This article is about the distinguished astronomer. For the noted rabbinical scholar of a similar name see: Isidore Epstein

Isidore Epstein

This article is about the distinguished rabbinical scholar. For the noted astronomer of a similar name see: Isadore Epstein Rabbi Dr. Isidore Epstein , was an Orthodox rabbi and rabbinical scholar in England, who served as the longtime principal of Jews' College, London. Ezekiel Isidore Epstein...

Isadore Epstein (1919, Tallinn

Tallinn

Tallinn is the capital and largest city of Estonia. It occupies an area of with a population of 414,940. It is situated on the northern coast of the country, on the banks of the Gulf of Finland, south of Helsinki, east of Stockholm and west of Saint Petersburg. Tallinn's Old Town is in the list...

, Estonia

Estonia

Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...

 – September 17, 1995, New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

) was an astronomer

Astronomer

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

. Epstein taught astronomy

Astronomy

Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 at Columbia University

Columbia University

Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...

 for 37 years. He completed his Ph.D. at Princeton University

Princeton University

Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....

, following which he was appointed as an instructor at Columbia in 1950, assistant professor in 1953, associate professor in 1957, and professor in 1971. He was named professor emeritus in 1987. He served as acting departmental chairman in 1959.

His early work at Columbia included development of theoretical models of the Sun

Sun

The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 (following on work he did with Martin Schwarzschild

Martin Schwarzschild

Martin Schwarzschild was a German American astronomer. He was the son of famed astrophysicist Karl Schwarzschild and the nephew of the Swiss astrophysicist Robert Emden.-Biography:...

 at Princeton). He was the first, in this connection, to recognize the importance of the opacity of matter in terms of its resistance to the flow of solar radiation, leading to the first models of the Sun to give sensible values for its energy output.

Epstein was a leader in the first modern surveys to find sites for observatories in the Southern Hemisphere

Southern Hemisphere

The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

. He studied the clarity and stability of the atmosphere

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

 and accessibility of sites in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, and Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 during the 1960s. Major observatories were constructed at all the sites he recommended, and he was particularly involved with the establishment of the Leoncito observatory

Leoncito Astronomical Complex

The Leoncito Astronomical Complex is an astronomical observatory in the San Juan Province of Argentina. The Leoncito Astronomical Complex is one of two observatories located within El Leoncito National Park, located in an area of the country which rarely sees cloud cover. The other facility is the...

 in Argentina. A long term study of stellar motions was instituted there, and Argentina's national observatory was moved to the site.
La Silla

La Silla Observatory

La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory organisation, and several others are partly maintained by ESO...

 and Cerro Tololo

Cerro Tololo Inter-American Observatory

The Cerro Tololo Inter-American Observatory is a complex of astronomical telescopes and instruments located at 30.169 S, 70.804 W, approximately 80 km to the East of La Serena, Chile at an altitude of 2200 metres. The complex is part of the National Optical Astronomy Observatory along with Kitt...

 observatories in Chile were sited based on Epstein's work, and Mauna Kea

Mauna Kea

Mauna Kea is a volcano on the island of Hawaii. Standing above sea level, its peak is the highest point in the state of Hawaii. However, much of the mountain is under water; when measured from its oceanic base, Mauna Kea is over tall—significantly taller than Mount Everest...

 in Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

was sited using his methods of site selection.

Sources

• Columbia University Record, Oct. 11 1986--Vol. 22, No. 6.