Vocation : Science : Astronomy

Jean Bosler (24 March 1878, Angers – 25 September 1973, Marseille) was a French astronomer and author of several books.
Recruited by Deslandres as an astronomer at l’observatoire de Paris, Bosler discovered in 1908 in the spectrum of Comet Morehouse the spectral lines of ionized nitrogen, which was the first evidence of that element in comets. Much of his research was on the physical properties and orbits of comets. He made a report on progress in astrophysics in the United States for the 1910 annual report of the Smithsonian Institution. In 1912, he showed in his doctoral dissertation (supervised by Henri Poincaré) that the Sun’s magnetic field, by means of the intermediary of the solar wind, explains many aspects of cometary tails, the aurora borealis and aurora australis, solar storms and telluric currents. During a solar eclipse in 1914, Bosler observed in the corona a spectral band “nouvelle, intense et unique” which he suggested was spectral evidence for coronium; however, in the 1930s subsequent research showed that the cause was a highly ionized form of iron. In 1916, he published an analysis of the circular form of lunar craters as caused by the impact of meteors.
In 1923 Bosler was named director of Marseille Observatory, a post he occupied until his retirement in 1948. Simultaneously with his directorship, he taught at the University of Marseille from 1923 to 1948. Bosler made important contributions to the theory of the evolution of stars and published the first textbook in French that dealt with the then recent discoveries of Hubble and the work on optical phenomena of such physicists as Michelson, Fabry and Perot.
Bosler won the Prix Jules Janssen in 1911 from the Société astronomique de France, the French astronomical society, and the Prix Lalande from l'Académie des sciences in 1913.
He came from the French branch of the Hessian family Boßler.Books

Les théories modernes du soleil (1910)
L’évolution des étoiles (1923)
Cours d’astronomie (1928)

Albertus (Albert) Antonie Nijland (30 October 1868 – 18 August 1936) was a Dutch astronomer. He was professor of astronomy at the Rijksuniversiteit Utrecht, and served as director of the Sterrewacht Sonnenborgh (now the Sterrekundig Instituut) of the university.
Nijland was born in Utrecht. In 1901 he participated in a Dutch solar eclipse expedition to Karang Sago, Sumatra.
He was noted for his observations of variable stars, and published a number of papers on the subject in Astronomische Nachrichten, and elsewhere, from 1917 until 1936. He proposed naming variable stars in each constellation using a simple numbering system beginning with V1, V2, ... and so forth. However the double-letter system starting with RR was already in
widespread use. As a result, variable stars after QZ were numbered according to Nijland's system beginning with V335.
In 1923 Nijland became member of the Royal Netherlands Academy of Arts and Sciences.The crater Nijland on the Moon is named after him.

Marcel Gilles Jozef Minnaert (12 February 1893 – 26 October 1970) was a Belgian-Dutch astronomer. He was born in Bruges and died in Utrecht. He is notable for his contributions to astronomy and physics and for a popular book on meteorological optics: Light and colour in the open air, first published in English in 1940.

Carl August von Steinheil (12 October 1801 – 14 September 1870) was a German physicist, inventor, engineer and astronomer.

Laurent Nottale (born 29 July 1952) is an astrophysicist, a retired director of research at CNRS, and a researcher at the Paris Observatory. He is the author and inventor of the theory of scale relativity, which aims to unify quantum physics and relativity theory.

Luíz Cruls or Luís Cruls or Louis Ferdinand Cruls (21 January 1848 – 21 June 1908) was a Belgian-Brazilian astronomer and geodesist. He was Director of the Brazilian National Observatory from 1881 to 1908, led the commission charged with the survey and selection of a future site for the capital of Brazil in the Central Plateau, and was co-discoverer of the Great Comet of 1882. Cruls was also an active proponent of efforts to accurately measure solar parallax and towards that end led a Brazilian team in their observations of 1882 Transit of Venus in Punta Arenas, Chile.

Antoine-Joseph Yvon Villarceau (15 January 1813 – 23 December 1883) was a French astronomer, mathematician, and engineer.
He constructed an equatorial meridian-instrument and an isochronometric regulator for the Paris Observatory.
He wrote Mécanique Céleste. Expose des Méthodes de Wronski et Composantes des Forces Perturbatrices suivant les Axes Mobiles (Paris: Gauthier-Villars, 1881) and Sur l'établissement des arches de pont, envisagé au point de vue de la plus grande stabilité (Paris: Imprimerie Impériale, 1853).
He is the eponym of Villarceau circles, which are two circular sections of a torus other than the two trivial ones.
A short street in the 16th arrondissement of Paris is named after Villarceau.

Louis Zimmer (8 September 1888 – 12 December 1970) was an astronomer and clockmaker to the King of Belgium. Most notably in 1930 he built the Jubilee (or Centenary) Clock, which is displayed on the front of the Zimmer tower. The Zimmer tower (Dutch: Zimmertoren) is a tower in Lier, Belgium, also known as the Cornelius tower, that was originally a keep of Lier's fourteenth-century city fortifications. In the museum near the tower in addition to many of Zimmer's other clock is the huge clock he constructed for the 1935 Brussels International Exposition. This is the clock was sent to the United States for the 1939 New York World's Fair. In June 1970 he was proclaimed Honorary Citizen of Lier. The asteroid Zimmer (№ 3064)(1984 BB1), was named after him in 1984.