well, look at it this way;
There are approximately 100,000,000,000 galaxies in the universe. Perhaps you could tack on another zero or two, but 100 billion is a conservative estimate.
The Milky Way, an average sized galaxy, has approximately 100,000,000,000 stars.
So not counting stars that are not part of any galaxy, there are roughly 10,000,000,000,000,000,000,000 stars in the universe. That's 10 sextillion stars! That's alot! of those 10 sextillion, we have been able to observe the extrasolar planetary systems of about 120 of them. That leaves us about 9,999,999,999,999,999,999,880 stars left to explore.
Even if the odds of an Earthlike planet forming are 1 in a million, that leaves us with a cool 100,000 Earth-like planets in the Milky Way, or 10,000,000,000,000 (10 trillion) Earth like planets in the universe.
In other words, it is exceedingly likely that one exists, but for now, we just don't know. There is a chance, however small, that Earth is the only planet in the universe with life, and there is also a chance, however small, that every 100th or even 10th star has an Earth-like planet.
The problem, of course, is not if one exists, but how to get there. The nearest star. Alpha Centauri, is 4 light years away, which is 23,516,000,000,000 miles away. And that is just a stone's throw in the universe. Andromeda, the nearest galaxy, is 2,500,000 light years away. That's a whooping 14,697,500,000,000,000,000 miles! Unless we figure out a way around that pesky speed of light, we aren't going anywhere, anytime soon.
2007-08-19 15:45:38
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answer #1
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answered by Anonymous
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MJR gets a star from me.
I just want to add that in our Solar System we can easily see that nothing has the attributes of Earth (and we have no technology to terraform, as somebody above pointed out).
As for planets orbiting other stars, I think everybody is expecting too much of science. The most we will ever know (or in the foreseeable future) is that one of these planets could be in a similar temperature range and some similar chemistry can be detected ; eg water, carbon.
The planets size and distance from its star can be inferred by its gravitational effect on the star, and its chemistry by spectroscopic technology.
Note the word I used is "inferred". We can't even come to a conclusion about life being present on Mars, our second closest neighbour. Nothing found so far out beyond the Solar System is anything like as suitable as Mars, yet as close as Mars is, and with probes marching all over it taking samples, scientists still don't know if life is even possible on Mars.
Now go a millions times as far away - that's how far the nearest stars are. You can't see the planets out there - they are inferred to be there by their effect on the their star. Their light will add a tiny difference to the light of the star so that with spectroscopy you can just about separate what chemistry is in the star and what morsel is actually attributable to the planet.
That will be the story for a very long time to come. The stars are just too far away.
2007-08-19 23:11:56
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answer #2
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answered by nick s 6
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I am certain of it, problem is, no one has yet discovered it. Who knows, you could be the first! Get out there and start looking, I know I am!
I hope this helps, good luck! I really hope you can find at least one of the rare planets!
2007-08-19 22:30:32
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answer #5
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answered by ngc7331 6
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