Extraterrestrial oceans are oceans or similar, vast bodies of liquid (namely, water) on celestial bodies beyond Earth. Earth, with oceanic water covering 71% of its surface, is the only known planet with liquid water on its surface and is certainly the only one in our own solar system. Oceans and water may be common in other star systems and or/on their planets and other orbiting celestial bodies: for example, water vapour has recently been found at the right spot in a protoplanetary disc.^[1] Animated map exhibiting the worlds oceanic waters. ... A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... This article is about Earth as a planet. ... The eight planets and three dwarf planets of the Solar System. ... Major features of the Solar System (not to scale; from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth and its Moon, and Mars. ... A star system or stellar system is a small number of stars that orbit each other,[1] bound by gravitational attraction. ... It has been suggested that multiple sections of steam be merged into this article or section. ...

Before modernity, large bodies of water and extensive water systems were thought to cover the Moon, Venus, and Mars. With increased telescopic resolution and enhanced observation techniques, these were ultimately disproven; however, the presence of water on Mars in the distant past remains a topic of contemporary debate. Apparent magnitude: up to -12. ... Adjectives: Venusian or (rarely) Cytherean Atmosphere Surface pressure: 9. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... This article does not cite any references or sources. ... Observation is an activity of a sapient or sentient living being (e. ...

Venus

Before space probes were landed, the idea of oceans on Venus was credible science. But it was discovered to be much too hot. Adjectives: Venusian or (rarely) Cytherean Atmosphere Surface pressure: 9. ...

Astronomers believe that Venus had liquid water and perhaps oceans in its very early history. Given that Venus has been completely resurfaced by its own active geology, the idea of a primeval ocean is hard to test. Venus, the second planet from the Sun, has an atmosphere very different from that of Earth. ... A global view of Venus made from a mosaic of radar images from the Magellan spacecraft, centred at 90 degrees longitude. ...

Earth's Moon

Lunar maria are vast basaltic plains on the Moon that were thought to be bodies of water by early astronomers, who referred to them as "seas". Assuming that the Giant impact hypothesis, there were never real seas or oceans on the moon. The Lunar maria (singular: mare, IPA: //) are large, dark, basaltic plains on Earths Moon, formed by ancient volcanic eruptions. ... Apparent magnitude: up to -12. ... The Big Splash. ...

Galileo expresses some doubt about the lunar 'seas' in his Dialogue Concerning the Two Chief World Systems. 'Salviati', who normally gives Galileo's own opinions, says: Galileo Galilei (15 February 1564 – 8 January 1642) was an Italian physicist, mathematician, astronomer, and philosopher who is closely associated with the scientific revolution. ... Dialogo sopra i due massimi sistemi del mondo (Dialogue Concerning the Two Chief World Systems) was Galileos comparison of the Copernican system, in which the Earth and other planets orbit the Sun, with the traditional Ptolemaic system, in which everything in the Universe circles around the Earth. ...

I say then that if there were in nature only one way for two surfaces to be illuminated by the sun so that one appears lighter than the other, and that this were by having one made of land and the other of water, it would be necessary to say that the moon's surface was partly terrene and partly aqueous. But because there are more ways known to us that could produce the same effect, and perhaps others that we do not know of, I shall not make bold to affirm one rather than another to exist on the moon...

What is clearly seen in the moon is that the darker parts are all plains, with few rocks and ridges in them, though there are some. The brighter remainder is all fill of rocks, mountains, round ridges, and other shapes, and in particular there are great ranges of mountains around the spots...

I think that the material of the lunar globe is not land and water, and this alone is enough to prevent generations and alterations similar to ours.

Ceres

The dwarf planet Ceres is believed to contain large amounts of water-ice.^[2] It might have a tenuous atmosphere.^[3] It is too cold for liquid water, but an ocean of water plus ammonia has been suggested.^[4] We will know more in 2015, when the Dawn Mission visits it. Spectral type: G[8] Absolute magnitude: 3. ... The Dawn Mission is a NASA mission that will send the Dawn spacecraft, a robotic space probe, to the asteroid belt. ...

Mars

Mars was never supposed to have oceans. Its dryness was long recognised, and gave credibility to the spurious 'canals'. It was thought it might have dried up from something more Earth-like. The initial discovery of a cratered surface made this seem unlikely. But further evidence has change this view. Liquid water may have existed on the surface of Mars in the distant past, and several basins on Mars have been proposed as dry sea beds. ^[5] The largest is Vastitas Borealis; others include Hellas Planitia and Argyre Planitia. Adjectives: Martian Atmosphere Surface pressure: 0. ... Vastitas Borealis is the largest lowland region of Mars. ... NASA image of Hellas Planitia Hellas Planitia, also known as the Hellas Impact Basin, is a roughly circular impact crater located in the southern hemisphere of the planet Mars. ... Argyre Planitia is a plain located in the Argyre impact basin in the southern highlands of Mars between -35 and -61 deg S and 27 and 62 deg W. The basin is approximately 1120 miles (1800 kilometers) wide, the second-largest impact basin on Mars after Hellas Planitia, and drops...

There is currently much debate over whether Mars once had an ocean of water in its northern hemisphere, and over what happened to it if it did. Recent findings by the Mars Exploration Rover mission indicate it had some long-term standing water in at least one location, but its extent is not known. Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... Artists Concept of Rover on Mars (credit: Maas Digital LLC) NASAs Mars Exploration Rover (MER) Mission is an ongoing robotic Mars exploration mission, commenced in 2003, that sent two rovers — Spirit and Opportunity — to explore the Martian surface and geology. ...

Jupiter

Liquid water is thought to be present under the surface of several natural satellites, particularly the Galilean moons of Europa, and, with less certainty, Callisto and Ganymede. A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Jupiters 4 Galilean moons, in a composite image comparing their sizes and the size of Jupiter (Great Red Spot visible). ... Apparent magnitude: 5. ... There is also an asteroid named 204 Kallisto. ... This article or section does not adequately cite its references or sources. ...

Saturn

Enceladus

Geysers have been found on Enceladus. These contain water vapour and may mean liquid water deeper down. ^[6] It could also be just ice. Strokkur geyser, Iceland A geyser is a type of hot spring that erupts periodically, ejecting a column of hot water and steam into the air. ... [5] Atmospheric characteristics Pressure trace, significant spatial variability [6], [7] Water vapour 91% [8] Carbon dioxide 3. ...

Titan

It was believed after the Voyager observations that Titan might have seas or oceans of liquid hydrocarbons. The Cassini-Huygens space mission initially discovered only what appeared to be dry lakebeds and empty river channels, suggesting that Titan had lost what surface liquids it might have had. Voyager Project redirects here. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the second largest moon in the solar system,[4] after Jupiters moon Ganymede. ... Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ...

A more recent fly-by of Titan made by Cassini has produced radar images that strongly suggest hydrocarbon lakes near the polar regions where it is colder.

Titan is also thought likely to have a subterranean water ocean under the mix of ice and hydrocarbons that forms its outer crust.^[7]

Uranus and Neptune

The planets Uranus and Neptune may possess large oceans of liquid water under their thick atmospheres, though their internal structure is not well understood at this time. It is agreed that they are different from Jupiter and Saturn. Atmospheric characteristics Atmospheric pressure 120 kPa Hydrogen 83% Helium 15% Methane 1. ... Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ...

Triton

Neptune's moon Triton may have once had internal oceans that have now frozen. This could also be true of other icy moons. Triton (trye-tÉ™n, IPA: , Greek Τρίτων), or Neptune I, is the planet Neptunes largest moon. ...

Beyond the Solar System

Our solar system may not be typical. Most of the 200+ solar systems look very different from ours, though there is probably a bias arising from the detection methods. The hope is for Earth-sized planets in the habitable zone,^[8] (which is also sometimes called the Goldilocks zone). Planets with oceans could include Earth-sized moons of giant planets, though it remains speculative whether such 'moons' really exist. An extrasolar planet, or exoplanet, is a planet beyond the Solar System. ... Any planet is an extremely faint light source compared to its parent star. ... In astronomy a habitable zone (HZ) is a region of space where conditions are favorable for life, as it can be found on earth. ...

Gliese 581 c

Gliese 581 c is at the right distance from its sun for liquid water to exist on the planet's surface^[9], thought it is five times the mass of the Earth. It is generally regarded as the first extrasolar planet discovered in the habitable zone. Since it does not transit its sun, there is no way to know if there is any water there. Gliese 581 c (IPA: ) is a super-earth extrasolar planet orbiting the red dwarf star Gliese 581. ... 2003 Transit of Mercury The term transit or astronomical transit has two meanings in astronomy: A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, as seen by an observer at some particular vantage point. ...

HD 209458b

HD 209458b may have water vapour in its atmosphere - this is currently being disputed. It is not cool enough for liquid water. HD 209458b is an extrasolar planet that orbits the Sun-like star HD 209458 in the constellation Pegasus, some 150 light years from Earths solar system. ...

Gliese 436 b

Gliese 436 b is believed to have 'hot ice'. It is not cool enough for liquid water: but if water molecules exist there, they are likely to be found also on planets at a suitable temperature.^[10] Gliese 436 b (IPA: ) (GJ 436 b)[1] is a Neptune-sized extrasolar planet orbiting the red dwarf star Gliese 436. ...

The detection of such a hot ice world has important consequences. It shows for the first time that planets similar to the "ice giants" Uranus and Neptune in our own Solar System exist at close distances from their star... Many of the planets of similar mass detected around other stars by the astronomers may therefore also be composed mainly of water. Some of them will have cooler temperatures, allowing the water on the surface to be liquid. Such planets covered by a single huge ocean have been dubbed "ocean planets" by the specialists.^[11]

HD 189733 b

In July 2007, evidence was published that HD 189733 b had water vapour in its atmosphere.^[12] Like HD 209458b, it would be too hot for liquid water. HD 209458b is an extrasolar planet that orbits the Sun-like star HD 209458 in the constellation Pegasus, some 150 light years from Earths solar system. ...

References

1. ^ Water reveals the perfect spot for other Earths
2. ^ Largest Asteroid Might Contain More Fresh Water than Earth
3. ^ Asteroid Ceres
4. ^ Dawn's destinations, Astronomy Now June 2007.
5. ^ Mars Probably Once Had A Huge Ocean
6. ^ Cassini Images of Enceladus Suggest Geysers Erupt Liquid Water at the Moon’s South Pole
7. ^ Mysterious signal hints at subsurface ocean on Titan
8. ^ Habitable planets may be common
9. ^ New Planet Could Harbor Water and Life
10. ^ Hot "ice" may cover recently discovered planet
11. ^ Astronomers Detect Shadow Of Water World In Front Of Nearby Star
12. ^ NASA's Spitzer Finds Water Vapor on Hot, Alien Planet

External link

• The Extrasolar Planets Encyclopaedia