1909 in science

• August 20 – Dwarf planet Pluto is photographed for the first time, at the Yerkes Observatory in Williams Bay, Wisconsin, U.S., 21 years before being identified.{{cite journal|last1=Buchwald|first1=Greg|last2=Dimario|first2=Michael|last3=Wild|first3=Walter|year=2000|title=Pluto is Discovered Back in Time|journal=Amateur–Professional Partnerships in Astronomy|location=San Francisco|volume=220|page=335|isbn=978-1-58381-052-1|bibcode=2000ASPC..220..355B}}
• Comet Halley first becomes visible on a photographic plate.

• Danish plant physiologist Wilhelm Johannsen introduces the term "Gene".{{Cite book |last=Johannsen |first=W. |url=https://www.biodiversitylibrary.org/bibliography/94247 |title=Elemente der exakten Erblichkeitslehre |publisher=G. Fischer |year=1909 |location=Jena |language=German |trans-title=Elements of the exact theory of heredity |doi=10.5962/bhl.title.94247}}
• Karl Landsteiner, Constantin Levaditi and Erwin Popper first isolate the poliovirus.{{cite journal|last1=Landsteiner|first1=Karl|last2=Popper|first2=Erwin|year=1909|title=Übertragung der Poliomyelitis acuta auf Affen|journal=Zeitschrift für Immunitätsforschung|volume=2|pages=377–390}}{{cite book|last=Paul|first=J. R.|title=A History of Poliomyelitis|publisher=Yale University Press|location=New Haven|year=1971|isbn=978-0-300-01324-5|series=Yale studies in the history of science and medicine}}
• Thomas Hunt Morgan produces heritable mutant Drosophila melanogaster.

• February 5 – Leo Baekeland announces the creation of the early plastic Bakelite, a hard thermosetting phenol formaldehyde resin, to the American Chemical Society.{{cite news|title=New Chemical Substance|journal=The New York Times|date=1909-02-06|url=https://timesmachine.nytimes.com/timesmachine/1909/02/06/101025892.pdf}}
• Summer – Fritz Haber and Carl Bosch first demonstrate the Haber process, the catalytic formation of ammonia from hydrogen and atmospheric nitrogen under conditions of high temperature and pressure.{{cite web|url=http://v3.espacenet.com/publicationDetails/biblio?CC=DE&NR=235421&KC=&FT=E|title=Original Patent for Synthesis of Ammonia|publisher=European Patent Office|accessdate=12 April 2011}}{{cite web|first=Chris|last=Bowlby|title=Fritz Haber: Jewish chemist whose work led to Zyklon B|url=https://www.bbc.co.uk/news/world-13015210|publisher=BBC News|date=2011-04-12|accessdate=2011-04-12|archiveurl=https://web.archive.org/web/20110412034923/http://www.bbc.co.uk/news/world-13015210|archivedate=12 April 2011|url-status=live}}
• The concept of p[H] as a measure of the acidity or basicity of an aqueous solution is introduced by Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory.{{cite journal|last=Sorensen|first=S. P. L.|title=Enzymstudien. II, Über die Messung und die Bedeutung der Wasserstoffionenkonzentration bei enzymatischen Prozessen|journal=Biochemische Zeitschrift|year=1909|volume=21|pages=131–304}}
• A team under German chemist Fritz Hofmann first synthesizes synthetic rubber (Methylkautschuk).

• January 16 – Ernest Shackleton's expedition locates the South Magnetic Pole.{{cite web|url=http://deeptow.whoi.edu/southpole.html|title=The Magnetic South Pole|publisher=Woods Hole Oceanographic Institution, Magnetics Group, Ocean Bottom Magnetology Laboratory|accessdate=2011-02-25|archive-url=https://web.archive.org/web/20160421112934/http://deeptow.whoi.edu/southpole.html|archive-date=2016-04-21|url-status=dead}}
• April 6 – Robert Peary, Matthew Henson, and four Eskimo explorers come within a few miles of the North Pole.
• October 8 – An earthquake in the Zagreb area leads Andrija Mohorovičić to identify the Mohorovičić discontinuity.

• L. E. J. Brouwer makes a proof of the Brouwer fixed-point theorem.{{cite book|first=Tony|last=Crilly|title=50 Mathematical Ideas you really need to know|location=London|publisher=Quercus|year=2007|isbn=978-1-84724-008-8|page=97}}

• August 30 – Discovery of the Burgess Shale Cambrian fossil site in the Canadian Rockies by paleontologist Charles Walcott of the Smithsonian Institution.
• Excavation of the dinosaur bone beds at what will become Dinosaur National Monument in the Uinta Mountains of the United States by paleontologist Earl Douglass working for the Carnegie Museum of Natural History.{{cite book|first=G. E.|last=Douglass|title=Speak to the Earth and It Will Teach You: The Life and Times of Earl Douglass, 1862–1931|year=2009|location=Charleston, South Carolina|publisher=BookSurge}}

• Paul Ehrenfest presents the Ehrenfest paradox.{{cite journal|last=Ehrenfest|first=Paul|year=1909|title=Gleichförmige Rotation starrer Körper und Relativitätstheorie|trans-title=Uniform Rotation of Rigid Bodies and the Theory of Relativity|journal=Physikalische Zeitschrift|volume=10|page=918|title-link=s:de:Gleichförmige Rotation starrer Körper und Relativitätstheorie}}
• Albert Einstein together with Marcel Grossmann starts to develop a theory which would bind metric tensor g_ik, which defines a space geometry, with a source of gravity, that is with mass.
• Hans Geiger and Ernest Marsden discover large angle deflections of alpha particles by thin metal foils.
• Ernest Rutherford and Thomas Royds demonstrate that alpha particles are doubly ionized helium atoms.

• July – Ivy Evelyn Woodward is admitted as the first woman Member of the Royal College of Physicians in the United Kingdom.{{cite book|title=A history of the Royal College of Physicians of London|volume=3|last=Cooke|first=A. M.|publisher=Clarendon Press for the Royal College of Physicians|year=1972|page=976}}{{cite book|title=Professions and Patriarchy|last=Witz|first=Anne|year=2016|place=London|publisher=Routledge|isbn=9781138135796|oclc=938993033}}
• September – Sigmund Freud delivers his only lectures in the United States, on psychoanalysis, at Clark University, Worcester, Massachusetts, giving public recognition to the subject in the anglophone world.
• Austro-Hungarian neurologist and psychiatrist Rezső Bálint first describes Bálint's syndrome.{{cite journal|doi=10.1159/000210464|title=Seelenlähmung des 'Schauens', optische Ataxie, räumliche Störung der Aufmerksamkeit|trans-title=Soul imbalance of 'seeing', optical ataxia, spatial disturbance of attention|language=German|journal=European Neurology|volume=25|pages=51–66|year=1909|last=Bálint|first=Rudolph|url=https://zenodo.org/record/1448605|access-date=2025-02-09|archive-date=2019-08-24|archive-url=https://web.archive.org/web/20190824130814/https://zenodo.org/record/1448605|url-status=live}}
• German neurologist Korbinian Brodmann defines the cytoarchitecture of the Brodmann area of the cerebral cortex.{{citation|first=K.|last=Brodmann|title=Vergleichende Lokalisationslehre der Großhirnrinde in ihren Prinzipien dargestellt auf Grund des Zellenbaues.|year=1909}}
• Brazilian physician and infectologist Carlos Chagas first describes Chagas disease.{{cite journal|last=Chagas|first=C.|title=Neue Trypanosomen|journal=Vorläufige Mitteilung Archiv für Schiffs-und Tropenhygiene|year=1909|volume=13|pages=120–2}}{{cite journal|author1=Redhead, S. A. |author2=Cushion, M. T. |author3=Frenkel, J. K. |author4=Stringer, J. R. |title=Pneumocystis and Trypanosoma cruzi: nomenclature and typifications|journal=Journal of Eukaryotic Microbiology|year=2006|pages=2–11|volume=53|issue=1|pmid=16441572|doi=10.1111/j.1550-7408.2005.00072.x}}{{cite journal|last=Chagas|first=C.|title=Nova tripanozomiase humana: Estudos sobre a morfolojia e o ciclo evolutivo do Schizotrypanum cruzi n. gen., n. sp., ajente etiolojico de nova entidade morbida do homem [New human trypanosomiasis: Studies about the morphology and life-cycle of Schizotripanum cruzi, etiological agent of a new morbid entity of man]|journal=Memórias do Instituto Oswaldo Cruz|year=1909|volume=1|issue=2|pages=159–218|issn=0074-0276|doi=10.1590/S0074-02761909000200008|doi-access=free}}{{cite journal|journal=História, Ciências, Saúde – Manguinhos|date=July 2009|volume=16|issue=Suppl 1|pages=13–34|title=The discovery of Trypanosoma cruzi and Chagas disease (1908–1909): tropical medicine in Brazil|last1=Kropf|first1=S. P.|last2=Sá|first2=Magali Romero|pmid=20027916|doi=10.1590/s0104-59702009000500002|doi-access=free}}
• French otolaryngologist Étienne Lombard discovers the Lombard effect.{{cite journal|last=Lombard|first=É.|title=Le signe de l'élévation de la voix|journal=Annales des Maladies de l'Oreille et du Larynx|volume=XXXVII|issue=2|pages=101–9|year=1911}}{{cite journal|author=Lane, H.|author2=Tranel, B.|title=The Lombard sign and the role of hearing in speech|journal=Journal of Speech and Hearing Research|volume=14|issue=4|pages=677–709|year=1971|doi=10.1044/jshr.1404.677}}
• In psychology, Edward B. Titchener makes the first published coinage of the term Empathy as a translation of the German {{lang|de|Einfühlungsvermögen}}.Lectures on the Experimental Psychology of the Thought-Processes. New York: Macmillan, 1909. {{cite web |title=empathy, n. |work=Oxford English Dictionary online version |publisher=Oxford University Press |url=https://www.oed.com/view/Entry/61284 |url-access=subscription |accessdate=2012-02-16 |archive-url=https://web.archive.org/web/20220304034318/https://www.oed.com/view/Entry/61284 |archive-date=2022-03-04 |url-status=live |date=December 2011 }} {{OEDsub}}

• March 18 – Einar Dessau uses a shortwave radio transmitter in Denmark.{{cite web|title=First Broadcast by Ham Radio Operator|url=https://infostory.com/2013/03/18/first-broadcast-by-ham-radio-operator-2/|work=The Story of Information|date=2013-03-18|accessdate=2019-10-17}}
• July 7 – General Electric applies to patent an electric toaster invented by Frank E. Shailor in the United StatesF. E. Shailor (1910-02-22) "Electric heater" {{US Patent|950058}}. and produces the GE model D-12, the first commercially successful model.{{cite web|url=http://www.toaster.org/museum.html|work=The Cyber Toaster Museum|last=Norcross|first=Eric|title=1900–1920|year=2006|publisher=The Toaster Museum Foundation|access-date=2022-11-20|url-status=dead|archive-url=https://web.archive.org/web/20080815211550/http://www.toaster.org/museum.html|archive-date=2008-08-15|via=Wayback Machine}}
• July 23 – White Star Liner RMS Republic (15,400 tons), sinking following a collision off Nantucket, becomes the first ship in history to issue a CQD distress signal, using Marconi wireless telegraphy.{{cite web|url=https://www.pbs.org/wgbh/amex/rescue/filmmore/transcript/transcript1.html|work=The American Experience|title=Rescue at Sea|publisher=PBS|accessdate=2012-03-22|archive-date=2012-11-09|archive-url=https://web.archive.org/web/20121109192118/http://www.pbs.org/wgbh/amex/rescue/filmmore/transcript/transcript1.html|url-status=dead}}{{cite book|first=William H.|last=Flayhart|title=Disaster at Sea|publisher=W. W. Norton & Company|year=2005|pages=206–210}}
• July 25 – Louis Bleriot is the first man to fly across the English Channel in a heavier-than-air craft.
• Kinemacolor, the first commercial "natural color" system for movies is invented.
• Johann Stumpf popularises the uniflow steam engine.{{cite book|first=H. W.|last=Dickinson|title=A Short History of the Steam Engine|publisher=Cambridge University Press|year=1938}}

• June 26 – The Science Museum, London is established as an institution in its own right.{{cite web |url=https://www.sciencemuseum.org.uk/about-us |title=About us| publisher = Science Museum | accessdate=2020-05-06 }}
• Commencement of fieldwork for the multidisciplinary Clare Island Survey (Ireland), under the direction of Robert Lloyd Praeger.

• Nobel Prizes
• Physics – Guglielmo Marconi, Karl Ferdinand Braun
• Chemistry – Wilhelm Ostwald
• Medicine – Emil Theodor Kocher

• January 5 – Stephen Cole Kleene (died 1994), American mathematician.
• February 9 – Giulio Racah (died 1965), Italian–Israeli mathematician and physicist.
• February 18 – Warren Elliot Henry (died 2001), American physicist.
• March 22 – Nathan Rosen (died 1995), Jewish American physicist.
• April 13 – Stanislaw Ulam (died 1984), Polish American mathematician.
• April 22 – Rita Levi-Montalcini (died 2012), Italian Jewish neurologist, recipient of the Nobel Prize in Physiology or Medicine.
• May 7 – Edwin H. Land (died 1991), American inventor and founder of Polaroid.
• September 14 – Peter Scott (died 1989), English conservationist.
• August 1 – Sibyl M. Rock (died 1981), American mathematician.
• November 24 – Gerhard Gentzen (died 1945), German-born mathematician.
• December 11 – Toshiko Yuasa (died 1980), Japanese nuclear physicist.
• December 14 – Edward Lawrie Tatum (died 1975), American geneticist, recipient of the Nobel Prize in Physiology or Medicine.

• January 12 – Hermann Minkowski (born 1864), German mathematician.
• February 26 – Hermann Ebbinghaus (born 1850), German psychologist.
• July 11 – Simon Newcomb (born 1835), Canadian American astronomer.
• August 14 – William Stanley (born 1829), English inventor.
• August 27 – Emil Christian Hansen (born 1842), Danish fermentation physiologist.
• October 19 – Cesare Lombroso (born 1835), Italian forensic psychiatrist.

{{Reflist}}

{{DEFAULTSORT:1909 In Science}}

Category:20th century in science

Category:1900s in science