A newly discovered planet is eerily similar to Earth and is sitting outside our solar system in what seems to be the ideal place for life, except for one hitch: It's a bit too big.
The planet is not too hot and not too cold, where water, which is essential for life, doesn't freeze or boil. And it has a shopping mall-like surface temperature of nearly 72 degrees, scientists say.
The planet, whose confirmation was announced Monday by NASA, was spied by the Kepler space telescope, which was launched on a planet-hunting mission in 2009.
"This is a phenomenal discovery in the course of human history," Geoff Marcy of the University of California at Berkeley, one of the pioneers of planet-hunting outside our solar system, said in an email.
The new planet — named Kepler-22b — has key aspects it shares with Earth. It circles a star that could be the twin of our sun and at just about the same distance. The planet's year of 290 days is even close to ours. It likely has water and rock.
The only trouble is that the planet is a bit big for life to exist on the surface. It is about 2.4 times the size of Earth. It could be more like the gas-and-liquid Neptune with only a rocky core and mostly ocean, scientists said.
Chief Kepler scientist William Borucki said he thinks the planet is somewhere between the size of Earth and Neptune. Measurements next summer may help astronomers have a better idea of its makeup, he said. The planet is 600 light years away. Each light year is 5.9 trillion miles. It would take a space shuttle 22 million years to get there.