Water in the universe
Much of the universe's water may be 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.
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 on:
Mercury - 3.4% in the atmosphere, and large amounts of water in Mercury's exosphere
Venus - 0.002% in the atmosphere
Earth - trace in the atmosphere (varies with climate)
Mars - 0.03% in the atmosphere
Jupiter - 0.0004% in the atmosphere
Saturn - in ices only
Enceladus (moon of Saturn) - 91% in the atmosphere
exoplanets known as HD 189733 b and HD 209458 b.
Liquid water is present on:
Earth - 71% of surface
Moon - small amounts of water have been found (in 2008) in the inside of volcanic pearls brought from Moon to Earth by the Apollo 15 crew in
Strong evidence suggests that liquid water is present just under the surface of Saturn's moon Enceladus and on Jupiter's moon Europa.
Water ice is present on:
Earth - mainly as ice sheets
polar ice caps on Mars
Comets and comet source populations (Kuiper belt and Oort cloud objects).
Water ice may be present on the Moon, Ceres, and Tethys. Water and other volatiles probably comprise much of the internal structures of Uranus and