This was the underlying question that drove the launch of the space observatory Kepler back in 2009. Although the craft has all but reached the end of its operational lifetime by now, astronomers are being kept busy sifting through thousands of potential alien planet signatures in the data it has compiled to date.
A study just released by astronomers at Berkeley and the University of Hawaii on Monday, November 4, 2013 strongly suggests that between 25 and 40 billion planets in our Milky Way Galaxy could be Earth-like. Although the numbers – obviously – vary widely, the order-of-magnitude educated guess is that ten billion of these alien planets are potentially habitable. The main conditions for tentative habitability are the planet’s distance from its parent star (such that liquid water can exist), and the size, so that the gravity isn’t crushing to life forms similar to humans.
“Planets seem to be the rule rather than the exception,” noted study leader Erik Petifura from the University of Berkeley. It was necessary to sift through three years of data collected by the Kepler Space Telescope in order to find these water-friendly planets. In truth, the figures are a result of extrapolations made from a smaller sample size using a program written by Petifura.
So far, astronomers have been able to study 3,538 of the alien planets found by the Kepler Space Telescope, of which just about 650 of these are Earth-sized. Just 104 of these are also in the habitable zone, but there are still thousands left from Kepler’s compiled data to be catalogued. Astronomer Jason Rowe puts a slight damper on too much optimism for planets precisely like Earth. “There’s a wide variety of systems out there. If you can imagine it, the Universe probably makes it.”
So far, the closest alien planet found by the Kepler Space Telescope is 12 light years away from Earth. Close is, of course, a relative term, as this 72 trillion mile distance is completely inaccessible to any craft man has ever made – by far. If the sun was a football field away from you, this planet would be on the moon.
The Kepler Space Telescope’s discoveries extend the scientific realm to tantalizing heights, and suggest that we may be close to discerning whether there’s actually life of our kind on any of these planets. Such discoveries are likely decades away, but they were inconceivable to us in our meager beginnings.