Jupiter's Galilean Moons Trivia Quiz

Answer: Io

Io is the most volcanically active object in our solar system and, even with its size coming in at less than a third of Earth's, it contains hundreds of active volcanoes at any given point. Loki is the most powerful of these, being the largest volcano in the solar system, and it (along with a handful of others on this satellite) is larger than Mount Everest.

It's appropriate that the name Io was chosen for this moon. Io was one of Jupiter's lovers in ancient myth. They were painted together often in Renaissance artworks.

Answer: Io

The reason for this distinctive colouration comes from Io's many volcanoes as they set off with plumes of sulfur compounds. This couples with lengthy lava floes that snake around the moon's surface, splitting up the yellow and green fields of sulfur under an otherwise thin and uneven atmosphere.

Naturally, this atmosphere isn't a safe one; the dense sulfur creates a dense and toxic environment outward, shot well beyond the surface by the constant, roiling volcanic activity.

Answer: Io

Io is more than 420,000 kilometres (260,000 miles) away from Jupiter, and that's longer than the distance from Earth to its own moon but, because of Jupiter's colossal size, Io experiences some of the most unusual gravitational forces in the solar system. If you were able to land on Io (you shouldn't) you would be experiencing strong gravity for a satellite, but still be much lighter than on Earth.

Because of its position in orbit, Io experiences shifts in its own make-up resulting from not only Jupiter, but the other satellites. Its spot next to Europa and Ganymede can often cause as much tidal adjustment as Jupiter does, making it quite volatile.

Answer: Europa

Not only is Europa smaller than Earth's moon, it's the smallest of the Galilean moons; Io is comparable in size to our moon while Ganymede and Callisto are significantly larger. Despite this, all four moons are relatively visible in the night sky and easy to spot with a common pair of binoculars.

Europa remains the sixth-largest moon in the solar system despite these stats and is not too unlike Earth in many ways, being composed of a central iron core, a thick mantle, and a watery surface.

Answer: Europa

The appearance and texture of this ice isn't unlike the ice in the Arctic Ocean on Earth and, as with other celestial bodies that have a solid surface and ice upon it, there has long been consideration towards the idea that it may contain extraterrestrial life. Pioneer space probes were sent on fly-bys of this and other Jovian moons to determine if this could, in fact, be the case, coming to the determination that the thick ice covers a warmer ocean beneath.

With the ice potentially reaching thirty kilometres (nineteen miles) in thickness and the ocean beneath going another hundred kilometres (sixty-two miles) deep, it would imply that Europa's water coverage has more volume than Earth's.

Answer: Europa

It was the Hubble Space Telescope that showed us this, as much of Earth's long-range visibility to that point was incapable of seeing some of the finer details of this and other moons beyond our immediate glance. When Galileo flew by in later decades, it brought back significant evidence that these were from cryogeysers capable of shooting water from deep within the moon's crust into the moon's atmosphere as far as two hundred kilometres (or one hundred twenty-five miles) out.

While it was hypothesized that Europa could be suitable for human life at one point, its volatility made this less likely the more scientists dug into this research.

Answer: Ganymede

Ganymede is the largest moon the our solar system-- even bigger than Mercury-- and amongst those in our quiz topic here, it would be followed by Callisto, Io, and Europa. Ganymede's surface is a mix between old and new terrain; it contains rough and cratered surfaces and appears to have formed through tectonic movement, not unlike Earth.

Although covered in a surface of silicate, making it appear grey, like our own moon, through a telescope, it's believed to contain an ocean within, and that ocean would have a higher volume than all the water on Earth.

Answer: Ganymede

As it was the largest of the Galilean moons, it would be unsurprising to know that Ganymede was the easiest to see, and it's believed that before Galileo located all of them with a telescope on January 7, 1610, a Chinese astronomer recorded having seen what would become Ganymede nearly two millennia earlier.

Galileo did, however, determine that the moons were in orbit around Jupiter when he 'discovered' them in his day, finding that they shifted positions around the planet night after night. A full orbit, for Ganymede, would be approximately seven Earth days.

Answer: Ganymede

The magnetosphere refers to the space around a planet that's capable of reflecting a certain amount of solar radiation, and it's this type of phenomenon that keeps a planet like Earth from getting too crispy or irradiated. Ganymede is unique in that it's the only moon in our solar system to exhibit the presence of a global magnetosphere, sharing the feature with Earth, Jupiter, Saturn, Neptune, Uranus, and Mars.

The magnetospheres of Mars and Ganymede, unlike the other bodies here, are too weak to trap plasma.

It definitely points to Ganymede being a bit more mysterious than it seems, and rife for possibility from a scientific point of view (and bearing the need for more research!).

Answer: Callisto

A unique geological feature, Gipul Catena stretches six hundred and twenty kilometres (or three hundred eighty-five miles) across the surface of this rocky moon which, as it turns out, is the most cratered body in our solar system, a consequence of having been in the collision course of numerous items over its lifetime. Gipul Catena is a series of impact craters that stretch across a straight line, likely caused by a single object that was disrupted in its journey, skidding across the surface of the satellite.

Answer: Callisto

Callisto is the third-largest moon in our solar system with only Ganymede (also a Galilean moon) and Titan (of Saturn) superseding it. Similar to Mercury, Callisto is also relatively flat (if not for all of the impact craters on it) and quite old (I mean, still talking in terms of billions of years). Because of its make-up, it's believed that it is almost entirely covered with impact craters. Mercury, similarly, has been subject to many collisions with celestial debris. Both may have been covered in geologically-active sections but, these days, they're relatively quiet and stable.

They just happen to be very far away from one another.

Answer: Callisto

The fourth-furthest satellite from Jupiter, it's actually quite small when seen from Jupiter's surface (not that you'd ever be able to be there). Even with Earth's moon being only two-thirds the size, Callisto is about five times as far away than the moon is to Earth. Because of Callisto's distance in Jupiter's orbit, it is not affected by the gravitational force of the three closer moons in the same way that they exert gravitational forces upon one another.

Instead, Jupiter acts as the sole influence on this moon, locking it into its orbit and causing it not to rotate on a magnetic axis.