People have looked at the stars for thousands of years, but only about 20 years ago did astronomers become interested in the stuff inbetween.
Reversing their focus on the sky, astronomers can see that dark patches in the Milky Way are really giant molecular clouds. These big blobs of gas can be many times the size of the sun. Eventually, these clouds fall in on themselves, the cool gas becomes hot and dense and a star is born.
