ESA’s Herschel space observatory has shown that water expelled from the moon Enceladus forms a giant torus of water vapour around Saturn. The discovery solves a 14-year mystery by identifying the source of the water in Saturn’s upper atmosphere.
Herschel’s latest results mean that Enceladus is the only moon in the Solar System known to influence the chemical composition of its parent planet.
Enceladus expels around 250 kg of water vapour every second, through a collection of jets from the south polar region known as the Tiger Stripes because of their distinctive surface markings.
These crucial observations reveal that the water creates a doughnut-shaped torus of vapour surrounding the ringed planet.
The total width of the torus is more than 10 times the radius of Saturn, yet it is only about one Saturn radius thick. Enceladus orbits the planet at a distance of about four Saturn radii, replenishing the torus with its jets of water. (read more)