A newly discovered planet orbiting Gliese 581 is the so far most Earthlike discovered yet. With scientists still marveling at the incredible similarities present in the new planet orbiting in the "habitable zone" around Gliese, and its relative proximity to Earth, the prospect of colonizing other worlds and finding planets that may have alien life on them seems closer to reality than ever.
20 years ago the prospect of finding another planet like Earth was one of the most distant and impossible seeming prospects to confront the world of science. The thought that anywhere in the galaxy there may or may not be alien life was more than enough to leave many scientists with the grim prospect that Earth may be the only planet habitable in the universe. And yet a planet just recently discovered is so close to Earth's own that many are calling it Earth's twin. Though the planet may be Earth's fraternal twin rather than an identical one, the discovery just goes to show how incredibly close a habitable or (better yet) inhabited planet may be. And given a couple million years it is possible Gliese 581's satellite may even be the perfect size for human life through natural events.
The planet rests at just the right distance from its sun, meaning water on its surface would remain liquid on its surface. Its size suggests the planet's surface would have a solid surface, and may even possess life on it if the conditions are right. Of course further study will be necessary to confirm this, and it's too early to even begin suggesting life may be present on Gliese 581's surface. But the perfect distance, size, and type of sun may provide a statistically significant image of what our universe is truly like and just how much life there probably is in it.
Gliese 581 is one of only 9 stars that have been studied thoroughly to discover whether Earthlike planets surround it. If Gliese 581g, the name of the possible Earth twin is truly anywhere near habitable, this is already showing a statistical significance of one out of nine systems discovered having possibly inhabitable planets orbiting it. If this were the case, then the billions of stars in our galaxy suggest life is not merely a rare occurrence in space, but could be quite prolific throughout the universe. So prolific, in fact, that there could be a whole 'Star Trek-like' universe out there complete with millions of various forms of life of varying degrees of advancement.
So with this new discovery coming forth in such a short period of time (only 15 years since the search really got underway) and already a planet being discovered that could very well possess life, what are the chances of more being out there that truly do?
And the proximity of only 20 lightyears away isn't as daunting as it may seem. A proposal by Stephen Hawking suggests that a rocket running constantly for six years could in theory achieve speeds approaching light speed, but never breaking them. By doing this the craft could reach a planet 20 light years away in a span of no more than 23 years travel. A long haul by any means, but one that the human race could theoretically perform with sufficient determination and technical ability.