Earth-Sized World Found Next Door

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.

“From statistical studies, low-mass planets are very frequently found in multiple systems,” lead researcher Xavier Dumusque, with the University of Geneva in Switzerland, wrote in an email to Discovery News.

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

Planets positioned the same distance as Earth is to the sun would take 365 days to orbit a parent star of the same type and size as the sun. Alpha Centauri B’s newly found world circles in just 3.2 days, but the star is roughly half the size of sun, which puts its habitable zone about where Venus is in our solar system. Venus orbits in 225 days.

source : http://news.discovery.com/space/earth-sized-planet-121017.html





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