Title: The Great Sunspot Group of March and April, 1947http://adsabs.harvard.edu/full/1947PASP...59..109H
The Megalesia, Megalensia, or Megalenses Ludi, was a festival (with games, ludi) celebrated in Ancient Romehttp://en.wikipedia.org/wiki/Megalesia
1905 Kangra earthquake was a major earthquake that occurred in India on 4 April 1905.http://astronomy.activeboard.com/t42101817/1905-kangra-earthquake/
The American Rocket Society (ARS) began its existence on April 4, 1930http://astronomy.activeboard.com/t35051171/american-rocket-society/USS Akron (ZRS-4) was a helium-filled rigid airship lost on April 4, 1933http://astronomy.activeboard.com/t48573473/uss-akron-zrs-4/
Project Ozma was a pioneering SETI experiment started in 1960http://en.wikipedia.org/wiki/Project_Ozma
Apollo 6 was launched on April 4, 1968http://www.astronomy.activeboard.com/t42101606/apollo-6/STS-6 was a Space Shuttle mission conducted by NASA using Space Shuttle Challenger, launched 4 April 1983,http://astronomy.activeboard.com/t42101626/sts-6/STS-83 was a mission of the United States Space Shuttle Columbia, launched on 4 April 1997http://en.wikipedia.org/wiki/STS-83Launch of the WGS-2 satellite was conducted by ULA, at 01:31 GMT on April 4, 2009http://astronomy.activeboard.com/t19603807/wideband-gapfiller-satellite-2/
Satoshi Furukawa (born April 4, 1964) is a Japanese surgeon and a JAXA astronaut.http://en.wikipedia.org/wiki/Satoshi_FurukawaKarl Wilhelm Reinmuth (April 4, 1892 in Heidelberg - May 6, 1979) was a German astronomer.http://en.wikipedia.org/wiki/Karl_Wilhelm_ReinmuthJoseph-Nicolas Delisle (4 April 1688 - 11 September 1768) was a French astronomer.http://en.wikipedia.org/wiki/Joseph-Nicolas_Delisle
Joseph Ashbrook (April 4, 1918 - August 4, 1980) was an American astronomer.https://en.wikipedia.org/wiki/Joseph_AshbrookThomas John Hussey (4 April 1792 - c. 1854) was an English clergyman and astronomer.http://en.wikipedia.org/wiki/Thomas_John_HusseyCho Gyeong-chul (April 4, 1929 - March 6, 2010) was a South Korean astronomer.http://en.wikipedia.org/wiki/Cho_Gyeong-chul
Marine Boy was one of the first colour anime cartoons to be shown in a dubbed form in the U.S.
The Good Life aired for four series and two specials from 4 April 1975 to 10 June 1978. http://en.wikipedia.org/wiki/The_Good_Life_(1975_TV_series)
NGC 5550 was discovered by John Herschel on the 4th April 1831.http://astronomy.activeboard.com/t57209846/ngc-5550/NGC 5655 was discovered by John Herschel on the 4th April 1831.http://astronomy.activeboard.com/t57209835/ngc-5655/
Supernova UDS10Wil was one of the most distant Type Ia supernova ever detected.
Asteroid (1798) Watts was discovered on 4 April 1949https://en.wikipedia.org/wiki/1798_Watts
The Ch'ing-yang event of 1490http://astronomy.activeboard.com/t57084034/ching-yang-event-of-1490/
In April, 1878, a large meteor was observed in broad daylight and falling about twenty miles south of Ballater.http://astronomy.activeboard.com/t57210635/april-1878-meteor/