Given the fact that Proxima b is within the habitable zone of its star, meaning liquid water could exist on the surface, it may also be the closest possible home for life outside of our solar system, the researchers said.
Because of its location, the researchers hope it provides an opportunity for possible “robotic exploration in the coming centuries.”
This artist’s impression shows a view of the surface of the planet Proxima b
“The good news is that it is so close,” study author Ansgar Reiners said. “It is not only nice for having it in our neighborhood, but it’s a dream come true for astronomers if we think about follow-up observation.”
Proxima Centauri coexists with a binary star in Alpha Centauri, a well-studied star system that serves as a neighbor to our sun.
Proxima b is a mere 4.2 light-years away from our solar system, or 266,000 times the distance between the Earth and the sun, which are 92.96 million miles apart. Previous rocky exoplanet discoveries, like those orbiting ultracool red dwarf star TRAPPIST – 1, were previously described as “close” at 40 light-years away.
“It’s not only the closest terrestrial planet found, it’s probably the closest planet outside our solar system that will ever be found because there is no star closer to the solar system than this one,” said lead study author Guillem Anglada-Escudé.
Out of a new discovery of 104 exoplanets, astronomers found four similar in size to Earth that are orbiting a dwarf star. Two of them have the potential to support life. The craft depicted in this illustration is the NASA Kepler Space Telescope, which has helped confirm the existence of thousands of exoplanets
“The only thing you can hope to find between that is Planet Nine, but that would (require) a solar system object or a brown dwarf that hasn’t been discovered,” researcher Pedro Amado added.
Here is what we know about the planet, as well as the questions that researchers hope to be able to answer.
Meet Proxima b
Proxima b is a rocky, terrestrial planet with a surface — unlike a gas giant, such as Jupiter — that is 1.3 times the size of Earth and orbits its star every 11.2 days. It is in a close orbit of Proxima Centauri: only 5% of the distance between the Earth and the sun. They are even closer together than Mercury and the sun. But because its star is much cooler and fainter than our sun, Proxima b has a temperature that is suitable for liquid water to exist on the surface without evaporating.
This infographic compares the orbit of the planet around Proxima Centauri (Proxima b) with the same region of the Solar System
Researchers estimate that if the planet has an atmosphere, which could be assumed but isn’t known, it may be between 86 to 104 degrees Fahrenheit (31 to 40 degrees Celsius) on the surface. Without an atmosphere, it could be -22 to -40 degrees Fahrenheit (-30 to -40 degrees Celsius). To put that in perspective, Earth would be -4 degrees (-20 degrees Celsius) if it didn’t have an atmosphere, Reiners said.
Given the proximity to its star, Proxima b is also subject to less pleasant factors like ultraviolet and X-ray flares that are 100 times the intensity of what Earth receives from the sun. In the paper, researchers estimated it to be 400 times the intensity, but recent research has caused them to create a new estimate, they said. If there is life on the planet, it would be affected by this radiation, but it is pure speculation as to what kind of effect.