Moons of Newfound Planets May Hold Necessities for Life

Scientists who want to find life outside the solar system might try the moons of some recently discovered planets, a study suggests.

Researchers recently found evidence of planets around the stars 16 Cygni B and 47 Ursa Majoris. If moons orbit those planets, “these are good places to look,” said researcher Darren M. Williams.

That’s because the planets are about the right distances from their stars that any moons might be about the right temperature to have liquid water, said Williams, a graduate student in astronomy and astrophysics at Pennsylvania State University.

The planets themselves are thought to be gas balls and so not amenable to life. The planets haven’t been seen, but scientists think they’ve detected the gravitational tugs of the planets on the stars.

There’s no evidence of any moons around the apparent planets. But Jupiter and Saturn have moons, so maybe the proposed giant planets around the two distant stars do, too, Williams said.

The idea of life on the moons is speculation, but Williams said he thought it was quite likely that microbial life exists there. He discusses the issue with colleagues in the Jan. 16 issue of the journal Nature.

To support life like that on Earth, a moon would need at least about one-eighth the Earth’s mass so that it could hang on to an atmosphere, the researchers concluded. Earth’s moon has only about one-tenth of this required mass.

And a moon would need a magnetic field to keep charged particles from chipping its atmosphere away, they said. Jupiter’s moon Ganymede was recently found to have a magnetic field.