Enceladus was discovered by William Herschel in 1789 and later found to launch jets into space.
Herschel spotted Enceladus on August 28, 1789, while using his enormous 40-foot reflecting telescope in England. Because the moon is faint and lies close to bright Saturn and its rings, astronomers knew little about it for nearly two centuries. Voyager observations in the early 1980s showed a bright, relatively smooth icy world, but Cassini revealed its extraordinary activity.
In 2005, Cassini detected water-rich plumes erupting from fractures near Enceladus’s south pole. The jets contain water vapor, ice particles and other compounds, and they feed much of Saturn’s diffuse E ring. Their source is a global subsurface saltwater ocean beneath the icy crust.
Enceladus is often confused with Europa, another ocean-bearing moon, but Europa belongs to Jupiter. Enceladus is especially important because its ocean material is naturally sprayed into space, allowing spacecraft to sample it without drilling through the ice.