updated 10/16/2012 9:19:41 PM ET 2012-10-17T01:19:41

Scientists have found an Earth-sized planet circling a neighbor star just 4 light-years away.

No need to brush up on extraterrestrial etiquette quite yet, however. The planet, which flies around its parent star 10 times closer than Mercury orbits the sun, probably is inhospitable for life since its temperature would be more than 2,240 degrees Fahrenheit -- far too hot for liquid water to exist on the surface. Water is believed to be necessary for life.

But the newly found planet orbiting Alpha Centauri B, a sun-like star roughly 25 trillion miles away, could have better-positioned siblings.

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So far, scientists have only ruled out the possibility of massive planets with orbital periods of 200 days or less around Alpha Centauri B, so that leaves plenty of room for the detection of low-mass planets in the star's so-called "habitable zone" -- the distance where water can exist on a planet's surface, Dumusque added.

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“Most of the low-mass planets are in systems of two, three, up to six or seven planets, so finding in our closest neighbor one Earth-mass planet ... opens a really good prospect for detecting planets in the habitable zone in the system that is very close to us,” astronomer Stephane Udry, with Geneva University in Switzerland, told reporters at a press conference on Tuesday.

"In that sense, it is a landmark," Udry said.

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The measurement is difficult because of variations in the star's light caused by other phenomenon, such as flares and magnetic storms, similar to sunspots on the sun.

“Trying to extract a signal that you are interested in when it is in the presence of “noise” -- in this case the variability of the star -- is difficult. One has to apply special analysis methods and tricks. The real challenge, in this particular case, was in how to analyze the data,” astronomer Artie Hatzes, with Thuringian State Observatory in Tautenburg, Germany, wrote in an email to Discovery News.

“I still have my doubts,” Hatzes added. “Even though there is clearly a signal in the data at 3.26 days, the nature of this is still open to debate.”

More data -- and more sensitive instruments -- will nail down whether the planet actually exists or not, and if it has any siblings.

“Everything we know about this system so far is extremely tantalizing," said astronomer Greg Laughlin, with the University of California in Santa Cruz. “This is our backyard and to find out that planet formation did occur there is just extraordinarily exciting.” The research appears in this week’s Nature.

© 2012 Discovery Channel


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