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Astronomers spot Kepler-186f, the most Earth-like planet yet

LOS ANGELES (AP) -- Astronomers have discovered what they say is the most Earth-like planet yet detected - a distant, rocky world that's similar in size to our own and exists in the Goldilocks zone where it's not too hot and not too cold for life.

The find, announced Thursday, excited planet hunters who have been scouring the Milky Way galaxy for years for potentially habitable places outside our solar system.

"This is the best case for a habitable planet yet found. The results are absolutely rock solid," University of California, Berkeley astronomer Geoff Marcy, who had no role in the discovery, said in an email.

The planet was detected by NASA's orbiting Kepler telescope, which examines the heavens for subtle changes in brightness that indicate an orbiting planet is crossing in front of a star. From those changes, scientists can calculate a planet's size and make certain inferences about its makeup.

The newfound object, dubbed Kepler-186f, circles a red dwarf star 500 light-years from Earth in the constellation Cygnus. A light-year is almost 6 trillion miles.

The planet is about 10 percent larger than Earth and may very well have liquid water - a key ingredient for life - on its surface, scientists said. That is because it resides at the outer edge of the habitable temperature zone around its star - the sweet spot where lakes, rivers or oceans can exist without freezing solid or boiling away.

The planet probably basks in an orange-red glow from its star and is most likely cooler than Earth, with an average temperature slightly above freezing, "similar to dawn or dusk on a spring day," Marcy said.

The discovery was detailed in Friday's issue of the journal Science.

Lead researcher Elisa Quintana at NASA's Ames Research Center said she considers the planet to be more of an "Earth cousin" than a twin because it circles a star that is smaller and dimmer than our sun. While Earth revolves around the sun in 365 days, this planet completes an orbit of its star every 130 days.

"You have a birthday every 130 days on this planet," she said.

Scientists cannot say for certain whether it has an atmosphere, but if it does, it probably contains a lot of carbon dioxide, outside experts said.

"Don't take off your breathing mask if you ever land there," said Lisa Kaltenegger, a Harvard and Max Planck Institute astronomer who had no connection to the research.

Despite the differences, "now we can point to a star and know that there really is a planet very similar to the Earth, at least in size and temperature," Harvard scientist David Charbonneau, who was not part of the team, said in an email.

Since its launch in 2009, Kepler has confirmed 961 planets, but only a few dozen are in the habitable zone. Most are giant gas balls like Jupiter and Saturn, and not ideal places for life. Scientists in recent years have also found planets slightly larger than Earth in the Goldilocks zone called "super Earths," but it is unclear if they are rocky.

The latest discovery is the closest in size to Earth than any other known world in the habitable region.

Kepler-186f is part of a system of five planets, all of which are roughly Earth's size. However, the other planets are too close to their star to support life.

Astronomers may never know for certain whether Kepler-186f can sustain life. The planet is too far away even for next-generation space telescopes like NASA's overbudget James Webb, set for launch in 2018, to study in detail.

Kepler completed its prime mission and was in overtime when one of the wheels that keep its gaze steady failed last year. NASA has not yet decided whether to keep using the telescope to hunt for planets on a scaled-back basis.


AP Science Writer Seth Borenstein contributed to this report.

Join the discussion

1000|Char. 1000  Char.
phoenix44al April 17 2014 at 3:15 PM

There is no place like home! No other planet is more beautiful and enchanting like our blue planet.
We are just one majestic planet, won't change it for another. All we have to do is to get along and learn to live side by side and treat our Mother Earth with due respect and try to conserve the little we have left for posterity.

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1 reply
ferrariqx phoenix44al April 17 2014 at 3:23 PM

Well, I understand the sentiment of your statement even though there isn't much truth to it. Since you've never traveled to another planet, much less the trillions of planets in the Universe, there is no way for you to know if their is one more beautiful. My guess is that there are wonders to behold on those planets just like there are on Earth.

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1 reply
nan.pelosi ferrariqx April 17 2014 at 3:29 PM

Dinosaurs did not become extinct, they just flew away!

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cedatty April 17 2014 at 3:31 PM

Stop this one. I want to get off. When can I leave?

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1 reply
pboucard50 cedatty April 17 2014 at 3:35 PM

You left years ago.

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1 reply
cedatty pboucard50 April 17 2014 at 4:14 PM

I not left. You da leftie.

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capowp April 17 2014 at 3:31 PM

Lets spend the time and money to fix this planet we now live on.

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2 replies
Say NO to libs! capowp April 17 2014 at 3:36 PM

We could if the politicians and their pals stopped pocketing most of what they steal from us in the BS name of Global Warming/Climate Change.

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pboucard50 capowp April 17 2014 at 3:37 PM

Why? Let's invest in some new endeavors, like we invested in this land of illegal Mexicans and Native Americans.

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Jim April 17 2014 at 11:06 PM

I just hope that it has no oil beneath its surface. When we are faced with going there to survive I would hope that the oligarchs are forced to remain here on Earth with their billions (perhaps trillions by then) of dollars in their gated communities.

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1 reply
mark and sheri Jim April 18 2014 at 12:52 AM

Huh? Bashing the Rich has WHAT to do with the article?

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hank1040 April 17 2014 at 3:30 PM

surely there is life in the expanse above us...in the scheme of things we can only wonder

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1 reply
pboucard50 hank1040 April 17 2014 at 3:38 PM

You really believe God messed up twice?

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a3bus26 April 17 2014 at 11:09 PM

pretty amazing if accurate

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Mr Gary April 17 2014 at 3:28 PM

this infomation fasinates me ever since my oldest son informed me that our name is on a disc. resting on a rover on the planet Mars.
Gary M Snyder

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Beautiful April 17 2014 at 11:14 PM

Until a method of traveling these kind of distances instantly, we can only conjecture what kind of life is there.
If it is anything like Star Trek, there will be scantly clad females, multi colored lighting and cool retro future furniture.

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2 replies
mdesah Beautiful April 17 2014 at 11:42 PM

Sounds good. Beam me down Scottie

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sportsagent4 Beautiful April 18 2014 at 12:22 AM

I want a sexy semi naked Klingon woman - did you see that episode?

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LPAldama April 17 2014 at 11:14 PM

See we are the Aliens !!!! You have'nt seen anything left.........

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Bernie April 17 2014 at 11:00 PM

>The planet probably basks in an orange-red glow from its star and is most likely cooler than Earth, with an average temperature slightly above freezing<

Good….. the Floridians won’t want to move there…….

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1 reply
anteekazoid Bernie April 18 2014 at 12:30 AM

They could end up driving there by accident.

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