European astronomers have discovered what appears to be a small, rocky planet orbiting the nearest star to the sun that could “theoretically” have water on its surface and support some form of life.
The “Earth-like” planet, named Proxima b, orbits Proxima Centauri, a red dwarf star located about 4.2 light years from our solar system. The Proxima Centauri was first discovered more than 100 years ago and has been well-studied, but this is the first time astronomers have been able to detect the presence of a terrestrial planet in the star’s so-called “habitable zone.”
Details of the discovery were published in the Nature journal on Wednesday.
The co-author of the paper, astronomer Guillem Anglada-Escude, and his colleagues came to their conclusions after analyzing Doppler data collected by two European Southern Observatory telescopes between 2000 and 2014, as well as observations made by the La Silla Observatory in Chile between January and March of this year. Doppler data can be used to measure the gravitational pull of a star’s orbiting planets.
The astronomers studied the movements of the Proxima Centauri star to determine whether the gravitational force of another celestial body is “tugging” at it. By measuring the duration and distance of the star’s shifts, they were able to calculate the mass and the orbit of the Proxima b planet.
The findings are “consistent with the presence of a warm, Earth-mass planet” that orbits Proxima Centauri every 11.2 days at a distance of about 7.5 million kilometres, according to the paper. That represents about five per cent of the distance between the Earth and the sun.
Because Proxima b appears to be within the temperate, or habitable, zone of its star, it could have liquid water, Anglada-Escude and his colleagues told reporters during a teleconference briefing on Tuesday.
Proxima b has a mass about 1.3 that of the Earth and could possibly have a life-sustaining surface temperature. However, the astronomers stressed that there are many questions about the planet that could go unanswered for decades – or even centuries.
The planet-hunters are not sure what kind of atmosphere – if any – Proxima b has. Because of its close orbit around the Proxima Centauri star, the planet is subjected to much more intense X-ray radiation than the Earth.
Astronomers are also not sure if Proxima b has a protective magnetic field similar to the Earth’s.
The next steps in Proxima b exploration will require creativity and further technological advances, scientists say. They hope that they can eventually create an experiment to properly measure the planet and design a “proper instrument” that can capture images of the Earth’s potential cousin.
