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. He was educated in England at Marlborough College and Trinity College, Cambridge. He worked at the Royal Greenwich Observatory and went on several solar eclipse expeditions. He was president of the Royal Astronomical Society from 1929 to 1931.
In 1910, Crommelin and Philip Herbert Cowell jointly received the Prix Jules Janssen, the highest award of the Société astronomique de France, the French astronomical society.
AC de la Cherois Crommelin had four children, of whom two were killed in a climbing accident on Pillar Rock, Ennerdale, in 1933. The de la Cherois line was succeeded through Crommelin's daughter Andrina de la Cherois Crommelin (m. Ritter).
An expert on comets, his calculation of orbits of what were then called Comet Forbes 1928 III, Comet Coggia-Winnecke 1873 VII, and Comet Pons 1818 II, in 1929, showed that these comets were one and the same periodic comet. The comet 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 determining the orbit rather than the possibly-multiple discoverers and re-discoverers at each apparition.
Crommelin took part over his career in numerous expeditions throughout the world to study solar eclipses. In 1919 he participated in the solar eclipse expedition to the city of Sobral, in Brazil, which aimed to determine the amount of the deflection of light caused by the gravitational field of the Sun. The results from these observations were crucial in providing confirmation of the General Theory of Relativity, which Albert Einstein had proposed in 1916.
Andrew de la Cherois also wrote a book on astronomy entitled "The Story of the Stars".Comet 27P/Crommelin
Crommelin (lunar crater)
Crommelin (crater on Mars)
Asteroid 1899 Crommelin