The year 1761 in science and technology included many events, some of which are listed here.

See also: 1760 in science, other events of 1761, 1762 in science and the list of years in science.

Astronomy

• June 6 - The first transit of Venus since Edmond Halley suggested that its observation could determine the distance from the Earth to the Sun. Joseph-Nicolas Delisle sets up a 62 station network for observing the transit. Those taking part include Nathaniel Bliss at Royal Greenwich Observatory, Joseph de Lalande in Paris, Tobias Mayer in Göttingen, César Cassini de Thury in Vienna, Nevil Maskelyne in St Helena, Jeremiah Dixon and South Africa, John Winthrop in Newfoundland, Alexandre Pingré in Rodrigues and Jean-Baptiste Chappe d'Auteroche in Siberia. For various reasons the data obtained is unsatisfactory, and plans begin to observe the next transit in 1769
• Mikhail Lomonosov also observes the transit of Venus and finds the first evidence that the planet has an atmosphere

Technology

• Opening of Matthew Boulton's Soho Manufactory

Awards

• Copley Medal: not awarded

Births

• January 17 - James Hall (d. 1832), geologist and physicist.
• February 1 - Christian Hendrik Persoon (d. 1836), mycologist.
• June 7 - John Rennie (d. 1821), civil engineer.
• November 30 - Smithson Tennant (d. 1815), chemist.
• December 21 - Jean-Louis Pons (d. 1831), astronomer.
• December 25 - William Gregor (d. 1817), mineralogist.

Deaths

• April 7 - Thomas Bayes, mathematician (born c. 1702)
• November 30 - John Dollond, English optician (born 1706)