When a massive star collapses, its core can become a neutron star: more than the Sun's mass crammed into a ball about 20 kilometres wide. The matter is so dense that a teaspoonful would weigh on the order of a billion tonnes. Atoms are crushed so hard that protons and electrons merge into neutrons.
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.