The asteroid Psyche, about 220 km wide, appears rich in iron and nickel, unlike the usual rocky asteroids. It may be the exposed core of a planetary embryo, stripped of its rocky mantle by collisions. Since we can never visit Earth's own core, a NASA spacecraft is due to reach Psyche in 2029.
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.