I learn something new every day: I had never heard of Bok globules. I would love to know how they got that name!
(PhysOrg.com) -- Bok globules are small interstellar clouds of very cold gas and dust that are so thick they are nearly totally opaque to visible light, although they can be studied with infrared and radio techniques. They were originally discovered as black splotches in front of dense fields of stars, and were even dubbed "holes in the heaven" because they appeared like holes in the stellar background.

Bok globules are typically less than 100 solar-masses in size, are relatively isolated, and often contain cores thought to be the embryos of new stars. It is this last feature that makes Bok globules particularly interesting to astronomers who want to use their relative simplicity to examine the very early stages of star formation under conditions much less confused than those in giant molecular cloud complexes like the Orion Nebula.