1620 in science

Astronomy

• The work of Copernicus is edited and released, as directed by the Congregation of the Index : nine sentences, which state the heliocentric system as certain, are either omitted or changed.

Cartography

• The atlas Atlante geografico d'Italia, compiled by Giovanni Antonio Magini, is published posthumously.

Chemistry

• The scientific method of reasoning is expounded by Francis Bacon in his Novum Organum.

Earth sciences

• Francis Bacon notices the jigsaw fit of the opposite shores of the Atlantic Ocean.

Medicine

• Nicholas Habicot, surgeon to the Duke of Nemours, publishes a report of four successful "bronchotomies" which he has performed; these include the first recorded case of a tracheotomy for the removal of a thrombus and the first pediatric tracheotomy, to extract a foreign body from a 14-year-old's esophagus.

Technology

• May 17 – The first carousel is seen at a fair.
• Cornelis Drebbel builds the first navigable submarine, in England.

Births

• April? – William Brouncker, Anglo-Irish mathematician
• July 21 – Jean Picard, French astronomer
• September 25 – François Bernier, French physician and traveller
• December 23 - Johann Jakob Wepfer, Swiss pathologist and pharmacologist
• Ralph Bathurst, English theologian, physician and academic
• Bernard de Gomme, Dutch-born military engineer
• Edme Mariotte, French physicist and priest
• Robert Morison, Scottish botanist and taxonomist

Deaths

• Simon Stevin, Flemish scientist