An Earth-like planet orbiting a small, cool star not far from our sun could be the best candidate so far for detecting life.
The “super-Earth”, a rocky planet about six times the mass of Earth, orbits close in around the star LHS 1140, a red dwarf star about 40 light years from Earth. It’s in the “Goldilocks region”, an orbit where it’s not too hot and not too cold, so liquid water can exist on its surface. It was spotted by scientists at the MEarth observatory, and the research is published today in Nature.
There have been nearly 3,500 exoplanets (planets outside our own solar system) discovered – a number that is growing daily, with NASA announcing the discovery of 715 new planets by the space telescope Kepler on 29 February 2014 alone. But LHS-1140b, as the new planet is known, is exciting to scientists because it may be possible to carry out an analysis of its atmosphere with existing telescopes.
“The star is close, and small, and quiet, in terms of flares and activity,” Dr Jason Dittmann, an astrophysicist at the Harvard Smithsonian Centre for Astrophysics and one of the authors of the study, told BuzzFeed News. “So it’s ticking all the boxes.”
“There have been lots of exoplanet discoveries,” Dr Lewis Dartnell, an astrobiologist at the University of Westminster who was not involved in the research, told BuzzFeed News. “But most of them are too far away, so the planet is too dim – you can’t get enough photons for spectroscopy of their atmospheres.
“This one is very exciting, in terms of it being close enough to do something about it.”
Spectroscopy is the study of the light given off by different chemicals. Each chemical gives off a unique spectral “fingerprint” of different wavelengths of light. It’s how we know what stars are made of.
Because LHS-1140b is so close, and the star it is orbiting is so dim, it will be comparatively visible. That means that, using telescopes that are currently being built, and even ones that currently exist, it may be possible to get some information about its atmosphere.
“We’re going to try to do it with some telescopes that exist now,” says Dittmann. “We can start chipping away at it with the Hubble Space Telescope and some of the big ground-based telescopes.
“But it’s mainly a study for the future.” He mentions the James Webb Space Telescope, which will be launched in 2018, and the Giant Magellan Telescope, which will be commissioned in 2022, as possible sources of more information.
The telescopes will mainly be looking for oxygen. “That’s the big one that everyone wants to see,” says Dittmann.
That’s because, on Earth, oxygen is produced by life – specifically, by plants, algae, and bacteria that use the sun’s energy to strip carbon from carbon dioxide and release the oxygen. But oxygen is a highly reactive gas, so it doesn’t stay in the atmosphere on its own for very long: It reacts with other things to form…