unless it happens to be the first word in a sentence or in a headline or title.
Actually the opposite is more logical...
The more the count, the more probably their are "usual charactistics".. and less options..