1773 in science
- October 13 – French astronomer Charles Messier discovers the Whirlpool Galaxy (pictured), 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.
- 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.
- January 17 – Captain James Cook becomes the first European explorer to cross the Antarctic Circle.
- Spring – Tobias Furneaux explores the coast of Van Diemen's Land.
- Scottish judge James Burnett, Lord Monboddo, begins publication of Of the Origin and Progress of Language, a contribution to evolutionary ideas of the Enlightenment.
- 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.
- 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" (hydrogen chloride) for fumigation of buildings.
- Istanbul Technical University is established (under the original name of Royal School of Naval Engineering) as the world's first comprehensive institution of higher learning dedicated to engineering education.
- Copley Medal: John Walsh
- John Harrison receives the Longitude prize for his invention of the marine chronometer.
- January 29 – Friedrich Mohs, German mineralogist (died 1839)
- April 9 – Marie Boivin, French midwife, inventor and obstetrics writer (died 1841)
- May 19 – Arthur Aikin, English chemist and mineralogist (died 1854)
- June 13 – Thomas Young, English physicist (died 1829)
- June 29 (bapt.) – John Bostock, English physician and geologist (died 1846)
- July 23 – Thomas Brisbane, Scottish astronomer (died 1860)
- August 23 – Abraham Colles, Anglo-Irish surgeon (died 1843)
- December 21 – Robert Brown, Scottish botanist (died 1858)
- December 27 – George Cayley, English pioneer of heavier-than-air flight (died 1857)
- July 16 – Nils Rosén von Rosenstein, Swedish pediatrician (born 1706)
- July 23 – George Edwards, English naturalist (born 1693)
- "Joseph Priestley". Science History Institute. Retrieved 21 March 2018.
- Bowden, Mary Ellen (1997). "Joseph Priestley". Chemical achievers : the human face of the chemical sciences. Philadelphia, PA: Chemical Heritage Foundation. pp. 5–7. ISBN 9780941901123.
- "Carl Wilhelm Scheele". History of Gas Chemistry. Center for Microscale Gas Chemistry, Creighton University. 2005-09-11. Retrieved 2007-02-23.
- "Icons, a portrait of England 1750-1800". Archived from the original on 17 August 2007. Retrieved 2007-08-25.