Crux - History

History

Crux was visible to the Ancient Greeks; Ptolemy regarded it as part of the constellation Centaurus. It was entirely visible as far north as Britain in the fourth millennium BC. However, the precession of the equinoxes gradually lowered its stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes. By AD 400, most of the constellation never rose above the horizon for Athenians.

The 15th century Venetian navigator Alvise Cadamosto made note of what was probably the Southern Cross on exiting the Gambia River in 1455, calling it the carro dell'ostro ("southern chariot"). However, Cadamosto's constellation had too many stars and was tilted incorrectly. Historians generally credit João Faras - astronomer and physician of King Manuel I of Portugal who accompanied Pedro Álvares Cabral in the discovery of Brazil in 1500 - for being the first European to depict it correctly. Faras sketched and described the constellation (calling it "Las Guardas") in a letter written on the beaches of Brazil on May 1, 1500, to the Portuguese monarch. Émerie Mollineux has also been cited as the first uranographer to distinguish Crux; his illustration dates to 1592. Later adopters of the constellation included Jakob Bartsch in 1624 and Augustin Royer in 1679. Royer is also sometimes cited as initially distinguishing Crux. Explorer Amerigo Vespucci depicted Crux as an almond, called "Mandorla".

The separation of Crux from Centaurus is generally attributed to the French astronomer Augustin Royer in 1679, but other historians attribute the invention of Crux to Petrus Plancius in 1613. However, Crux was later published by Jakob Bartsch in 1624.