Ozone is an inorganic molecule made up of three atoms of oxygen. It appears as a colorless to pale blue unstable toxic gas with a distinctively pungent smell and powerful oxidizing properties. Ozone has a boiling point of -112°C and a melting point of -192.2°C. At atmospheric pressure, ozone can partially dissolve in water. At standard pressure and temperature, the solubility of ozone is thirteen times that of oxygen. It is mostly found in the stratosphere, where it protects the Earth from the Sun's harmful ultraviolet radiation. Ozone absorbs the ultraviolet radiation and continuously converts it into heat.