This moon of Saturn is an active icy world with volcanoes of water erupting from beneath the surface feeding the E-ring of the planet. The large subsurface ocean beneath the crust is likely to be habitable for life.
A bit of History
Discovered by William Herschel on August 28, 1789, its name comes from Greek mythology(Giant Enceladus). Not a lot was known until Voyager 1 and Voyager 2 spacecraft passed nearby the planet in 1980 and 1981. Later in 2005, the Cassini spacecraft discovered the presence of water and captured some incredible pictures of the coldest satellite of Saturn.
Place around Saturn
From the total of 82 moons of Saturn, Enceladus is the 6th largest moon of the planet. 2nd closest major moon(There are some objects in Saturn’s rings which may or may not be considered as moons) to Saturn after Mimas. It orbits Saturn every 32.9 hours, fast enough to be observed in a single night.
It is in a 2:1 orbital resonance with the moon: Dione(fourth closest major moon of Saturn). This orbital resonance means Enceladus completes 2 revolutions around Saturn for every 1 Revolution of Dione around the planet. This plays a major role in the orbit of the Enceladus, forcing it to be non-circular (eccentricity = 0.0047). This results in Tidal forces which heat up the interior of the moon.
Cryovolcanism on Enceladus
The moon is located at 9.5 Astronomical Units from our star. A major reason why water cannot exist in the liquid state on its surface. But the Tidal forces acting on the moon heats up the core, melting the innermost layer of ice and forms a subsurface ocean (Process known as ‘Tidal Heating’). This water then erupts from the weakest parts of the crust with a speed of about 1200 km/hr. This exceeds the escape velocity on Enceladus. With no gravitational influence of the moon on this material, it adds the water crystals to the E-Ring of Saturn. Some water crystals gravitate back towards the surface of Enceladus, renewing it continuously.
During the Cassini Mission, the spacecraft was able to pass through the plumes of the volcanoes. And with the help of Cosmic Dust Analyzer on-board, it was able to detect the presence of amino acids, carbon dioxide, methane, nitrogen, and water in the plumes, contributing to the possibility of life beneath the surface of Enceladus.
Fun Facts
The icy surface on the active south pole is constantly stretching and buckling due to gravitational forces.
Enceladus has the whitest, most reflective surface in the solar system.
Enceladus sprays geysers of water ice, creating a ring of its own around Saturn(E Ring).
Enceladus is small enough to fit into the length of the United Kingdom.
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