Ammonium ion detected in space

The space between the stars, which is called the interstellar medium is not empty. Although the density of matter is very low (about 10,000 particles per cm3), there is a rich variety of atoms and molecules that populate it. The most abundant material, as in the rest of the universe is hydrogen (in three variants: ionized, atomic and molecular) and helium. But there are also molecules of all kinds, to over a hundred have come to find. Since the most abundant and simple, water (H2O), to large, complex organic chains as acetone or benzene.