ROEMER EMA Christensen (Roemer Ole Christensen)

(1644-1710)
Born September 25, 1644 in Aarhus (Jutland). He graduated from the University of Copenhagen. In 1671-1681 he worked at the Paris Observatory under Dzh.Kassini. In 1681 he was invited to the University of Copenhagen for the post of professor of mathematics and astronomy. He founded and headed by the Copenhagen Observatory. Roemer belongs to the first definition of the speed of light. Using Constructed Dzh.Kassini tables motion of Jupiter's moons, . Roemer explained the delay time of the eclipse of the first satellite (for the case, . when Earth and Jupiter are furthest from each other) on the time of the eclipse with the smallest distance between the finite velocity of light,
. The delay was 22 minutes, during which time the light had to overcome a distance equal to the diameter of the Earth's orbit (according to modern data, is the distance light travels approximately 17 minutes).
Roemer also known as the inventor of the transit instrument (1689), meridian circle (1690), an equatorial mount telescope. Remer died in Copenhagen on 23 September 1710.