... then later reformed. Atmospheric scientists frequently observe emissions from hydroxyl (OH) and oxygen (O2) molecules and from sodium (Na) and oxygen (O) atoms in Earth’s skies and it is this latter atom, oxygen, that gives terrestrial auroras...
... up salts left over from evaporated oceans, are being lifted into the martian atmosphere by winds. The sodium chloride dust then reacts with molecules containing hydrogen to create hydrogen chloride. "You need water vapour...