Earth-Sized World May be the Nearest Exoplanet Able to Support Life

Fagjun | Published 2017-11-17 22:31

At just 11 light years away. the exoplanet Ross 128b may be the closest planet to Earth that can support life, making it a prime target for the search for extraterrestrials.


Illustration of Ross 128b and its star [Image by ESO/M. Kornmesser]

 

 

The only other known planet closer to Earth than Ross 128b is Proxima b, which orbits the red dwarf Proxima Centauri. Ross 128b, meanwhile, orbits another red dwarf named Ross 128. Scientists thought that Proxima b may be able to support life, though this has become less and less likely. Ross 128b renews hope that a planet outside our solar system, but still relatively close to Earth, may be able to support life.

 

Scientists think that Ross 128b may have a somewhat mild climate, with temperatures that range from -60 degrees Celsius to 20 degrees Celsius. Thus, the planet may have bodies of water from which life may spring or may have already sprung.



A Special Kind of Red Dwarf


Ross 128, front and center [Image by Sloan Digital Sky Survey]

 

 

Astronomers were able to discover Ross 128b using the High Accuracy Radial velocity Planet Searcher (HARPS) in Chile. By using this instrument, astronomers can examine the light emitted by stars to detect the gravitational effects--and thus the existence--of an orbiting planet.

 

A new study reveals that after 12 years of observations, astronomers have discovered the existence of a planet about 30 percent larger than Earth. “There wasn’t a ‘eureka’ moment here where we were able to suddenly say, wow, we have a planet,” says Xavier Bonfils, one of the researchers. “We accumulated data over many years, and only gradually the signal built up and became significant.”

 

The surface of Proxima b which may be lashed by radiation from Proxima Centaurus [Image by ESO/M. Kornmesser]

 

 

Though the planet orbits quite close to its host star, especially as compared to the distance of Earth from the Sun, it’s actually in the habitable zone. Usually, the habitable zones of red dwarf systems are relatively closer to the star itself. The water on planets in habitable zones neither freeze nor evaporate and are thought to stay in liquid form. Thus, this makes it more likely that life as we know it can arise on the planet.

 

However, though planets in the habitable zones of red dwarfs may have liquid water, they may also be too close to the star. Red dwarfs are notoriously feisty, with frequent and intense  eruptions of ultraviolet radiation.



The Closest Habitable Exoplanet


La Silla Observatory in Chile, which houses HARPS [Photo by ESO - A. Ghizzi Panizza]

 

 

Thus, planets orbiting close to a red dwarf may be irradiated, making them unlikely to be able to sustain life on their surface. This is what makes Proxima b an unlikely candidate for the search for extraterrestrial life.

 

Scientists say that Ross 128 is calmer and quieter than its peers, and also older that Proxima Centauri by about two billion years. It’s likely that Ross 128b receives just 1.38 times more radiation than Earth.

 

As if all that wasn’t enough, scientists have also found that Ross 128b is actually moving closer and closer to Earth. In about 79,000 years, which is a relatively short time in cosmic terms, Ross 128b will move past Proxima b to become the closest exoplanet to Earth. For now, however, we’ll have to be satisfied with observing this intriguing new neighbor from a relatively close but still tantalizingly far distance.

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