Geysers of Enceladus. [They don't actually all erupt at once.]

William Herschel, discoverer of the planet Uranus, also discovered Saturn's moon Enceladus [en.SELL.ah.dus] in 1789.

John Herschel – William Herschel's son – used Greek mythology to name Saturn's moons in 1847.
At the beginning of time, Gaea the Earth goddess, and Ouranos the sky god, ruled. The Titans (giants) were their offspring. Enceladus was one of their offspring. In the war between the old gods and the gods of Olympus, Enceladus fought the goddess Athena. When he chased her, she threw the island of Sicily at him, crushing him under it. When he tried to move, it caused earthquakes. That's how the volcano Etna got the nickname “the breath of Enceladus” when it erupted.

Although Enceladus is named for a giant, the moon isn't very big.
Enceladus is 500 km (300 miles) across. Our Moon is seven times bigger than that.

It takes only 33 hours for Enceladus to orbit Saturn.
Enceladus is closer to Saturn than the Moon is to Earth, so it moves faster. Like the Moon, Enceladus keeps the same face always turned towards its planet.

Enceladus is extremely cold.
Saturn is about ten times farther from the Sun that we are, so it's cold out there. And Enceladus is the coldest of Saturn's moons. Its brilliant white surface is brighter than fresh snow, so it reflects almost all of the sunlight that hits it. Our Moon is closer to the Sun and bigger than Enceladus, but it has a dark gray surface that reflects only about 10% of the sunlight that it gets.

The temperature on Enceladus is around -198°C (-324 °F). The coldest temperature ever measured on Earth was −89.2 °C (−128.6 °F) in Antarctica.

Even though Enceladus is very cold on the surface, it's warm enough inside to have a liquid ocean under the ice.
At least some of the energy that warms it probably comes from the gravitational pull of a neighboring moon.

Enceladus has different types of terrain.
Terrain is an area of land and its natural features. There are lots of craters from meteorite hits on a body that doesn't have an atmosphere to protect it. This is why the Moon and Mercury have cratered terrains. Enceladus has some cratered terrain, but it also has a lot of smooth terrain. The smooth surface must be new, because it covered over the old craters.

Enceladus is an active body.
Remember that in an ancient myth, an erupting volcano was the breath of Enceladus. Interestingly, it turns out that the moon Enceladus has active volcanoes and also geysers.

It seems odd for Enceladus to have volcanoes, because it's so cold. How could it be erupting molten rock or shooting steam from a hole in the ground? The answer is cryovolcanoes and cryogeysers. (Cryo means extremely cold.) Enceladus's geysers shoot out water vapor mixed with some gases, organic molecules and microscopic ice particles. Cryovolcanic eruptions could be what created the moon's smooth icy surface.

Many scientists think that Enceladus could be a good place to look for microscopic life.
When searching for life, three essential ingredients are: (1) water, (2) an energy source, and (3) organic molecules.

Organic molecules aren't alive, but they are needed for life as we know it. The Cassini spacecraft that studied Saturn found them in samples from Enceladus's erupting geysers. And we know that there is water as well as the energy that keeps the ocean liquid.