* Astronomy

The Sun enters the zodiac sign Aries on the 20th March

The March (Northern Vernal) Equinox on the 20th March

Chicagohenge occurs when the sun sets directly along Chicago's streets.
http://astronomy.activeboard.com/t59848017/chicagohenge/

The Dutch East India Company was a chartered company established in 1602
http://en.wikipedia.org/wiki/Dutch_East_India_Company

The General theory of relativity was published by Albert Einstein in 1916.
http://astronomy.activeboard.com/t30408705/general-relativity/

Eyjafjallajökull eurupted in 2010
http://astronomy.activeboard.com/t34782947/eyjafjallajoekull-volcano/?page=6

The European Space Research Organisation was established on the 20th March 1964
http://en.wikipedia.org/wiki/ESRO#The_Auger_years_.281964-67.29

The Fox Astronomical Observatory was dedicated on March 20, 1977
http://en.wikipedia.org/wiki/Fox_Observatory

Yuri Georgiyevich Shargin is a cosmonaut in the Russian Space Forces. 
http://en.wikipedia.org/wiki/Yuri_Shargin

Pavel Petrovich Parenago (20 March 1906 - 5 January 1960) was a Soviet astronomer
http://en.wikipedia.org/wiki/Pavel_Petrovich_Parenago

Timothy David Puckett (born 1962) is an amateur astronomer
https://en.wikipedia.org/wiki/Puckett_Observatory#Tim_Puckett

Dimitri Manuel Mihalas (March 20, 1939 - November 21, 2013) was a laboratory fellow at Los Alamos
http://en.wikipedia.org/wiki/Dimitri_Mihalas

Atahualpa (20 March 1497 - 29 August 1533) was the last Sapa Inca of the Tawantinsuyu (the Inca Empire)
http://en.wikipedia.org/wiki/Inca_Empire#Inca_civil_war_and_Spanish_conquest

Publius Ovidius Naso (20 March 43 BC - AD 17/18), known as Ovid in the English-speaking world, was a Roman poet 
http://astronomy.activeboard.com/t48347978/publius-ovidius-naso-43-bc-ad-1718/

Dame Vera Lynn, DBE (born Vera Margaret Welch on 20 March 1917), widely known as "The Forces' Sweetheart" is an English singer, songwriter and actress.
http://en.wikipedia.org/wiki/Vera_Lynn

Mary Bateman (1768-20 March 1809) was an English criminal and alleged witch
http://en.wikipedia.org/wiki/Mary_Bateman

Messier 93 was discovered by Charles Messier on the 20th March 1781.
http://astronomy.activeboard.com/t57071009/messier-93/

NGC 2759 was discovered by British astronomer William Herschel on the 20th March 1787.
http://astronomy.activeboard.com/t57163392/ngc-2759/

NGC 2935 was discovered by William Herschel using on the 20th March 1786.
http://astronomy.activeboard.com/t57070986/ngc-2935/

Messier 95 was discovered by Pierre Méchain on the 20th March 1781.
http://astronomy.activeboard.com/t49267595/messier-95/

Messier 96 was discovered by Pierre Méchain on the 20th March 1781.
http://astronomy.activeboard.com/t57070958/messier-96/

NGC 3383 was discovered by John Herschel on the 20th March 1835.
http://astronomy.activeboard.com/t57070934/ngc-3383/

NGC 3668 was discovered by William Herschel on the 20th March 1790.
http://astronomy.activeboard.com/t57070929/ngc-3668/

NGC 4504 was discovered by William Herschel on the 20th March 1789.
http://astronomy.activeboard.com/t57070910/ngc-4504/

NGC 4521 was discovered by William Herschel on the 20th March 1790.
http://astronomy.activeboard.com/t57070902/ngc-4521/

NGC 4545 was discovered by William Herschel on the 20th March 1790.
http://astronomy.activeboard.com/t57070896/ngc-4545/

NGC 4627 was discovered by William Herschel on the 20th March 1787.
http://astronomy.activeboard.com/t63444469/ngc-4627/

NGC 4631 was discovered by William Herschel on the 20th March 1787. 
http://astronomy.activeboard.com/t59730561/ngc-4631/

NGC 4656 was discovered by William Herschel on the 20th March 1787.
http://astronomy.activeboard.com/t63444602/ngc-4656/

NGC 4657 was discovered by William Herschel on the 20th March 1787
http://astronomy.activeboard.com/t63444807/ngc-4657/

NGC 5195 (also known as Messier 51b) was discovered by Pierre Méchain on the 20th March 1781.
http://astronomy.activeboard.com/t10655886/the-whirlpool-galaxy/