美国国家公共电台 NPR Astronomers Find 7 Earth-Size Planets Around A Nearby Star（在线收听）

AUDIE CORNISH, HOST:

Today, scientists announced a big discovery around a star in the constellation Aquarius - seven planets about the size of Earth. And as NPR's Nell Greenfieldboyce reports, they're most likely rocky planets that could be cozy enough for life.

NELL GREENFIELDBOYCE, BYLINE: The star is about 40 light years away, right nearby in the cosmic sense. It's reddish, dim and tiny.

MICHAEL GILLON: Ten times smaller than the sun.

GREENFIELDBOYCE: Astronomer Michael Gillon is at the University of Liege in Belgium. He says the seven Earth-sized worlds are crowded close to their star, closer than the planet Mercury orbits our own sun. But because this star is so small and cool, its planets shouldn't be scorching hot. Temperatures are probably mild.

GILLON: And so they are potentially habitable. As we say, this doesn't mean habitable for a human being. We don't know. But they could have liquid water at least.

GREENFIELDBOYCE: And he says because they're close together, if you were able to stand on the surface of one of these planets and look up...

GILLON: You would see the other ones as we see the moon or a bit smaller. The view would be very impressive.

GREENFIELDBOYCE: This unusual planetary system is described in the journal "Nature," and it now holds the record for the most Earth-sized planets ever found around one star. That's why NASA held a press conference today to announce the find. Someone asked the researcher from Belgium if the planets had names yet.

GILLON: Well, we have plenty of possibilities, which are all related to Belgium beers, but we don't think they will become official, so.

GREENFIELDBOYCE: Right now the planets are just named after their host star. Now, some scientists think this star might not be so hospitable. It's not like our own sun. Early on in its life, it might have fried the planets with intense radiation. But Sara Seager, a planetary scientist at MIT, says we no longer have to just speculate. We can start looking for signs of life.

SARA SEAGER: Because nature usually is smarter than we are. And if there's any way for a life to get a foothold, we like to believe it will.

GREENFIELDBOYCE: What scientists will do next is probe the planet's atmospheres with the Hubble Space Telescope. Indeed, they've already started. Nikole Lewis is an astronomer at the Space Telescope Science Institute in Baltimore. She says these planets are ideal for this type of work.

NIKOLE LEWIS: And we can start to begin this journey in trying to understand what the air is like around rocky planets outside of our solar system.

GREENFIELDBOYCE: An even better sense of that alien air should come from a new space telescope which NASA will launch next year. Nell Greenfieldboyce, NPR News.