Asaph Hall III (October 15, 1829 – November 22, 1907) was an American astronomer who is best known for having discovered the two moons of Mars, Deimos and Phobos, in 1877.

His paternal grandfather Asaph Hall I (June 11, 1735 – March 29, 1800) was a Revolutionary War officer and Connecticut state legislator.

[2][3] His father died when he was 13, leaving the family in financial difficulty, so Hall left school at 16 to become an apprentice to a carpenter.

In 1856, Hall took a job at the Harvard College Observatory in Cambridge, Massachusetts, and turned out to be an expert computer of orbits.

Hall became assistant astronomer at the US Naval Observatory in Washington, D.C. in 1862, and within a year of his arrival he was made professor.

The experiment involved repetitively throwing at random a fine steel wire onto a plane wooden surface ruled with equidistant parallel lines.

This paper, an experiment on Buffon's needle problem, is a very early documented use of random sampling (which Nicholas Metropolis would name the Monte Carlo method during the Manhattan Project of World War II) in scientific inquiry.

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

In 1884, Hall showed that the position of the elliptical orbit of Saturn's moon, Hyperion, was retrograding by about 20° per year.

During Mars' closest approach in 1877, Hall was encouraged by Angeline Stickney, his wife, to search for the Martian moons.

Hall wrote "The chance of finding a satellite appeared to be very slight, so that I might have abandoned the search had it not been for the encouragement of my wife.

Hall had previously seen what appeared to be a Martian moon on August 10, but due to bad weather, he could not definitively identify them until later.