1781 – M85 (NGC 4382) was discovered on April 4th, 1781, by Pierre Méchain.
M85 measures approximately 125,000 light years across, and lies about 60 million light years away in the constellation of Coma Berenices. It is a member of the Virgo Cluster.
It is thought possible that M85 might be the result of two galaxies merging billions of years ago.
1858 – Discovery by Robert Luther of Asteroid 53 Kalypso.
Kosmos 28 was launched on April 4th 1964.
1968 saw the launch, on this day, of Apollo VI to test the ability of the Saturn V to get an almost full payload to the Moon and back, and to repeat an earlier test of the Command Module’s heat shield. Apollo VI was the final unmanned launch of the program.
The flight was not without incident, caused in part by unusually strong vibrations shortly after lift-off. A couple of the engines shut down prematurely, necessitating a lower than expected “parking orbit”, and a lack of fuel on re-entry meant that the speed of a real lunar return could not be simulated.