Enceladus
What is Enceladus?
Moons· Diameter 504 km. A small moon of Saturn that sprays water from a hidden ocean into space through cracks at its south pole. Salt, organic molecules and phosphorus found in the spray make it a key target in the search for life.
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Orbit and size
| Diameter | 504 km |
|---|---|
| Parent | Saturn |
| Note | south-polar geysers feed the E ring |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Parent planet and sibling moons
Enceladus: a snow-white shell over a warm sea
Enceladus is one of the whitest objects in the solar system, sending back almost all the sunlight that hits it. It is whiter than fresh snow. Ice grains from the south-polar jets fall back onto the surface like snow, constantly coating it anew. The south polar region in particular has almost no craters, which means its surface was renewed very recently in geological terms.
Because it reflects nearly all its sunlight, the surface stays around −200 °C even at midday. Yet beneath it lies a liquid ocean. On its first close flyby in 2005, Cassini found that the tiger stripes were warmer than their surroundings. Temperatures measured over the stripes were nearly 100 degrees higher, showing where heat from below leaks out through the ice.
Evidence also showed that the ocean wraps around the whole moon. In 2015 the Cassini team studied seven years of images and found that Enceladus wobbles very slightly as it orbits. The size of the wobble could be explained only if the icy shell moves separately from the rocky core, which requires an ocean between them. In 2023 the James Webb Space Telescope caught the south-polar plume stretching 9,600 km, about twenty times the moon's diameter.
The moon in depth
Enceladus is only 504 km across, a small icy moon. Yet near its south pole, four long cracks shoot jets of water into space. The cracks look like stripes and are called 'tiger stripes'. The water quickly freezes into ice grains, and some of them spread around Saturn to form the faint E ring.
From 2005 to 2015 the Cassini spacecraft flew straight through these jets several times to measure what they contain. It found salt, tiny grains of silica, hydrogen gas and organic molecules, and in 2023 phosphorus was confirmed as well. The salt means the hidden ocean is in contact with rock, and the silica and hydrogen are clues that hot water rises from vents on the ocean floor.
On Earth, too, hot water rises from vents deep on the sea floor, and living things gather around them, feeding on chemical energy instead of sunlight. The ocean of Enceladus may have a similar energy source, which is why this small moon has become a key target in the search for life. Because the jets carry ocean water into space on their own, a spacecraft can sample it simply by flying through, with no landing needed. Zooming in on Saturn in the orbit view shows Enceladus circling within the E ring.
Frequently asked
- How big is Enceladus?
- The diameter of Enceladus is 504 km.
- What is notable about Enceladus?
- The note of Enceladus is south-polar geysers feed the E ring.
- Which planet does Enceladus orbit?
- Enceladus orbits Saturn.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.