Much of the universe’s water is produced as a byproduct of star formation. When stars are born, their birth 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. Interstellar clouds eventually condense into solar nebulae and solar systems such as ours.
Water vapor is present in
- 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
- Atmosphere of Mars: 0.03%
- Atmosphere of Jupiter: 0.0004%
- Atmosphere of Saturn – in ices only
- Enceladus (moon of Saturn): 91%
- exoplanets known as HD 189733 b and HD 209458 b.
Liquid water is present on
- Earth: 71% of surface
- Europa: 100 km deep subsurface ocean
Strong evidence suggests that liquid water is present just under the surface of Saturn’s moon Enceladus.
Water ice is present on
- Earth – mainly as ice sheets
- polar ice caps on Mars
- Saturn’s rings
- Pluto and Charon
- Comets and comet source populations (Kuiper belt and Oort cloud objects).
Water ice may be present on Ceres and Tethys. Water and other volatiles probably comprise much of the internal structures of Uranus and Neptune and the water in the deeper layers may be in the form of ionic water in which the molecules break down into a soup of hydrogen and oxygen ions, and deeper down as superionic water in which the oxygen crystallises but the hydrogen ions float around freely within the oxygen lattice.
Some of the Moon’s minerals contain water molecules. For instance, in 2008 a laboratory device which ejects and identifies particles found small amounts of the compound in the inside of volcanic rock brought from Moon to Earth by the Apollo 15 crew in 1971. NASA reported the detection of water molecules by NASA’s Moon Mineralogy Mapper aboard the Indian Space Research Organization’s Chandrayaan-1 spacecraft in September 2009.