FIGURE 2.14 Shown here is a possible pathway toward making the sugar molecule glycoaldehyde, which was detected by the NRAO Green Bank Telescope in the Sagittarius B2 cloud of gas and dust. Material expelled from the vicinity of forming stars collides with a nearby molecular cloud (such as Sagittarius B2), generating shock waves. The heating associated with the shock allows chemical reactions to occur among atoms and small molecules that are embedded on the surfaces and in the interiors of small grains in the cloud. The resulting larger molecules that are formed, such as glycoaldehyde, are ejected from the grains thanks also to the shock waves, and end up in the surrounding gas where they can be detected. The red atoms are oxygen; the grey, carbon; and the yellow, hydrogen. SOURCE: Bill Saxton, NRAO/AUI/NSF.