The constellation Centaurus, featuring Alpha Centauri, 1603.
© Science Museum / Science & Society Picture Library
Illustration taken from 'Uranometria' (1603) by Johann Bayer, showing consellations of Centaurus. Alpha Centauri is the star positioned on the front hoof of the centaur. German astronomer and lawyer Johann Bayer (1572-1625) invented the system for naming stars using letters from the Greek alphabet, a system still used today for the brighter stars - those visible to the human eye without the aid of a telescope. 'Uranometria' depicts the positions of nearly 1000 stars in addition to those identified by Tycho Brahe. Alpha Centauri is a double star and the second closest star to our own Sun, 4.35 light years away (only Proxima Centauri, a red dwarf star in the same system is closer). It is a very similar star to the Sun, leading to speculation that it could have planets harbouring life.