|
|
Calderas And Cliffs Near Io'
…
| Title |
Calderas And Cliffs Near Io's South Pole |
| Explanation |
Braving intense radiation [ http://www-spof.gsfc.nasa.gov/Education/Iradbelt.html ] belts [ http://www-spof.gsfc.nasa.gov/Education/wotherms.html ], the Galileo spacecraft once again [ http://galileo.jpl.nasa.gov/news/status/ status000222.html ] flew past the surface of Jupiter's moon Io [ http://sse.jpl.nasa.gov/features/planets/ jupiter/io.html ] (sounds like EYE-oh [ http://spaceplace.jpl.nasa.gov/gll_io_fact.htm ]) on February 22. Combining high resolution black and white images from that flyby with color data recorded last summer has resulted in this dramatic view [ http://photojournal.jpl.nasa.gov/ cgi-bin/PIAGenCatalogPage.pl?PIA02534 ] of a region near the volcanic moon's south pole. An active and alien landscape, the bright white areas are likely due to sulfur dioxide frost and seem to be concentrated near ridges and cliffs. The three ominous black spots, each about 6-12 miles across, are volcanic craters or calderas [ http://volcano.und.nodak.edu/vwdocs/vwlessons/lessons/ Hot_Spot/Hot_Spot10.html ] covered with recent dark lava. A sinuous channel connects the lower left caldera with a yellowish lava flow. Io is small, but its continuous [ http://www-a.jpl.nasa.gov/galileo/ganymede/ 122096.html ] activity is driven by the drastic tides [ http://co-ops.nos.noaa.gov/restles1.html ] induced by Jupiter [ http://sse.jpl.nasa.gov/features/planets/ jupiter/jupiter.html ] and the other Jovian moons. It is estimated that the resulting volcanism [ http://volcano.und.edu/vwdocs/planet_volcano/Io/ Overview.html ] completely resurfaces Io [ http://antwrp.gsfc.nasa.gov/apod/ap970321.html ] every million years. |
|
Jupiter's Moons Thebe, Amalt
…
| Title |
Jupiter's Moons Thebe, Amalthea, and Metis |
| Explanation |
The robot spacecraft Galileo [ http://eis.jpl.nasa.gov/~skientz/galileo/ ] in orbit around Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] has recently photographed the inner moons of Jupiter in greater detail than ever before. These pictures [ http://www2.jpl.nasa.gov/files/images/captions/pia02531.txt ] of Thebe [ http://www.solarviews.com/eng/thebe.htm ], Amalthea [ http://www.solarviews.com/eng/amalthea.htm ], and Metis [ http://www.solarviews.com/eng/metis.htm ] are shown to scale, and reveal details as small as three kilometers across. Amalthea [ http://www.seds.org/nineplanets/nineplanets/amalthea.html#amalthea ], by contrast, has a total length of about 200 kilometers. The moons [ http://antwrp.gsfc.nasa.gov/apod/ap971127.html ] are composed mostly of ice, are much smaller than Jupiter's more famous Galilean satellites [ http://www.jpl.nasa.gov/galileo/moons/moons.html ] (Io [ http://www.seds.org/nineplanets/nineplanets/io.html ], Europa [ http://www.seds.org/nineplanets/nineplanets/europa.html ], Ganymede [ http://www.seds.org/nineplanets/nineplanets/ganymede.html ], and Callisto [ http://www.seds.org/nineplanets/nineplanets/callisto.html ]), and orbit between Io and Jupiter's rings [ http://antwrp.gsfc.nasa.gov/apod/ap980916.html ]. Thebe appears dominated by a huge impact crater [ http://gdcinfo.agg.emr.ca/toc.html?/crater/world_craters.html ] 40 kilometers across. Astronomers are uncertain of the origin of the unusual white gash at the bottom of Amalthea [ http://www.jpl.nasa.gov/galileo/amalthea/ ]. |
|
Io Rotating
| Title |
Io Rotating |
| Explanation |
The surface of Io is continually changing. Jupiter's moon [ http://antwrp.gsfc.nasa.gov/apod/ap990920.html ] is the home to many powerful volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap991126.html ] so active they are effectively turning the moon inside out. The above time-lapse sequence [ http://solarviews.com/cap/jup/vio1.htm ] is a composite of images taken during two space missions that approached the violent moon: Voyager [ http://vraptor.jpl.nasa.gov/voyager/voyager_fs.html ] and Galileo [ http://www.jpl.nasa.gov/galileo/mission.html ]. The sequence shows Io [ http://www.seds.org/nineplanets/nineplanets/io.html ] during a complete rotation, which corresponds to a complete revolution around Jupiter [ http://www.jpl.nasa.gov/galileo/Jovian.html ] since Io [ http://cass.jsc.nasa.gov/pub/research/outerp/io.html ] always keeps the same face toward the giant planet. The rampant volcanism is thought to be caused by Jupiter's more distant Galilean Moons [ http://solarviews.com/eng/galdisc.htm ] (Europa [ http://www.seds.org/nineplanets/nineplanets/europa.html ], Ganymede [ http://www.seds.org/nineplanets/nineplanets/ganymede.html ], and Callisto [ http://www.seds.org/nineplanets/nineplanets/callisto.html ]) pulling on Io and continually distorting its shape, causing internal frictional [ http://www.cord.edu/dept/physics/p128/lecture99_12.html ] heating. Io is composed mostly of rock, with the yellow color originating from sulfur [ http://chemlab.pc.maricopa.edu/periodic/S.html ]. The causes of many of the other colors remain a topic of research [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999Icar..140..265G ]. |
|
A Close-Up of Aurora on Jupi
…
| Title |
A Close-Up of Aurora on Jupiter |
| Explanation |
Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] has aurorae [ http://www.geo.mtu.edu/weather/aurora/ ]. Like Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990131.html ], the magnetic field [ http://liftoff.msfc.nasa.gov/academy/space/mag_field.html ] of the gas giant funnels charged particles released from the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap970411.html ] onto the poles. As these particles strike the atmosphere, electrons [ http://www-spof.gsfc.nasa.gov/Education/welect.html ] are temporarily knocked away from existing gas molecules [ http://www.chemistry.mcmaster.ca/faculty/bader/aim/ ]. Electric force [ http://www.colorado.edu/physics/2000/waves_particles/wavpart2.html ] attracts these electrons back. As the electrons [ http://www.aip.org/history/electron/ ] recombine to remake neutral molecules, auroral light [ http://antwrp.gsfc.nasa.gov/apod/ap980901.html ] is emitted. In the above recently released photograph [ http://oposite.stsci.edu/pubinfo/PR/2000/38/index.html ] by the Hubble Space Telescope [ http://www.stsci.edu/hst/ ] taken in ultraviolet light [ http://snoopy.gsfc.nasa.gov/~orfeus2/ultraviolet.html ], the aurorae [ http://antwrp.gsfc.nasa.gov/apod/ap000917.html ] appear as annular sheets around the pole. Unlike Earth's aurorae [ http://antwrp.gsfc.nasa.gov/apod/ap970402.html ], Jupiter's aurorae [ http://antwrp.gsfc.nasa.gov/apod/ap980123.html ] include several bright streaks and dots [ http://oposite.stsci.edu/pubinfo/PR/2000/38/faq.html ]. These marks are caused by magnetic flux tubes connecting Jupiter [ http://antwrp.gsfc.nasa.gov/apod/jupiter.html ] to its largest moons [ http://antwrp.gsfc.nasa.gov/apod/ap001118.html ]. Specifically, Io [ http://antwrp.gsfc.nasa.gov/apod/ap001024.html ] caused the bright streak on the far left, Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap000620.html ] caused the bright dot below center, and Europa [ http://www.seds.org/nineplanets/nineplanets/europa.html ] caused the dot to its right. |
|
Jupiter, Europa, and Callist
…
| Title |
Jupiter, Europa, and Callisto |
| Explanation |
As the robot Cassini spacecraft [ http://www.jpl.nasa.gov/cassini/english/spacecraft/ ] rounds Jupiter [ http://www.jpl.nasa.gov/galileo/jupiter/jupiter.html ] on its way toward Saturn [ http://www.seds.org/nineplanets/nineplanets/saturn.html ], it has taken a sequence of images [ http://ciclops.lpl.arizona.edu/ciclops/images_jupiter.html ] of the gas giant with its four largest moons [ http://antwrp.gsfc.nasa.gov/apod/ap001118.html ]. Previously released images have highlighted Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap001212.html ] and Io [ http://antwrp.gsfc.nasa.gov/apod/ap001226.html ]. Pictured above [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02861 ] are the two remaining Galilean satellites [ http://www.jpl.nasa.gov/galileo/ganymede/discovery.html ]: Europa [ http://www.hawastsoc.org/solar/eng/europa.htm ] and Callisto [ http://cass.jsc.nasa.gov/pub/research/outerp/call.html ]. Europa [ http://www.jpl.nasa.gov/galileo/moons/europa.html ] is the bright moon superposed near Jupiter's Great Red Spot [ http://antwrp.gsfc.nasa.gov/apod/ap001123.html ], while Callisto is the dark moon near the frame edge. Callisto [ http://www.jpl.nasa.gov/galileo/moons/callisto.html ] is so dark that it would be hard to see here if its brightness was not digitally enhanced. Recent evidence indicates [ http://www.jpl.nasa.gov/galileo/news/release/press001216.html ] that both moons hold salt-water seas under surface ice that might be home to extra-terrestrial life. By noting the times that moons disappeared and reappeared behind Jupiter in 1676, Ole Roemer [ http://es.rice.edu/ES/humsoc/Galileo/Catalog/Files/roemer.html ] was able to make the first accurate estimation of the speed of light [ http://www.stats.uwaterloo.ca/~rwoldfor/papers/sci-method/paperrev/node4.html ]. |
|
Jupiter, Io, and Shadow
| Title |
Jupiter, Io, and Shadow |
| Explanation |
Just as planets orbit our Sun, Jupiter's Moons [ http://antwrp.gsfc.nasa.gov/apod/ap001118.html ] orbit Jupiter. Pictured above [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02860 ] is the closest of Jupiter's Galilean Satellites [ http://www.jpl.nasa.gov/galileo/ganymede/discovery.html ], Io [ http://www.seds.org/nineplanets/nineplanets/io.html ], superposed in front of the giant planet it circles. To the left of Io [ http://www.hawastsoc.org/solar/eng/edu/moonio.htm ] is a dark spot that is its own shadow. The tremendous complexities that can be seen in Jupiter's banded, swirling atmosphere [ http://antwrp.gsfc.nasa.gov/apod/ap970310.html ] are being studied and may provide insight as to how Earth's atmosphere [ http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html ] behaves. The above true-color contrast-enhanced image [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02860 ] was taken [ http://ciclops.lpl.arizona.edu/ciclops/images_jupiter.html ] two weeks ago by the robot spacecraft Cassini [ http://quest.arc.nasa.gov/saturn/qa/cassini/ ], currently passing Jupiter [ http://antwrp.gsfc.nasa.gov/apod/jupiter.html ] and on its way to Saturn [ http://antwrp.gsfc.nasa.gov/apod/saturn.html ] in 2004. Engineers continue to study [ http://www.jpl.nasa.gov/jupiterflyby/news/mission_status.html ] the Cassini spacecraft [ http://www.jpl.nasa.gov/basics/cassini.htm ] itself to understand why it required more force than normal to turn one of its maneuvering wheels. |
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Europa Rotating
| Title |
Europa Rotating |
| Explanation |
Evidence has been mounting that beneath the vast planes of ice that cover Europa [ http://antwrp.gsfc.nasa.gov/apod/ap961120.html ] lies water -- liquid oceans that might be home to alien life [ http://www.sciam.com/0497issue/0497scicit7.html ]. The smallest of Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ]'s Galilean Moons [ http://solarviews.com/eng/galdisc.htm ] (which include Io [ http://www.seds.org/nineplanets/nineplanets/io.html ], Ganymede [ http://www.seds.org/nineplanets/nineplanets/ganymede.html ], and Callisto [ http://www.seds.org/nineplanets/nineplanets/callisto.html ]), Europa's deep interior is composed of mostly of silicate rock [ http://windows.arc.nasa.gov/cgi-bin/tour_def/glossary/silicate_rock.html ]. Upon close inspection, many surface cracks [ http://antwrp.gsfc.nasa.gov/apod/ap980310.html ] stop abruptly only to continue on somewhere else -- indicating surface plates that might be sliding [ http://antwrp.gsfc.nasa.gov/apod/ap970410.html ]. The above time-lapse sequence [ http://www.solarviews.com/cap/jup/veuropa1.htm ] is a composite of images taken during the Voyager spacecraft [ http://vraptor.jpl.nasa.gov/voyager/voyager_fs.html ] flyby of the moon twenty years ago. Not all regions are resolved in high detail. The movie shows Europa [ http://www.seds.org/nineplanets/nineplanets/europa.html ] during a complete rotation, which corresponds to a complete revolution around Jupiter [ http://www.jpl.nasa.gov/galileo/Jovian.html ] since Europa [ http://cass.jsc.nasa.gov/pub/research/outerp/euro.html ] always keeps the same face toward the giant planet. The cause of many of the surface colors on Europa [ http://www.solarviews.com/eng/europa.htm ] also remains a topic of research [ http://antwrp.gsfc.nasa.gov/apod/ap010116.html http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1988Icar...75..437B ]. |
|
Jupiter Moon Movie
| Title |
Jupiter Moon Movie |
| Explanation |
South is toward the top in this frame from a stunning movie featuring Jupiter and moons recorded last Thursday from the Central Coast of New South Wales, Australia. In fact, three jovian moons [ http://antwrp.gsfc.nasa.gov/apod/ap001118.html ] and two red spots are ultimately seen in the full video as they glide around [ http://skytonight.com/observing/objects/javascript/ 3307071.html ] the solar system's ruling gas giant. In the early frame above, Ganymede [ http://www.nineplanets.org/ganymede.html ], the largest moon in the solar system, is off the lower right limb of the planet, while intriguing Europa [ http://www2.jpl.nasa.gov/galileo/moons/europa.html ] is visible against Jupiter's cloud tops, also near the lower right. Jupiter's new red spot junior [ http://redspotjr.christone.net/ ] is just above the broad white band in the planet's southern (upper) hemisphere. In later frames, as planet and moons rotate (right to left), red spot junior moves behind Jupiter's left edge while the Great Red Spot [ http://heritage.stsci.edu/1999/29/index.html ] itself comes into view from the right. Also finally erupting into view at the right, is Jupiter's volcanic moon, Io [ http://www.nineplanets.org/io.html ]. To download the full 2 megabyte movie as an animated gif file, click on the picture. |
|
Io in True Color
| Title |
Io in True Color |
| Explanation |
The strangest moon in the Solar System [ http://www.nineplanets.org/overview.html ] is bright yellow. This picture [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02308 ], showing Io's true colors, was taken in 1999 July by the Galileo spacecraft [ http://www.jpl.nasa.gov/galileo/spacecraft.html ] currently orbiting Jupiter. Io's colors derive from sulfur [ http://chemlab.pc.maricopa.edu/periodic/S.html ] and molten silicate rock [ http://www.windows.ucar.edu/cgi- bin/tour_def/glossary/silicate_rock.html ]. The unusual surface of Io [ http://antwrp.gsfc.nasa.gov/apod/ap961029.html] is kept very young by its system of active volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap960805.html ]. The intense tidal gravity [ http://www.clupeid.demon.co.uk/tides/simple.html ] of Jupiter [ http://www.solarviews.com/eng/jupiter.htm ] stretches Io [ http://antwrp.gsfc.nasa.gov/apod/ap981016.html ] and damps wobbles caused by Jupiter's other Galilean moons [ http://www.jpl.nasa.gov/galileo/ganymede/discovery.html ]. The resulting friction [ http://www.pa.uky.edu/~phy211/Friction_book.html ] greatly heats Io [ http://antwrp.gsfc.nasa.gov/apod/ap980706.html ]'s interior, causing molten rock [ http://cmex.arc.nasa.gov/data/catalog/VolcanismOnMars/MoltenRock.html ] to explode through the surface. Io's volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap000606.html ] are so active that they are effectively turning the whole moon inside out. Some of Io [ http://www.nineplanets.org/io.html ]'s volcanic lava is so hot it glows in the dark [ http://adsabs.harvard.edu/cgi-bin/nph- bib_query?bibcode=1998Icar..135..181M ]. |
|
Callisto: Dark Smashed Iceba
…
| Title |
Callisto: Dark Smashed Iceball |
| Explanation |
Callisto [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/callisto.html ] is a dirty battered world, showing the most beaten surface of Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950625.html ]'s major moons. Made of a rocky core covered by fractured ice, Callisto [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/callisto.html ]'s past collisions with large meteors are evident as large craters surrounded by concentric rings. The four largest moons of Jupiter: Io [ http://antwrp.gsfc.nasa.gov/apod/ap950803.html ], Europa [ http://antwrp.gsfc.nasa.gov/apod/ap950905.html ], Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap950904.html ], and Callisto were all discovered by Galileo [ http://galileo.imss.firenze.it/museo/4/index.html ] and Marius [ http://seds.lpl.arizona.edu/billa/tnp/help.html#M ] in 1610 with early telescopes and are now known as the Galilean satellites. The NASA spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/ ] is scheduled to arrive at Jupiter is December of 1995. Tomorrow's picture: Distant Galaxies |
|
Jupiter's Moon Amalthea
| Title |
Jupiter's Moon Amalthea |
| Explanation |
Amalthea is Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap951013.html ]'s fifth largest moon, much smaller than the four Galilean [ http://bang.lanl.gov/video/stv/arshtml/arstoc.html ] satellites Io [ http://antwrp.gsfc.nasa.gov/apod/ap950803.html ], Europa [ http://antwrp.gsfc.nasa.gov/apod/ap950905.html ], Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap950904.html ], and Callisto [ http://antwrp.gsfc.nasa.gov/apod/ap950906.html ]. The orbit of Amalthea [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/amalthea.html#amalthea ] is inside of these moons, and with its long axis always pointing toward Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950625.html ]. It's dark surface color is probably due to sulfur being expelled from Io [ http://antwrp.gsfc.nasa.gov/apod/ap950804.html ]. Amalthea is not massive enough for its internal gravity to make it spherical. Amalthea [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/amalthea.html ] was discovered in 1892 by Edward Barnard. |
|
Jupiter, Io, and Ganymede's
…
| Title |
Jupiter, Io, and Ganymede's Shadow |
| Explanation |
Jupiter [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/jupiter.html ], the solar system [ http://antwrp.gsfc.nasa.gov/apod/ap950819.html ]'s largest planet, is seen here next to Io [ http://antwrp.gsfc.nasa.gov/apod/ap950803.html ], its closest Galilean [ http://bang.lanl.gov/video/stv/arshtml/arstoc.html ] moon. On the cloud tops of Jupiter [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/jupiter.html ] near the left edge of the picture can be seen a dark circular spot which is caused by the shadow of Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950625.html ]'s largest moon Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap950904.html ]. Jupiter [ http://nssdc.gsfc.nasa.gov/photo_gallery/PhotoGallery-Jupiter.html ]'s cloud tops show light bands and dark belts. The clouds are primarily composed of hydrogen [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ] and helium [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#helium ], but their intense colors are probably caused by very small amounts of heavier elements such as sulfur or organic (carbon-containing) compounds. |
|
Jupiter, Io and Shadow
| Title |
Jupiter, Io and Shadow |
| Explanation |
Pictured above [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA02860 ] is the innermost of Jupiter's Galilean satellites [ http://www.jpl.nasa.gov/galileo/ganymede/ discovery.html ], Io, superposed in front of the gas giant planet. To the left of Io [ http://www.seds.org/nineplanets/nineplanets/io.html ] is a dark spot that is Io's own shadow. A solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap021206.html ] would be seen from within the shadow spot on Jupiter. Viewed from [ http://space.jpl.nasa.gov ] planet Earth, similar shadows of Jupiter's large moons can often be seen crossing [ http://antwrp.gsfc.nasa.gov/apod/ap980202.html ] the giant planet's disk. But during the next several months, the Galilean moons can also be seen crossing in front of each other [ http://skyandtelescope.com/observing/objects/planets/ article_771_1.asp ] as, for a while, their orbits lie nearly edge-on when viewed [ http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=105&vbody=3&month=12&day=20¢ury=20&decade=0&year=2&hour=21&minute=35&rfov=30&fovmul=-1&bfov=30 ] by earthbound observers. This true-color contrast-enhanced image was taken [ http://ciclops.lpl.arizona.edu/ciclops/images_jupiter.html ] two years ago by the robot spacecraft Cassini, as it passed Jupiter on its way [ http://antwrp.gsfc.nasa.gov/apod/ap021104.html ] to Saturn in 2004. |
|
Io Volcano Culann Patera
| Title |
Io Volcano Culann Patera |
| Explanation |
What causes the unusual colors surrounding Io's volcanoes? Io [ http://www.nineplanets.org/io.html], the innermost large moon [ http://www.jpl.nasa.gov/galileo/ganymede/discovery.html ] of Jupiter [ http://www.solarviews.com/eng/jupiter.htm ], is known to be the most tumultuous body [ http://antwrp.gsfc.nasa.gov/apod/ap010715.html ] in the Solar System [ http://www.nineplanets.org/overview.html ]. Approximately the size of Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap010218.html ], Io undergoes nearly continuous volcanic eruptions [ http://antwrp.gsfc.nasa.gov/apod/ap000606.html ] from an interior heated by gravitational tides [ http://burro.astr.cwru.edu/Academics/Astr221/Gravity/tides.html ] from Jupiter and Jupiter's other large moons. The robot spacecraft Galileo [ http://galileo.jpl.nasa.gov/mission/space-intro.html ] currently orbiting Jupiter has been monitoring the active volcano Culann Patera [ http://pirlwww.lpl.arizona.edu/missions/Galileo/releases/19May_i25culann.html ] over the past few years. The above images [ http://photojournal.jpl.nasa.gov/catalog/PIA03885 ] indicate that the volcano [ http://volcano.und.nodak.edu/volcanoes.html ] has produced not only red and black colored lava flows [ http://volcanoes.usgs.gov/Hazards/What/Lava/lavaflow.html ], but yellow sulfur [ http://pearl1.lanl.gov/periodic/elements/16.html ] patches from explosive plumes. Green colors may arise when these processes affect the same terrain. White patches may be caused, in part, by sulfur dioxide [ http://www.epa.gov/air/aqtrnd95/so2.html ] snow. As Galileo [ http://nssdc.gsfc.nasa.gov/planetary/galileo.html ] has fulfilled its mission objectives [ http://antwrp.gsfc.nasa.gov/apod/ap021218.html http://nssdc.gsfc.nasa.gov/planetary/galileo.html#objective ] and is running low on maneuvering fuel, NASA plans to crash [ http://astrobiology.arc.nasa.gov/news/expandnews.cfm?id=392 ] the spacecraft into Jupiter during 2003. |
|
Galileo Photographs Ganymede
| Title |
Galileo Photographs Ganymede |
| Explanation |
Ganymede's surface is slowly being pulled apart. This photo of Ganymede [ http://antwrp.gsfc.nasa.gov/apod/lib/gany01_gal.txt ] was released earlier today [ http://newproducts.jpl.nasa.gov/galileo/ganymede/g1images.html ] by the Galileo team at NASA. The Galileo Spacecraft [ http://newproducts.jpl.nasa.gov/galileo/scpics.html ] arrived at Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950625.html ] in December 1995. In late June, the spacecraft passed within 10,000 kilometers of Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap950904.html ]'s icy surface, and took pictures showing complex surface details for the first time. The line-like features in this photo are sunlit ridges rising above Ganymede [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/ganymede.html ]'s ice-plains. The circular features are impact craters. Ganymede [ http://bang.lanl.gov/solarsys/ganymede.htm ] is the largest moon of Jupiter [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/jupiter.html ] and hence the largest of the four Galilean satellites: Io [ http://antwrp.gsfc.nasa.gov/apod/ap950803.html ], Europa [ http://antwrp.gsfc.nasa.gov/apod/ap950905.html ], Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap960627.html ], and Callisto [ http://antwrp.gsfc.nasa.gov/apod/ap950906.html ]. |
|
Erupting Volcanoes on Io
| Title |
Erupting Volcanoes on Io |
| Explanation |
Jupiter's moon Io has active volcanoes. The Voyager spacecraft [ http://www.jpl.nasa.gov/mip/voyager.html ] caught several erupting when they passed the energetic moon in 1979. In the above picture, several of Io's volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap950804.html ] are visible and one is seen actually erupting. Debris from this explosive event can be seen on the upper left of the photo, just beyond Io's edge. Io [ http://antwrp.gsfc.nasa.gov/apod/ap950803.html ]'s volcanism is thought to be caused by the large tidal distortions raised by Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950625.html ], Europa [ http://antwrp.gsfc.nasa.gov/apod/ap950905.html ], and Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap950904.html ]. These tides stretch Io [ http://antwrp.gsfc.nasa.gov/apod/ap960719.html ], cause internal friction, and thus heat the interior. The hot interior then expands and forces its way out through volcanoes. Currently, the spacecraft Galileo [ http://antwrp.gsfc.nasa.gov/apod/ap951206.html ] is orbiting Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap951208.html ] and photographing Jupiter's Galilean moons [ http://antwrp.gsfc.nasa.gov/apod/ap960710.html ]. |
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Galileo's First Color Image
…
| Title |
Galileo's First Color Image of Io |
| Explanation |
Above is the first color image [ http://newproducts.jpl.nasa.gov/galileo/ganymede/g1io.html ] of Jupiter's volcanic moon Io [ http://bang.lanl.gov/solarsys/io.htm ] released by the Galileo Project. (Io sounds like "eye-oh".) The image was made on June 25 when the Galileo spacecraft approached within 1.4 million miles. It reveals features as small as 14 miles across - comparable to the resolution of the best 1979 vintage Voyager [ http://vraptor.jpl.nasa.gov/voyager/voyager.html ] images. The Voyager flybys discovered active volcanos [ http://antwrp.gsfc.nasa.gov/apod/ap950804.html ] on Io's mottled surface [ http://antwrp.gsfc.nasa.gov/apod/ap950803.html ] and this image indicates that dramatic changes have occurred since [ http://newproducts.jpl.nasa.gov/galileo/status960718.html ], notably in the region of the Masubi volcano located in Io's southern hemisphere. This region, apparently covered with new deposits of sulfur and sulfur dioxide frost deposited by volcanic eruption, is seen as the pronounced white area at the bottom of the picture. While scientists continue to analyze this image and other recent Galileo data [ http://newproducts.jpl.nasa.gov/galileo/status960503.html ] the robot spacecraft will continue to explore Jupiter's moons [ http://NewProducts.jpl.nasa.gov/galileo/jup_sky/ ]. Its next scheduled close encounter [ http://newproducts.jpl.nasa.gov/galileo/tourhilites.html ] is set for September 6th with the moon Ganymede [ http://antwrp.gsfc.nasa.gov/apod/lib/gal_gan_lib.html ]. Higher resolution images of Io are also expected during the ongoing mission. |
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Ancient Cratered Plains on G
…
| Title |
Ancient Cratered Plains on Ganymede |
| Explanation |
The largest moon in the Solar System shows regions that are ancient and battered. The high density of craters demonstrate that patches of Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap960711.html ] are indeed billions of years old. This photo [ http://antwrp.gsfc.nasa.gov/apod/lib/pr47067.txt ] is one of a series [ http://antwrp.gsfc.nasa.gov/apod/lib/gal_gan_lib.html ] released by NASA [ http://newproducts.jpl.nasa.gov/galileo/ ] two days ago from the Galileo spacecraft orbiting Jupiter [ http://galileo.ivv.nasa.gov/fact/ ]. The large impact crater on the left is 19 kilometers across, while dark indentations in Ganymede [ http://newproducts.jpl.nasa.gov/galileo/ganymede/fact.html ]'s crusty surface-ice run diagonally. Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap950904.html ] is composed of half rock and half water-ice. The Galileo spacecraft [ http://nauts.com/histpace/vehicles/histgalileo.html ] will continue to orbit Jupiter [ http://quest.arc.nasa.gov/galileo/About/jupiter.html ] over the next 16 months and send back data about Jupiter [ http://hea-www.harvard.edu/scied/Jupiter/jupiterpage.html ] and its four largest moons: Io [ http://antwrp.gsfc.nasa.gov/apod/ap950803.html ], Europa [ http://antwrp.gsfc.nasa.gov/apod/ap950905.html ], Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap960627.html ], and Callisto [ http://antwrp.gsfc.nasa.gov/apod/ap950906.html ]. |
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Galileo Views Io Eruption
| Title |
Galileo Views Io Eruption |
| Explanation |
Io's surface is active [ http://antwrp.gsfc.nasa.gov/apod/ap950803.html ]. Geyser-like eruptions from volcanoes on this Jovian [ http://antwrp.gsfc.nasa.gov/apod/lib/jupiter.html ] moon were seen by both Voyager spacecraft in 1979 and were also spotted this year in late June by Galileo's camera [ http://newproducts.jpl.nasa.gov/galileo/ganymede/p47209.html ] from a distance of about 600,000 miles. The blue plume seen at the moon's edge (magnified in the inset) arises from Ra Patera [ http://antwrp.gsfc.nasa.gov/apod/ap950804.html ], a large shield volcano, and extends about 60 miles above the surface. The blue color is attributed to condensing and freezing sulfur dioxide gas. Galileo images have also revealed that the plume glows in the dark - perhaps due to fluorescence of excited sulfur and oxygen ions. Io's surface is cold, its temperature averages about -230 degrees Fahrenheit [ http://www.unidata.ucar.edu/staff/blynds/tmp.html ], " so why is it so active? " The most likely cause is the gravitational tug of war over Io between Jupiter and the other Galilean moons which perturbs Io's orbit. The orbital changes would result in tidal force variations heating Io's interior and and generating the sulfurous volcanic activity [ http://volcano.und.nodak.edu/ ]. |
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When Moons and Shadows Dance
| Title |
When Moons and Shadows Dance |
| Explanation |
It's no wonder Jupiter is [ http://galileo.jpl.nasa.gov/jupiter/ jupiter.html ] a favorite target for [ http://www.lpl.arizona.edu/~rhill/alpo/jup.html ] even modest earthbound telescopes. The most massive planet in the solar system [ http://www.seds.org/nineplanets/ nineplanets/datamax.html ] with four of the largest moons also boasts the famous Great Red Spot [ http://csep10.phys.utk.edu/astr161/lect/jupiter/ redspot.html ], a giant hurricane-like storm system over three hundred years old. Recorded on December 15, 2002 between 7:19 and 8:40 UT, over a thousand digital images were processed and stacked to create this spectacular 21 frame animation of the Jovian system [ http://antwrp.gsfc.nasa.gov/apod/ap001118.html ]. South is up and as the Great Red Spot tracks across the face of Jupiter, innermost Galilean [ http://www.jpl.nasa.gov/galileo/ganymede/ discovery.html ] moon Io enters the scene at the far right. Io occults (passes in front of) the edge of the more sedately orbiting Ganymede with Io's shadow [ http://antwrp.gsfc.nasa.gov/apod/ap021207.html ] moving quickly across the gas giant's cloud tops, just below the Red Spot. While the moon Callisto is outside the field of view, its large, dark shadow is also visible crossing the Jovian disk at the upper left. Viewed from Earth, the orbits of the Galilean moons presently lie nearly edge-on, offering many chances to observe similar dances of Jupiter's moons [ http://skyandtelescope.com/observing/objects/planets/ article_771_1.asp ]. |
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Volcano Euboea Fluctus On Io
| Title |
Volcano Euboea Fluctus On Io |
| Explanation |
Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950625.html ]'s moon Io [ http://antwrp.gsfc.nasa.gov/apod/ap960815.html] is turning out to be our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap950819.html ]'s geologic powerhouse. The churning moon was photographed again just recently on June 27th and again shows signs of violent activity. Shown above are photographs [ http://antwrp.gsfc.nasa.gov/apod/ap960908.html http://galileo.ivv.nasa.gov/ganymede/082796.html ] of the volcano Euboea Fluctus taken at different times. The black and white photograph on the upper left was taken by the Voyager 1 [ http://antwrp.gsfc.nasa.gov/apod/ap960908.html http://vraptor.jpl.nasa.gov/voyager/voyager.html ] spacecraft when it flew by in 1979, the upper right and lower left photographs were taken in 1996 by the Galileo spacecraft [ http://antwrp.gsfc.nasa.gov/apod/ap951206.html ], while the lower right photograph is a color image taken by Voyager 2, also in 1979. The upper right Galileo picture has been artifically changed to simulate the color sensitivity of the Voyager [ http://antwrp.gsfc.nasa.gov/apod/ap960629.html ] 2 mission. The marked difference in the two images is highlighted by new red and yellow deposits. These markings may indicate that Euboea Fluctus erupts in an unusual fashion, possibly caused by an obstruction near the volcanic vent. |
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Eruption on Io
| Title |
Eruption on Io |
| Explanation |
There it goes again. Gas and rock were catapulted hundreds of kilometers into space as Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ]'s most volatile moon, Io [ http://www.seds.org/nineplanets/nineplanets/io.html ], showed yet another impressive volcanic display [ http://antwrp.gsfc.nasa.gov/apod/ap960805.html ] in this just-released photograph by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ]. This time the culprit was Pele [ http://antwrp.gsfc.nasa.gov/apod/ap961205.html ], a volcano thought previously inactive since photographed by the passing Voyager [ http://www.jpl.nasa.gov/mip/voyager.html ] 1 spacecraft in 1979. The explosion is visible on Io [ http://galileo.ivv.nasa.gov/ganymede/g1io.html ]'s lower left in this false-color photograph [ http://oposite.stsci.edu/pubinfo/PR/97/21.html ], taken in July 1996. Io's thin atmosphere and low gravity allow volcanic plumes [ http://vulcan.wr.usgs.gov/Hazards/Tephra/haz_aircraft.html ] to rise higher than they would on Earth. |
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Jupiter's Dry Spots
| Title |
Jupiter's Dry Spots |
| Explanation |
Known for its spectacular images of Jupiter's moons, Io [ http://antwrp.gsfc.nasa.gov/apod/ap970321.html ], Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap961223.html ], Callisto [ http://antwrp.gsfc.nasa.gov/apod/ap970218.html ], and Europa [ http://antwrp.gsfc.nasa.gov/apod/ap970417.html ], the robot spacecraft Galileo has also aggressively explored the Jovian atmosphere. In December of 1995 [ http://antwrp.gsfc.nasa.gov/apod/ap951208.html ], Galileo's atmospheric probe descended into Jupiter's clouds [ http://antwrp.gsfc.nasa.gov/apod/ap961127.html ] and reported a surprising absence of water [ http://ccf.arc.nasa.gov/dx/basket/storiesetc/PROB1_22.html ]. It is now believed that the probe entered through one of Jupiter's dry spots [ http://galileo.ivv.nasa.gov/europa/p48700.html ], similar to the dark region in this image of the swirling Jovian cloud deck [ http://galileo.ivv.nasa.gov/europa/p48698.html ]. The smallest features visible here are tens of miles in size. These dry regions appear to correspond to locations where winds converge creating downdrafts. The downdrafts generate local cloudless clearings through which Jupiter's deeper warmer layers [ http://antwrp.gsfc.nasa.gov/apod/ap960123.html ] can be glimpsed. Just as the dark areas are extremely dry [ http://galileo.ivv.nasa.gov/status970605.html ], the surroundings are full of moisture. The contrast is analogous to the desert and tropics of Earth [ http://antwrp.gsfc.nasa.gov/apod/ap961012.html ]. |
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Io: The Prometheus Plume
| Title |
Io: The Prometheus Plume |
| Explanation |
Two sulfurous eruptions are visible on Jupiter's volcanic moon Io [ http://antwrp.gsfc.nasa.gov/apod/ap970321.html ] in this color composite Galileo image [ http://galileo.ivv.nasa.gov/callisto/p48956.html ]. On the left, over Io's limb, a new bluish plume rises about 86 miles above the surface of a volcanic caldera [ http://www.op.dlr.de/ne-hf/SRL-1/p44422-caldera.html ] known as Pillan Patera. In the middle of the image, near the night/day shadow line, the ring shaped Prometheus plume is seen rising 45 miles above Io [ http://cass.jsc.nasa.gov/pub/research/outerp/io.html ] while casting a shadow to the right of the volcanic [ http://volcano.und.nodak.edu/vw.html ] vent. Named for the Greek god [ http://edweb.sdsu.edu/people/bdodge/scaffold/GG/titan.html ] who gave mortals fire, the Prometheus [ http://adhocalypse.arts.unimelb.edu.au/fcf/ucr/student/1996/ a.coulter/hot/prometh.htm ] plume is visible in every image ever made [ http://galileo.ivv.nasa.gov/ganymede/110696.html ] of the region dating back to the Voyager flybys [ http://nssdc.gsfc.nasa.gov/imgcat/html/ object_page/vg1_1636836.html ] of 1979 - presenting the possibility that this plume has been continuously active [ http://www-a.jpl.nasa.gov/galileo/ganymede/122096.html ] for at least 18 years. This image was recorded on June 28 at a distance of 372,000 miles. |
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Jupiter And Family
| Title |
Jupiter And Family |
| Explanation |
This composite image [ http://galileo.ivv.nasa.gov/ganymede/052997.html ] features classic portraits of members of one of the Solar System's [ http://antwrp.gsfc.nasa.gov/apod/ap961214.html ] most prominent families - Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap970920.html ] and its four large "Galilean" [ http://antwrp.gsfc.nasa.gov/apod/ap960830.html ] moons. Starting from the top the moons are Io [ http://antwrp.gsfc.nasa.gov/apod/ap970321.html ], Europa [ http://antwrp.gsfc.nasa.gov/apod/ap970117.html ], Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap961107.html ], and Callisto [ http://antwrp.gsfc.nasa.gov/apod/ap961209.html ]. The top-to-bottom order is also the order of increasing distance from Jupiter. These are big moons indeed which attend the largest planet [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/jupiter.html ]. The smallest of the lot, Europa, is the size of Earth's moon [ http://antwrp.gsfc.nasa.gov/apod/ap970924.html ] while Ganymede is the largest moon in the Solar System. In fact, Ganymede with a diameter of 3,100 miles, is larger than the planets Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap961217.html ] and Pluto [ http://antwrp.gsfc.nasa.gov/apod/ap960311.html ]. The swirling Great Red Spot [ http://antwrp.gsfc.nasa.gov/apod/ap960827.html ] appears at the edge of Jupiter. A hurricane-like storm system that has persisted for over 300 years, two to three earths could fit inside it. Battered Callisto's [ http://antwrp.gsfc.nasa.gov/apod/ap950906.html ] image was recorded during the 1979 flyby of Voyager [ http://antwrp.gsfc.nasa.gov/apod/ap960629.html ]. The other portraits were taken by the Galileo spacecraft [ http://galileo.ivv.nasa.gov/spacecraft.html ] which began exploring the Jovian system in 1995. |
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Jupiter's Inner Moons
| Title |
Jupiter's Inner Moons |
| Explanation |
The potato-shaped inner moons of Jupiter [ http://www.seds.org/nineplanets/nineplanets/amalthea.html ] are lined-up in this mosaic [ http://galileo.ivv.nasa.gov/ganymede/PIA01076.html ]"family portrait" [ http://antwrp.gsfc.nasa.gov/apod/ap970929.html ] of these tiny Jovian satellites. The individual images were recorded over the last year by NASA's Galileo spacecraft and are scaled to the moons' relative sizes. Left to right in increasing order of distance from Jupiter [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/joviansatfact.html ] are Metis (longest dimension 37 miles), Adrastea (12 miles), Amalthea [ http://galileo.ivv.nasa.gov/amalthea/ ] (154 miles), and Thebe (72 miles). All these moons orbit in the zone between Io [ http://antwrp.gsfc.nasa.gov/apod/ap971110.html ] and Jupiter's rings [ http://antwrp.gsfc.nasa.gov/apod/ap970807.html ], are bombarded by high-energy ions within the Jovian magnetosphere [ http://antwrp.gsfc.nasa.gov/apod/ap961018.html ], and are probably locked in synchronous rotation [ http://www.seds.org/nineplanets/nineplanets/help.html#syncrot ] by Jupiter's strong gravity. Why are they shaped like potatoes? Like the asteroids [ http://antwrp.gsfc.nasa.gov/apod/ap970630.html ] and the diminutive moons of Mars [ http://antwrp.gsfc.nasa.gov/apod/ap961222.html ], their own gravity is not strong enough to mold them into spheres. |
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Io in True Color
| Title |
Io in True Color |
| Explanation |
The strangest moon in the Solar System [ http://www.nineplanets.org/overview.html ] is bright yellow. This picture [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02308 ], showing Io's true colors, was taken in 1999 July by the Galileo spacecraft [ http://www.jpl.nasa.gov/galileo/spacecraft.html ] that orbited Jupiter from 1995 to 2003. Io's colors derive from sulfur [ http://chemlab.pc.maricopa.edu/periodic/S.html ] and molten silicate rock [ http://www.windows.ucar.edu/cgi- bin/tour_def/glossary/silicate_rock.html ]. The unusual surface of Io [ http://antwrp.gsfc.nasa.gov/apod/ap961029.html ] is kept very young by its system of active volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap960805.html ]. The intense tidal gravity [ http://www.clupeid.demon.co.uk/tides/simple.html ] of Jupiter [ http://www.solarviews.com/eng/jupiter.htm ] stretches Io [ http://antwrp.gsfc.nasa.gov/apod/ap981016.html ] and damps wobbles caused by Jupiter's other Galilean moons [ http://www.jpl.nasa.gov/galileo/ganymede/discovery.html ]. The resulting friction [ http://www.pa.uky.edu/~phy211/Friction_book.html ] greatly heats Io [ http://antwrp.gsfc.nasa.gov/apod/ap980706.html ]'s interior, causing molten rock [ http://cmex.arc.nasa.gov/data/catalog/VolcanismOnMars/MoltenRock.html ] to explode through the surface. Io's volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap000606.html ] are so active that they are effectively turning the whole moon inside out. Some of Io [ http://www.nineplanets.org/io.html ]'s volcanic lava is so hot it glows in the dark [ http://adsabs.harvard.edu/cgi-bin/nph- bib_query?bibcode=1998Icar..135..181M ]. |
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A Triple Eclipse on Jupiter
| Title |
A Triple Eclipse on Jupiter |
| Explanation |
Part of Jupiter is missing. Actually, three parts appear to be missing. In reality though, the three dark spots seen in the above photograph [ http://www.opi.arizona.edu/newsrel/science/jan98/3moons.htm ] are only shadows. The unusual alignment of three of Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ]'s moons between the Jovian giant [ http://bang.lanl.gov/solarsys/jupiter.htm ] and the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap960518.html ] was imaged last November 10th. The shadows of Io [ http://antwrp.gsfc.nasa.gov/apod/ap971110.html ], Callisto [ http://antwrp.gsfc.nasa.gov/apod/ap950906.html ], and Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap961107.html ] move across Jupiter as these moons progress in their orbits. It was by noting the times of eclipse of Jupiter's moons in 1675 that Ole Roemer [ http://es.rice.edu/ES/humsoc/Galileo/Catalog/Files/roemer.html ] became the first person to measure [ http://www.pd.astro.it/~v_astro/ESO/astronomyonline/market/experiments/advanced/skills302.html ] the speed of light [ http://www.best.com/~dolphin/chistory.html ]. When a shadow from Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap980108.html ] crosses the Earth's surface, the people inside the shadow see an eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap951024.html ] of the Sun. |
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Occultations and Rising Moon
…
| Title |
Occultations and Rising Moons |
| Explanation |
On April 23, the rising crescent Moon occulted [ http://www.skypub.com/occults/occults.html ] (passed in front of) Venus and Jupiter. The double occultation was a rare event [ http://antwrp.gsfc.nasa.gov/apod/ap980428.html ] and only visible from certain locations tracing a path [ http://www.skypub.com/occults/jupiter/980423a.html ] across Earth's surface. This dramatic telephoto picture [ http://eclipse.span.ch/moonsrising.htm ] was taken at [ http://eclipse.span.ch/live.htm ] one such location, Ascension Island [ http://volcano.und.nodak.edu/vwdocs/volc_images/africa/ascension.html ] in the South Atlantic. The sunlit crescent is over-exposed revealing the rest of the lunar surface illuminated by faint earthshine [ http://antwrp.gsfc.nasa.gov/apod/ap960530.html ]. Venus is emerging just beyond the crescent's tip and Jupiter is trailing above the dark lunar edge with a spot of light, Jupiter's moon Ganymede, between the lunar limb and the planet's disk. Look closely at Jupiter and you can see yet another Jovian moon [ http://antwrp.gsfc.nasa.gov/apod/ap970929.html ], Io, just visible against Jupiter's glare! |
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Pastel Planet, Triple Eclips
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| Title |
Pastel Planet, Triple Eclipse |
| Explanation |
This false-color [ http://hubblesite.org/newscenter/newsdesk/archive/releases/ 2004/30/ ] image of banded gas giant Jupiter shows a triple eclipse in progress on March 28 - a relatively rare [ http://antwrp.gsfc.nasa.gov/apod/ap980202.html ] event, even for a large planet with [ http://antwrp.gsfc.nasa.gov/apod/ap001118.html ] many moons. Captured by the Hubble Space Telescope's near-infrared camera are shadows of [ http://hubblesite.org/newscenter/newsdesk/archive/releases/ 2004/30/image/b ] Jupiter's moons Ganymede (left edge), Callisto (right edge) and Io, three black spots crossing the sunlit Jovian cloud tops. In fact, Io itself [ http://antwrp.gsfc.nasa.gov/apod/ap020706.html ] is visible as [ http://hubblesite.org/newscenter/newsdesk/archive/releases/ 2004/30/image/c ] a white spot near picture center with a bluish Ganymede above and to the right, but Callisto is off the right hand edge of the scene. Viewed from Jupiter's perspective, these shadow crossings [ http://antwrp.gsfc.nasa.gov/apod/ap030227.html ] would be seen as solar eclipses, analogous to the Moon's shadow [ http://antwrp.gsfc.nasa.gov/apod/ap040926.html ] crossing the sunlit face of planet Earth. Historically [ http://www.what-is-the-speed-of-light.com/ early-thoughts-speed-of-light.html ], timing the eclipses of Jupiter's moons allowed astronomer Ole Roemer [ http://www.college-optometrists.org/college/ museum/observatory/roemer.htm ] to make the first accurate measurement [ http://www.what-is-the-speed-of-light.com/ roemer-speed-of-light.html ] of the speed of light in 1676. |
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Io Aurora
| Title |
Io Aurora |
| Explanation |
Alluring aurora surrounding Io [ http://photojournal.jpl.nasa.gov/ cgi-bin/PIAGenCatalogPage.pl?PIA01637 ] (eye-oh) appear as a ghostly glow while the volcanic moon orbits [ http://antwrp.gsfc.nasa.gov/apod/ap970623.html ] within Jupiter's dark shadow. Gas giant Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] is off to the right of this image, recorded in May by the robot Galileo spacecraft's solid state imaging camera [ http://www.jpl.nasa.gov/galileo/sepo/ ] from a distance of about 1.3 million kilometers. Energetic charged particles colliding with Io's atmospheric gases create the vivid colors and produce the red and green glow analogous to the aurora of Earth [ http://antwrp.gsfc.nasa.gov/apod/ap970402.html ]. The striking blue light is caused by dense volcanic plumes [ http://www-a.jpl.nasa.gov/galileo/ganymede/122096.html ] and may indicate regions electrically connected to Jupiter itself [ http://antwrp.gsfc.nasa.gov/apod/ap980123.html ]. |
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