Over the past few days, the space science world has been utterly aflutter with news of a major, major discovery.
Today, the European Southern Observatory announced a huge discovery.
As part of their Pale Red Dot campaign, a team of scientists trained an ESO telescope at Proxima Centauri, one of the closest stars to our planet, only four light years away.
What they’ve found was a likely terrestrial exoplanet circling the star in the so-called Goldilocks zone, which is the right distance a planet needs to be from a star to contain liquid water.
We’re calling it Proxima b. It is a little bigger than Earth, and orbits Proxima Centauri every 11 days.
From the ESO release on the discovery:
Although Proxima b orbits much closer to its star than Mercury does to the Sun in the Solar System, the star itself is far fainter than the Sun. As a result Proxima b lies well within the habitable zone around the star and has an estimated surface temperature that would allow the presence of liquid water. Despite the temperate orbit of Proxima b, the conditions on the surface may be strongly affected by the ultraviolet and X-ray flares from the star — far more intense than the Earth experiences from the Sun
Two separate papers discuss the habitability of Proxima b and its climate. They find that the existence of liquid water on the planet today cannot be ruled out and, in such case, it may be present over the surface of the planet only in the sunniest regions, either in an area in the hemisphere of the planet facing the star (synchronous rotation) or in a tropical belt (3:2 resonance rotation). Proxima b’s rotation, the strong radiation from its star and the formation history of the planet makes its climate quite different from that of the Earth, and it is unlikely that Proxima b has seasons.
Scientists can’t predict precisely what Proxima b’s atmosphere is like, and are cautious to warn that the planet could be completely inhabitable. Look how much closer it is to Proxima Centauri than Mercury is to our sun.
But since Proxima Centauri is much dimmer than our sun, this planet still could contain liquid water.
The actual suitability of this kind of planet to support water and Earth-like life is a matter of intense but mostly theoretical debate. Major concerns that count against the presence of life are related to the closeness of the star. For example gravitational forces probably lock the same side of the planet in perpetual daylight, while the other side is in perpetual night. The planet’s atmosphere might also slowly be evaporating or have more complex chemistry than Earth’s due to stronger ultraviolet and X-ray radiation, especially during the first billion years of the star’s life. However, none of the arguments has been proven conclusively and they are unlikely to be settled without direct observational evidence and characterisation of the planet’s atmosphere
Proxima Centauri is a stone’s throw away from Earth on a galactic scale. Indeed, Stephen Hawking already announced a plan to send a probe to Proxima Centauri within the next 20 years, which could reach the star 20 years after launch.
Now, will it see life? Maybe. Maybe.