1773 in science

Astronomy

• October 13 – French astronomer Charles Messier discovers the Whirlpool Galaxy , an interacting, grand design spiral galaxy located at a distance of approximately 23 million light-years in the constellation Canes Venatici.
• Lagrange presents his work on the secular equation of the Moon to the Académie française, introducing the idea of the potential of a body. He also publishes on the attraction of ellipsoids.

Chemistry

• Hilaire Rouelle discovers urea.
• Carl Wilhelm Scheele and Joseph Priestley independently isolate oxygen, called by Priestley "dephlogisticated air" and Scheele "fire air".
• Antoine Baumé publishes his textbook Chymie expérimentale et raisonnée in Paris.

Exploration

• January 17 – English Captain James Cook becomes the first European explorer to cross the Antarctic Circle.
• Spring – English Captain Tobias Furneaux explores the coast of Van Diemen's Land.
• June 4 – September 30 – British Royal Navy Phipps expedition towards the North Pole, which produces the first scientific description of the polar bear and the ivory gull.

Linguistics

• Scottish judge James Burnett, Lord Monboddo, begins publication of Of the Origin and Progress of Language, a contribution to evolutionary ideas of the Enlightenment.

Mathematics

• Lagrange considers a functional determinant of order 3, a special case of a Jacobian. He also proves the expression for the volume of a tetrahedron with one of the vertices at the origin as one sixth of the absolute value of the determinant formed by the coordinates of the other three vertices.

Medicine

• October 12 – North America's first insane asylum opens for 'Persons of Insane and Disordered Minds' in Williamsburg, Virginia.
• Medical Society of London founded by John Coakley Lettsom.
• Louis-Bernard Guyton de Morveau proposes the use of "muriatic acid gas" for fumigation of buildings.

Technology

• David Hartley patents a method of fireproofing construction for buildings and ships in Britain.

Institutions

• Istanbul Technical University is established as the world's first comprehensive institution of higher learning dedicated to engineering education.

Awards

• Copley Medal: John Walsh
• John Harrison receives the Longitude prize for his invention of the marine chronometer.

Births

• January 29 – Friedrich Mohs, German mineralogist
• February 24 - Jean Boniface Textoris, French military surgeon
• April 9 – Marie Boivin, French midwife, inventor and obstetrics writer
• May 19 – Arthur Aikin, English chemist and mineralogist
• June 13 – Thomas Young, English physicist
• June 29 – John Bostock, English physician and geologist
• July 23 – Thomas Brisbane, Scottish astronomer and Governor of New South Wales
• August 23 – Abraham Colles, Anglo-Irish surgeon
• October 28 – Simon Goodrich, English mechanical engineer
• December 21 – Robert Brown, Scottish botanist
• December 27 – George Cayley, English pioneer of heavier-than-air flight

Deaths

• July 16 – Nils Rosén von Rosenstein, Swedish pediatrician
• July 23 – George Edwards, English naturalist