Louis Thollon (2 May 1829 – 8 April 1887) was a French astronomer. He was born in Ambronay,

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

. Beginning in 1881, Thollon joined the staff of the new Nice Observatory where he undertook a long-term observation program of the Sun using a spectroscope of his own design. In the process, he recorded a solar

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

consisting of 3,000 absorption lines in the optical band. In 1882, he joined André Puiseux on an expedition to

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

to observe the

solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season i ...

on 17 May. The same year he traveled to

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

to watch the Venus transit, but was met with disappointment due to poor weather. He was awarded the Prix Lalande in 1885 for his large map of the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

, which was not published until after his death in 1890.Hentschel K. (2007) Thollon, Louis. In: Hockey T. et al. (eds) The Biographical Encyclopedia of Astronomers. Springer, New York, NY During the 1886 Mars opposition, he assisted the observatory director, Henri Perrotin, in observing the planet with a reflecting telescope. Both men reported that they spotted '' canali'' on the surface of the planet, apparently confirming the 1877 discovery of these features by Italian astronomer Giovanni Schiaparelli. Thollon died at age 57 in

Lyon Lyon (Franco-Provençal: ''Liyon'') is a city in France. It is located at the confluence of the rivers Rhône and Saône, to the northwest of the French Alps, southeast of Paris, north of Marseille, southwest of Geneva, Switzerland, north ...

, France.

References

{{DEFAULTSORT:Thollon, Louis 1829 births 1887 deaths 19th-century French astronomers Recipients of the Lalande Prize