1966 in science
The year 1966 in science and technology involved some significant events, listed below.

Astronomy and space exploration
 February 3 – The unmanned Soviet Luna 9 spacecraft makes the first controlled  rocket-assisted landing on the Moon.
 March 1 – Venera 3 Soviet space probe crashes on Venus becoming the first spacecraft to land on another planet's surface.
 March 16 – NASA spacecraft Gemini 8 (David Scott, Neil Armstrong) conducts the first docking in space, with an Agena target vehicle.
 March 31 – The Soviet Union launches Luna 10 which later becomes the first spacecraft to enter orbit around the Moon.
 November – Notable display of the Leonids over the Americas.
 December 15 – Janus, one of the moons of Saturn, is identified by Audouin Dollfus (it had been first photographed on October 29).
 December 18 – Epimetheus, another of the moons of Saturn, is discovered, but mistaken for Janus which shares its orbit and they are not distinguished until 1978.
 Mullard Space Science Laboratory established in England.

Earth Science
 Walter C. Pitman and James Heirtzler present the "magic" Eltanin marine magnetic anomaly profile that confirms the hypothesis of seafloor spreading at mid-ocean ridges.

Biology
 The first live specimen of a mountain pygmy possum (Burramys parvus), Australia's only truly hibernating marsupial, previously known only from the fossil record, is discovered.
 German entomologist Willi Hennig's Phylogenetic Systematics is published in English, advancing the study of cladistics.

Computer science
 Martin Richards designs the BCPL programming language.
 Roger MacGowan and Frederick Ordway first suggest the concept of machine superorganisms in Intelligence in the Universe.

Mathematics
 The Fabius function is published.
 Chen Jingrun publishes Chen's theorem: every sufficiently large even number can be written as the sum of a prime and a semiprime.
 David Mumford introduces Mumford–Tate groups.
 Euler's sum of powers conjecture is disproven by L. J. Lander and T. R. Parkin when, through a direct computer search on a CDC 6600, they have found the counterexample 275 + 845 + 1105 + 1335 = 1445. Their paper announcing the result is one of the shortest published scientific articles ever published.

Physiology and medicine
 Gynecologist John McLean Morris and biologist Gertrude Van Wagenen at the Yale School of Medicine report the successful use of oral high-dose estrogen pills for post-coital contraception in women and rhesus macaque monkeys respectively.
 Victor A. McKusick publishes the first edition of his catalogue of all known genes and genetic disorders, Mendelian Inheritance in Man.
 Andreas Rett first describes Rett syndrome.

Psychology
 Human Sexual Response is published by Masters and Johnson.
 On Aggression and Behind the Mirror are published by Konrad Lorenz.

Technology
 January – First proposals for optical fiber communication presented by Charles K. Kao with George Hockham.
 October 16 – The "Caspian Sea Monster" ground-effect vehicle first flies in the Soviet Union.
 Marie Van Brittan Brown originates the home security system in the United States.

Awards
 Fields Prize in Mathematics: Michael Atiyah, Paul Joseph Cohen, Alexander Grothendieck and Stephen Smale
 Nobel Prizes
 Physics – Alfred Kastler
 Chemistry – Robert S. Mulliken
 Medicine – Peyton Rous, Charles Brenton Huggins
 Turing Award – Alan Perlis

Births
 February 23 – Didier Queloz, Swiss astronomer.
 April 14 – Polina Bayvel, Ukrainian-born optical communications engineer.
 May 17 – Adrian Owen, English neuroscientist.
 June 13 – Grigori Perelman, Russian mathematician.
 July 8 – Ralf Altmeyer, German virologist.
 August 7 – Jimmy Wales, American internet entrepreneur.

Deaths
 January 15 – Sergei Korolev (born 1907), Soviet space scientist.
 March 1 – Fritz Houtermans (born 1903), Prussian-born Dutch physicist.
 March 12 – Sydney Camm (born 1893), English aircraft designer.
 June 20 – Monsignor Georges Lemaître (born 1894), Belgian physicist.
 July 7 – George de Hevesy (born 1885), Hungarian winner of the Nobel Prize in Chemistry.
 August 10 – Felix Andries Vening Meinesz (born 1887), Dutch geophysicist.
 October 1 – Mary Logan Reddick (born 1914), African American neuroembryologist.
 October 3 – Rolf Maximilian Sievert (born 1896), Swedish physicist.