As its interior cools, the Moon contracts. Its rigid crust buckles into thousands of cliffs visible in images from NASA's LRO orbiter. As a result, its radius has shrunk by about 45 to 50 meters over a few hundred million years. This slow shrinking still triggers moonquakes today.
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.