Saturns heksagon
Saturns heksagon er et vedvarende heksagonalt mønster i skyene på Saturns nordpol. Heksagonen roterer rundt om den nordlige polarhvirvel ved ca. 78 grader nordlig bredde (78°N). Den blev opdaget af Voyager 1 i 1980 og bekræftet af Cassini i 2006.[1][2][3]
Hver af siderne af det sekskantede skymønster er ca. 13.800 km lang, hvilket gør dem længere end diameteren af Jorden.[4] Hele strukturen roterer med en periode på 10t 39m og 24s, samme periode som Saturns radiostråling fra dens indre.[5] Men formationerne skifter ikke længdekreds som de andre skyer i den synlige atmosfære.[6]
Saturns sydpol har ikke en sekskant, ifølge Hubble-teleskopets observationer,[kilde mangler] men den har også en hvirvel, og der er også en hvirvel inde i den nordlige heksagon.[kilde mangler]
Billedgalleri
Sekskanten fotograferet 27. november 2012
Nærbillede af den nordlige polarhvirvel 27. november 2012
Saturns heksagon ved den nordlige pol (billedet er filtreret).
Animation af heksagonen (infrarød).
Kildehenvisninger
Litteratur
- Godfrey, D.A. (1988): A hexagonal feature around Saturn's North Pole (engelsk) – Icarus, bind 76, nr. 2. Bibcode: 1988Icar...76..335G
- Godfrey, D.A. (9. marts 1990): The Rotation Period of Saturn's Polar Hexagon (engelsk) – Science, bind 247, nr. 4947. Bibcode: 1990Sci...247.1206G
- Sanchez-Lavega, A.; Lecacheux, J.; Colas, F.; Laques, P. (1993): Ground-based observations of Saturn's north polar SPOT and hexagon (engelsk) – Science, bind 260, nr. 5106. Bibcode: 1993Sci...260..329S
- Baines, Kevin H.; Momary , Thomas W.; Fletcher, Leigh N.; Showman, Adam P.; Roos-Serote, Maarten; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D. (2009): Saturn's north polar cyclone and hexagon at depth revealed by Cassini/VIMS (engelsk) – Planetary and Space Science, bind 57, nr. 14–15. Bibcode: 2009P&SS...57.1671B
Referencer
- ^ Godfrey, D.A. (1988). "A hexagonal feature around Saturn's north pole". Icarus. 76 (2): 335-56. Bibcode:1988Icar...76..335G. doi:10.1016/0019-1035(88)90075-9.
- ^ Sanchez-Lavega, A.; Lecacheux, J.; Colas, F.; Laques, P. (1993). "Ground-Based Observations of Saturn's North Polar Spot and Hexagon". Science. 260 (5106): 329-32. Bibcode:1993Sci...260..329S. doi:10.1126/science.260.5106.329. PMID 17838249.
- ^ Overbye, Dennis (6. august 2014). "Storm Chasing on Saturn". New York Times. Hentet 6. august 2014.
- ^ New images show Saturn's weird hexagon cloud MSNBC, 12. december 2009
- ^ Godfrey (1990), s. 1206–1208
- ^ Baines (2009), s. 1671–1681
Eksterne henvisninger
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Planet Saturn - Vortex and Rings
http://www.nasa.gov/jpl/cassini/pia18274
The Cassini spacecraft captures three magnificent sights at once: Saturn's north polar vortex and hexagon along with its expansive rings.
The hexagon, which is wider than two Earths, owes its appearance to the jet stream that forms its perimeter. The jet stream forms a six-lobed, stationary wave which wraps around the north polar regions at a latitude of roughly 77 degrees North.
This view looks toward the sunlit side of the rings from about 37 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on April 2, 2014 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers.
The view was obtained at a distance of approximately 1.4 million miles (2.2 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 43 degrees. Image scale is 81 miles (131 kilometers) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
For more information about the Cassini-Huygens mission visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .
The spinning vortex of Saturn's north polar storm resembles a deep red rose of giant proportions surrounded by green foliage in this false-color image from NASA's Cassini spacecraft. Measurements have sized the eye at 1,250 miles (2,000 kilometers) across with cloud speeds as fast as 330 miles per hour (150 meters per second).
This image is among the first sunlit views of Saturn's north pole captured by Cassini's imaging cameras. When the spacecraft arrived in the Saturnian system in 2004, it was northern winter and the north pole was in darkness. Saturn's north pole was last imaged under sunlight by NASA's Voyager 2 in 1981; however, the observation geometry did not allow for detailed views of the poles. Consequently, it is not known how long this newly discovered north-polar hurricane has been active.
The images were taken with the Cassini spacecraft narrow-angle camera on Nov. 27, 2012, using a combination of spectral filters sensitive to wavelengths of near-infrared light. The images filtered at 890 nanometers are projected as blue. The images filtered at 728 nanometers are projected as green, and images filtered at 752 nanometers are projected as red. In this scheme, red indicates low clouds and green indicates high ones.
The view was acquired at a distance of approximately 261,000 miles (419,000 kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 94 degrees. Image scale is 1 mile (2 kilometers) per pixel.
This raw, unprocessed image of Saturn was taken on November 27, 2012 and received on Earth November 27, 2012. The camera was pointing toward Saturn at approximately 400048 kilometers away, and the image was taken using the P0 and CB2 filters. The image has not been validated or calibrated. A validated/calibrated image will be archived with the Planetary Data System in 2013.
The Cassini Solstice Mission is a joint United States and European endeavor. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.
The original NASA image has been altered by cropping slightly, removal of artifacts and brightening.
Satellite picture of the "hexagon on Saturn" - it is a hexagon twice as wide as Earth around Saturn's north pole. First observed by the Voyager 1 probe in the 1980s, the hexagon has been sighted still by the Cassini probe
This raw, unprocessed image of Saturn was taken on November 27, 2012 and received on Earth November 27, 2012. The camera was pointing toward Saturn at approximately 376171 kilometers away, and the image was taken using the CB2 and IRP0 filters. The image has not been validated or calibrated. A validated/calibrated image will be archived with the Planetary Data System in 2013.
The Cassini Solstice Mission is a joint United States and European endeavor. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.
The original NASA image has been altered by cropping slightly and removal of artifacts.