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Associated Press
This undated handout artist concept provided by Harvard Smithsonian Center for Astrophysics shows the newly discovered planets named Kepler-62e and -f. Scientists using NASA's Kepler telescope have found two distant planets that are in the right place and are the right size for potential life. This handout image from Harvard-Smithsonian Center for Astrophysics shows an artist concept of what these two planets, called Kepler-62-e and Kepler-62-f look like. The larger planet in the left corner is somewhat covered by ice and is f, which is farther from the star. The planet below it is e, which is slightly warmer and has clouds and may be a water world. (AP Photo/Harvard Smithsonian Center for Astrophysics)

WASHINGTON — NASA's planet-hunting telescope has discovered two planets that seem like ideal places for some sort of life to flourish. They are just the right size and in just the right place near their star.

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.

The discoveries, published online Thursday in the journal Science, mark a milestone in the search for planets where life could exist.

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 Mars.

The planets are slightly wider than Earth, but not too big. Kepler-62-e is like a Hawaiian world and Kepler-62-f is a bit nippy, more Alaskan, Borucki said.

The planets circle a star that is 7 billion years old — about 2.5 billion years older than our sun.

"If there's life at all on those planets, it must be very advanced," said Borucki.