An Alien Earth May Be in Our Cosmic Back Yard
"Looking at thousands of red dwarf stars in the Kepler field, the lead investigator (Courtney Dressing from the Center for Astrophysics) found several dozen stars with candidate planets (probable companions that have not yet been confirmed). Out of those, she found three that were about the size of Earth, as well as being in their stars’ habitable zones, the right distance from their stars to have liquid water. Accounting for planets with orbits that don’t let them transit from our view, what she found is that 6 percent of red dwarf stars have Earth-sized planets at the right distance from the star to be potentially habitable.
That’s 1 out of 16. Out of 75 billion stars. That’s a lot of Earths. In fact, using that number and applying some statistics, Dressing and her team calculate that on average, in this part of the galaxy, Earth-like planets are only 13 light-years apart. That’s a long way to walk, but in galactic terms, that’s incredibly close. Only about three-dozen stars are known that are within 13 light-years of Earth. Could one of them bear a planet like home?"
It boggles the mind that, finally, soon, astronomers in the next 1-2 generations may actually be able to confidently say whether life might exist on other planets throughout the cosmos.
If we can determine the likelihood of life-bearing worlds, we can determine the likelihood of life.
Planets have to fall under certain criteria to have the potential to bear life as we know it. They have to be in a certain habitable "zone" around the sun - within a certain range of radii, to get that "not too hot, not too cold" effect, so liquid water can exist. Likelihood of greenhouse effect, density, etc - all these traits of worlds should eventually come into focus as better and better detection techniques are developed. Eventually, hopefully, astronomers will be able to point to some planet orbiting some star under some particular conditions and say, "Yes, it as a statistical probability that life exits on that world."
Of course, until we are able to visit such a planet (or, miraculously, contact it's inhabitants) we can't know anything for absolute sure. Heck, we live right next door to Mars and as of early 2013 we're still not sure if life ever existed there at all. But we know exponentially more about the possibility of Martian life now than we did even 15 years ago. I would predict if life on Mars exists, or ever did exist, we'll likely know for sure within the next 20 years. We're that close. So based on this article we're also very close, statistically speaking, to making a good, firm prediction about the probability of life on planets outside our solar system.
After years and years of fictional speculation about people loving on other planets around the galaxy - after imagining the lives of people living on Vulcan, Tatooine, Gallifrey, Arakis, Centauri Prime, Caprica, Tangaroa, Krypton, Hala, Aiur and many others - to imagine that the basic building blocks of such a larger universe, habitable planets, may actually exist and that we may confirm it in our lifetime is staggering.