1991 in science

• May 18 – Helen Sharman becomes the first British person in space, flying with the Soyuz TM-12 mission.{{cite news|url=http://news.bbc.co.uk/onthisday/hi/dates/stories/may/18/newsid_2380000/2380649.stm|title=1991: Sharman becomes first Briton in space|work=BBC News|accessdate=2008-02-01|date=1991-05-18|archiveurl= https://web.archive.org/web/20080307014408/http://news.bbc.co.uk/onthisday/hi/dates/stories/may/18/newsid_2380000/2380649.stm|archivedate=2008-03-07|url-status=live}}
• October 29 – The Galileo probe becomes the first spacecraft to visit an asteroid (951 Gaspra).
• Steven Balbus and John F. Hawley publish their insights on magnetorotational instability.{{cite journal|last1=Balbus|first1=Steven A.|last2=Hawley|first2=John F.|year=1991|title=A powerful local shear instability in weakly magnetized disks|journal=The Astrophysical Journal|volume=376|pages=214–233|bibcode=1991ApJ...376..214B|doi=10.1086/170270}}
• Asteroid 6859 Datemasamune is discovered by Masahiro Koishikawa.
• Asteroid 11514 Tsunenaga is discovered by Masahiro Koishikawa.
• There are four lunar eclipses: three penumbral on January 30, July 26, and June 27, and one minor partial lunar eclipse on December 21.
• There are two solar eclipses: one annular eclipse on January 15, and a very long total eclipse on July 11 (lasting 6 minutes and 53 seconds).

• Carbon nanotubes discovered in the insoluble material of arc-burned graphite rods by Sumio Iijima of NEC.{{cite journal|first=Sumio|last=Iijima|title=Helical microtubules of graphitic carbon|journal=Nature|volume=354|pages=56–58|date=7 November 1991|doi=10.1038/354056a0|issue=6348|bibcode=1991Natur.354...56I|s2cid=4302490}}{{cite journal|title=Who should be given the credit for the discovery of carbon nanotubes?|doi=10.1016/j.carbon.2006.03.019|first1=Marc|last1=Monthioux|journal=Carbon|volume=44|year=2006|url=http://www.cemes.fr/fichpdf/GuestEditorial.pdf|page=1621|last2=Kuznetsov|first2=Vladimir L.|issue=9|bibcode=2006Carbo..44.1621M |accessdate=2012-02-03}}

• February 26 – Tim Berners-Lee introduces WorldWideWeb (the first web browser), and a WYSIWYG HTML editor.
• May 14 – Nicola Pellow, an intern working under the direction of Berners-Lee, introduces Line Mode Browser, the first cross-platform web browser.
• June 5 – Phil Zimmermann posts the first Pretty Good Privacy (PGP) data encryption program.{{cite web|url=http://www.philzimmermann.com/EN/news/PGP_10thAnniversary.html|title=PGP Marks 10th Anniversary|first=Philip|last=Zimmermann|date=2001-06-05|accessdate=2012-01-28|archive-date=2011-05-14|archive-url=https://web.archive.org/web/20110514200112/http://www.philzimmermann.com/EN/news/PGP_10thAnniversary.html|url-status=dead}}
• June 23 – The video game Sonic the Hedgehog is first released, propelling the Sega Genesis 16-bit console into mass popularity.
• August 6 – The first website goes online at CERN.{{cite web|title=Welcome to info.cern.ch, the website of the world's first-ever web server|publisher=CERN|url=http://info.cern.ch/|accessdate=25 May 2008|archiveurl=https://web.archive.org/web/20080527152659/http://info.cern.ch/|archivedate=27 May 2008|url-status=live}}{{cite web|title=World Wide Web—Archive of world's first website|publisher=World Wide Web Consortium|url=http://www.w3.org/History/19921103-hypertext/hypertext/WWW/TheProject.html|accessdate=25 May 2008}}{{cite web|title=World Wide Web—First mentioned on USENET|date=6 August 1991|url=http://groups.google.co.uk/group/alt.hypertext/msg/06dad279804cb3ba?dmode=source&hl=en|accessdate=25 May 2008|archiveurl=https://web.archive.org/web/20080512015304/http://groups.google.co.uk/group/alt.hypertext/msg/06dad279804cb3ba?dmode=source&hl=en|archivedate=12 May 2008|url-status=dead}}{{cite web|title=The original post to alt.hypertalk describing the WorldWideWeb Project|work=Google Groups|date=9 August 1991|url =https://groups.google.com/group/comp.archives/browse_thread/thread/9fb079523583d42/37bb6783d03a3b0d?lnk=st&q=&rnum=2&hl=en#37bb6783d03a3b0d|accessdate=25 May 2008}}
• The Trojan Room coffee pot at the Computer Laboratory, University of Cambridge, England, inspires the first webcam.
• October - Apple releases the PowerBook laptop computer.

• October 1 – The New Zealand Resource Management Act 1991 comes into effect.

• Alan Hildebrand and others provide support for the Alvarez hypothesis for the Cretaceous–Paleogene extinction event by proposing the Chicxulub crater in the Yucatán Peninsula of Mexico as the impact site for a large asteroid 66 million years ago.{{cite journal|author=Pope, Kevin O.|title=Mexican site for K/T impact crater?|journal=Nature|volume=351|date=9 May 1991|page=105|issue=6322|doi=10.1038/351105a0|bibcode = 1991Natur.351..105P |s2cid=36707836|display-authors=etal|doi-access=free}}{{cite journal|author1=Hildebrand, Alan R. |author2=Penfield, Glen T. |author3=Kring, David A. |author4=Pilkington, Mark |author5=Zanoguera, Antonio Camargo |author6=Jacobsen, Stein B. |author7=Boynton, William V. |title=Chicxulub Crater: a possible Cretaceous/Tertiary Boundary impact crater on the Yucatán Peninsula, Mexico|date=September 1991|volume=19|issue=9|journal=Geology|pages=867–871|doi=10.1130/0091-7613(1991)019<0867:CCAPCT>2.3.CO;2|bibcode=1991Geo....19..867H}}{{cite journal|author=Schulte, Peter|title=The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous- Paleogene Boundary|journal=Science|volume=327|pages=1214–1218|year=2010|doi=10.1126/science.1177265|pmid=20203042|issue=5970|bibcode=2010Sci...327.1214S|s2cid=2659741|url=http://doc.rero.ch/record/210367/files/PAL_E4389.pdf|display-authors=etal}}
• The Ames crater impact structure is identified in Major County, Oklahoma.

• July – English physicist Philip Candelas and colleagues show that mirror symmetry could be used to solve problems in enumerative geometry.{{cite journal|last1=Candelas |first1=Philip|last2=de la Ossa|first2=Xenia|last3=Green|first3=Paul|last4=Parks|first4=Linda|year=1991|title=A pair of Calabi–Yau manifolds as an exactly soluble superconformal field theory|journal=Nuclear Physics B|volume=359|issue=1|pages=21–74|doi=10.1016/0550-3213(91)90292-6|bibcode = 1991NuPhB.359...21C }}
• Qiudong Wang produces a global solution to the n-body problem.{{cite journal|last=Wang|first=Qiudong|title=The global solution of the n-body problem|journal=Celestial Mechanics and Dynamical Astronomy|issn=0923-2958|volume=50|issue=1|year=1991|pages=73–88|bibcode=1990CeMDA..50...73W|doi=10.1007/BF00048987|s2cid=118132097}}

• January 1 – Finland joins CERN.
• July 1 – Poland joins CERN.
• October 15 – the "Oh-My-God particle", the first ultra-high-energy cosmic ray measured at an energy of {{val|3|e=20|u=eV}} (40,000,000 times that of the highest energy protons that have been produced in a particle accelerator), is observed at the University of Utah HiRes observatory in Dugway Proving Ground, Utah.

• Takotsubo cardiomyopathy first studied.

• July 1 – World's first GSM telephone call made in Finland.

• The first open-access scientific online archive, arXiv, is begun as a preprint service for physicists, initiated by Paul Ginsparg.

• Nobel Prizes
• Physics – Pierre-Gilles de Gennes
• Chemistry – Richard R. Ernst
• Medicine – Erwin Neher, Bert Sakmann
• Turing Award – Robin Milner

• February 28 – Sheree Atcheson, Sri Lankan-Irish computer scientist

• January 30 – John Bardeen (b. 1908), American physicist, co-inventor of the transistor and twice winner of the Nobel Prize in Physics.
• February 6 – Salvador Luria (b. 1912), Italian-born biologist, co-winner of the Nobel Prize in Physiology or Medicine.
• February 23 – Sir Charles Illingworth (b. 1899), British surgeon.
• March 1 – Edwin H. Land (b. 1909), American inventor of the Land Camera.
• June 2 – Mary Loveless (b. 1899), American immunologist.
• June 5 – Min Chueh Chang (b. 1908), Chinese American embryologist.
• July 4 – Victor Chang (b. 1936), Australian cardiac surgeon, murdered.
• August 23 – Florence B. Seibert (b. 1897), American biochemist.
• December 2 – Anne Beloff-Chain (b. 1921), British biochemist.

{{Portal|1990s|Science}}

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Category:20th century in science

Category:1990s in science