木星 北極の動画　


ALPO-Japan
Jupiter north pole anyme Image 2000/12/09(UT)

The Cassini-Huygens

Cassini

The Cassini-Huygens mission
Japanese
j001209cass2.gif742kB gif anyme 木星北極　全周円形
j001209cass2.mov7343kB QT anyme 木星北極　全周円形　上と同じ
j001209cass0.gif5938kB gif anyme 木星北極　全周楕円
j001209cass0.avi10558kB avi anyme 木星北極　全周楕円　上と同じ
j001209cass.gif3459kB gif anyme 木星北極　部分
j001209cass.avi9394kB avi anyme 木星北極　部分 上と同じ
カッシニ探査機が木星北極を2000/10/01〜2000/12/09の間撮影し北極の様子を動画にしたものです。
ファイル画たいへん大きいのでご注意ください。

English
j001209cass0.gif5938kB gif anyme north pole　whole surrounding areas gif
j001209cass0.avi10558kB avi anyme north pole　whole surrounding areas avi
j001209cass.gif3459kB gif anyme north pole　Part expansion gif
j001209cass.avi9394kB avi anyme north pole　Part expansion avi

Persistent polar storms and zonal winds on Jupiter can be seen in thismagnified quadrant from a movie projecting images from NASA's Cassinispacecraft as if the viewer were looking down at Jupiter's north pole andthe planet were flattened.
The sequence covers 70 days, from October 1 to December 9, 2000. Cassini's narrow-angle camera captured the images of Jupiter's atmospherein the near-infrared region of the spectrum.

Like the accompanying full-circle movie of polar winds, this zoomed-inversion shows that the polar region has coherent flows, despite itschaotic, mottled appearance. There are thousands of spots, each an activestorm similar in size to the largest storms on Earth. The spotsoccasionally change latitude or merge with each other, but usually theylast for the entire 70 days. Until now, the lifetime of those storms wasunknown.

The mystery of Jupiter's weather is why the storms last so long. Storms onEarth last for a week before they break up and are replaced by otherstorms. This movie heightens the mystery because it shows long-livedstorms at the highest latitudes, where the weather patterns are moredisorganized than at low latitudes.

Cassini collected images of Jupiter for months before and after it passedthe planet on December 30, 2000. Six images or more of the planet in eachof several spectral filters were taken at evenly spaced intervals over thecourse of Jupiter's 10-hour rotation period. The entire sequence wasrepeated generally every other Jupiter rotation, yielding views of everysector of the planet at least once every 20 hours.

The images used for the movie shown here were taken every 20 hours througha filter centered at a wavelength of 756 nanometers, where there arealmost no absorptions in the planet's atmosphere. Images from eachrotation were assembled first into a cylindrical map. The 84 resultingcylindrical maps, spanning 70 Earth days or 168 Jupiter rotations, weretransformed to polar stereographic projections, making a map centered onthe north pole. This clip shows detail by zooming in on one quadrant ofthe full-circle polar projection. Jupiter's alternating eastward andwestward jet streams flow in concentric rings around the pole.

For more information, see the Cassini Project home page,http://www.jpl.nasa.gov/cassini/ and the Cassini Imaging Team home page, http://ciclops.lpl.arizona.edu/ciclops/ .

Cassini is a cooperative project of NASA, the European Space Agency andthe Italian Space Agency. The Jet Propulsion Laboratory, a division of theCalifornia Institute of Technology in Pasadena, manages the Cassinimission for NASA's Office of Space Science, Washington, D.C.


Image Note:
Image Credit: NASA/JPL/Southwest Research Institute



Bands of eastward and westward winds on Jupiter appear as concentricrotating circles in this movie composed of Cassini spacecraft images thathave been re-projected as if the viewer were looking down at Jupiter'snorth pole and the planet were flattened.
The sequence covers 70 days, from October 1 to December 9, 2000. Cassini'snarrow-angle camera captured the images of Jupiter's atmosphere in thenear-infrared region of the spectrum.

What is surprising in this view is the coherent nature of the high-latitudeflows, despite the very chaotic, mottled and non-banded appearance of theplanet's polar regions. This is the first extended movie sequence to showthe coherence and longevity of winds near the pole and the features blownaround the planet by them.

There are thousands of spots, each an active storm similar to the size tothe largest of storms on Earth. Large terrestrial storms usually lastonly a week before they dissolve and are replaced by other storms. Butmany of the Jovian storms seen here, while occasionally changing latituteor merging with each other, persist for the entire 70 days. Until now, thelifetime of the high-latitude features was unknown. Their longevity is amystery of Jovian weather.

Cassini collected images of Jupiter for months before and after it passedthe planet on December 30, 2000. Six or more images of the planet in eachof several spectral filters were taken at evenly spaced intervals over thecourse of Jupiter's 10-hour rotation period. The entire sequence wasrepeated generally every other Jupiter rotation, yielding views of everysector of the planet at least once every 20 hours.

The images used for the movie shown here were taken every 20 hours througha filter centered at a wavelength of 756 nanometers, where there are almostno absorptions in the planet's atmosphere. The images covering eachrotation were mosaicked together to form a cylindrical map extending from75 degrees north to 75 degrees south in latitude and covering 360 degreesin longitude. The movie consists of 84 such maps, spanning 70 Earth daysin time or 168 Jupiter rotations.

Transforming the cylindrical maps into polar stereographic projectionsproduces a movie of what Jupiter would look like if viewed from the pole.Jupiter's alternating eastward and westward jet streams flow in concentricrings around the pole, with equatorial motions visible in the corners. The dark features flowing counterclockwise near the equator are"hot spots" where cloud cover is relatively thin.

The high-latitude movements call into question one notion concerning windcirculation on Jupiter. The model in question suggests that Jupiter'salternating bands of east-west winds are the exposed edges of deeperrotating cylinders that extend north-south through the planet. However,the east-west winds that the movie shows in polar regions don't fit thatmodel. The cylinders whose edges would form those bands would have to gothrough the innermost portion of the planet, where the cylinders' differentrotations could not be maintained. Jupiter's wind pattern may involve amix of rotation-on-cylinders near the equator and some other circulationmechanism near the poles.

For more information, see the Cassini Project home page,http://www.jpl.nasa.gov/cassini/ and the Cassini Imaging Team home page, http://ciclops.lpl.arizona.edu/ciclops/ .

Cassini is a cooperative project of NASA, the European Space Agency andthe Italian Space Agency. The Jet Propulsion Laboratory, a division of theCalifornia Institute of Technology in Pasadena, manages the Cassinimission for NASA's Office of Space Science, Washington, D.C.


Image Note:
Image Credit: NASA/JPL/Southwest Research Institute

[NASA/JPL/Space Science Institute]
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