Atmosphere of Pluto: Difference between revisions
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The atmosphere of Pluto is different from that on earth on a number of points: |
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[[Image:Charon 2.jpg|400px|thumb|right|400px|Artist's concept of Charon seen through the tenuous atmosphere of Pluto.]] |
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It undergoes [[temperature inversion]] in that Pluto's upper atmosphere is about 50 degrees warmer (103K or -170 °C) than the surface (53K or -220 °C) while Pluto's lower atmosphere is 40 degrees warmer |
It undergoes [[temperature inversion]] in that Pluto's upper atmosphere is about 50 degrees warmer (103K or -170 °C) than the surface (53K or -220 °C) while Pluto's lower atmosphere is 40 degrees warmer |
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Pluto's upper atmosphere consists mostly nitrogen, with traces of methane and |
Pluto's upper atmosphere consists mostly [[nitrogen]], with traces of [methane]], and [[carbon monoxide]] derived from the ices on its surface.<ref>{{cite web|title= Nitrogen in Pluto's Atmosphere|author= Ken Croswell|url=http://www.kencroswell.com/NitrogenInPlutosAtmosphere.html|year=1992|accessdate=2007-04-27}}</ref>, while the lower atmosphere is methane rich.<ref>E. Lellouch et al. 2009, A&A, in press, Pluto's lower atmosphere structure and methane abundance from high-resolution spectroscopy and stellar occultations. E. Lellouch, B. Sicardy, and C. de Bergh </ref> |
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As Pluto moves away from the Sun, its [[atmosphere]] gradually freezes and falls to the ground. As it edges closer to the Sun, the temperature of Pluto's solid surface increases, causing the ices to [[Sublimation (physics)|sublimate]] into gas. This creates an [[anti-greenhouse effect]]; much like [[sweat]] cools the body as it evaporates from the surface of the skin, this sublimation has a cooling effect on the surface of Pluto. Scientists using the [[Submillimeter Array]] have recently discovered that Pluto's temperature is about {{convert|43|K|C|0|sp=us|abbr=on}}, 10 K colder than expected.<ref>{{cite web |
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| url = http://www.cnn.com/2006/TECH/space/01/03/pluto.temp/index.html |
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| title = Astronomers: Pluto colder than expected |
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| author = T. Ker |
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| publisher = Space.com (via CNN.com) |
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| year = 2006 |
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| accessdate = 2006-03-05 |
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}}</ref> |
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Pluto was found to have an atmosphere from an [[occultation]] observation in 1985; the finding was confirmed and significantly strengthened by extensive observations of another occultation in 1988. When an object with no atmosphere occults a star, the star abruptly disappears; in the case of Pluto, the star dimmed out gradually.<ref>{{cite web |
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| title = IAUC 4097 |
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| url = http://cfa-www.harvard.edu/iauc/04000/04097.html#Item0 |
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| year = 1985 |
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| accessdate = 2007-03-26}}</ref> From the rate of dimming, the atmospheric pressure was determined to be 0.15 [[Pascal (unit)|pascal]], roughly 1/700 000 that of Earth.<ref>{{cite web |
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| title = The atmospheres of Pluto and other trans-Neptunian objects |
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| author = R. Johnston |
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| url = http://www.johnstonsarchive.net/astro/pluto.html |
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| year = 2006 |
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| accessdate = 2007-03-26 |
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}}</ref> |
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In 2002, another occultation of a star by Pluto was observed and analysed by teams led by Bruno Sicardy of the [[Paris Observatory]],<ref>{{cite journal |
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| url = http://calys.obspm.fr/~sicardy/pluton/pr_obs_en.html |
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| title = Large changes in Pluto's atmosphere as revealed by recent stellar occultations |
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| journal = Nature |
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| volume = 424 |
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| doi = 10.1038/nature01766 |
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| author = B. Sicardy |
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| coauthors = T. Widemann, et al. |
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| publisher = Nature |
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| date = 2003-07-10 |
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| accessdate = 2006-03-05 |
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| pages = 168 |
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| format = {{dead link|date=March 2009}} – <sup>[http://scholar.google.co.uk/scholar?hl=en&lr=&q=intitle%3ALarge+changes+in+Pluto%27s+atmosphere+as+revealed+by+recent+stellar+occultations&as_publication=Nature&as_ylo=&as_yhi=&btnG=Search Scholar search]</sup> |
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}}</ref> [[James L. Elliot]] of [[MIT]],<ref>{{cite web |
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| url = http://web.mit.edu/newsoffice/2002/pluto.html |
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| title = Pluto is undergoing global warming, researchers find |
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| publisher = Massachusetts Institute of Technology |
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| date = 2002-10-09 |
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| accessdate = 2007-03-20 |
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}}</ref> and [[Jay Pasachoff]] of [[Williams College]].<ref>{{cite web |
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| url = http://www.williams.edu/admin/news/releases.php?id=162 |
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| title = Williams Scientists Contribute to New Finding About Pluto |
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| publisher = Williams College |
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| date = 2003-07-09 |
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| accessdate=2007-03-20 |
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}}</ref> The atmospheric pressure was estimated to be 0.3 pascal, even though Pluto was farther from the Sun than in 1988 and thus should have been colder and had a more rarefied atmosphere. One explanation for the discrepancy is that in 1987 the south pole of Pluto came out of shadow for the first time in 120 years, causing extra nitrogen to sublimate from the polar cap. It will take decades for the excess nitrogen to condense out of the atmosphere.<ref>{{cite web |
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| title = Puzzling Seasons and Signs of Wind Found on Pluto |
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| author = R. R. Britt |
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| work = Space.com |
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| url = http://www.space.com/scienceastronomy/pluto_seasons_030709.html |
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| year = 2003 |
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| accessdate = 2007-03-26 |
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}}</ref> Another stellar occultation was observed by the MIT-Williams College team of James Elliot, [[Jay Pasachoff]], and a [[Southwest Research Institute]] team led by Leslie Young on June 12, 2006 from sites in Australia.<ref> {{cite web |
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| author = J. L. Elliot, M. J. Person, A. A. S. Gulbis, E. R. Adams, E. A. Kramer, C. A. Zuluaga, R. E. Pike, J. M. Pasachoff, S. P. Souza, B. A. Babcock, J. W. Gangestad, A. E. Jaskot, P. J. Francis, R. Lucas, A. S. Bosh |
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| year=2006 |
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| title = The Size of Pluto's Atmosphere As Revealed by the 2006 June 12 Occultation |
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| url = http://adsabs.harvard.edu/abs/2006DPS....38.3102 |
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| journal = American Astronomical Society |
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| work = E Pasadena Division of Planetary Sciences |
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|accessdate=2007-04-12}}</ref> |
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<!--The results were reported at the October meeting of the Division of Planetary Sciences--> |
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In October 2006, Dale Cruikshank of NASA/Ames Research Center (a New Horizons co-investigator) and his colleagues announced the spectroscopic discovery of [[ethane]] on Pluto's surface. This ethane is produced from the photolysis or radiolysis (i.e., the chemical conversion driven by sunlight and charged particles) of frozen methane on Pluto's surface and suspended in its atmosphere.<ref>{{cite web |
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| author = A. Stern |
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| authorlink = Alan Stern |
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| date = November 1, 2006 |
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| url = http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_11_1_2006.php |
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| title = Making Old Horizons New |
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| work = The PI's Perspective |
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| publisher = Johns Hopkins University Applied Physics Laboratory |
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| accessdate = 2007-02-12 |
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}}</ref> |
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==See also== |
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[[Pluto]] |
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[[Atmosphere]] |
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==Notes== |
==Notes== |
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<references/> |
<references/> |
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Revision as of 13:12, 23 March 2009
The atmospheric pressure on Pluto is only about one hundred thousandth of that on Earth, or about 0.015 millibars.
It undergoes temperature inversion in that Pluto's upper atmosphere is about 50 degrees warmer (103K or -170 °C) than the surface (53K or -220 °C) while Pluto's lower atmosphere is 40 degrees warmer
Pluto's upper atmosphere consists mostly nitrogen, with traces of [methane]], and carbon monoxide derived from the ices on its surface.[1], while the lower atmosphere is methane rich.[2]
As Pluto moves away from the Sun, its atmosphere gradually freezes and falls to the ground. As it edges closer to the Sun, the temperature of Pluto's solid surface increases, causing the ices to sublimate into gas. This creates an anti-greenhouse effect; much like sweat cools the body as it evaporates from the surface of the skin, this sublimation has a cooling effect on the surface of Pluto. Scientists using the Submillimeter Array have recently discovered that Pluto's temperature is about 43 K (−230 °C), 10 K colder than expected.[3]
Pluto was found to have an atmosphere from an occultation observation in 1985; the finding was confirmed and significantly strengthened by extensive observations of another occultation in 1988. When an object with no atmosphere occults a star, the star abruptly disappears; in the case of Pluto, the star dimmed out gradually.[4] From the rate of dimming, the atmospheric pressure was determined to be 0.15 pascal, roughly 1/700 000 that of Earth.[5]
In 2002, another occultation of a star by Pluto was observed and analysed by teams led by Bruno Sicardy of the Paris Observatory,[6] James L. Elliot of MIT,[7] and Jay Pasachoff of Williams College.[8] The atmospheric pressure was estimated to be 0.3 pascal, even though Pluto was farther from the Sun than in 1988 and thus should have been colder and had a more rarefied atmosphere. One explanation for the discrepancy is that in 1987 the south pole of Pluto came out of shadow for the first time in 120 years, causing extra nitrogen to sublimate from the polar cap. It will take decades for the excess nitrogen to condense out of the atmosphere.[9] Another stellar occultation was observed by the MIT-Williams College team of James Elliot, Jay Pasachoff, and a Southwest Research Institute team led by Leslie Young on June 12, 2006 from sites in Australia.[10]
In October 2006, Dale Cruikshank of NASA/Ames Research Center (a New Horizons co-investigator) and his colleagues announced the spectroscopic discovery of ethane on Pluto's surface. This ethane is produced from the photolysis or radiolysis (i.e., the chemical conversion driven by sunlight and charged particles) of frozen methane on Pluto's surface and suspended in its atmosphere.[11]
See also
Notes
- ^ Ken Croswell (1992). "Nitrogen in Pluto's Atmosphere". Retrieved 2007-04-27.
- ^ E. Lellouch et al. 2009, A&A, in press, Pluto's lower atmosphere structure and methane abundance from high-resolution spectroscopy and stellar occultations. E. Lellouch, B. Sicardy, and C. de Bergh
- ^ T. Ker (2006). "Astronomers: Pluto colder than expected". Space.com (via CNN.com). Retrieved 2006-03-05.
- ^ "IAUC 4097". 1985. Retrieved 2007-03-26.
- ^ R. Johnston (2006). "The atmospheres of Pluto and other trans-Neptunian objects". Retrieved 2007-03-26.
- ^ B. Sicardy (2003-07-10). "Large changes in Pluto's atmosphere as revealed by recent stellar occultations" ([dead link] – Scholar search). Nature. 424. Nature: 168. doi:10.1038/nature01766. Retrieved 2006-03-05.
{{cite journal}}: External link in|format=|coauthors=ignored (|author=suggested) (help) - ^ "Pluto is undergoing global warming, researchers find". Massachusetts Institute of Technology. 2002-10-09. Retrieved 2007-03-20.
- ^ "Williams Scientists Contribute to New Finding About Pluto". Williams College. 2003-07-09. Retrieved 2007-03-20.
- ^ R. R. Britt (2003). "Puzzling Seasons and Signs of Wind Found on Pluto". Space.com. Retrieved 2007-03-26.
- ^ J. L. Elliot, M. J. Person, A. A. S. Gulbis, E. R. Adams, E. A. Kramer, C. A. Zuluaga, R. E. Pike, J. M. Pasachoff, S. P. Souza, B. A. Babcock, J. W. Gangestad, A. E. Jaskot, P. J. Francis, R. Lucas, A. S. Bosh (2006). "The Size of Pluto's Atmosphere As Revealed by the 2006 June 12 Occultation". American Astronomical Society. Retrieved 2007-04-12.
{{cite web}}: More than one of|work=and|journal=specified (help)CS1 maint: multiple names: authors list (link) - ^ A. Stern (November 1, 2006). "Making Old Horizons New". The PI's Perspective. Johns Hopkins University Applied Physics Laboratory. Retrieved 2007-02-12.