Johannes Franz Hartmann (11 January 1865 – 13 September 1936) was a German

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

and

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

. In 1904, while studying the

spectroscopy Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectro ...

of Delta Orionis he noticed that most of the spectrum had a shift, except the

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

lines, which he interpreted as indicating the presence of

interstellar medium The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It f ...

Asimov Isaac Asimov ( ; – April 6, 1992) was an Russian-born American writer and professor of biochemistry at Boston University. During his lifetime, Asimov was considered one of the "Big Three" science fiction writers, along with Robert A. ...

, ''

Asimov's Biographical Encyclopedia of Science and Technology ''Asimov's Biographical Encyclopedia of Science and Technology'' is a history of science by Isaac Asimov, written as the biographies of initially 1000 scientists and later with over 1500 entries. Organized chronologically, beginning with Imhotep ( ...

'' 2nd Revised edition He was the director of the La Plata Astronomical Observatory, Argentina, from November 1922 to May 1934, and was also known under the name Juan Hartmann. He oriented the work of the observatory towards

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...

and discovered the three

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

s of the main-belt, 965 Angelica, 1029 La Plata and 1254 Erfordia at La Plata between 1921 and 1932. His doctorate was from the

University of Leipzig Leipzig University (), in Leipzig in Saxony, Germany, is one of the world's oldest universities and the second-oldest university (by consecutive years of existence) in Germany. The university was founded on 2 December 1409 by Frederick I, Electo ...

in 1891 on lunar eclipses. The lunar crater '' Hartmann'' on the far side of the Moon was named in his honor. Note, however, that the asteroid 3341 Hartmann was named after William K. Hartmann and is unrelated to him. Delegates to the Fourth Conference International Union for Cooperation in Solar Research at Mount Wilson Observatory

Delegates to the Fourth Conference International Union for Cooperation in Solar Research at Mount Wilson Observatory

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Lista de cientificos

1865 births 1936 deaths 19th-century German astronomers Discoverers of asteroids * 20th-century German physicists 20th-century German astronomers German expatriates in Argentina 19th-century German physicists {{Germany-astronomer-stub

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