As the gas and dust of the disc of a galaxy is squashed by the spiral arms, the gas condenses onto stardust grains to form molecular clouds, so-called because they contain molecules, which we explain later in this story. These are so dense that light cannot pass through them. They are the dark areas we see when we look at the Milky Way. When seen through a telescope they often reflect the light of nearby stars.
Image of M16 molecular cloud by NASA, ESA, STScI, J. Hester and P. Scowen (Arizona State University)
In the we can identify many of the molecules which uses: , , and have been identified. , are possibly out there too, all forming on and eventually getting frozen into . This means that the raw materials of life are common in the Universe. ?
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