Arsenic has been added to the substances that form the poisonous atmosphere of Jupiter and Saturn. Keith S. University of Arizona Noll and his coworkers have found arsine (ArH3) in the atmosphere of two giant planets. Arsine is not very abundant (0,3-1,1 ppm in Jupiter and 0,7-2,7 ppm in Saturn), but it is important if we take into account the size of the planets. Arsenic has been the eighth element discovered on these planets and the heaviest (PM = 74,92).