A massive star fuses ever heavier elements in its core, all the way up to iron. But fusing iron absorbs energy instead of releasing it. Out of fuel, the core, heavier than the Sun, collapses in under a second, shrinking from the size of Earth to a ball about 20 kilometres across. The rebound from that implosion sets off the supernova.
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.