NASA spots scores of potentially livable worlds

WASHINGTON — An orbiting NASA telescope is finding whole new worlds of possibilities in the search for alien life, spotting more than 50 potential planets that appear to be in the habitable zone.

In just a year of peering out at a small slice of the galaxy, the Kepler telescope has discovered 1,235 possible planets outside our solar system. Amazingly, 54 of them are seemingly in the zone that could be hospitable to life — that is, not too hot or too cold, Kepler chief scientist William Borucki said.

Until now, only two planets outside our solar system were even thought to be in the "Goldilocks zone." And both those discoveries are highly disputed.

Fifty-four possibilities is "an enormous amount, an inconceivable amount," Borucki said. "It's amazing to see this huge number because up to now, we've had zero."

The more than 1,200 newfound celestial bodies are not confirmed as planets yet, but Borucki estimates 80 percent of them will eventually be verified. Some think the figure may be even higher.

After confirmation, it's another big step to prove that a confirmed planet has some of the basic conditions needed to support life, such as the proper size, composition, temperature and distance from its star. More advanced aspects of habitability such as atmospheric conditions and the presence of water and carbon require telescopes that aren't built yet.

Just because a planet is in the habitable zone doesn't mean it has life. Mars is a good example of that. And even if some these planets are found to contain life, it may not be intelligent life; it could be bacteria or mold or some kind of life form people can't even imagine.

All the celestial bodies Kepler looks at are in our Milky Way galaxy, but they are so far away that traveling there is not a realistic option. In some cases it would take many millions of years with current technology.

But what Kepler is finding in distant parts of the galaxy could be applied to exploring closer stars, astronomers say. And there's always the chance that scientists could pick up the signatures of life in alien atmospheres using more sophisticated instruments, or even find innovative ways to make contact with faraway civilizations.

"Our grandchildren will have to decide what's the next step," Borucki said at a NASA news conference. "Do they want to go there? Do they want to send a robot?"

Worlds galore
Before Wednesday, the count of confirmed planets outside the solar system stood at 519. That means Kepler could triple the number. Those findings are from Kepler's scanning of just one-four-hundredth of the night sky, so the actual number of planets out there is presumably hundreds of times greater, Borucki said.

That is exciting to astronomers, since the more planets there are, the greater the odds that life exists elsewhere in the universe.

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Yale University astronomer Debra Fischer, who wasn't part of the Kepler team but serves as an outside expert for NASA, said the new information "gives us a much firmer footing" to hope for worlds that could harbor life.

Another outside astronomer, Lisa Kaltenegger of Harvard University, called the findings "exciting good news."

Kepler also found that there are many more relatively small planets than there are giant planets. That is encouraging, too: Astronomers think a planet needs to be solid — rocky like Earth or Mars — for life to develop. And very large planets are unlikely to be solid; they are more prone to be gas behemoths like Jupiter.

Sixty-eight of the planet candidates Kepler found are considered Earth-sized, including the first ones ever discovered to be smaller than Earth. An additional 288 planets were less than twice the size of Earth, which is still in that optimum zone for life.

Only five of the 54 potentially habitable celestial bodies are close to the size of Earth, while the rest approach the gassy girths of Neptune or Jupiter, Borucki said. Such gas giants shouldn't necessarily be ruled out as locales for life: It's possible that moons orbiting those planets could be habitable — like Pandora, the fictional moon of Prometheus in the movie "Avatar." Borucki even speculated that an alien civilization would welcome the variety.

"For your Christmas vacation you could go from one moon to another," he joked.

Real-estate values going up
To be in the habitable zone, a planet has to be the proper distance from its star so that it could have liquid water on its surface, at least sometimes. The proper distance varies by star; smaller, weaker stars, for example, would require planets to be closer to be habitable.

Because of the various factors that could make planets more prone to life, University of California Santa Cruz astronomer Greg Laughlin created a formula that puts a dollar value on these far-off planets, with the idea that the first planet that is incredibly similar to Earth would have a value of $1 million.

Until Wednesday, the highest value Laughlin assigned to an exoplanet, which is what astronomers call a planet outside our solar system, was a measly $158. One of Kepler's new discoveries is worth nearly a quarter-million dollars, Laughlin figures.

Kepler was launched in 2009 and orbits the sun between Earth and Mars. It needs time to find planets, identifying them by watching them repeatedly move past the star they orbit.

Kepler scientists are strict about calling candidate planets confirmed. Out of the hundreds of candidate planets announced last year, only 15 of Kepler's discoveries had been confirmed  — including six that were announced Wednesday. All of those six are way too hot for life.

More on extrasolar planets:

• Planetary six-pack poses puzzles
• Planet hunters sift through piles of data
• Probe finds 'planetary missing link'
• Millions of Earths? Talk causes a stir

This report was supplemented by msnbc.com.