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Asaph Hall

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description Asaph Hall Overview

Asaph Hall III was a 19th-century American astronomer primarily associated with the United States Naval Observatory in Washington, D.C. He is most famous for his 1877 discovery of the two natural satellites of Mars, which he named Phobos and Deimos. Hall identified these moons using the observatory's newly installed 26-inch refracting telescope, meticulously calculating their orbits despite significant initial observational challenges.

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What did Asaph Hall discover in 1877?

Asaph Hall discovered Phobos and Deimos, the two known natural satellites of Mars. He made the discovery in 1877 while working at the United States Naval Observatory.

Where did Asaph Hall work?

Hall was associated with the United States Naval Observatory in Washington, D.C. His Mars-moon observations were made through the observatory's astronomical program.

Who named the moons of Mars Phobos and Deimos?

Asaph Hall gave the moons the names Phobos and Deimos after figures associated with fear and terror in Greek mythology. The names fit their connection with Mars, the Roman god of war.

Why was discovering Mars's moons difficult?

Phobos and Deimos are small and appear close to the much brighter planet Mars. Hall had to search carefully during favorable observing conditions in 1877 to separate the moons from Mars's glare.