Olympus Mons rises about 22 kilometres, two and a half times Everest's height, and its base spans over 600 km. Its slopes are so gentle that a hiker at the summit couldn't see its edge, hidden beyond the horizon. With no plate tectonics, Martian magma piled up in the same spot for hundreds of millions of years.
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.