Io has more than 400 active volcanoes, some throwing plumes hundreds of kilometres high. The engine is gravity: Jupiter and neighbouring moons knead its interior like a stress ball, heating it through friction. Its surface is repaved so fast that impact craters are almost nowhere to be seen.
A large share of Earth's water molecules formed in the interstellar cloud that existed before the Sun was even born, more than 4.6 billion years ago. You are literally drinking a cosmic fossil.
By day, the Martian sky looks butterscotch because of fine dust hanging in the air. But at dusk, those same grains scatter blue light forward, creating a bluish glow around the Sun. Rovers have photographed these blue sunsets: the exact reverse of what we see on Earth.