Europa (Moon)
0Loading crowd target
0Loading crowd target
6correct to beat the crowd
44 free Europa (Moon) trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Europa is the smallest of Jupiter's four Galilean moons and the most tantalising: a billiard-ball-smooth ball of ice, slightly smaller than our Moon, with a salty ocean beneath its crust that may hold more water than all of Earth's seas. Tidal kneading from Jupiter keeps that ocean liquid, which is why NASA's Europa Clipper and ESA's Juice are on their way. These 44 questions cover the discovery by Galileo (and maybe Simon Marius), the Zeus-lover naming scheme, the 3.55-day orbit, the 100 km water layer and thick-ice debate, lineae, lenticulae and Conamara Chaos, the magnesium-sulfate streaks, the Hubble plume, the brutal radiation dose, and the missions from Pioneer and Voyager through Galileo, Juno, Juice and Clipper's poem-bearing plate. Easy questions stick to the basics; the expert tier asks about albedo, eccentricity and flyby distances. Every answer is cited to a page we checked, with a short explanation so you learn something even when you miss.
30 of 44 questions with answers and explanations. Play the quiz
Q 01What powers NASA's Europa Clipper spacecraft on its mission to Jupiter?
Solar panels
Solar panels. Sunlight at Jupiter is about 25 times fainter than at Earth, so the probe carries enormous arrays to gather enough power.
Q 02Any life in Europa's ocean might cluster around which seafloor feature, as deep-sea creatures do on Earth?
Hydrothermal vents
Hydrothermal vents. No sunlight reaches beneath the ice, so anything living there would have to run on chemical energy, as the communities around Earth's vents do.
Q 03Galileo first named Europa and its three sister moons after which powerful family, his patrons?
The Medici
The Medici. Galileo called the four moons the Medicean Stars to honour his patrons, but the tribute faded and astronomers now call them the Galilean moons after him instead.
Q 04Among Jupiter's four Galilean moons, Europa is which?
The smallest
The smallest. Yet it drew NASA's largest planetary spacecraft: Europa Clipper, launched in 2024 to find out whether this little world could support life.
Q 05Europa is slightly smaller than which body?
The Moon
The Moon. Europa is about 90% as wide, so it would look much the same size in our night sky, yet far brighter, because its icy surface reflects several times more sunlight.
Q 06Like all the Galilean satellites, Europa is named after what kind of figure?
A lover of Zeus
A lover of Zeus. In the myth he took the form of a white bull, and when the Phoenician princess Europa climbed on his back he carried her off across the sea.
Q 07Its young, shifting ice gives Europa which record among the Solar System's known solid bodies?
Smoothest
Smoothest. Europa has no mountains or tall cliffs, a flatness that suggests its icy crust was once soft and mobile.
Q 08What keeps Europa's subsurface ocean liquid?
Tidal heating
Tidal heating. Europa's slightly oval orbit carries it nearer to and farther from Jupiter, so the planet's gravity keeps stretching and relaxing it, and that flexing generates heat.
Q 09Charged particles splitting Europa's surface ice produce a very thin atmosphere made mainly of which gas?
Oxygen
Oxygen. Charged particles from Jupiter split the frozen water into hydrogen and oxygen; the lighter hydrogen drifts off into space, leaving a wisp of oxygen that no living thing made.
Q 10Galileo's 1610 discovery of Europa and its sister moons was strong evidence against which old belief?
Everything orbits the Earth
Everything orbits the Earth. Here were four bodies plainly circling Jupiter instead, which backed Copernicus's idea that the Earth is not the centre of all motion in the heavens.
Q 11Europa's suspected water plumes would echo the proven jets of which moon of Saturn?
Enceladus
Enceladus. NASA's Cassini probe flew straight through its jets and sampled the spray, a trick scientists hope to repeat at Europa if its plumes prove real.
Q 12Which rocket launched NASA's Europa Clipper in October 2024?
Falcon Heavy
Falcon Heavy. Congress had ordered NASA to fly the probe on its own Space Launch System, but NASA later won permission to buy a commercial launch instead.
Q 13Who launched the Jupiter Icy Moons Explorer (Juice) in April 2023?
The European Space Agency
The European Space Agency. Juice rode an Ariane 5 from French Guiana and is taking eight years to reach Jupiter, stealing speed from flybys of Earth and Venus on the way.
Q 21Which observatory spotted signs of a possible water plume near Europa's south pole in 2012?
Hubble
Hubble. It never saw water itself: its spectrograph caught a faint ultraviolet aurora, read as water vapour being torn apart above the pole, and the plumes are still unconfirmed.
Q 22Which probes made the first flybys of Jupiter and Europa, in 1973 and 1974?
Pioneer 10 and 11
Pioneer 10 and 11. Pioneer 10 was the first spacecraft to cross the asteroid belt and reach Jupiter, though its photos of Europa were too coarse to show the cracks later probes revealed.
Q 23The Voyager probes' 1979 photos showed that Europa has surprisingly few of which surface feature?
Impact craters
Q 14How did NASA deliberately end the Galileo probe's mission in 2003?
Crashed it into Jupiter
Crashed it into Jupiter. NASA destroyed its own orbiter rather than risk it one day hitting Europa and contaminating the hidden ocean it had helped to reveal.
Q 15In Greek myth, the princess Europa was carried across the sea and became queen of where?
Crete
Crete. There she became the mother of Minos, the legendary king whose labyrinth was said to hold the Minotaur.
Q 16Since Europa always shows Jupiter the same face, how would the planet appear from that side?
Fixed in one spot
Fixed in one spot. Europa turns once on each 3.5-day lap, so from its near side Jupiter would hang in place and never set, while from the far side it could never be seen.
Q 17Which technology will Europa Clipper use to peer through the ice shell and gauge its thickness?
Radar
Radar. The probe will beam radio waves into the ice and read the echoes, which should show how thick the shell is and whether pockets of water lie inside it.
Q 18Europa's hidden ocean is thought to hold about how much water compared with all of Earth's oceans?
About twice as much
About twice as much. Europa is only a quarter as wide as Earth, but its ocean is thought to be 60 to 150 km deep, far deeper than any sea on our planet.
Q 19What are the dark streaks crisscrossing Europa's surface called?
Lineae
Lineae. They look like cracks where the icy crust pulled apart and darker material welled up to fill the gap, much as new seafloor forms along Earth's mid-ocean ridges.
Q 20In 2019, scientists found that yellow patches on Europa's surface are which everyday substance?
Table salt
Table salt. Lab tests showed plain sodium chloride turns yellow under conditions like those on Europa's surface, and finding it there suggests the hidden ocean may be chemically closer to Earth's seas than anyone thought.
Impact craters. Old surfaces are pocked with them, so finding only a handful meant something keeps wiping Europa's face clean, and its surface is now judged to be geologically young.
Q 24Which orbiter made a close flyby of Europa in September 2022?
Juno
Juno. It raced past about 350 km above the ice with only a two-hour window to gather data, the closest any spacecraft had come to Europa since Galileo in 2000.
Q 25Europa Clipper's looping route to Jupiter uses gravity assists from Earth and which other planet?
Mars
Mars. The probe skimmed about 880 km above its surface in March 2025 to bend its path, because flying straight to Jupiter would have taken far more propellant.
Q 26Fully unfolded in space, Europa Clipper stretches about the length of what?
A basketball court
A basketball court. It will never land: the plan is to swoop past Europa 49 times, on some passes dipping to just 25 km above the ice.
Q 27In 2023 the James Webb Space Telescope found which carbon-bearing gas frozen on Europa's surface?
Carbon dioxide
Carbon dioxide. It was concentrated in a patch of young, recently disturbed ice, so scientists think the carbon welled up from the ocean below instead of arriving on meteorites.
Q 28Which Space Shuttle, later the last ever to fly, carried the Galileo probe into orbit in 1989?
Atlantis
Atlantis. Its cargo's booster was too weak for a direct flight, so Galileo spent six years borrowing speed from flybys of Venus and Earth before it reached Jupiter.
Q 29What is thought to carve the 15-metre blades of ice that may cover Europa's equator?
Direct sunlight
Direct sunlight. With the Sun overhead, the ice turns straight to vapour and deepens into blades called penitentes, which would make any landing there treacherous.
Q 30Galileo publicly accused Simon Marius, a rival astronomer, of what?
Plagiarism
Plagiarism. Marius said he saw Jupiter's moons first, but his earliest recorded observation, dated 1609 on the old Julian calendar, fell in January 1610 by Galileo's calendar, a day after Galileo's own.