Io Trivia Questions

That's Ganymede, not Io. Io is slightly larger than Earth's Moon, but Ganymede is the largest moon, bigger than Mercury.

Galileo spotted Io, Europa, Ganymede, and Callisto in January 1610, revolutionizing astronomy by showing moons orbit another planet.

Io is the innermost of Jupiter's large moons, and its elliptical orbit causes flexing that generates enormous internal heat.

Io has over 400 active volcanoes, making it the most geologically active world, due to tidal heating from Jupiter's gravity.

Io's surface is dominated by sulfur and sulfur dioxide frost, giving it yellow, orange, and red colors—not water ice like Europa.

Io's sulfur dioxide atmosphere partially freezes onto the surface during its night side, then sublimates back into gas when sunlight returns.

Io likely has a partially molten mantle, but not a global ocean of magma. Its interior is mostly solid rock with pockets of melt.

Some of Io's volcanic plumes, like from Pele, shoot sulfurous material hundreds of kilometers high, far above the moon's surface.