* Astronomy

World Meteorological Day is held annually on March 23.
http://en.wikipedia.org/wiki/World_Meteorological_Organization#World_Meteorological_Day @tjdelsanto

In ancient Latvia, Lieldienas ("big days") was the celebration of Vernal Equinox on March 23.
http://en.wikipedia.org/wiki/Lieldienas

The Tubilustrium Roman ceremony was observed on March 23
http://en.wikipedia.org/wiki/Tubilustrium

The last known eruption of Mount Iwaki was on March 23, 1863. 
http://en.wikipedia.org/wiki/Mount_Iwaki

35 tonnes of explosive charges exploded near the Broadmarsh Crater (creating the Longfellow crater group) on 23 March 1917
http://en.wikipedia.org/wiki/Battle_of_Vimy_Ridge

The Teapot ESS nuclear detonation was detonated on March 23, 1955.

Spoiler

On March 23, 1815 USS Hornet captured HMS Penguin in a short battle off Tristan da Cunha. 
http://en.wikipedia.org/wiki/Capture_of_HMS_Penguin

Albert Hanlin Crews, Jr. (born March 23, 1929) is a former USAF astronaut. 
http://en.wikipedia.org/wiki/Albert_H._Crews

Cosmonaut Valentin Bondarenko died after a fire in a high-oxygen isolation chamber on March 23, 1961
http://en.wikipedia.org/wiki/Valentin_Bondarenko

Forrest S. McCartney (March 23, 1931 - July 17, 2012) was a former director of NASA's John F. Kennedy Space Centre. 
http://en.wikipedia.org/wiki/Forrest_S._McCartney

Arkhip Mikhailovich Lyul'ka (1908 - 1984), was a Soviet scientist and designer of jet engines
http://en.wikipedia.org/wiki/Arkhip_Lyulka

Wernher von Braun (March 23, 1912 - June 16, 1977) was a German rocket engineer
http://en.wikipedia.org/wiki/Wernher_von_Braun

Vasily Grigoryevich Zaytsev (March 23, 1915 - December 15, 1991) was a Soviet sniper during World War II
http://en.wikipedia.org/wiki/Vasily_Grigoryevich_Zaitsev

William 'Strata' Smith (23 March 1769 - 28 August 1839) was an English geologist, credited with creating the first nationwide geological map. 
http://astronomy.activeboard.com/t59872524/william-smith-1769-1839/

Amalie Emmy Noether (23 March 1882 - 14 April 1935) was a German mathematician
https://en.wikipedia.org/wiki/Emmy_Noether

Sir Norman Robert Pogson KBE (March 23, 1829 in Nottingham - June 23, 1891 in Chennai, India) was an English astronomer.
http://en.wikipedia.org/wiki/N._R._Pogson

John Beverley Oke (23 March 1928 - 2 March 2004) was an astronomer and professor of astronomy at Caltech
http://en.wikipedia.org/wiki/John_Beverley_Oke

Alan Michael Dressler (born 23 March 1948) is an American astronomer at the Carnegie Institution for Science of Washington, D.C..
http://en.wikipedia.org/wiki/Alan_Dressler

Pierre-Simon, marquis de Laplace (23 March 1749 - 5 March 1827) was a French mathematician and astronomer
http://en.wikipedia.org/wiki/Pierre-Simon_Laplace

Susan Cunningham (1842 - 1921) was an mathematician and astronomer 
http://www.agnesscott.edu/lriddle/women/cunning.htm

Richard Anthony Proctor (23 March 1837 - 12 September 1888) was an English astronomer.
https://en.wikipedia.org/wiki/Richard_A._Proctor

Baron Jurij Bartolomej Vega (born March 23, 1754 - September 26, 1802) was a Slovene mathematician
http://en.wikipedia.org/wiki/Jurij_Vega

Henry Beam Piper (March 23, 1904 - c. November 6, 1964) was an American science fiction author. 
http://en.wikipedia.org/wiki/H._Beam_Piper

Lt. Natasha "Tasha" Yar was chief of security aboard the Starfleet starship USS Enterprise-D
http://en.wikipedia.org/wiki/Tasha_Yar

NGC 2561 was discovered by Lewis Swift on the 23rd March 1887.
http://astronomy.activeboard.com/t57098716/ngc-2561/

NGC 2996 was discovered by John Herschel on the 23rd March 1835.
http://astronomy.activeboard.com/t63311740/ngc-2996/

NGC 3633 was discovered by Lewis Swift on the 23rd March 1887.
http://astronomy.activeboard.com/t57098714/ngc-3633/

NGC 3652 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098710/ngc-3652/

NGC 3658 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098708/ngc-3658/

NGC 3665 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098702/ngc-3665/

NGC 4048 was discovered by John Herschel on the 23rd March 1827.
http://astronomy.activeboard.com/t57098700/ngc-4048/

NGC 4520 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098696/ngc-4520/

NGC 4813 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098691/ngc-4813/

Messier 64 was discovered by Edward Pigott on the 23rd March 1779.
http://astronomy.activeboard.com/t43342077/messier-64/

NGC 4878 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098680/ngc-4878/

NGC 4879 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098675/ngc-4879/

NGC 4888 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098672/ngc-4888/

NGC 4925 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098667/ngc-4925/

NGC 4942 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098665/ngc-4942/

NGC 4978 was discovered by John Herschel on the 23rd March 1827.
http://astronomy.activeboard.com/t57098662/ngc-4978/

NGC 4990 was discovered by Heinrich d'Arrest on the 23rd March 1865.
http://astronomy.activeboard.com/t57098658/ngc-4990/

NGC 5190 was discovered by John Herschel on the 23rd March 1827.
http://astronomy.activeboard.com/t57098657/ngc-5190/

NGC 5459 was discovered by Lewis Swift on the 23rd March 1887.
http://astronomy.activeboard.com/t57098648/ngc-5459/

NGC 5478 was discovered by William Herschel on the 23rd March 1789.
http://astronomy.activeboard.com/t57098641/ngc-5478/