William Herschel discovered Saturn's moon Enceladus
On this day · 28 August 1789
Spotting a faint speck beside Saturn's rings, Herschel found a moon that would later astonish scientists with its icy plumes.
On August 28, 1789, the British astronomer William Herschel spotted a faint point of light orbiting Saturn and recognized it as a new moon. He made the find during the first observations with his enormous 40-foot reflecting telescope, fitted with a 49-inch mirror and then the largest in the world, at his home in Slough, England.
Herschel believed he had found Saturn’s sixth moon. His son John Herschel later proposed the name Enceladus, after one of the Titans of Greek mythology, in keeping with a scheme for naming the planet’s moons.
Two centuries on, NASA’s Cassini orbiter revealed water-vapor plumes erupting from the moon’s south pole.
Those findings pointed to a subsurface ocean of salty water beneath the icy crust, making this tiny moon, only about 500 km across, one of the solar system’s most promising places to search for conditions suited to life.
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