Are habitable planets common? And how close?

In 2007, a team of Swiss, French and Portuguese astronomers discovered a planet with a radius only 50% larger than that of Earth. Its location within the habitable zone of its solar system indicates that any water on its surface may exist in liquid form. This planet is in orbit around a red dwarf called Gliese 581, one of the 100 closest stars to us, located only about 20 light-years away in the direction of the constellation Libra the Scales.

When you look up at a starry sky, do you ever wonder if there are Earth-like planets – and maybe even life – elsewhere in the universe?

Stéphane Udry: Those questions were already asked more than 2,000 years ago by the ancient Greeks, and we are at a very special point in time where science can start to answer at least part of that question.

That was Stéphane Udry at the University of Geneva in Switzerland. He was lead author of a 2007 paper reporting a planet – not much larger than Earth – in the habitable zone of a star only 20 light-years away.

Udry said 200 planets have been discovered so far in our galaxy. But this planet appears to have the right ingredients for life. Temperatures on its surface might be right for water to be in liquid form. Udry said he believes most stars probably have rocky Earth-like planets and – because the building blocks for life are common in the universe – life may be common as well.

Stéphane Udry: And we are just now starting to find them because we have improved the capacity of our instrumentation.

Astronomers are now hoping to identify traces of atmospheric gases that may be signs of life on other worlds.

Thanks to Research Corporation, a foundation for the advancement of science.

Our thanks to:
Stéphane Udry
Astronomer
University of Geneva in Switzerland