Astronomers find another Earth-size world relatively close to the Sun


It comes after Nasa announced earlier this year that scientists had found a new solar system filled with planets similar to the Earth which could support life.

The properties of this newly discovered planet - called Ross 128 b - make it a target in the search for life elsewhere in the cosmos.

It is also the closest planet to be discovered orbiting an inactive red dwarf star, which scientists say increases the potential for sustaining life.

"HARPS is a spectrograph specially created to measure the radial velocity of the stars", Nicola Astudillo-Defru, an astronomer with the Geneva Observatory in Switzerland and a member of the team that made the discovery, told Popular Mechanics in an e-mail.

First there was Proxima b, the Earth-sized planet orbiting the closest star to us, Proxima Centauri. And when they are found, then ESO's Extremely Large Telescope (ELT) will be on hand to help detect vital organic biomarkers, such as oxygen, in the atmospheres of exoplanets close to us.

Red dwarfs are some of the coolest, faintest - and most common - stars in the Universe.

She added: "This discovery is based on more than a decade of HARPS intensive monitoring together with state-of-the-art data reduction and analysis techniques".

Although discoveries of this type are relatively uncommon at present, it is likely that temperate exoplanets such as these will be found in greater number with advancing technology. The study in the journal Astronomy & Astrophysics finds the best estimate for its surface temperature is between -60° and 20° C. As reported by astronomers, its location to the day-star is 20 times closer than Earth.

What remains unclear, according to the study, is whether the exoplanet is within the star's habitable zone, the orbital range at which it is possible for liquid water to exist on a planet's surface.

In the search for habitable worlds beyond our Solar System, astronomers generally look for low-mass, rocky and temperate planets much like our own.

"In fact, lead author Xavier Bonfils (Institut de Planétologie et d'Astrophysique de Grenoble - Université Grenoble-Alpes/CNRS, Grenoble, France), named their HARPS programme The shortcut to happiness, as it is easier to detect small cool siblings of Earth around these stars, than around stars more similar to the Sun", the ESO explained. The scientists still have to constrain where that habitable zone lies to figure out if Ross 128 b rests inside it.

It might now be 11 light-years from Earth, but Ross 128 is moving towards us and is expected to become our nearest stellar neighbour in 79,000 years.

But Ross 128 doesn't seem to be doing this, so it's considered "quieter", which means the planet is a more comfortable place for life to form without being subjected to such violent episodes from time to time.

At "just" 4.2 light-years away, Proxima b is the closest exoplanet with a mild temperature.