Ernst Öpik

Ernst Julius Öpik was born in Port Kunda on October 22, 1893. Educated at Moscow Imperial University, Öpik joined the Tartu Observatory in 1921, where he revolutionized extragalactic astronomy.

In 1922, using rotating stellar dynamics, Öpik proved that the Andromeda Nebula was a massive independent star system situated 1.5 million light-years away, resolving the Great Debate on the scale of the universe years before Edwin Hubble. In 1932, he postulated the existence of a vast reservoir of comets at the edge of the solar system (the Öpik-Oort cloud). Fleeing Soviet occupation in 1944, he directed Armagh Observatory for three decades.