1540 in science

Astronomy

• Georg Joachim Rheticus publishes De libris revolutionum Copernici narratio prima in Danzig, an abstract of Copernicus' as yet unpublished De revolutionibus orbium coelestium and the first printed publication of Copernican heliocentrism.
• Peter Apian publishes Astronomicon Caesareum. The tails of comets always point away from the sun.
• Alessandro Piccolomini De Le Stelle Fisse is the first star atlas in which stars are labelled with letters.

  Chemistry

• Valerius Cordus discovers and describes a method of synthesizing ether by adding sulfuric acid to ethyl alcohol.

  Exploration

• May 9 – Hernando de Alarcón sets sail to explore the Baja California peninsula; on September 26 he enters the Colorado River.

  Metallurgy

• Vannoccio Biringuccio's manual on metalworking, De la pirotechnia, is published posthumously.

  Physiology and medicine

• Publication in London of the first printed book in English on obstetrics, The Byrth of Mankynde, a translation attributed to Richard Jonas from Rösslin's De partu hominis. It will continue to be issued in new editions for more than a century.

  Births

• January 28 – Ludolph van Ceulen, German mathematician.
• c. February or March – Francis Drake, English explorer.
• Roch Le Baillif, French physician.
• François Viète, French mathematician.
• possible date – Pieter Dirkszoon Keyser, Frisian navigator.

  Deaths

• probable date – Johann Georg Faust, German alchemist.