Since its founding in 1891, many people have passed through the doors of the Vatican Observatory.  A quick perusal of our guestbook reveals several Names, including Popes, nobel laureates, astronauts, actors, and saints. Today’s guestbook entry is from March 20, 1911, when P. H. Cowell made a visit. Next to his name, Philip Herbert Cowell F.R.S. (1870-1949) wrote, “Nautical Almanac Office, Gray’s Inn, London.” He was superintendent of the H.M. Nautical Almanac Office, part of the Royal Greenwich Observatory, from 1910-1930. As an astronomer, he was particularly dedicated to celestial mechanics, computing and refining the orbits of many comets and other solar system bodies. He developed a method for computing perturbations in an orbit that proved to be both relatively simple and robust.  He is known for refining the orbit of the moon and resolving a discrepancy between its observed orbit and its theoretical orbit. He also showed that the supposed perturbations of the orbit of Neptune–that suggested the existence … Continue reading →