Juno mission

Io has more than 400 active volcanoes, mountains taller than Everest, lakes of molten sulfur, and a surface that repaints itself every few decades. It is the most volcanically active body in the solar system — and its power source is not radioactivity or solar heat, but the gravitational squeeze of Jupiter and its sibling moons.

Jupiter's Great Red Spot has been spinning continuously for at least 350 years — longer than the United States has existed. It reaches 500 km deep, its color comes from chemistry that scientists still argue about, and it has been shrinking for a century. But it is not dying. Here is what we actually know.