Ejnar Hertzsprung

Ejnar Hertzsprung
Hertzsprung (right) and Karl Schwarzschild in front of the Göttingen Observatory building in 1909.
Born	(1873-10-08)8 October 1873 Copenhagen, Denmark
Died	21 October 1967(1967-10-21) (aged 94) Roskilde, Denmark
Alma mater	Copenhagen Polytechnic (DTU)
Known for	Hertzsprung–Russell diagram
Awards	Bruce Medal 1937

Ejnar Hertzsprung (8 October 1873 – 21 October 1967) was a Danish astronomer born in Copenhagen. During 1912, together with Henry Norris Russell, he developed the Hertzsprung–Russell diagram.

Hertzsprung–Russell diagram.

In 1913 he determined the distances to several Cepheid variable stars in terms of parallax, and was thus able to calibrate the relationship discovered by Henrietta Leavitt (the discoverer of Cepheid variables) between their periods and luminosity. In this determination he made a mistake, possibly a slip of the pen, putting the stars 10 times too close; he used this relationship to estimate the distance to the nearby galaxy the Small Magellanic Cloud. From 1919 to 1946 Hertzsprung worked at Leiden Observatory in the Netherlands, starting in 1937 as director. Among his graduate students at Leiden was Gerard Kuiper.

Sources

• Sky & Telescope, January, 1968, Sky Publishing Corporation, Cambridge