The new planet around Alpha Centauri B matches Earth only in terms of its mass - making it among the smallest exoplanets we know of.

BBC: Exoplanet around Alpha Centauri is nearest-ever

But careful measurements over four years showed that the planet whips around Alpha Centauri B in just 3.6 days, and is estimated to have a surface temperature of about 1, 200C.

BBC: Exoplanet around Alpha Centauri is nearest-ever