In fact, the voids between the stars are anything but vacuous. Interstellar space is permeated by clouds of gas and dust. These dusty clouds are places where stars are born and where complicated chemical reactions form organic molecules, including amino acids. Many years ago, Earth-orbiting satellites noticed a stream of cosmic dust shooting past our planet. It's been detected again and again by NASA spacecraft, including Pioneer, Voyager and Galileo.
Astronomers now believe that the source is a cloud of gas from between the stars.
Instead of just watching the dust shoot by, it began collecting samples for a probable return to Earth in 2006. They may be small, but they're very important. Outside of stars, dust grains are the major repository of heavy elements in our Galaxy. One of their most important properties is opacity. When astronomers peer through telescopes across the galaxy, they can't see very far because interstellar dust absorbs light.