Paul and Prosper Henry
Paul Pierre Henry was born on the 21st August, 1848 at Nancy, France. He and his younger brother Prosper Henry (born 10th December 1849) grew up to become two of the greatest pioneers of Astrophotography and were also responsible for the construction of some of the finest telescopes ever made. The two brothers were inseparable and worked together throughout their lives in close collaboration.
Little is known of their early life save that they came from a modest family, and were educated at a local Catholic School. They began their careers as opticians working in their home town of Nancy. In 1864 they came to Paris, and began work at the Paris Observatory in the Department of Meteorology, Paul in 1864 and Prosper a year later.
In 1868 they were promoted to assistant astronomers by Urbain Le Verrier, then Director of the Observatory. In 1871 Delaunay who succeeded Le Verrier as Director, recognized the Henry Brothers talent for optics and transferred them to the Department of Astronomy.
In 1871 they began the task of completing the late Jean Chacornac’s charts of the Ecliptic, begun in 1852, but not completed. The work involved competing 72 charts, each 13” square covering a 50 field of view containing stars down to magnitude 13. They became alarmed at the number of stars they found in the region of the Milky Way.
There were so many stars that to chart them visually was impossible. They then began experimenting with photography as a means to speed up the process. Their work on the ecliptic charts brought an added bonus; between them they found a total of 14 asteroids, the first Liberatrix discovered in September 1872.
In August of 1884 their results were presented to the French Academy Sciences by Admiral Amedee Mouchez then Director of the Paris Observatory. Such was the success of their work that they commissioned to construct a 13.4” (33cm) Photographic Refractor.
In the field of Astrophotography their greatest contribution came in 1885-6, when they were the first to take successful photographs of the planets, when they imaged Jupiter and Saturn.
Prior to this time others had tried including contemporary pioneers like Warren de La Rue, but failed; his images of 1857 were only ½ mm across, and were therefore barely visible!
During the course of their career the Henry Brothers continued to construct telescopes, and in collaboration with the engineer Paul Gauthier produced some of the finest ever made. In particular they were responsible for the 30” Refractor at the Nice Observatory and the great 32.7” Refractor at the Paris Observatory at Meudon.
Paul Henry died on the 4th January 1905 at Montrouge on the outskirts of Paris, after suffering a thrombosis in his brain. His beloved brother Prosper had died 18 months earlier after a climbing accident whilst on holiday at Pralognan, in Savoy on the 25th July 1903.
The Henry Brothers received many awards during their lifetime, but it is probably the naming of the lunar crater Henry Frères which would have pleased them the most. In recognition of the work of Paul Henry and his brother Prosper, the Minor Planet Centre, two asteroids were named after them ‘P.P. Henry’ and ‘P.M. Henry’.
In life they were inseparable in death they are remembered forever on the surface of the Moon with a single crater.
Several works by the Henry Brothers have been sold at auction, including 'Photographie d'une portion de Cassiopée' sold at Christie's South Kensington 'PHOTOGRAPHS' in 2001 for $24,998.
