The discovery of new exoplanets rekindles the debate about the existence of possible extraterrestrial life.

Gliese 667Cb was initially thought to be a good candidate for life.

In E.T we do not know the exact location of the planet the alien calls home. In Battlestar Galactica there is a human civilization that inhabits twelve planets, but in an imprecise place in the Milky Way. And of course, in Star Wars we also don’t know where the very, very distant galaxy in which the saga takes place is located.

Although in many cases science fiction does not offer a real – or realistic – reference to the origin of the extraterrestrials that star in their stories, the most recent discoveries of planets may serve as inspiration for future occasions or that some of them end up offering them a new species to include in your stories.

Since the discovery of the first planet orbiting a star other than the Sun was announced in 1992, the number of exoplanets discovered has continued to rise to more than 3,000. And with each discovery comes the great question, the one that worries society as a whole: can there be life in them? LHS 1140b is the latest candidate for a living planet as scientists, missions and radio telescopes continue to survey the universe for something more.

The new rocky planet

This week, a team of researchers has revealed the existence of a rocky planet (LHS 1140b) located 40 light years away: the new best candidate to search for signs of life. As with the rest of potentially habitable exoplanets, this world is at a distance from its star that would allow it to have water in a liquid state.

But that is not all. According to him paper published in the magazine Nature that details its characteristics, the conditions of its star are especially favorable. LHS 1140, the red dwarf around which this super-earth revolves, emits less high-energy radiation than other stars with a similar mass — 15% that of our Sun — and, furthermore, it does not emit flares.

This promising announcement is just the last of the countless that have made us think, from time to time, about the possible existence of extraterrestrial life, either in bacterial form or in some more advanced version similar to the alien humanoids that have populated the movies of Science fiction.

A new planetary system

In February, NASA had half the world with its heart in a fist when it held a press conference that, due to the hype with which it was announced, seemed the final one: the confirmation that aliens had been discovered. After a tweet clarifying that they were not aliens, the aerospace agency revealed the existence of a new planetary system 39 light years from Earth with 7 planets the size of our blue home. And although they were not the 12 from Battlestar Galactica, the discovery was of great relevance.

Turning around the star TRAPPIST-1, three of the celestial objects are in the habitable zone of the planet. Although at first optimism spread, and even with an important discovery, we now know that the proximity between these three possible lands raises the possibility that they are blocked by tidal forces, always presenting the same face to their star. This would make them have a face with high temperatures and illuminated and another in perpetual darkness, something that would make life difficult.

A very close star

Before the commotion caused by the TRAPPIST-1 planets and the newly discovered rocky world, the exoplanet Proxima Centauri b, orbiting within the habitable zone of the red dwarf star Proxima Centauri, the closest to the Sun, was the one that starred in the Headlines.

Could this Earth-size planet support life? Although initially the forecasts were tremendously optimistic, a study published in The Astrophysical Journal Letters revealed that, considering the age of its red dwarf star and the proximity of the planet to this star, Proxima Centauri b is exposed to a quantity of ultraviolet light and X-ray emissions that would imply a high loss of oxygen from the atmosphere, which would prevent the formation of water.

The other candidates

It should not be forgotten that in recent decades and especially in recent years, exoplanets, and even habitable ones, have sprung up like mushrooms. In 2011, scientists discovered Gliese 667Cc, in a triple star system in the constellation Scorpio. At a distance of 23.6 light years, the planet orbited within the stellar habitable zone and became the closest known habitable planet to Earth.

A few years later, in 2014, Kepler-186f, an exoplanet orbiting the red dwarf star Kepler-186, was discovered. This was the first habitable one of a similar size to our blue planet to be found. For its part, Kepler 438b, discovered in 2015 orbiting a red dwarf star more than 470 light years from Earth, is still today the one that most closely resembles our home, with a similarity index of 88%.

The planet Kepler 442b, compared to Earth.

The planet Kepler 442b, compared to Earth.
Wikipedia

But there the thing does not end there. Kepler 442b, located at a distance of 1,100 light years – and the fourth among the largest candidates for a terrestrial analog, with an index of similarity to the Earth of 84% -; or the planets Kepler 62e, Kepler 62f and Kepler 452b, the latter moving around a star similar to our Sun, have on other occasions been the strongest candidates for a planet more similar to Earth.

The problem? As with other more recent discoveries, life may not have actually developed on any of these potentially habitable planets due to the activity of its star and the extreme conditions that would present due to its influence.

However, there is room for hope. Although the conditions are not the most favorable, some of the aforementioned exoplanets can harbor life, even if it is not as we imagine it (or as Hollywood has painted it for us). In addition, new missions such as TESS, which is scheduled to launch by NASA in 2017, and technologies such as the James Webb space telescope and the MeerKAT radio telescope, will improve and expand the search for new lands and, with it, the possibility of finding life and of finding another planet that is fully and truly habitable, one like the one ET called home.