Scientists discover 'Goldilocks planets'
WASHINGTON — NASA's planet-hunting telescope has discovered two planets that seem like ideal places for some sort of life to flourish. And they are just the right size and in just the right place.
One is toasty, the other nippy.
The distant duo are the best candidates for habitable planets that astronomers have found so far, said William Borucki, the chief scientist for NASA's Kepler telescope. And it's got astronomers thinking that similar planets that are just about right for life — “Goldilocks planets” — might be common in the universe.
The discoveries, published online Thursday in the journal Science, mark a milestone in the search for planets where life could exist. In the four years that Kepler has been trailing Earth's orbit, the telescope has found 122 exoplanets — planets outside our solar system.
In the past, those planets haven't fit all the criteria that would make them right for life of any kind from microbes to man.
Many planets aren't in the habitable zone — where it's not too hot and not too cold for liquid water. And until now, the few found in that ideal zone, were just too big. Those are likely to be gas balls like Neptune and that's not suitable for life.
Similarly, any Earth-size planets weren't in the right place near their stars, Borucki said.
In the Goldilocks game of looking for other planets like ours, the new discoveries, called Kepler-62-e and Kepler-62-f are just right. And they are fraternal twins. They circle the same star, an orange dwarf, and are next to each other — closer together than Earth and its neighbor Mars.
The planets are slightly wider than Earth, but not too big. Kepler-62-e is a bit balmy, like a Hawaiian world and Kepler-62-f is a bit frosty, more Alaskan, Borucki said.
The pair is 1,200 light-years away; a light-year is almost 6 trillion miles.
“This is the first one where I'm thinking ‘Huh, Kepler-62-f really might have life on it',” said study co-author David Charbonneau of Harvard. “This is a very important barrier that's been crossed. Why wouldn't it have life?”
To make it warm enough for life the planet would need greenhouse gas trapping its star's heat because the star only gives off one-fifth the energy of our sun, but that's something that is likely to happen, Borucki said.