Voyager photograph of Io. Click on image for full size (35K JPG) Courtesy of NASA

Scientists at the University of Colorado at Boulder found evidence supporting a theory that salt is present on Io. Io is one of Jupiter's many moons. Recent observations from the National Science Foundation's Kitt Peak National Observatory in Arizona led to the discovery of chlorine in Io's atmosphere.

Chlorine(Cl) along with sodium(Na) makes sodium chloride(NaCl), also known as common table salt. Salt is a very important mineral. The proportion of chlorine in Io's atmosphere is billions of times larger than Earth's. The chlorine is released into the air by huge volcanoes on the surface.

On Earth, most salt is produced when salt water evaporates. Scientists believe there may be underwater rivers on the moon producing the NaCl. It may also be produced by chemical reactions in Io's atmosphere.

Chlorine is a very important gas that breaks down ozone in Earth's atmosphere. This knowledge will help scientists understand Io's atmosphere and may eventually lead to a better understanding of our own environment.