Andrew Claude de la Cherois Crommelin

Andrew Claude de la Cherois Crommelin (6 February 1865 – 20 September 1939) was an astronomer of French and Huguenot descent who was born in Cushendun, County Antrim, Ireland.<ref name="obit_mnras">Template:Cite journal</ref><ref name="obit_obs">Template:Cite journal</ref><ref name="obit_jbaa">Template:Cite journal</ref><ref name="biogencastron">Template:Cite book</ref><ref name="odnb">Template:Cite encyclopedia</ref> He was educated in England at Marlborough College and Trinity College, Cambridge. After a spell teaching at Lancing College he found permanent employment at the Royal Greenwich Observatory in 1891.<ref>Template:Acad</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> He joined the Royal Astronomical Society in 1888 and was its president from 1929-1931. In 1895 he joined the British Astronomical Association and was president from 1904-1906 and directed its comet section 1898-1901 and 1907-1938.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

In 1910 for their studies of Halley’s Comet Crommelin and Philip Herbert Cowell jointly received the Prix Jules Janssen from the Société astronomique de France.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> For this work they also received the Lindemann prize of the Astronomische Gesellschaft in Germany.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite book</ref>

In 1914 Crommelin published an introductory book on astronomy “The Star World”.<ref>Template:Cite book</ref>

Crommelin had four children, of whom two died in a climbing accident on Pillar Rock, Ennerdale, in 1933.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The de la Cherois line was succeeded through Crommelin's daughter Andrina. The author May Crommelin was one of Andrew’s cousins.

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Andrew Claude de la Cherois Crommelin.

An expert on comets, his calculation of orbits of previously identified Comet Pons 1818 II, Comet Coggia-Winnecke 1873 VII, and Comet Forbes 1928 III in 1929, showed that these were one and the same periodic comet.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> It thus received the rather unwieldy name "Comet Pons-Coggia-Winnecke-Forbes". In 1948, he was posthumously honored when the comet was renamed after him alone (today, in modern nomenclature, it is designated 27P/Crommelin). This is similar to the case of Comet Encke, where the periodic comet is named after the person who determined the orbit rather than the possibly-multiple discoverers and re-discoverers at each apparition. In 1937 Crommelin and Mary Proctor jointly published a book entitled "Comets: Their Nature, Origin, and Place in the Science of Astronomy”.<ref>Template:Cite book</ref>

Crommelin took part in several solar eclipse expeditions including those of 1896, 1900 and 1905.<ref>Template:Cite journal</ref><ref>Template:Cite book</ref><ref>Template:Cite book</ref> In 1919 he went to Sobral, in Brazil, and measured the amount of deflection of light caused by the gravitational field of the Sun.<ref>Template:Cite journal</ref> The results from these observations were crucial in providing confirmation of the General Theory of Relativity, which Albert Einstein had proposed in 1916.

Named after Crommelin

• Comet 27P/Crommelin
• Crommelin (lunar crater)
• Crommelin (Martian crater)
• Asteroid 1899 Crommelin<ref>Template:Cite book</ref>