Richard A. Prager (November 30, 1883 – July 20, 1945) was a

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

Career

Prager was born in

Hannover, Germany Hanover (; german: Hannover ; nds, Hannober) is the capital and largest city of the German state of Lower Saxony. Its 535,932 (2021) inhabitants make it the 13th-largest city in Germany as well as the fourth-largest city in Northern Germany a ...

. He became an assistant in the German

Academy of Sciences An academy of sciences is a type of learned society or academy (as special scientific institution) dedicated to sciences that may or may not be state funded. Some state funded academies are tuned into national or royal (in case of the Unite ...

in 1908. The following year he became division head of the ''Observatorio Nacional'' in

Santiago, Chile Santiago (, ; ), also known as Santiago de Chile, is the capital (political), capital and largest city of Chile as well as one of the largest cities in the Americas. It is the center of Chile's most densely populated Regions of Chile, region, t ...

,Hentschel, Klaus (ed.) (1996). ''Physics and National Socialism: An Anthology of Primary Sources'', p. 117, fn. 6. Birkhauser. . where he remained until 1913. He then returned to

Berlin Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ...

, becoming an observer at the Berlin-Babelsberg Observatory. In 1916 he became a professor. He was an early pioneer of stellar photoelectric

photometry Photometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electrom ...

. He is noted for his work in the field of

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

s, and he made numerous contributions to ''Astronomische Nachrichten'' on this topic. In 1938 he was imprisoned by the German

Nazis Nazism ( ; german: Nazismus), the common name in English for National Socialism (german: Nationalsozialismus, ), is the far-right totalitarian political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in Na ...

. His friends in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

obtained his release in 1939, and he moved to the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

where he accepted a position at the

Harvard Observatory The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United St ...

. However his health had suffered from his imprisonment and from his separation from his family, and he died only six years later. The crater

Prager Prager (variants: Praeger, Preger) is a surname, which may refer to: Prager * David Prager (born 1977), American TV producer and blogger * Dennis Prager (born 1948), U.S. conservative radio talk show host, columnist and public speaker ** PragerU, ...

on the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

is named in his honor.

References

1883 births 1945 deaths 20th-century German astronomers Harvard College Observatory people German expatriates in Chile German emigrants to the United States {{Germany-astronomer-stub