On This Date in History - April 4

Daily Extra :

Astronomy & Space Word of The Day

tidal heating: Frictional heating of a satellite's interior due to flexure caused by the gravitational pull of its parent planet and possibly neighboring satellites.

Who Was Born Today?:

1809: Benjamin Pierce, U.S. mathematician and astronomer
1940: Vladimir Timofeyevich Isakov, Russia, cosmonaut

Who Died Today?:

1807: Joseph Jerome Le Francais de Lalande, French astronomer, dies

Today in History:

1947: Largest group of sunspots on record

1960: Project Ozma begins at Green Bank radio astronomy center

1961: Three astronauts selected for Mercury-Redstone flight (MR-3) were ordered to take refresher course in Navy centrifuge at Johnsville, PA

1968: Apollo 6 launched atop Saturn V; unmanned

1983: 6th space shuttle mission, Challenger 1 launched

1997: DMSP Titan 2 launched

1997: STS-83, Columbia 22, launches

Featured Astronomy Image of the Week

Check out the former Astronomy Picture of the Day. See what surprises await you this week.