Heinrich Louis D'Arrest

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Heinrich Louis d'Arrest (July 13, 1822 - June 14, 1875) was a German astronomer, born in Berlin. His name is sometimes given as Heinrich Ludwig d'Arrest. While still a student at the University of Berlin, d'Arrest was party to Johann Gottfried Galle's search for Neptune. On September 23, 1846, he suggested that a recently drawn chart of the sky, in the region of Urbain Le Verrier's predicted location, could be compared with the current sky to seek the displacement characteristic of a planet, as opposed to a stationary star. Neptune was discovered that very night. D'Arrest's later work at the Leipzig Observatory led him, in 1851, to the discovery of the comet named for him (formally designated 6P/d'Arrest). He also studied asteroids (he discovered 76 Freia) and nebulae. In 1864 D'Arrest made an unsuccessful search for Martian satellites, and posited an upper limit of 70 minutes of arc as the distance from Mars within which a moon should be sought.