User:Reedman72/sandboxEnceladus intro
Enceladus is the sixth-largest moon of Saturn.[1] It was discovered in 1789 by William Herschel.[2]Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface. The Voyagers showed that the diameter of Enceladus is only 500 kilometers (310 mi), about a tenth of that of Saturn's largest moon, Titan, and that it reflects almost all of the sunlight that strikes it. Voyager 1 found that Enceladus orbited in the densest part of Saturn's diffuse E ring, indicating a possible association between the two, while Voyager 2 revealed that despite the moon's small size, it had a wide range of terrains ranging from old, heavily cratered surfaces to young, tectonically deformed terrain, with some regions with surface ages as young as 100 million years old.
In 2005 the Cassini spacecraft performed several close flybys of Enceladus, revealing the moon's surface and environment in greater detail. In particular, the probe discovered a water-rich plume venting from the moon's south polar region. This discovery, along with the presence of escaping internal heat and very few (if any) impact craters in the south polar region, shows that Enceladus is geologically active today. Moons in the extensive satellite systems of gas giants often become trapped in orbital resonances that lead to forced libration or orbital eccentricity; proximity to Saturn can then lead to tidal heating of Enceladus's interior, offering a possible explanation for the activity.
On April 3 2014, NASA reported that evidence for a large underground ocean of liquid water on Enceladus had been found by the Cassini spacecraft. Cryovolcanoes at the south pole shoot large jets of water vapor, other volatiles, and some solid particles like [[NaCl] crystals and ice particles into space, totaling approximately 200 kg per second.[3][4][5] Some of this water falls back onto the moon as "snow", some of it adds to Saturn's rings, and some of it reaches Saturn. The discovery of the plume has added further weight to the argument that material released from Enceladus is the source of the E ring.
Because of the presence water at or near the surface, Enceladus may be one of the best places to look for extraterrestrial life. By contrast, the water thought to be on Jupiter's moon Europa is locked under a very thick layer of surface ice, though recent evidence may show that Europa also experiences water plumes.[6]Analysis of the outgassing suggests that it originates from a body of subsurface liquid water, which along with the unique chemistry found in the plume, has fueled speculations that Enceladus may be important in the study of astrobiology.[7] According to the scientists at Nasa, evidence of an underground ocean suggests that Enceladus is one of the most likely places in the Solar System to "host microbial life".[8][9]
Name[edit]
Enceladus is named after the Giant Enceladus of Greek mythology. The name Enceladus—like the names of each of the first seven satellites of Saturn to be discovered—was suggested by William Herschel's son John Herschel in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope.[10] He chose these names because Saturn, known in Greek mythology as Cronus, was the leader of the Titans.
Features on Enceladus are named by the International Astronomical Union (IAU) after characters and places from Burton's translation of the Arabian Nights.[11] Impact craters are named after characters, while other feature types, such as fossae (long, narrow depressions), dorsa (ridges), planitia (plains), and sulci (long parallel grooves), are named after places. 57 features have been officially named by the IAU; 22 features were named in 1982 based on the results of the Voyager flybys, and 35 features were approved in November 2006 based on the results of Cassini's three flybys in 2005.[12]
- ^ Planetary Body Names and Discoverers. Retrieved March 22, 2006.
- ^ Herschel, W.; Account of the Discovery of a Sixth and Seventh Satellite of the Planet Saturn; With Remarks on the Construction of Its Ring, Its Atmosphere, Its Rotation on an Axis, and Its Spheroidical Figure, Philosophical Transactions of the Royal Society of London, Vol. 80 (1790), pp. 1–20
- ^ Lovett, Richard A. "Secret life of Saturn's moon: Enceladus". Cosmos Magazine. Retrieved 29 August 2013.
- ^ Hansen, C. J.; Esposito, L.; Stewart, A. I.; Colwell, J.; Hendrix, A.; Pryor, W.; Shemansky, D.; West, R. (2006-03-10). "Enceladus' Water Vapor Plume". Science. 311 (5766): 1422–1425. doi:10.1126/science.1121254. PMID 16527971.
- ^ Spencer, J. R.; Nimmo, F. (May 2013). "Enceladus: An Active Ice World in the Saturn System". Annual Review of Earth and Planetary Sciences. 41: 693. doi:10.1146/annurev-earth-050212-124025.
- ^ "Jupiter Moon Europa May Have Water Geysers Taller Than Everest - Yahoo News". News.yahoo.com. 2013-12-12. Retrieved 2014-04-03.
- ^ Cassini Images of Enceladus Suggest Geysers Erupt Liquid Water at the Moon’s South Pole. Retrieved March 22, 2006.
- ^ a b Platt, Jane; Bell, Brian (3 April 2014). "NASA Space Assets Detect Ocean inside Saturn Moon". NASA. Retrieved 3 April 2014.
- ^ a b Iess, L.; Stevenson, D.J.; Parisi, M.; Hemingway, D.; Jacobson, R.A.; Lunine, J.I.; Nimmo, F.; Armstrong, J.w.; Asmar, S.w.; Ducci, M.; Tortora, P. (4 April 2014). "The Gravity Field and Interior Structure of Enceladus". Science (journal). 344 (6179): 78–80. doi:10.1126/science.1250551. Retrieved 3 April 2014.
- ^ As reported by William Lassell, Monthly Notices of the Royal Astronomical Society, Vol. 8, No. 3, pp. 42–43 1848 January 14
- ^ Blue, J.; (2006) Categories for Naming Planetary Features. Retrieved November 16, 2006.
- ^ Blue, J.; (2006); New Names for Enceladus, 13 November 2006. Retrieved November 16, 2006.