A team of astronomers in Europe has found what appears to be an Earth-like planet with many of the right conditions to support life. And it’s only 44 light years away – practically around the corner, in cosmic terms.
The newfound planet, dubbed HD 40307g, is within its host star's “habitable zone.” That means it’s just the right distance away from its sun to allow liquid water, which is critical for life as we know it.
The planet is about seven times the mass of Earth, so it’s likely heavy enough to have an atmosphere, says the discovery team in this week’s issue of the journal Astronomy & Astrophysics.
One of the astronomers who discovered the new planet, Guillem Anglada-Escude of the University of Goettingen, says the planet’s star, HD 40307, is “a perfectly quiet” old dwarf star that’s orbited by five already-discovered planets.
“So there is no reason why such a planet could not sustain an Earth-like climate,” he said in a statement.
What’s most exciting is that this new planet is likely rotating on its own axis as it orbits, creating a daytime and nighttime, like that seen on Earth.
Hundreds of exoplanets – planets that exist outside our solar system -- have been discovered in the last two centuries, but only a few have been in the “habitable zone.” And of them, only a fraction actually rotate as they orbit, so one side of the planet is always in darkness.
What’s als exciting about the discovery is how it was made. The astronomers found the planet by examining data from the HARPS spectrograph, an instrument attached to a telescope at the European Southern Observatory in Chile that helps to pinpoint stars.
The HARPS device is able to pick up tiny changes in the colour of the light coming from a host star as it wobbles under the gravitational pull of its planets.
"This significantly increased our sensitivity and enabled us to reveal three new planets around the star," said Mikko Tuomi.
Carnegie co-author Paul Butler says the spectrograph will allow astronomers to search for smaller Earth-sized planets around the nearest stars.
“This, of course, increases our chances of finding more in that orbital sweet spot that we call the habitable zone -- the zone where it is not too cold, nor too hot for liquid water to exist,” he said in a statement.
Earlier this year, the Kepler spacecraft found a planet with a similar orbit. However, Kepler 22d is located 600 light years away – nowhere near as close as HD 40307g.
