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

Ambronay Ambronay () is a commune in the Ain department in the Auvergne-Rhône-Alpes region of eastern France. Geography The commune of Ambronay is at the centre of a semicircle of mountains at the foot of the westernmost foothills of the Jura Mountain ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

. Beginning in 1881, Thollon joined the staff of the new

Nice Observatory The Nice Observatory (french: Observatoire de Nice) is an astronomical observatory located in Nice, France on the summit of Mount Gros. The observatory was founded in 1879, by the banker Raphaël Bischoffsheim. The architect was Charles Garni ...

where he undertook a long-term observation program of the Sun using a

spectroscope An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...

of his own design. In the process, he recorded a solar

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

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

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to observe the solar eclipse on 17 May. The same year he traveled to

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to watch the

Venus transit frameless, upright=0.5 A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a trans ...

, 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, 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

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, 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 Giovanni Virginio Schiaparelli ( , also , ; 14 March 1835 – 4 July 1910) was an Italian astronomer and science historian. Biography He studied at the University of Turin, graduating in 1854, and later did research at Berlin Observatory, ...

. Thollon died at age 57 in

Lyon Lyon,, ; Occitan language, Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the List of communes in France with over 20,000 inhabitants, third-largest city and Urban area (France), second-largest metropolitan area of F ...

, France.

References

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