The name, like the names of each of the first seven satellites of Saturn to be discovered, was suggested by William Herschel's son John Herschel in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope. Only its orbital characteristics were known, with estimations of its mass, density and albedo.Įnceladus is named after the giant Enceladus of Greek mythology. Prior to the Voyager missions the view of Enceladus improved little from the dot first observed by Herschel. At such times, the reduction in glare from the rings makes the moons easier to observe. Like many satellites of Saturn discovered prior to the Space Age, Enceladus was first observed during a Saturnian equinox, when Earth is within the ring plane. Its faint apparent magnitude ( H V = +11.7) and its proximity to the much brighter Saturn and Saturn's rings make Enceladus difficult to observe from Earth with smaller telescopes. History Discovery Athena (left) fighting Enceladus (right)Įnceladus was discovered by William Herschel on August 28, 1789, during the first use of his new 1.2 m (47 in) 40-foot telescope, then the largest in the world, at Observatory House in Slough, England. Ongoing research on Cassini data suggests that Enceladus's hydrothermal environment could be habitable to some of Earth's hydrothermal vent's microorganisms, and that plume-found methane could be produced by such organisms. Ĭassini performed chemical analysis of Enceladus's plumes, finding evidence for hydrothermal activity, possibly driving complex chemistry. Its resonance with Dione excites its orbital eccentricity, which is damped by tidal forces, tidally heating its interior and driving the geological activity. Like many other satellites in the extensive systems of the giant planets, Enceladus is trapped in an orbital resonance. These geyser observations, along with the finding of escaping internal heat and very few (if any) impact craters in the south polar region, show that Enceladus is currently geologically active. The existence of Enceladus' subsurface ocean has since been mathematically modelled and replicated. In 2014, NASA reported that Cassini had found evidence for a large south polar subsurface ocean of liquid water with a thickness of around 10 km (6 mi). According to NASA scientists, the plumes are similar in composition to comets. Some of the water vapor falls back as "snow" the rest escapes and supplies most of the material making up Saturn's E ring. More than 100 geysers have been identified. Cryovolcanoes near the south pole shoot geyser-like jets of water vapor, molecular hydrogen, other volatiles, and solid material, including sodium chloride crystals and ice particles, into space, totaling about 200 kilograms (440 pounds) per second.
In particular, Cassini discovered water-rich plumes venting from the south polar region.
In 2005, the spacecraft Cassini started multiple close flybys of Enceladus, revealing its surface and environment in greater detail. Despite its small size, Enceladus has a wide range of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrain.Įnceladus was discovered on August 28, 1789, by William Herschel, but little was known about it until the two Voyager spacecraft, Voyager 1 and Voyager 2, flew by Saturn in 19.
Consequently, its surface temperature at noon only reaches −198 ☌ (75.1 K −324.4 ☏), far colder than a light-absorbing body would be. Enceladus is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the Solar System. It is about 500 kilometers (310 miles) in diameter, about a tenth of that of Saturn's largest moon, Titan. Trace, significant spatial variability Įnceladus is the sixth-largest moon of Saturn (19th largest in the Solar System).
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