Asaph Hall
The persistent astronomer who, in 1877, peered through a telescope and found the two tiny moons orbiting the red planet Mars.
1829–1907 (age 78)·American astronomer·Birthday: October 15
Biography
Asaph Hall discovered Phobos and Deimos, the moons of Mars, in August 1877. Largely self-educated after his father's death forced him to leave school at 13, he worked as a carpenter while studying mathematics and astronomy at night. His skill earned him a position at the Harvard College Observatory and later the U.S. Naval Observatory. Using the world's largest refracting telescope, he hunted for Martian moons after many astronomers had given up. His wife, Angelina, urged him to continue when he was ready to quit. The next night he spotted Phobos; days later, Deimos. He calculated the orbits of planetary satellites and determined the mass of Mars.
#1 When Asaph Was Born
The biggest hits of 1829
Asaph's Life & Times
The world at every milestone
1829Born
1834Started school
1842Became a teenager
1845Could drive
1847Could vote
1850Turned 21
1859Turned 30
1869Turned 40
President: Ulysses S. Grant
1879Turned 50
President: Rutherford B. Hayes
1889Turned 60
Eiffel Tower opens in Paris
President: Benjamin Harrison
1899Turned 70
President: William McKinley
1907Died at 78
Financial panic grips Wall Street
President: Theodore Roosevelt
Key Achievements
- Discovered the two moons of Mars, Deimos and Phobos, in August 1877 using the U.S. Naval Observatory's 26-inch telescope.
- Calculated the orbits of the moons of Saturn and other outer planets with great precision.
- Determined the mass of the planet Mars through careful orbital analysis.
- Served as a professor of mathematics at the U.S. Naval Observatory and Harvard University.
Did You Know?
He was married to mathematician and astronomer Angelina Stickney, who famously encouraged him to continue his search for Martian moons.
The largest crater on Phobos, one of the moons he discovered, is named 'Stickney' after his wife.
He began his working life as a carpenter's apprentice before pursuing astronomy.
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