One advantage of that method is that it reveals the size of the planet. Most exoplanets - worlds orbiting other stars - are found by the transit method, where the planet passes in front of the star, making a mini-eclipse that's detectable as a drop in starlight. Because the star is so faint this makes the planet cold, about -200☌. It orbits the star once every five years, which would put it about 1.5 times farther from Proxima than Earth is from the Sun. But they found the planetary candidate, if it exists, has a mass of about 12 times that of Earth (with a large uncertainty of +12 and -5), so it's probably roughly the size of Uranus or Neptune.
This second candidate planet, called Proxima Centauri c (or just Proxima c), was found using a combination of two methods: reflex velocity and astrometry. Were it not so close to us - a mere 4.244 light years away, in a galaxy 120,000 light years across - we'd hardly pay it any attention.Įxcept… in August 2016 astronomers announced they had confirmed the presence of a planet orbiting the diminutive star, and moreover it's very roughly the same mass as Earth, orbiting Proxima in its habitable zone.Īnd now, astronomers have announced what may very well be a second planet orbiting the star! Unremarkable, even more so for being one of hundreds of billions of such stars in our Milky Way alone. It's a red dwarf: Tiny, cool, faint, orbiting a pair of more Sun-like stars we collectively call Alpha Centauri. The closest star in the Universe to the Sun is Proxima Centauri.
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