Asaph Hall had been given responsibility in…

Asaph Hall had been given responsibility in 1875 for the United States Naval Observatory's 26-inch (66-centimeter) telescope, the largest refracting telescope in the world at this time, with which he discovers Phobos, the inner moon of Mars, on August 11, 1887, and Deimos, the outer moon of Mars, on August 18.

Hall also notices a white spot on Saturn which he uses as a marker to ascertain the planet's rotational period.

Hallwas born in Goshen, Connecticut, the son of Asaph Hall II (1800-42), a clockmaker, and Hannah Palmer (1804-80).

His grandfather Asaph Hall I was a Revolutionary War officer and Connecticut state legislator.

His father had died when he was thirteen, leaving the family in financial difficulty, so Hall had left school at sixteen to become an apprentice to a carpenter, and had later enrolled at the Central College in McGrawville, New York, where he studied mathematics and took classes from an instructor of geometry and German, Angeline Stickney.

They married in 1856, in which year Hall had taken a job at the Harvard College Observatory in Cambridge, Massachusetts.

He has turned out to be an expert computer of orbits.

Hall had become assistant astronomer at the US Naval Observatory in Washington DC in 1862, and within a year of his arrival he had been made professor.