1596 in science

Astronomy

• David Fabricius discovers the first non-supernova variable star, Omicron Ceti.
• Johannes Kepler's Mysterium Cosmographicum is the first published defense of the Copernican system of planetary motion.

  Botany

• Gaspard Bauhin publishes Pinax theatri botanici, an early classified flora.

  Mathematics

• Ludolph van Ceulen computes π to twenty decimal places using inscribed and circumscribed polygons.

  Medicine

• William Slingsby discovers that water from the Tewitt Well mineral spring at Harrogate in North Yorkshire, England, possesses similar properties to that from Spa, Belgium.
• Li Shizhen's Compendium of Materia Medica is published posthumously in an illustrated edition.

  Earth sciences

• Abraham Ortelius, in the last edition of his Thesaurus geographicus, considers the possibility of continental drift.

  Exploration

• June 17 – Willem Barents makes the first documented discovery of Spitsbergen in the Svalbard archipelago.

  Technology

• John Harington describes the "Ajax", a precursor to the modern flush toilet, in The Metamorphosis of Ajax.

  Births

• March 31 – René Descartes, French-born philosopher and mathematician.
• approximate date – Peter Mundy, English traveller.

  Deaths

• January 27 – Sir Francis Drake, English explorer.
• September 15 – Leonhard Rauwolf, German botanist and physician.
• September – Pieter Dirkszoon Keyser, Frisian navigator.