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Jimmy Westlake: Kepler finds planets galore

One of the 150

One of the 150,000 stars caught in the Kepler spacecraft's steady stare, Kepler-11 has at least six planets orbiting it. Five of the six orbit closer to their sun than our innermost planet, Mercury, orbits our sun. None of these planets seem to orbit within their star's "habitable zone," but additional planets lying in larger, cooler orbits have not been ruled out.

— It's still hard for me to think that before 1995, there were only nine planets known to exist in the universe, and all of them orbited the sun. (Of course, this was before Pluto was demoted, thus leaving us with eight planets.)

It was then that astronomers announced the discovery of a new planet orbiting a distant sun-like star named 51 Pegasi. This first planet found orbiting another star was a huge deal, not only because it was so different from any planet in our solar system, but also because it proved that our solar system was not a fluke, that there was at least one other solar system out there.

The floodgates opened after 1995 and astronomers began finding dozens, even hundreds of other planetary systems. Their methods preferentially located huge Jupiter-like planets in close, fast and hot orbits around their stars. As of Feb. 1, 2011, astronomers had catalogued 526 exoplanets, none of which could really be considered Earth-like. That's the holy grail — finding an Earth-sized planet in its star's habitable zone, where water exists not as steam or ice, but as a cool liquid.

On Feb. 2, NASA announced that its Kepler space telescope had detected 1,235 new planets in a patch of sky no larger than your hand held out at arm's length. What's more is that 54 of these worlds seem to orbit in the habitable zone around their stars, and of these, five are Earth-sized worlds. Has the holy grail been found?

The Kepler spacecraft has been perpetually staring at the same patch of sky in the constellation of Cygnus for more than a year now, watching for tiny telltale blinks in the more than 150,000 stars that it monitors. A blink could mean that a planet is transiting across the face of its star, creating a mini-eclipse. If the blink recurs in a regular, periodic manner, chances are that it is, indeed, a distant planet. Kepler's goal is to determine, statistically, how many of the 100 billion-plus stars in our Milky Way galaxy host planets, and not just planets, but Earth-like planets. With this newest announcement, one might conclude that planets are even more numerous than the stars.

But not so fast.

Before scientists can say beyond a shadow of a doubt that these 1,235 new planets really do exist, other telescopes — on the ground and in the sky — must confirm the Kepler observations. Then and only then can we add their numbers to the growing list of exoplanets. Still, Kepler mission scientists are confident that at least 80 percent of the new finds will pan out and that within this batch of potential planets will come the first confirmation of another Earth.

Why is this important? Back in the 16th century, Nicolaus Copernicus first proposed that the Earth was not in a privileged position at the center of the universe. The discovery of other Earths would remove one of the last remaining pedestals elevating Earth above all other planets in the universe. The last pedestal will fall when we discover life itself on a distant, alien world. Can that discovery be too far off?

Jimmy West­lake teaches astronomy and physics at Colorado Moun­tain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published across the world. Visit Westlake's website at http://www.jwestlake.com.