1584 in science

Astronomy

• Completion of Tycho Brahe's subterranean observatory at Stjerneborg.
• Giordano Bruno, in England, publishes his "", including the cosmological tracts La Cena de le Ceneri, De la Causa, Principio et Uno and De l'Infinito Universo et Mondi.

Cartography

• Lucas Janszoon Waghenaer publishes the first atlas of nautical charts, Spieghel der zeevaerdt.
• The Italian Jesuit Matteo Ricci, in Zhaoqing, produces the first Chinese world map, on wood, Yudi Shanhai Quantu.
• Abraham Ortelius publishes Itinerarium per nonnullas Galliæ Belgicæ partes in Antwerp.

Exploration

• June 4 – Walter Ralegh sends Philip Amadas and Arthur Barlowe to explore the Outer Banks of Virginia, with a view to establishing an English colony; they locate Roanoke Island.

Mathematics

• Jean Errard publishes Premier livre des instruments mathématiques at Nancy.
• Fabrizio Mordente publishes Il Signor del Compasso Fabritio Mordente. Con altri istromenti mathematici, suo fratello Gasparo da ritrovati at Antwerp and introduces the parallel rulers.
• Zhu Zaiyu calculates equal temperament.

Medicine

• Jacques Guillemeau publishes his ophthalmology textbook Traite des maladies de l'oeil.
• Thomas Muffet publishes De jure et praestantia chemicorum medicamentorum.

Technology

• March 12 – Louis de Foix begins construction of Cordouan lighthouse on the Gironde estuary.
• Jost Bürgi invents the cross-beat escapement for clocks.

Other events

• Nikola Vitov Gučetić publishes Sopra le Metheore d' Aristotile giving explanations for the causes of winds and of the movement of air in caves.

Births

• March 22? – Grégoire de Saint-Vincent, Flemish mathematician
• William Baffin, English explorer
• Giovanni Baptista Ferrari, Italian botanist and linguist
• Walter Rumsey, Welsh judge and amateur scientist

Deaths

• June 13 – János Zsámboky, Hungarian physician and scholar
• July 12 – Steven Borough, English explorer
• Simon Baudichon, French physician