Estonian astronomer and astrophysicist who rose to prominence in the 1920s. He has won a number of awards throughout his career including the Gold Medal of the Royal Astronomical Society in 1975, and the Bruce Medal in 1976.
He studied at the University of Moscow and the University of Tartu.
He correctly predicted the frequency of craters on Mars long before they were determined by space probes.
He was the son of Anna and Karl Opik.
He was born in the same country as composer Heino Eller.