Valles Marineris, the largest canyon system known, stretches about 4,000 km, nearly a fifth of the way around Mars. In places it plunges 7 km deep, around four times deeper than the Grand Canyon. No river carved it: the Martian crust split apart as the region bulged upward.
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.