M. Kommesser/EsoArtist’s rendering of the planet Proxima Centauri b, which is similar to Earth and orbits the star Proxima CentauriM. Kommesser/Eso
Proxima Centauri b, a newly discovered planet, is the latest focus of the search for life beyond Earth. It was described by an international team led by astrophysicist Guillem Anglada-Escudé at Queen Mary, University of London (Nature, August 25, 2016), and its mass is only slightly greater than Earth’s. The planet takes a little over 11 days to orbit Proxima Centauri, the star closest to the Sun, and a spacecraft traveling at 20% of the speed of light could reach it in about 20 years. Proxima Centauri belongs to a family known as dwarf M stars; much research has been done on these stars because their planets can be detected when a shift in the star’s light is prompted by the planet’s gravitational tug. Anglada-Escudé’s team used telescopes at the European Southern Observatory (ESO) in Chile to detect the effect in the case of Proxima Centauri b. The distance between the new planet and its sun suggests that the planet’s temperature would allow it to have liquid water, a characteristic considered essential to the emergence and evolution of life. It remains to be seen whether the planet has an atmosphere and magnetic field like Earth, which would protect its surface both from explosions of Proxima Centauri as well as from the X-rays that the star emits. New instruments, like the James Webb Space Telescope – scheduled for launching by NASA in 2018 – may help find these answers.
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