If the Universe were infinite, eternal and full of stars, every line of sight would end on the surface of a star, and the night sky would blaze like the Sun. This is Olbers' paradox. The answer: the Universe has a finite age, so light from very distant stars hasn't had time to reach us. Expansion also dims the light from the farthest ones.
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.