On this day in 1877, American astronomer Asaph Hall discovered the Martian moon Phobos while at the US Naval Observatory in Washington, D.C. He had discovered Mar’s other moon Deimos six days earlier.
Oddly enough, the idea of two moons orbiting Mars was first proposed in 1726 by Jonathan Swift in his tale Gulliver’s Travels. In the book, astronomers on the flying island of Laputia were noted to have
… discovered two lesser stars, or satellites, which revolve around Mars, whereof the innermost is distant from the center of the primary exactly three of his diameters, and the outermost five: the former revolves in the space of ten hours, and the latter in twenty-one and a half.
All Professor Hall had to do was confirm the work of the Laputian astronomers.
Our Awesome Universe 