A planet just like ours?

This undated handout artist rendering provided by NASA shows Kepler-22b, a planet known to comfortably circle in the habitable zone of a sun-like star. It is the first planet that NASA's Kepler mission has confirmed to orbit in a star's habitable zone — the region around a star where liquid water, a requirement for life on Earth, could persist.

WASHINGTON — 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 smack in the middle of what astronomers call the Goldilocks zone, that hard-to-find place that’s not too hot, 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 near 72 degrees, scientists say.

The planet’s confirmation was announced Monday by NASA along with other discoveries by its Kepler telescope, which was launched in 2009.

That’s the first planet confirmed in the habitable zone for Kepler, which had already found Earth-like rocky planets elsewhere. Twice before astronomers have announced a planet found in that zone, but neither have been as promising.

“This is a phenomenal discovery in the course of human history,” Geoff Marcy of University of California, Berkeley, one of the pioneers of planet-hunting outside our solar system, said in an email. “This discovery shows that we Homo sapiens are straining our reach into the universe to find planets that remind us of home. We are almost there.”

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 the planet’s a bit big for life to exist on the surface. The planet is about 2.4 times the size of Earth. It could be more like the gas-and-liquid Neptune with a rocky core and mostly ocean. “It’s so exciting to imagine the possibilities,” said Natalie Batalha, the Kepler deputy science chief.