Phobos, the larger of Mars's two moons, orbits so close that it creeps about 2 metres nearer every century. Within a few tens of millions of years, tidal forces will tear it apart: it will either crash into Mars or spread into a ring around it. Mars could then look like a miniature Saturn.
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.