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UH astronomers estimate Milky Way has 17-billion earth-sized planets

By Alicia Chang

AP Science Writer

LAST UPDATED: 11:45 a.m. HST, Jan 07, 2013

LONG BEACH, Calif.>> University of Hawaii astronomers hunting for Earth-like planets now have many places to look. 

A new estimate released today suggested the Milky Way galaxy is home to at least 17 billion planets similar in size to our planet. That's more than two Earth-size planets for every person on the globe.

Just how many are located in the sweet spot where water could exist is "simply too early to call," said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, who presented his work at an astronomy meeting today.

It's the first reliable tally of the number of worlds outside the solar system that are the size of Earth, but the hunt for our twin is far from over.

Despite the explosion of exoplanet discoveries in recent years, one find remains elusive: A planet that's not only the right size but also in the so-called Goldilocks zone where it's not too hot or too cold for water to be in liquid form on the surface.

The sheer number of Earth-size planets gives astronomers a starting point to narrow down which ones are in the habitable zone.

Fressin and his team came up with their figure by conducting a fresh analysis of data collected by NASA's Kepler spacecraft, which was launched in 2009 to track down other Earths. They estimated at least one in six stars in the galaxy hosts a planet the size of ours, translating to at least 17 billion Earth-size worlds.

Using a different method, a team from UH and the University of California, Berkeley separately came up with a similar estimate. They calculated 17 percent of distant stars have planets that are the same size as Earth or slightly larger.

The findings were presented at the American Astronomical Society in Long Beach, Calif.

Meanwhile, the Kepler spacecraft continues to spot planets as they pass between Earth and the star they orbit. It found 461 new candidate planets, bringing the total to 2,740 potential planets, said mission scientist Christopher Burke at the SETI Institute.

Most of the new Kepler finds were driven by discoveries of Earth-size planets and super-Earths. Four of those are thought to reside in the Goldilocks zone, but more observations are needed.

Fressin said it's clear that rocky planets abound outside the solar system.

"If you look up on a starry night, each star you're looking at — almost each one of them — has a planetary system," Fressin said.

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Nevadan wrote:
This is news? One year ago, NASA showed a photo of "a lake on the moon". Wow! We can now build a colony on the moon, ala Newt Gingrich in his famous speech last year, seeking the Republican presidential candidacy. NASA conveniently forgot that the moon is surrounding by vacuum, and water cannot survive in vacuum. NASA is desperate, and losing credibility. So is UH astronomers?
on January 7,2013 | 08:54AM
MizuInOz wrote:
I suppose you are right. How can there possibly be any other planets revolving around any other stars in our galaxy, much less the entire Universe? I guess God, G_D, Allah or whomever you find as your creator in residence is only capable of creating and then ruling and reigning on one planet at a time. Pretty limiting thinking. I know you didn't say any of that but it is an excuse that is used to deny the remote possibility of earth like planets somewhere else "out there"... Poor Kepler.Just can't get a break. Even the Vatican has come to the conclusion of the possibility of potential visitors from elsewhere. they now have a special emissary to greet any extra-terrestrial visitors. These findings are not from desperation nor to persuade the religious. They are one of the results of an extensive survey for exo-planets by academics using tools put in place by NASA. However, Nevadan, it may seem like a real gamble to consider that there might be some value in all of this unless of course you can build a rockin' Vegas on one of these places. Aye? Many of the advances that you enjoy on a daily basis are because of research by astrophysicists. Do you use a mobile phone, computer, watch television, drink pure water, etc? Thank the desperate NASA folks for some of those advances. Aloha Kakou
on January 7,2013 | 09:20AM
Nevadan wrote:
Aloha UH Astronomers. I know you guys are good. Some of you probably know me in real person. But making a big deal out of an oral report at a professional meeting reflects desperation, and lacks credibility. Your work was not peer-reviewed. I would like to see you guys submit a report to the journals NATURE or SCIENCE. Report it when accepted.
on January 7,2013 | 09:54AM
Mythman wrote:
You mean Earth is not the only meaningful planet there is and therefore Barry is not the most important person in the galaxy and maybe the universe? That it might be possible that other planets have governments that spend even more dollars than Barry's government? I'm in shock.
on January 7,2013 | 11:07AM
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