Öpik, Ernst Julius (1893–1985)

Estonian astronomer whose work on the nature of meteors and comets was instrumental in the development of heat-deflective surfaces for spacecraft on their re-entry into the Earth's atmosphere.

Öpik was born near Rakvere and studied at Tartu, where he spent most of his academic career 1921–44. He then moved to Germany, becoming professor at the Baltic University in 1945. Three years later, Öpik moved to Northern Ireland, where he eventually became director of the Armagh Observatory. From 1956 onward he held a concurrent post at the University of Maryland, USA.

Öpik was the originator of a method for counting meteors that requires two astronomers to scan simultaneously. His theories on surface events in meteors upon entering the Earth's atmosphere at high speed (the ablation, or progressive erosion, of the outer layers) proved to be extremely important in the development of heat shields and other protective devices to enable a spacecraft to withstand the friction and the resulting intense heat upon re-entry.

Much of Öpik's other work was directed at the analysis of comets that orbit our Sun. He postulated that the orbit of some of these comets may take them as far away as 1 light year.