Our universe is a very dusty place. Dust usually shows its presence by blocking out light emitted from stars or nebulae behind it, sometimes creating the illusion of a horse's head or a sombrero hat. But nobody really knows what a typical interstellar dust grain looks like.

Dark skies are disappearing from the world. With modernization comes artificial lighting that brightens the night. While these lights allow modern humans to see, much light is wasted up into the sky. This light...

What's happened since the universe started? The time spiral shown here features a few notable highlights. At the spiral's center is the Big Bang, the place where time, as we know it, began about 13.8 billion years ago.