1845 in science

The year 1845 in science and technology involved some significant events, listed below.

AstronomyEdit

April – Lord Rosse discovers that the nebula M51 has a spiral structure.
September–October – Cornish mathematician John Couch Adams communicates to James Challis and George Biddell Airy his calculations demonstrating that a body (Neptune) is perturbing the orbit of Uranus.<ref>Template:Cite journal</ref>
November 10 – Urbain Le Verrier presents to the Académie des sciences in Paris a memoir showing that existing theories fail to account for the motion of Uranus.<ref>Template:Cite EB1911</ref>
Construction begins in Ireland of the "Leviathan of Parsonstown", a telescope built by Lord Rosse.

August–September – Previously unknown Potato blight strikes the potato crop in Ireland: start of the Great Famine.<ref>{{#invoke:citation/CS1|citation

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August – John Franklin's expedition with HMS Erebus and HMS Terror to find the Northwest Passage is last seen entering Baffin Bay prior to its mysterious disappearance.<ref>Template:Cite book</ref>

December 27 – Anesthesia is used in childbirth for the first time, by Dr Crawford Long in Jefferson, Georgia.

September 13 – Michael Faraday discovers that an intense magnetic field can rotate the plane of polarized light, the Faraday effect.
C. H. D. Buys Ballot confirms the Doppler effect for sound waves.<ref>Template:Cite journal</ref>
Kirchhoff's circuit laws are first described by German physicist Gustav Kirchhoff.

July 26–August 10 – Isambard Kingdom Brunel’s iron steamship Great Britain makes the Transatlantic Crossing from Liverpool to New York, the first screw propelled vessel to make the passage.<ref>Template:Cite book</ref><ref>{{#invoke:citation/CS1|citation

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January 14 – Physikalische Gesellschaft zu Berlin established and begins publishing Fortschritte der Physik and Verhandlungen.
August 28 – The journal Scientific American begins publication.
Alexander von Humboldt's Kosmos: Entwurf einer physischen Weltbeschreibung begins publication.

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February 17 (Old Style March 1) – Fyodor Pirotsky (died 1898), Ukrainian-born Russian military and electrical engineer and inventor.
March 3 – Georg Cantor (died 1918), Russian-born German mathematician.
March 27 – Wilhelm Röntgen (died 1923), German physicist, discoverer of X-rays, Nobel laureate.
April 21 – William Healey Dall (died 1927), American malacologist and explorer.
May 4 – William Kingdon Clifford (died 1879), English geometer.
May 16 – Élie Metchnikoff (died 1916), Russian-born microbiologist, Nobel laureate.
June 16 – Heinrich Dressel (died 1920), German archaeologist.
July 4 – Thomas Barnardo (died 1905), Irish-born physician and philanthropist.
September 11 – Émile Baudot (died 1903), French telegraph engineer.
November 14 – Ulisse Dini (died 1918), Italian mathematician.