The constellation Orion, 1603.
© Science Museum / Science & Society Picture Library
Illustration taken from 'Uranometria' (1603) by Johann Bayer, showing the constellation of Orion (the Hunter). 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. Orion is one of the best known constellations in the night sky. Features of interest to astronomers include the Great Orion Nebula and the Horsehead Nebula, as well as the supergiant stars Betelgeuse and Rigel, both over 40,000 times more luminous than our Sun.