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Propeller Belt
| Description |
Propeller Belt |
| Full Description |
+ View Image with Labels The Cassini spacecraft captures eight new propeller-like features within Saturn's A ring in what may be the propeller "hot zone" of Saturn's rings. Propeller features form around small moonlets that are not massive enough to clear out ring material, but are still able to pull smaller ring particles into a shape reminiscent of an airplane propeller. Scientists believe that propellers represent moonlet wakes, which are denser than the surrounding ring material and appear bright in the images. Propellers were first discovered in Cassini images taken during Saturn orbit insertion in 2004. This new image is from a more extensive study of the full A ring and provides evidence that these features are not distributed evenly as previously thought, but are instead grouped in a 3,000 kilometer-wide (1,860 mile) propeller belt. This image shows four new propellers and was put together from images in the Planetary Data System, a web site which archives and distributes scientific data from NASA planetary missions. The largest propeller seen here is noted in the white dashed box, and it indicates the presence of a 150-meter (490-foot) moonlet. The size is inferred from the radial separation of the propeller wings. The propeller is seen in another image and is shown in the upper left box. The reappearance of the propellers clearly demonstrates the orbital motion of the propellers. The region enclosed in the red box is zoomed and shown in the top panel of Propeller Close Up. Three additional propellers are noted with white dashed circles on the right. Very bright and round spots are artifacts. But some of the bright elongated and non-saturated streaks could be smaller propellers that are not resolved in the image. This view is made up of two images from a set of 26 images with a complete radial coverage of the A ring and part of the Cassini division taken during an occultation of the star Antares (alpha Scorpii, brightest spot on top) on Aug. 20, 2005. In this clear filter image, the Cassini spacecraft narrow-angle camera observed the unlit side of the rings, with a phase angle of 126 degrees. The images were taken at 1 minute intervals with 0.05 seconds exposure time. Image resolution is 1 kilometer (0.6 miles) 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 was designed, developed and assembled at JPL. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . *Credit:* NASA/JPL/Space Science Institute/University of Colorado |
| Date |
October 24, 2007 |
|
Propeller Belt
| Description |
Propeller Belt |
| Full Description |
+ View Image without Labels The Cassini spacecraft captures eight new propeller-like features within Saturn's A ring in what may be the propeller "hot zone" of Saturn's rings. Propeller features form around small moonlets that are not massive enough to clear out ring material, but are still able to pull smaller ring particles into a shape reminiscent of an airplane propeller. Scientists believe that propellers represent moonlet wakes, which are denser than the surrounding ring material and appear bright in the images. Propellers were first discovered in Cassini images taken during Saturn orbit insertion in 2004. This new image is from a more extensive study of the full A ring and provides evidence that these features are not distributed evenly as previously thought, but are instead grouped in a 3,000 kilometer-wide (1,860 mile) propeller belt. This image shows four new propellers and was put together from images in the Planetary Data System, a web site which archives and distributes scientific data from NASA planetary missions. The largest propeller seen here is noted in the white dashed box, and it indicates the presence of a 150-meter (490-foot) moonlet. The size is inferred from the radial separation of the propeller wings. The propeller is seen in another image and is shown in the upper left box. The reappearance of the propellers clearly demonstrates the orbital motion of the propellers. The region enclosed in the red box is zoomed and shown in the top panel of Propeller Close Up. Three additional propellers are noted with white dashed circles on the right. Very bright and round spots are artifacts. But some of the bright elongated and non-saturated streaks could be smaller propellers that are not resolved in the image. This view is made up of two images from a set of 26 images with a complete radial coverage of the A ring and part of the Cassini division taken during an occultation of the star Antares (alpha Scorpii, brightest spot on top) on Aug. 20, 2005. In this clear filter image, the Cassini spacecraft narrow-angle camera observed the unlit side of the rings, with a phase angle of 126 degrees. The images were taken at 1 minute intervals with 0.05 seconds exposure time. Image resolution is 1 kilometer (0.6 miles) 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 was designed, developed and assembled at JPL. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . *Credit:* NASA/JPL/Space Science Institute/University of Colorado |
| Date |
October 24, 2007 |
|
Antares and Rho Ophiuchi
| Title |
Antares and Rho Ophiuchi |
| Explanation |
Why is the sky near Antares and Rho Ophiuchi [ http://www.seds.org/billa/twn/antx.html ] so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap990829.html ]. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap000111.html ]. Backlit dust [ http://antwrp.gsfc.nasa.gov/apod/ap990509.html ] clouds block starlight and so appear dark [ http://antwrp.gsfc.nasa.gov/apod/ap990511.html ]. Antares [ http://antwrp.gsfc.nasa.gov/apod/ap980726.html ], a red supergiant [ http://www.lcse.umn.edu/research/RedGiant/ ] and one of the brighter stars in the night sky [ http://www.astro.wisc.edu/~dolan/constellations/extra/brightest.html ], lights up the yellow-red clouds on the upper left. Rho Ophiuchi [ http://antwrp.gsfc.nasa.gov/apod/ap960312.html ] lies at the center of the blue nebula on the right. The distant globular cluster [ http://antwrp.gsfc.nasa.gov/apod/globular_clusters.html ] M4 is visible just below Antares [ http://www.astro.wisc.edu/~dolan/constellations/hr/6134.html ], and to the left of the red cloud engulfing Sigma Scorpii [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992A%26A...261..203P ]. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ]. |
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IC 4603: Reflection Nebula i
…
| Title |
IC 4603: Reflection Nebula in Ophiuchius |
| Explanation |
Why does this starfield photograph resemble an impressionistic painting [ http://www.ibiblio.org/wm/paint/glo/impressionism/ ]? The effect is created not by digital trickery [ http://antwrp.gsfc.nasa.gov/apod/ap030324.html ] but by large amounts of interstellar dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ]. Dust, minute globs rich in carbon [ http://www.nyu.edu/pages/mathmol/modules/carbon/carbon1.html ] and similar in size [ http://www.lakeair.com/particle.html ] to cigarette smoke [ http://amos.indiana.edu/library/scripts/smoke.html ], frequently starts in the outer atmospheres of large, cool, young stars. The dust [ http://nedwww.ipac.caltech.edu/level5/March02/Li/Li_contents.html ] is dispersed as the star dies and grows as things stick to it in the interstellar medium [ http://www-ssg.sr.unh.edu/ism/intro.html ]. Dense dust clouds are opaque [ http://antwrp.gsfc.nasa.gov/apod/ap030202.html ] to visible light [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ] and can completely hide background stars. For less dense clouds, the capacity of dust to preferentially reflect blue [ http://www.why-is-the-sky-blue.org/why-is-the-sky-blue.html ] starlight becomes important, effectively blooming the stars blue light out and marking the surrounding dust. Nebular gas emissions, typically brightest in red light [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ], can combine to form areas seemingly created on an artist's canvas. Photographed above [ http://ryutao.main.jp/english/stl_ant.html ] is roughly four square degrees of the nebula IC 4603 [ http://antwrp.gsfc.nasa.gov/apod/ap060714.html ] near the bright star Antares [ http://en.wikipedia.org/wiki/Antares ] toward the constellation [ http://en.wikipedia.org/wiki/Constellation ] of Ophiuchus [ http://www.seds.org/Maps/Stars_en/Fig/ophiuchus.html ]. |
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The Colorful Clouds of Rho O
…
| Title |
The Colorful Clouds of Rho Ophiuchi |
| Explanation |
The many spectacular colors of the Rho Ophiuchi [ http://www.seds.org/billa/twn/antx.html ] (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star Rho Ophiuchi [ http://coolcosmos.ipac.caltech.edu/image_galleries/legacy/iras_rhooph_gc/captio n.html ] and nearby stars reflects [ http://antwrp.gsfc.nasa.gov/apod/reflection_nebulae.html ] more efficiently off this portion of the nebula than red light. The Earth's daytime sky appears blue [ http://www.why-is-the-sky-blue.org/why-is-the-sky-blue.html ] for the same reason. The red and yellow regions shine primarily because of emission [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ] from the nebula's atomic and molecular gas. Light from nearby blue stars - more energetic than the bright star Antares [ http://www.astro.uiuc.edu/~kaler/sow/antares.html ] - knocks electrons [ http://www-istp.gsfc.nasa.gov/Education/welect.html ] away from the gas, which then shines when the electrons recombine with the gas. The dark regions [ http://antwrp.gsfc.nasa.gov/apod/ap030202.html ] are caused by dust grains [ http://nedwww.ipac.caltech.edu/level5/Mathis/Mathis1.html ] - born in young stellar atmospheres - which effectively block light emitted behind them. The Rho Ophiuchi star clouds [ http://antwrp.gsfc.nasa.gov/apod/ap000521.html ], well in front of the globular cluster [ http://www.seds.org/messier/glob.html ] M4 [ http://antwrp.gsfc.nasa.gov/apod/ap000523.html ] visible above [ http://www.noao.edu/outreach/aop/observers/antares.html ] on far lower left, are even more colorful than humans can see [ http://www.colormatters.com/optics.html ] - the clouds emits light in every wavelength band [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ] from the radio [ http://imagers.gsfc.nasa.gov/ems/radio.html ] to the gamma-ray [ http://imagers.gsfc.nasa.gov/ems/gamma.html ]. |
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IC 4603: Reflection Nebula i
…
| Title |
IC 4603: Reflection Nebula in Ophiuchius |
| Explanation |
Why does this starfield photograph resemble an impressionistic painting [ http://www.ibiblio.org/wm/paint/glo/impressionism/ ]? The effect is created not by digital trickery [ http://antwrp.gsfc.nasa.gov/apod/ap030324.html ] but by large amounts of interstellar dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ]. Dust, minute globs rich in carbon [ http://www.nyu.edu/pages/mathmol/modules/carbon/carbon1.html ] and similar in size [ http://www.lakeair.com/particle.html ] to cigarette smoke [ http://amos.indiana.edu/library/scripts/smoke.html ], frequently starts in the outer atmospheres of large, cool, young stars. The dust [ http://nedwww.ipac.caltech.edu/level5/March02/Li/Li_contents.html ] is dispersed as the star dies and grows as things stick to it in the interstellar medium [ http://www-ssg.sr.unh.edu/tof/Outreach/Interstellar/index.html?what1.html ]. Dense dust clouds are opaque [ http://antwrp.gsfc.nasa.gov/apod/ap030202.html ] to visible light [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ] and can completely hide background stars. For less dense clouds, the capacity of dust to preferentially reflect blue [ http://www.why-is-the-sky-blue.org/why-is-the-sky-blue.html ] starlight becomes important, effectively blooming the stars blue light out and marking the surrounding dust. Nebular gas emissions, typically brightest in red light [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ], can combine to form areas seemingly created on an artist's canvas. Photographed above [ http://home.earthlink.net/~gstevens916/pic4603.htm ] is roughly one square degree of the nebula IC 4603 [ http://www.psiaz.com/Schur/astro/filmimagepages/rho.html ] near the bright star Antares [ http://antwrp.gsfc.nasa.gov/apod/ap980726.html ] toward the constellation [ http://www.adlerplanetarium.org/history/exhibits/constellations/timeline.html ] of Ophiuchus [ http://www.seds.org/Maps/Stars_en/Fig/ophiuchus.html ]. |
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Antares and Rho Ophiuchi
| Title |
Antares and Rho Ophiuchi |
| Explanation |
Why is the sky near Antares and Rho Ophiuchi [ http://www.seds.org/billa/twn/antx.html ] so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap960903.html ]. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap960606.html ]. Backlit dust [ http://antwrp.gsfc.nasa.gov/apod/ap961119.html ] clouds block starlight and so appear dark [ http://antwrp.gsfc.nasa.gov/apod/ap961005.html ]. Antares [ http://antwrp.gsfc.nasa.gov/apod/ap970624.html ], a red supergiant [ http://antwrp.gsfc.nasa.gov/apod/ap970922.html http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1992AJ%2E%2E%2E%2E104%2E%2E821M&db_key=AST&nosetcookie=1 ] and one of the brighter stars in the night sky [ http://www.astro.wisc.edu/~dolan/constellations/extra/brightest.html ], lights up the yellow-red clouds on the upper left. Rho Ophiuchi [ http://antwrp.gsfc.nasa.gov/apod/ap960312.html ] lies at the center of the blue nebula on the right. The distant globular cluster [ http://antwrp.gsfc.nasa.gov/apod/ap970916.html ] M4 is visible just below Antares [ http://www.astro.wisc.edu/~dolan/constellations/hr/6134.html ], and to the left of the red cloud engulfing Sigma Scorpii [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1992A%26A%2E%2E%2E261%2E%2E203P&db_key=AST&nosetcookie=1 ]. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum [ http://heasarc.gsfc.nasa.gov/docs/learning_center/basic/emspectrum.html ]. |
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Antares and Rho Ophiuchi
| Title |
Antares and Rho Ophiuchi |
| Explanation |
Why is the sky near Antares and Rho Ophiuchi [ http://www.seds.org/billa/twn/antx.html ] so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap031229.html ]. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap000111.html ]. Backlit dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ] clouds block starlight and so appear dark [ http://antwrp.gsfc.nasa.gov/apod/ap030202.html ]. Antares [ http://antwrp.gsfc.nasa.gov/apod/ap980726.html ], a red supergiant [ http://hyperphysics.phy-astr.gsu.edu/hbase/astro/redsup.html ] and one of the brighter stars in the night sky [ http://www.astro.wisc.edu/~dolan/constellations/extra/brightest.html ], lights up the yellow-red clouds on the upper left. Rho Ophiuchi [ http://www.iso.vilspa.esa.es/galleries/ism/rhooph.html ] lies at the center of the blue nebula on the right. The distant globular cluster [ http://antwrp.gsfc.nasa.gov/apod/globular_clusters.html ] M4 [ http://antwrp.gsfc.nasa.gov/apod/ap000523.html ] is visible just below Antares [ http://www.astro.wisc.edu/~dolan/constellations/hr/6134.html ], and to the left of the red cloud engulfing Sigma Scorpii [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992A%26A...261..203P ]. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ]. |
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The Colorful Clouds of Rho O
…
| Title |
The Colorful Clouds of Rho Ophiuchi |
| Explanation |
The many spectacular colors of the Rho Ophiuchi [ http://www.seds.org/billa/twn/antx.html ] (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star Rho Ophiuchi [ http://coolcosmos.ipac.caltech.edu/image_galleries/legacy/iras_rhooph_gc/caption.html ] and nearby stars reflects [ http://antwrp.gsfc.nasa.gov/apod/reflection_nebulae.html ] more efficiently off this portion of the nebula than red light. The Earth's daytime sky appears blue [ http://www.why-is-the-sky-blue.org/why-is-the-sky-blue.html ] for the same reason. The red and yellow regions shine primarily because of emission [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ] from the nebula's atomic and molecular gas. Light from nearby blue stars - more energetic than the bright star Antares [ http://www.astro.uiuc.edu/~kaler/sow/antares.html ] - knocks electrons [ http://www-istp.gsfc.nasa.gov/Education/welect.html ] away from the gas, which then shines when the electrons recombine with the gas. The dark regions [ http://antwrp.gsfc.nasa.gov/apod/ap030202.html ] are caused by dust grains [ http://nedwww.ipac.caltech.edu/level5/Mathis/Mathis1.html ] - born in young stellar atmospheres - which effectively block light emitted behind them. The Rho Ophiuchi star clouds [ http://antwrp.gsfc.nasa.gov/apod/ap000521.html ], well in front of the globular cluster [ http://www.seds.org/messier/glob.html ] M4 [ http://antwrp.gsfc.nasa.gov/apod/ap000523.html ] visible above [ http://www.noao.edu/outreach/aop/observers/antares.html ] on far lower left, are even more colorful than humans can see [ http://www.colormatters.com/optics.html ] - the clouds emits light in every wavelength band [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ] from the radio [ http://imagers.gsfc.nasa.gov/ems/radio.html ] to the gamma-ray [ http://imagers.gsfc.nasa.gov/ems/gamma.html ]. |
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East of Antares
| Title |
East of Antares |
| Explanation |
East of Antares [ http://antwrp.gsfc.nasa.gov/apod/ap020526.html ], dark markings seem to sprawl through the crowded star fields toward the center of our Milky Way Galaxy. Cataloged in [ http://adsabs.harvard.edu/cgi-bin/ bib_query?1919ApJ....49....1B ] the early 20th century by astronomer E. E. Barnard [ http://astro.uchicago.edu/yerkes/virtualmuseum/ Barnardfull.html ], the obscuring interstellar dust clouds include [ http://www.saguaroastro.org/content/ Best-of-Barnards-Dark-Nebulae.htm ] B72 [ http://antwrp.gsfc.nasa.gov/apod/ap050521.html ], B77, B78, and B59, seen in silhouette [ http://antwrp.gsfc.nasa.gov/apod/ap001229.html ] against the starry background. Here, their combined shape suggests smoke rising from a pipe, and so the dark nebula's popular name is the Pipe Nebula. This gorgeous and expansive view [ http://panther-observatory.com/gallery/deepsky/doc/ Pipe_200mm.htm ] was recorded in very dark skies over Hakos, Namibia [ http://www.fallingrain.com/world/WA/40/Hakos.html ]. It covers a full 10 by 7 degree field in the pronounceable [ http://www.astronomyclub.org/learn/Say_What.htm ] constellation Ophiuchus. |
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