A total solar eclipse occurred on December 12, 1871.http://en.wikipedia.org/wiki/Solar_eclipse_of_December_12,_1871A partial solar eclipse occurred on December 12, 1909.http://en.wikipedia.org/wiki/Solar_eclipse_of_December_12,_1909
Rigel culminates at midnight on December 12http://en.wikipedia.org/wiki/Rigel
The Siege of Maarat ended on 12 December 1098https://en.wikipedia.org/wiki/Siege_of_Ma%27arra#Siege
USS Cairo was sunk on 12 December 1862https://en.wikipedia.org/wiki/USS_Cairo
The first amateur satellite simply named OSCAR-1, was launched on December 12, 1961http://astronomy.activeboard.com/t46697940/oscar-1-satellite/Small Astronomy Satellite 1, Uhuru, a NASA X-Ray satellite launched on December 12, 1970 http://en.wikipedia.org/wiki/Small_Astronomy_Satellite_1Kwangmyongsong-3 Unit 2 was launched on 12 December 2012 http://en.wikipedia.org/wiki/Kwangmy%C5%8Fngs%C5%8Fng-3_Unit_2
Kenneth "Hock" Todd Ham (born December 12, 1964) is a retired American astronauthttp://en.wikipedia.org/wiki/Kenneth_HamSteven Alan Hawley (born December 12, 1951) is a former NASA astronaut http://en.wikipedia.org/wiki/Steven_HawleyEugene Michael Chudnovsky (born 12 December 1948) is a Distinguished Professor of Physicshttp://en.wikipedia.org/wiki/Eugene_Chudnovsky
Alfred Werner (12 December 1866 - 15 November 1919) was a Swiss chemisthttps://en.wikipedia.org/wiki/Alfred_WernerJames Challis (12 December 1803 - 3 December 1882) was an English clergymanhttp://en.wikipedia.org/wiki/James_Challis
Father Christmas (12 December 1788 - 3 December 2015)http://www.bbc.co.uk/news/world-europe-35009259
Ulrike Luise Tillmann (born 12 December 1962) is a mathematicianhttps://en.wikipedia.org/wiki/Ulrike_TillmannValter Giuliani (born 12 December 1960) is an Italian astronomer.http://it.wikipedia.org/wiki/Valter_GiulianiGeorges-Antoine-Pons Rayet (December 12, 1839 - June 14, 1906) was a French astronomer.http://en.wikipedia.org/wiki/Georges_Rayet
On 12 December 1901, the first transatlantic wireless transmission was received at Signal Hillhttp://en.wikipedia.org/wiki/Signal_Hill,_Newfoundland_and_Labrador
NGC 6217 was discovered by William Herschel on the 12th December 1797.http://astronomy.activeboard.com/t55890828/ngc-6217/
The North America Nebula (NGC 7000) was first photographed by Max Wolf in Heidelberg on the 12th December 1890.https://en.wikipedia.org/wiki/North_America_Nebula
Mu Arae b's discovery was announced on December 12, 2002http://en.wikipedia.org/wiki/Mu_Arae_b
Asteroid 253 Mathilde was discovered by Johann Palisa on the 12 November 1885.https://en.wikipedia.org/wiki/253_Mathilde
Asteroid 7796 Járacimrman was discovered by the Brera-Merate Observatory on 12 December 1973 https://en.wikipedia.org/wiki/7796_J%C3%A1racimrman
Puppides-Velides: Up to 15 meteors per hour may be observed on the 12th Decemberhttp://astronomy.activeboard.com/t56181924/puppides-velides/
The Southern Ontario fireball observed on December 12, 2011http://astronomy.activeboard.com/t46718431/southern-ontario-meteor/
Meteorites
December 12, 1872 - a meteorite hits a wall close to the market town of Banbury in England.http://astronomy.activeboard.com/t23107936/banbury-meteorite/No historical meteorite falls today, AFAIK