Does Europa really have an ocean?

Scientists are confident it does. Magnetic measurements from the Galileo spacecraft are best explained by a salty liquid ocean beneath the ice, and the surface features support this. Its exact depth and the thickness of the ice above it are still uncertain.

Could there be life on Europa?

It is possible, but unknown. Europa seems to have liquid water, chemical ingredients and possibly a source of energy, the basic needs of life as we know it. No life has been detected, and current missions aim to assess habitability rather than find life directly.

About −160°C at the equator and around −220°C near the poles, cold enough that the ice is as hard as rock.

When will Europa Clipper arrive?

Europa Clipper launched in October 2024 and is due to arrive at Jupiter in 2030, after which it is planned to make dozens of close flybys of Europa.

Can I explore Europa in the app?

Yes. You can land on Europa's icy surface and explore its cracks, ridges and chaos terrain in interactive 3D, with Jupiter hanging in the sky above.

A cracked shell of ice over a hidden ocean, under the giant face of Jupiter

Europa's ice

3D landscape · Europa, moon of Jupiter

Land here and explore →

Europa is the smallest of the four large moons of Jupiter discovered by Galileo Galilei in 1610, slightly smaller than our own Moon at about 3,100 km across. Its surface is one of the smoothest in the Solar System, a shell of water ice criss-crossed by long cracks and ridges, with very few impact craters. In this app you can land on Europa's ice and explore it in interactive 3D, with Jupiter looming overhead.

Beneath the ice, scientists are confident there is a deep ocean of liquid salty water, perhaps holding more water than all of Earth's oceans combined. Water, chemical ingredients and a source of energy are thought to be the basic needs of life as we know it, and Europa may have all three. That is why NASA's Europa Clipper and ESA's JUICE missions are now on their way to the Jupiter system.

Key facts

Diameter: ≈ 3,120 kmAbout 90% of the width of Earth's Moon
Surface gravity: ≈ 13% of Earth'sSlightly less than on our Moon
Surface temperature: ≈ −160°C at the equatorColder still, around −220°C, near the poles
Orbit around Jupiter: ≈ 3.5 daysAlways keeping the same face towards the planet
Ice shell thickness: Uncertain: a few to tens of kmMany estimates fall around 15–25 km
Ocean depth: Perhaps 60–150 kmEstimated; possibly twice the volume of Earth's oceans
Surface age: Perhaps 40–90 million yearsYoung for the Solar System, judged from its few craters
Atmosphere: Extremely thin oxygenFar too thin to breathe or to make a sky
Europa Clipper: Launched October 2024Due to arrive at Jupiter in 2030

The ice shell

Europa's surface is made almost entirely of water ice, frozen as hard as rock at such low temperatures. It is very bright, reflecting much of the sunlight that reaches it, and its pale surface is streaked with reddish-brown markings that may contain salts and sulphur compounds, possibly brought up from below or delivered by particles from Jupiter's surroundings. Hubble observations suggest that some of this material includes ordinary sodium chloride, table salt.

How thick the shell is remains one of the big open questions. Estimates range from just a few kilometres to more than 25 km, and many models favour a shell around 15–25 km thick, possibly with a cold, brittle outer layer over warmer, slowly churning ice below. The answer matters for life: a thinner shell, or pockets of water within the ice, could make it easier for material to move between the surface and the ocean.

Lineae, ridges and chaos terrain

Europa's most striking features are lineae, dark lines that run for hundreds or even thousands of kilometres across the surface. Seen up close, many are double ridges: pairs of raised ridges, often a few hundred metres high, with a groove between them. They are thought to form as the ice cracks under the strain of tides and then refreezes, but the exact process, and whether liquid water is involved, is still debated.

In other places the surface is broken into chaos terrain, a jumble of ice blocks and rafts that seem to have shifted and tilted in a slushy matrix before freezing again, rather like pack ice on a frozen sea. Conamara Chaos and Thera Macula are well-known examples. Some scientists think chaos regions form above pockets of liquid water or warm ice in the shell. Bands where the surface appears to have pulled apart, and a handful of craters, complete the picture.

So few craters

Europa has very few large impact craters, which tells scientists its surface is young, perhaps tens of millions of years old. Its ice must be renewed or reshaped over time, burying older scars.

The hidden ocean

The strongest evidence for Europa's ocean came from NASA's Galileo spacecraft, which orbited Jupiter from 1995 to 2003. Its magnetometer detected that Europa disturbs Jupiter's magnetic field in a way best explained by a layer of electrically conducting liquid, most likely salty water, beneath the ice. The cracks and chaos terrain on the surface fit that picture.

The ocean stays liquid because of tides. Europa's slightly oval orbit, kept that way by the pull of its neighbours Io and Ganymede, means Jupiter's gravity squeezes and stretches it constantly, producing heat inside. The ocean is thought to sit on a rocky sea floor, where reactions between water and rock, and perhaps hydrothermal vents like those on Earth's ocean floor, could provide chemical energy. Combined with water and the elements found on the surface, this is why Europa is considered potentially habitable, although no life has been found.

Cold, radiation and plumes

Standing on Europa would be deadly without protection. The surface is around −160°C at the equator and colder towards the poles. There is virtually no air, only a thin layer of oxygen produced as radiation splits water molecules in the ice. Europa also orbits within Jupiter's intense radiation belts, where charged particles trapped by the planet's magnetic field strike the surface. An unprotected person would receive a lethal dose quickly, and spacecraft must be heavily shielded and limit their time close to the moon.

Several observations hint that Europa may sometimes vent plumes of water vapour into space. Hubble Space Telescope images from 2012 and 2016 showed possible plumes, and a re-examination of Galileo data supported the idea. Other searches have found nothing, so the plumes remain tentative and may be rare or intermittent. In 2023, the James Webb Space Telescope detected carbon dioxide concentrated in Tara Regio, a region of chaos terrain, which scientists think may have come from the ocean below.

Jupiter filling the sky

Because Europa is tidally locked, one hemisphere always faces Jupiter. From there the giant planet hangs in the same part of the black sky, appearing more than 20 times wider than the full Moon looks from Earth, its cloud bands and storms clearly visible. It goes through phases as Europa orbits, and the Sun regularly disappears behind it, plunging the surface into eclipse.

From Europa you might also see the other large moons. Volcanic Io, closer to Jupiter, would appear as a yellowish disc, and Ganymede and Callisto would look like bright points or small discs depending on their positions. The Sun, about five times further away than from Earth, would look much smaller and give only around a twenty-fifth of the light Earth receives.

Europa Clipper and JUICE

NASA's Europa Clipper launched on 14 October 2024 aboard a SpaceX Falcon Heavy. It is the largest spacecraft NASA has built for a planetary mission, with huge solar arrays to work in the dim sunlight near Jupiter. After gravity assists from Mars and Earth, it is due to enter orbit around Jupiter in 2030. Rather than orbiting Europa itself, which would expose it to too much radiation, it is planned to make dozens of close flybys, mapping the surface, measuring the ice shell with radar, sampling any plumes and studying the ocean's likely properties.

ESA's JUICE, the Jupiter Icy Moons Explorer, launched in April 2023 and is expected to reach Jupiter around 2031. Its main target is Ganymede, which it is planned to orbit, but it will also make flybys of Callisto and two of Europa. Working together, the two missions should give scientists their best view yet of whether Europa's hidden ocean could support life.

Surprising facts about Europa's ice

Europa's ocean may hold about twice as much water as all of Earth's oceans, despite the moon being smaller than ours.
The ocean is kept liquid by tides: Jupiter's gravity flexes Europa as it orbits, warming its interior.
Some of the dark material on Europa's surface appears to contain ordinary table salt.
Europa's surface may be only tens of millions of years old, younger than many dinosaur fossils.
Europa Clipper is planned to fly past Europa dozens of times rather than orbit it, to limit its exposure to radiation.
From Europa's Jupiter-facing side, the planet never rises or sets but stays fixed in the sky.

Frequently asked questions

Does Europa really have an ocean?: Scientists are confident it does. Magnetic measurements from the Galileo spacecraft are best explained by a salty liquid ocean beneath the ice, and the surface features support this. Its exact depth and the thickness of the ice above it are still uncertain.
Could there be life on Europa?: It is possible, but unknown. Europa seems to have liquid water, chemical ingredients and possibly a source of energy, the basic needs of life as we know it. No life has been detected, and current missions aim to assess habitability rather than find life directly.
How cold is Europa?: About −160°C at the equator and around −220°C near the poles, cold enough that the ice is as hard as rock.
When will Europa Clipper arrive?: Europa Clipper launched in October 2024 and is due to arrive at Jupiter in 2030, after which it is planned to make dozens of close flybys of Europa.
Can I explore Europa in the app?: Yes. You can land on Europa's icy surface and explore its cracks, ridges and chaos terrain in interactive 3D, with Jupiter hanging in the sky above.

Keep exploring

The landscapes in Ember’s Universe are procedural 3D scenes modelled on real places. The landforms, plants and light follow the real thing, but the details are generated, not mapped.

Sources