1973 in science

Astronomy and space exploration

• March 7 – Comet Kohoutek is discovered
• April 6 – Launch of Pioneer 11 spacecraft
• May 14 – Skylab, the United States' first space station, is launched.
• Solar eclipse of June 30, 1973 – Very long total solar eclipse visible in NE South America, the Atlantic, and central Africa. During the entire Second Millennium, only seven total solar eclipses exceed seven minutes of totality; this is the last. Observers aboard a Concorde jet are able to stretch totality to about 74 minutes by flying along the path of the moon's umbra.
• July 25 – Soviet Mars 5 space probe launched.
• November 3 – Mariner program: NASA launches the Mariner 10 toward Mercury ; it will be the first space flight to use gravity assist.
• December 3 – Pioneer program: Pioneer 10 sends back the first close-up images of Jupiter.
• December 7 – The "Big Ear" at the Ohio State University Radio Observatory begins a full-time search for extraterrestrial intelligence radio survey, running continuously until 1995.

Biology

• December 28 – Endangered Species Act signed into law in the United States.

Cartography

• Waldo R. Tobler introduces the Tobler hyperelliptical projection.

Chemistry

• A successful method of Vitamin B₁₂ total synthesis is reported by the groups of Robert Burns Woodward and Albert Eschenmoser.
• Akira Endo identifies the first statin, mevastatin.

Computer science

• March 1 – Xerox PARC releases the Xerox Alto, the first computer designed to support an operating system based on a graphical user interface.
• September – The TV Typewriter appears on the cover of Radio-Electronics. Designed by Don Lancaster, it is a video terminal that can display two pages of 16 lines of 32 upper case characters on a standard television set.
• October – A form of the suffix automaton is introduced by Peter Weiner.
• November 21 – The sci-fi movie Westworld is the first feature film to use digital image processing.

Cryptography

• October – Asymmetric key algorithms for public-key cryptography developed by James H. Ellis, Clifford Cocks and Malcolm J. Williamson at the United Kingdom Government Communications Headquarters.

Earth sciences

• Derek Ager publishes The Nature of the Stratigraphical Record.

History of science

• May 5–July 28 – BBC Television series The Ascent of Man, written and presented by Jacob Bronowski, first airs; there is also an accompanying bestselling book.

Mathematics

• Fischer Black and Myron Scholes first articulate the Black–Scholes mathematical model used in the financial field containing certain derivative investment instruments.
• Jürgen Stückrad and Wolfgang Vogel introduce the Buchsbaum ring.

Physiology and medicine

• August – Production of monoclonal antibodies involving human–mouse hybrid cells is first described by Jerrold Schwaber.
• The term "dendritic cell" is coined by Ralph M. Steinman working with Zanvil A. Cohn.
• The term "Norrmalmstorgssyndromet", translated as Stockholm syndrome, is coined by Nils Bejerot.

Psychiatry

• David Rosenhan publishes the results of his experiment into the validity of psychiatric diagnosis.
• The American Psychiatric Association publishes the 1st edition of its Principles of Medical Ethics, incorporating the 'Goldwater rule'.
• December 15 – The American Psychiatric Association removes the definition of homosexuality as a mental disorder from the 2nd edition of its Diagnostic and Statistical Manual of Mental Disorders.

Technology

• April 2 – The LexisNexis computerized legal research service begins.
• April 3 – The first handheld mobile phone call is made by Martin Cooper of Motorola in New York City.
• June 4 – A United States patent for the Docutel automated teller machine is granted to Donald Wetzel, Tom Barnes and George Chastain.
• Ichiro Kato, Waseda University, develops the world's first full-scale humanoid robot, Wabot-1.

Institutions

• March 6 – The Montenegrin Academy of Sciences and Arts, founded as the Montenegrin Society for Science and Arts, elects its first members.

Awards

• Nobel Prizes
• * Physics – Leo Esaki, Ivar Giaever, Brian David Josephson
• * Chemistry – Ernst Otto Fischer, Geoffrey Wilkinson
• * Medicine – Karl Von Frisch, Konrad Lorenz, Nikolaas Tinbergen
• Turing Award – Charles W. Bachman

Births

• May 19 – Alice Roberts, English evolutionary biologist, biological anthropologist and science and archaeology popularizer
• October 5 – Cédric Villani, French mathematician and politician
• November 19 – Nim Chimpsky, chimpanzee
• December 5 – Luboš Motl, Czech theoretical physicist

Deaths

• February 11 – J. Hans D. Jensen, German nuclear physicist
• February 20 – Alf Lysholm, Swedish mechanical engineer.
• March 12 – David Lack, English ornithologist
• March 14 – Howard H. Aiken, American computing pioneer
• March 28 – C. Doris Hellman, American historian of science
• March 30 – William Justin Kroll, Luxembourgish metallurgist
• May 21 – Grigore Moisil, Romanian mathematician, died in Canada
• July 1 – Laurens Hammond, American inventor
• August 9 – Preben von Magnus, Danish virologist
• August 12 – Walter Rudolf Hess, Swiss physiologist, recipient of the Nobel Prize in Physiology or Medicine
• August 16 – Selman Waksman, Ukrainian-born Jewish-American biochemist and microbiologist
• November 25 – Elisa Leonida Zamfirescu, Romanian engineer
• December 10 – Wolf V. Vishniac, American microbiologist
• December 17 – Charles Greeley Abbot, American astrophysicist