Thick clouds of dust lie between us and the heart of the Milky Way. In visible light, they dim the galactic centre by a factor of around a trillion, making it completely invisible to us. To study it, astronomers observe in infrared, radio waves or X-rays, which pass through the veil.
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.