Water In the universe
Much of the universe’s water is produced as a byproduct of star formation. The formation of stars is accompanied by a strong outward wind of gas and dust. When this outflow of material eventually impacts the surrounding gas, the shock waves that are created compress and heat the gas. The water observed is quickly produced in this warm dense gas.

On 22 July 2011, a report described the discovery of a gigantic cloud of water vapor containing “140 trillion times more water than all of Earth’s oceans combined” around a quasar located 12 billion light years from Earth. According to the researchers, the “discovery shows that water has been prevalent in the universe for nearly its entire existence”.

Water has been detected in interstellar clouds within our galaxy, the Milky Way. Water probably exists in abundance in other galaxies, too, because its components, hydrogen and oxygen, are among the most abundant elements in the universe. Based on models of the formation and evolution of the Solar System and that of other star systems, most other planetary systems are likely to have similar ingredients.

Water vapor
Water is present as vapor in:

Atmosphere of the Sun: in detectable trace amounts

Atmosphere of Mercury: 3.4%, and large amounts of water in Mercury’s exosphere

Atmosphere of Venus: 0.002%

Earth’s atmosphere: ≈0.40% over full atmosphere, typically 1–4% at surface; as well as that of the Moon in trace amounts

Atmosphere of Mars: 0.03%

Atmosphere of Ceres

Atmosphere of Jupiter: 0.0004% – in ices only; and that of its moon Europa

Atmosphere of Saturn – in ices only; Enceladus: 91% and Dione (exosphere)

Atmosphere of Uranus – in trace amounts below 50 bar

Atmosphere of Neptune – found in the deeper layers>

Extrasolar planet atmospheres: including those of HD 189733 b and HD 209458 b, Tau Boötis b, HAT-P-11b, XO-1b, WASP-12b, WASP-17b, and WASP-19b.

Stellar atmospheres: not limited to cooler stars and even detected in giant hot stars such as Betelgeuse, Mu Cephei, Antares and Arcturus.

Circumstellar disks: including those of more than half of T Tauri stars such as AA Tauri as well as TW Hydrae, IRC +10216 and APM 08279+5255, VY Canis Majoris and S Persei.

Water vapor, water vapour or aqueous vapor is the gaseous phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Water vapor is transparent, like most constituents of the atmosphere. Under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by condensation. It is less dense than most of the other constituents of air and triggers convection currents that can lead to clouds.