More than 300 meteorites found on Earth came from Mars. Blasted off by violent impacts, they drifted through space before falling here. Their origin is proven: gas trapped inside some of them matches the Martian atmosphere measured by the Viking landers. Museums held Martian rocks as early as the 1800s without knowing it.
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.