‘Super-Earth’ 40 light years away is best chance of finding life outside Solar System, say scientists

Sarah Knapton

Point a high-powered telescope at the constellation Cetus, the sea monster, and it is just possible to make out a dim red dwarf star shining in the tail.

Although it might seem unspectacular, orbiting around that star is a rocky planet that could hold the answer to whether we are alone in the universe.

Scientists say the planet is a ‘Super-Earth’ which is the best place to look for signs of life outside of the Solar System.

Early indications suggest it has an atmosphere, and sits within the ‘Goldilocks Zone’ where it is neither too hot nor too cold for liquid water to exist.

This chart shows the location of the faint red star LHS 1140 which is orbited by LHS 1140b Credit: ESO/IAU and Sky & Telescope

And it is only 40 light years from Earth meaning that it could be possible to send a signal.

“This is the most exciting exoplanet I’ve seen in the past decade,” said lead author Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics.

“We could hardly hope for a better target to perform one of the biggest quests in science - searching for evidence of life beyond Earth.”

The planet was found by an international team of scientists who have been studying data from European Space Observatory’s High Accuracy Radial velocity Planet Searcher (HARPS) instrument which looks for regular changes in brightness of stars, which suggests a planet is passing by in orbit.

The new world - dubbed LHS 1140b - is ten times closer to its parent star than Earth but because a red dwarf is far cooler than our own yellow dwarf, the planet still sits in the habitable zone.

“The present conditions of the red dwarf are particularly favourable - LHS 1140b spins more slowly and emits less high-energy radiation than other similar low-mass stars,” added team member Nicola Astudillo-Defru from Geneva Observatory, Switzerland.

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For life as we know it to exist, a planet must have liquid surface water and retain an atmosphere.

In this case, the planet’s large size and closeness to its sun means that a magma ocean could have existed on its surface for millions of years, which fed steam into the atmosphere, replenishing the planet with water.

Astronomers estimate the age of the planet to be at least five billion years, just a little older than Earth. They also deduced that it has a diameter 1.4 times larger than Earth.

But with a mass around seven times greater than Earth, and hence a much higher density, it implies that the exoplanet is probably made of rock with a dense iron core.

There have been several recent breakthroughs in the hunt for alien life outside of the Solar System. In February scientists announced they had found a solar system strikingly like our own, which they called Trappist-1. Experts said it contained no less than seven Earth-sized worlds.

This artist's impression shows the exoplanet LHS 1140b, which orbits a red dwarf star 40 light-years from Earth Credit: ESO/spaceengine.org

Last August Professor Stephen Hawking announced a project to send spacecraft to the Alpha Centauri system Proxima B, which is five light years away, and is also thought to contain a rocky planet which could harbour life.

However, experts said the new discovery could outshine all others.

Team member Xavier Delfosse, of  French National Center for Scientific Research in France, said: “The LHS 1140 system might prove to be an even more important target for the future characterisation of planets in the habitable zone than Proxima b or Trappist-1.

“This has been a remarkable year for exoplanet discoveries”

The research was published in the journal Nature.

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