Ernst Öpik

Ernst Öpik
Ernst Öpik
Born	23 October 1893(1893-10-23) Kunda, Lääne-Viru, Estonia
Died	10 September 1985(1985-09-10) (aged 91) Bangor, Northern Ireland, United Kingdom
Nationality	Estonian
Fields	astronomy
Institutions	Armagh Observatory
Alma mater	University of Moscow University of Tartu
Notable awards	Gold Medal of the Royal Astronomical Society in 1975 Bruce Medal in 1976

Ernst Julius Öpik (23 October 1893 – 10 September 1985) was a noted Estonian astronomer and astrophysicist who spent the second half of his career (1948–1981) at the Armagh Observatory in Northern Ireland.

Education

Öpik was born in Kunda, Estonia. He went to the University of Moscow to specialize in the study of minor bodies, such as asteroids, comets, and meteors. He completed his doctorate at the University of Tartu.

Astronomical work

In 1916 Öpik published article in Astrophysical Journal, where he estimates the densities of visual binary stars. It is interesting to note that in his sample was ο₂ Eridani, a white dwarf star. Öpik determined its density as 25,000 times the density of the Sun but concluded that the result is impossible.

In 1922, Ernst Öpik published a paper where he estimated the distance of the Andromeda Galaxy. Using a novel and simple astrophysical method, he determined the distance as 450 kpc. His result was in good accordance with other estimates of these days (100 to 1000 kpc) and were closer to recent estimates (778 kpc) than Hubble's result (275 kpc). His method is still widely used.

In 1922 he correctly predicted the frequency of craters on Mars long before they were detected by space probes. In 1932 he postulated a theory concerning the origins of comets in our solar system. He believed that they originated in a cloud orbiting far beyond the orbit of Pluto. This cloud is now known as the Oort cloud or alternatively the Öpik-Oort Cloud in his honour. He also invented a rocking camera for the study of meteors. In 1951 he published a paper concerning the triple-alpha process, describing the burning of helium-4 into carbon-12 in the cores of red giant stars. However, this achievement is often overlooked because Edwin Salpeter's paper on the same subject had already been published by the time Öpik's paper reached Britain and the United States.

In 1972, Öpik published a very important piece on the origin of the Moon by capture in the Irish Astronomical Journal (vol. 10, pp. 190-238). He included breakup and re-assembly of rings into which the Moon was broken.

Yarkovsky Effect connection

The Yarkovsky Effect was discovered by the Russian civil engineer Ivan Osipovich Yarkovsky (1844–1902), who worked on scientific problems in his spare time. Writing in a pamphlet around the year 1900, Yarkovsky noted that the diurnal heating of a rotating object in space would cause it to experience a force that, while tiny, could lead to large long-term effects in the orbits of small bodies, especially meteoroids and small asteroids. Yarkovsky's remarkable insight would have been consigned to oblivion had it not been for Öpik, who read Yarkovsky's pamphlet sometime around 1909. Decades later, Öpik, recalling the pamphlet from memory, discussed the possible importance of the Yarkovsky Effect for moving meteoroids about the solar system.

Exile

Öpik fled his native country in 1944 because the approaching Red Army raised fear among Estonians. Living as a refugee in Germany, he became the Estonian chancellor of the Baltic University in Exile in the displaced persons camps. In 1948 he was offered a post in Armagh and remained there despite offers of lucrative jobs in America.

Awards

He won the Gold Medal of the Royal Astronomical Society in 1975 and the Bruce Medal in 1976.

Legacy

The asteroid 2099 Öpik is named in his honour. His grandson, Lembit Öpik, was formerly the Liberal Democrat Member of Parliament for Montgomeryshire, and has some astronomical connection in that he is a noted supporter of searching for asteroids that may collide with the Earth.

The crater Öpik on the Martian moon Phobos is also named for him.

External links

• Sonoma State University on Ernst Öpik
• Armagh Observatory on Ernst Öpik
• Evening Standard (London); "Lembit and his Very Cheeky Family"