Alpha Centauri

Alpha Centauri is the closest star system and closest planetary system to Earth's Solar system at 4.37 light-years (1.34 parsecs) from the Sun. The name is Latinized from a Centauri. It is a binary star system consisting of A and B stars: Proxima Centauri is a dislodged partner. Stephen Hawking, Yuri Milner and Mark Zuckerberg helm the board for a new initiative, Breakthrough Starshot, whose technology could be used to someday reach Earth's neighboring star Alpha Centauri after just a 20-year journey. Besides being an easy target — it's among the closest stars to the sun — astronomers have been eying our stellar neighbors for potential Earth-like planets.

Properties
To the naked eye, the two main components appear to be a single star with an apparent magnitude of −0.27, the brightest star in the southern constellation of Centaurus and the third-brightest in the night sky, outshone only by Sirius and Canopus. Alpha Centauri A has 1.1 times the mass and 1.519 times the luminosity of the Sun, while Alpha Centauri B is smaller and cooler, at 0.907 times the Sun's mass and 0.445 times its luminosity.