|
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Lightning on Earth
| Title |
Lightning on Earth |
| Explanation |
Nobody knows what causes lightning. It is known that charges [ http://physics.bu.edu/~duffy/PY106/Charge.html ] slowly separate in some clouds [ http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/cldtyp/home.rxml ] causing rapid electrical discharges [ http://www.eng.tau.ac.il/Pages/Departments/Inter/edp_lab/ ] (lightning), but how electrical charges [ http://physicsstudio.indstate.edu/java/potential/ProyectI.html ] get separated in clouds [ http://www.geo.mtu.edu/department/classes/ge406/tjbrabec/cloud.html ] remains a topic of much research. Nevertheless, lightning [ http://wvlightning.com/info.html ] bolts are common in clouds during rainstorms, and on average 6000 lightning bolts occur between clouds and the Earth every minute. Above [ http://www.noao.edu/image_gallery/html/im0426.html ], several lightning strokes were photographed behind Kitt Peak National Observatory [ http://www.noao.edu/outreach/kpoutreach.html ] in Arizona [ http://www.state.az.us/ ]. Lightning [ http://bondo.wsc.mass.edu/dept/garp/faculty/lightn.htm ] has also been found on the planets Venus [ http://www.lpl.arizona.edu/~hansell/lightning/poster.html ], Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap971216.html ], Saturn [ http://learn.jpl.nasa.gov/projectspacef/bkg130b.html ], and Uranus [ http://www.spacetoday.org/SolSys/Uranus/Uranus.html ]. NASA [ http://www.nasa.gov/ ] launched the TRMM mission [ http://trmm.gsfc.nasa.gov/news.html ] in 1997 that continues to measure rainfall and lightning [ http://thunder.msfc.nasa.gov/primer/ ] on planet Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990131.html ]. |
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Eight Planets and New Solar
…
| Title |
Eight Planets and New Solar System Designations |
| Explanation |
How many planets are in the Solar System? This popular question now has a new formal answer according the International Astronomical Union [ http://en.wikipedia.org/wiki/International_Astronomical_Union ] (IAU): eight. Last week, the IAU voted [ http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html ] on a new definition for planet [ http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html ] and Pluto [ http://antwrp.gsfc.nasa.gov/apod/ap010319.html ] did not make the cut. Rather, Pluto was re-classified as a dwarf planet [ http://en.wikipedia.org/wiki/Dwarf_planet ] and is considered as a prototype for a new category of trans-Neptunian objects [ http://en.wikipedia.org/wiki/Trans-Neptunian_object ]. The eight planets now recognized by the IAU are: Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap040912.html ], Venus [ http://antwrp.gsfc.nasa.gov/apod/ap040516.html ], Earth [ http://antwrp.gsfc.nasa.gov/apod/ap050102.html ], Mars [ http://antwrp.gsfc.nasa.gov/apod/ap060730.html ], Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap050911.html ], Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap041225.html ], Uranus [ http://antwrp.gsfc.nasa.gov/apod/ap010826.html ], and Neptune [ http://antwrp.gsfc.nasa.gov/apod/ap010821.html ]. Solar System objects now classified as dwarf planets are: Ceres [ http://antwrp.gsfc.nasa.gov/apod/ap060821.html ], Pluto [ http://antwrp.gsfc.nasa.gov/apod/ap060624.html ], and the currently unnamed 2003 UB313 [ http://antwrp.gsfc.nasa.gov/apod/ap060207.html ]. Planets, by the new IAU definition, must be in orbit around the sun, be nearly spherical, and must have cleared the neighborhood around their orbits. The demotion of Pluto [ http://www.nineplanets.org/pluto.html ] to dwarf planet status is a source of continuing dissent [ http://www.badastronomy.com/bablog/2006/08/18/colbert-takes-neil-tyson-down/ ] and controversy [ http://newswire.ascribe.org/cgi-bin/behold.pl?ascribeid=20060818.063045&time=07%2006%20PDT&year=2006&public=0 ] in the astronomical community. |
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New Moons For Saturn
| Title |
New Moons For Saturn |
| Explanation |
Which planet has the most moons? For now, it's Saturn. Four newly discovered [ http://www.eso.org/outreach/press-rel/pr-2000/ phot-29-00.html ] satellites bring the ringed planet's total to twenty-two, just edging out Uranus' [ http://antwrp.gsfc.nasa.gov/apod/ap971103.html ] twenty-one for the most known [ http://www.eso.org/outreach/press-rel/pr-2000/ phot-19-00.html ] moons in the solar system. Of course, the newfound Saturnian satellites [ http://www.nasm.edu/ceps/etp/saturn/satmoons.html ] are not large [ http://antwrp.gsfc.nasa.gov/apod/ap000820.html ] and photogenic [ http://antwrp.gsfc.nasa.gov/apod/ap000129.html ]. The faint S/2000 S 1, the first discovered in the year 2000, is the tiny dot indicated at the lower right of this August 7th image made with the ESO 2.2 meter telescope at La Silla, Chile [ http://www.ls.eso.org/index.html ]. (An eye-catching spiral galaxy at the upper left is in the very distant background!) Unlike Saturn's larger moons whose almost circular orbits lie near the planet's equatorial plane, all four newly discovered moons have irregular [ http://www.obs-nice.fr/gladman/urhome.html ], skewed orbits drifting far from the planet. With sizes in the 10 to 50 kilometer range, they are are likely captured asteroids. The international team of astronomers involved in the discoveries hopes to get many observations of the tiny satellites [ http://www.obs-nice.fr/saturn/ ] allowing accurate orbital computations before Saturn is [ http://www.jpl.nasa.gov/cassini/ ] lost in the solar glare around March 2001. The team has also found several other irregular satellite candidates which are now being followed. Saturn's only previously known irregular satellite is Phoebe [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/ phoebe.html ], discovered over 100 years ago by W. H. Pickering, |
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Uranus: The Tilted Planet
| Title |
Uranus: The Tilted Planet |
| Explanation |
Uranus is the third largest planet in our Solar System [ http://www.nineplanets.org/overview.html ] after Jupiter [ http://antwrp.gsfc.nasa.gov/apod/jupiter.html ] and Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap010826.html http://www.solarviews.com/eng/saturn.htm ]. Uranus [ http://www.nineplanets.org/uranus.html ] is composed mostly of rock and ices, but with a thick hydrogen [ http://chemlab.pc.maricopa.edu/periodic/h.html ] and helium [ http://antwrp.gsfc.nasa.gov/apod/ap010120.html ] atmosphere. The blue hue of Uranus' atmosphere arises from the small amount of methane [ http://scifun.chem.wisc.edu/chemweek/methane/methane.html ] which preferentially absorbs red light. This picture [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA01360 ] was snapped by the Voyager 2 spacecraft [ http://nssdc.gsfc.nasa.gov/planetary/voyager.html ] in 1986 - the only spacecraft ever to visit Uranus. Uranus [ http://antwrp.gsfc.nasa.gov/apod/uranus.html ] has many moons [ http://antwrp.gsfc.nasa.gov/apod/ap990531.html ] and a ring system [ http://antwrp.gsfc.nasa.gov/apod/ap971126.html ]. Uranus, like Venus [ http://antwrp.gsfc.nasa.gov/apod/venus.html ], has a rotation axis that is greatly tilted and sometimes points near the Sun. It remains an astronomical mystery why Uranus' axis [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1991LPIP...22...59S ] is so tilted. Uranus and Neptune [ http://antwrp.gsfc.nasa.gov/apod/neptune.html ] are quite similar: Uranus is slightly larger but less massive. |
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Jupiter's Rings
| Title |
Jupiter's Rings |
| Explanation |
Astronomers using NASA's Voyager [ http://nssdc.gsfc.nasa.gov/planetary/voyager.html ] spacecraft to search for a ring system around Jupiter discovered these faint rings in 1979. Unlike Saturn's bright rings which are composed of chunks of rock and ice, Jupiter's rings [ http://ringside.arc.nasa.gov/www/jupiter/jupiter.html ] appear to consist of fine particles of dust. One possibility is that the dust is produced by impacts with Jupiter's inner moons. This false color image has been computer enhanced. The gas giant planets, Jupiter, Saturn, Uranus, and Neptune are all known to have rings. For more information about planetary ring systems see the Planetary Rings Node [ http://ringside.arc.nasa.gov/ ]. Tomorrow's picture: A Volcanic Moon |
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Uranus' Ring System
| Title |
Uranus' Ring System |
| Explanation |
The rings of Uranus [ http://antwrp.gsfc.nasa.gov/apod/ap950816.html ] are thin, narrow, and dark compared to other planetary ring systems. Brightened artificially by computer, the ring particles reflect as little light as charcoal, although they are really made of ice chucks darkened by rock. This false-color, infrared picture [ http://www.stsci.edu/pubinfo/PR/96/15/A.html ] from the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap950810.html ] taken in July 1995 shows the rings in conjunction to the planet. The infrared [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#infrared ] light allows one to see detail in different layers of Uranus' [ http://antwrp.gsfc.nasa.gov/apod/lib/uranus.html ] atmosphere, which has been digitally enhanced with false color. Three other planets in our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap950819.html ] are known to have rings: Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950802.html ], Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap950705.html ], and Neptune [ http://antwrp.gsfc.nasa.gov/apod/ap950817.html ]. Four of Uranus [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/uranus.html ]' moons are visible outside the ring plane. The rings of Uranus [ http://ringside.arc.nasa.gov/www/uranus/uranus.html ] were discovered from ground-based observations in 1977. |
|
Ringed Planet Uranus
| Title |
Ringed Planet Uranus |
| Explanation |
Yes it does look like Saturn, but Saturn is only one of four [ http://antwrp.gsfc.nasa.gov/apod/ap020616.html ] giant [ http://antwrp.gsfc.nasa.gov/apod/ap020215.html ] ringed [ http://antwrp.gsfc.nasa.gov/apod/ap981020.html ] planets [ http://ringmaster.arc.nasa.gov/neptune/neptune.html ] in our Solar System. And while Saturn has the brightest rings, this system of rings and moons actually belongs to planet Uranus, imaged here [ http://www.eso.org/outreach/press-rel/pr-2002/ phot-31-02.html ] in near-infrared light by the Antu [ http://antwrp.gsfc.nasa.gov/apod/ap000707.html ] telescope at the ESO Paranal Observatory in Chile. Since gas giant Uranus' [ http://www.seds.org/nineplanets/nineplanets/uranus.html ] methane-laced atmosphere absorbs sunlight at near-infrared wavelengths the planet appears substantially darkened, improving the contrast between the otherwise relatively bright planet and the normally faint rings. In fact, the narrow Uranian rings [ http://ringmaster.arc.nasa.gov/uranus/ uranus.html ] are all but impossible to see in visible light with earthbound telescopes and were discovered [ http://tdc-www.harvard.edu/occultations/ uranus25/ ] only in 1977 as careful astronomers noticed the then unknown rings blocking light from background stars. The rings are thought to be younger than 100 million years and may be formed of debris from the collision of a small moon with a passing comet or asteroid-like object. With moons [ http://antwrp.gsfc.nasa.gov/apod/ap000930.html ] named for characters [ http://antwrp.gsfc.nasa.gov/apod/ap990227.html ] in Shakespeare's plays, the distant ringed world Uranus [ http://vraptor.jpl.nasa.gov/voyager/vgrur_fs.html ] was last visited in 1986 by the Voyager 2 spacecraft. |
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Lightning on Jupiter
| Title |
Lightning on Jupiter |
| Explanation |
Does lightning occur only on Earth? Spacecraft in our Solar System have detected radio signals consistent with lightning [ http://wwwghcc.msfc.nasa.gov/lisotd.html ] on other planets, including Venus [ http://www.seds.org/nineplanets/nineplanets/venus.html ], Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ], Saturn [ http://www.seds.org/nineplanets/nineplanets/saturn.html ], Uranus [ http://www.seds.org/nineplanets/nineplanets/uranus.html ], and Neptune [ http://www.seds.org/nineplanets/nineplanets/neptune.html ]. In the above photograph [ http://galileo.ivv.nasa.gov/callisto/050197.html ], optical flashes from Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap970109.html ] were photographed recently by the Galileo orbiter [ http://galileo.ivv.nasa.gov/mission.html ]. Each of the circled dots indicates lightning [ http://www.nofc.forestry.ca/~kanderso/ltgfaq.html ]. The numbers label lines of latitude [ http://www.met.fsu.edu/explores/latlon.html ]. The size of the largest spot is about 500 kilometers across and might be high clouds illuminated by several bright lightning strokes. |
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An Auroral Ring on Jupiter
| Title |
An Auroral Ring on Jupiter |
| Explanation |
Do other planets have aurora? Terrestrial [ http://work.ucsd.edu:5141/cgi-bin/http_webster?terrestrial ] and spacecraft observations have found evidence for aurora on Venus [ http://www.seds.org/nineplanets/nineplanets/venus.html ], Mars [ http://antwrp.gsfc.nasa.gov/apod/ap970609.html http://www.seds.org/nineplanets/nineplanets/mars.html ], Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ], Saturn [ http://www.seds.org/nineplanets/nineplanets/saturn.html ], Uranus [ http://www.seds.org/nineplanets/nineplanets/uranus.html ], and Neptune [ http://www.seds.org/nineplanets/nineplanets/neptune.html ]. In the above false-color photograph [ http://galileo.ivv.nasa.gov/callisto/043097.html ], a good portion of an auroral ring [ http://antwrp.gsfc.nasa.gov/apod/ap970609.html http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996BAAS%2E%2E%2E28%2E2123P&db_key=AST&nosetcookie=1 ] was captured recently in optical light by the Galileo spacecraft [ http://galileo.ivv.nasa.gov/spacecraft.html ] in orbit around Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap970609.html http://antwrp.gsfc.nasa.gov/cgi-bin/cossc/apod_search?jupiter ]. Auroral rings [ http://antwrp.gsfc.nasa.gov/apod/ap970609.html http://www.geo.mtu.edu/weather/aurora/ ] encircle a planet's magnetic pole, and result from charged particles spiraling down magnetic field lines. Although the surroundings near Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap960803.html ] are much different than Earth [ http://antwrp.gsfc.nasa.gov/apod/ap961230.html ], the auroral rings [ http://antwrp.gsfc.nasa.gov/apod/ap970402.html ] appear similar. |
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Solar System Portrait
| Title |
Solar System Portrait |
| Explanation |
On another Valentine's Day [ http://www.poets.org/poems/poems.cfm?prmID=1166 ] (February 14, 1990), cruising four billion miles from the Sun, the Voyager 1 [ http://antwrp.gsfc.nasa.gov/apod/ap031120.html ] spacecraft looked back to make this first ever family portrait [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA00451 ] of our Solar System. The complete portrait is a 60 frame mosaic [ http://nssdc.gsfc.nasa.gov/photo_gallery/ photogallery-solarsystem.html ] made from a vantage point 32 degrees above the ecliptic plane [ http://antwrp.gsfc.nasa.gov/apod/ap001014.html ]. Voyager's wide angle camera frames sweep through the inner Solar System (far left) linking up with gas giant Neptune, at the time the Solar System's [ http://www.seds.org/nineplanets/nineplanets/overview.html ] outermost planet (scroll right). Positions [ http://nssdc.gsfc.nasa.gov/image/planetary/solar_system/ family_diagram.jpg ] for Venus, Earth [ http://www.seds.org/billa/psc/pbd.html ], Jupiter, Saturn, Uranus, and Neptune are indicated by the corresponding letters while the Sun is the bright spot near the center of the circle of frames. The inset frames [ http://antwrp.gsfc.nasa.gov/apod/ap980517.html ] for each of the planets are from Voyager's narrow field camera. Unseen in the portrait are Mercury [ http://www.psrd.hawaii.edu/Jan97/Mercury Unveiled.html ], too close to the Sun to be detected, and Mars, unfortunately hidden by sunlight scattered in the camera's optical system. Small, faint Pluto's [ http://antwrp.gsfc.nasa.gov/apod/ap011018.html ] position was not covered. |
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Irregular Moons Discovered A
…
| Title |
Irregular Moons Discovered Around Uranus |
| Explanation |
Where did these two irregular moons of Uranus [ http://www.seds.org/nineplanets/nineplanets/uranus.html ] originate? Last week two previously undiscovered moons [ http://www.cita.utoronto.ca/~gladman/utpress.html ] of the distant gas planet were confirmed [ http://cfa-www.harvard.edu/iauc/06700/06765.html ], the first in irregular orbits. All fifteen previously known moons [ http://www.seds.org/nineplanets/nineplanets/uramoons.html ] of Uranus [ http://bang.lanl.gov/solarsys/uranus.htm ] are 'regular', circling near the planet's equator. Most of these were discovered by the passing Voyager 2 spacecraft [ http://vraptor.jpl.nasa.gov/voyager/voyager.html ] in 1986. These newly discovered moons [ http://www.news.cornell.edu/science/Oct97/new_moons.hrs.html ] are thought to be odd-shaped and about 100 km across. They are considered irregular, though, because they orbit in odd directions and far from Uranus [ http://antwrp.gsfc.nasa.gov/apod/ap950816.html ]. If Uranus' irregular moons have the same origin as those orbiting Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ], Saturn [ http://pds.jpl.nasa.gov/planets/welcome/saturn.htm ], and Neptune [ http://spacelink.msfc.nasa.gov/Instructional.Materials/Curriculum.Materials/Sciences/Astronomy/Our.Solar.System/Neptune/ ], then they were probably caught from orbits around the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap960518.html ]. Moons like this are discovered by their motion. One of these moons is shown above [ http://www.cita.utoronto.ca/~gladman/ ] as the circled point of light moving from left to right. (To stop the movie from repeating, click "stop" on most browsers.) |
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A Sky Full Of Planets
| Title |
A Sky Full Of Planets |
| Explanation |
Look up tonight [ http://www.cnn.com/TECH/9712/01/heavenly.show.ap/ ]. Just after sunset, the crescent moon and all five "naked-eye" planets (Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap971130.html ], Venus [ http://antwrp.gsfc.nasa.gov/apod/ap971014.html ], Mars [ http://antwrp.gsfc.nasa.gov/apod/ap970528.html ], Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap971030.html ], and Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap970829.html ]) will be visible (depending on your latitude), lying near our solar system's ecliptic plane [ http://antwrp.gsfc.nasa.gov/apod/ap970927.html ]. Venus and Jupiter will shine brilliantly as the brightest "stars" in the sky, but Mercury will be near the horizon and hard to see. A pair of binoculars will also reveal Uranus and Neptune and observers with a telescope and a good site may even be able to glimpse faint Pluto just above the Western horizon in the fading twilight (not shown on the chart above). Enjoy this lovely spectacle any clear night [ http://www.skypub.com/whatsup/dec97sky.html ] through about December 8. A similar gathering is expected in May 2000 [ http://www.skypub.com/special/alignmnt/whypanic.html ] but the planets will be hidden from view by the solar glare. A night sky as full of planets as this one will occur again though ... in about 100 years. |
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Lightning on Earth
| Title |
Lightning on Earth |
| Explanation |
Nobody knows what causes lightning. It is known that charges [ http://physics.bu.edu/~duffy/PY106/Charge.html ] slowly separate in some clouds [ http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/cldtyp/home.rxml ] causing rapid electrical discharges [ http://van.hep.uiuc.edu/van/qa/section/Electricity_and_Magnets/Stuff_that_Sparks/20020722034338.htm ] (lightning), but how electrical charges [ http://www.sciencemadesimple.com/static.html ] get separated in clouds [ http://www.geo.mtu.edu/department/classes/ge406/tjbrabec/cloud.html ] remains a topic of much research. Nevertheless, lightning [ http://wvlightning.com/info.html ] bolts are common in clouds during rainstorms, and on average 6000 lightning bolts occur between clouds and the Earth every minute. Above [ http://www.astro.umd.edu/openhouse/gallery/2004-07KPNO/index.html ], several lightning strokes were photographed under a starry sky behind Kitt Peak National Observatory [ http://www.noao.edu/outreach/kpoutreach.html ] near Tucson, Arizona [ http://www.state.az.us/ ]. Lightning [ http://www.nationalgeographic.com/lightning/ ] has also been found on the planets Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap971216.html ], Saturn [ http://news.bbc.co.uk/2/hi/science/nature/3920597.stm ], and Uranus [ http://www.spacetoday.org/SolSys/Uranus/UranusVoyager.html ]. NASA [ http://www.nasa.gov/ ] launched the TRMM mission [ http://trmm.gsfc.nasa.gov/ ] in 1997 that continues to measure rainfall and lightning [ http://thunder.msfc.nasa.gov/primer/ ] on planet Earth [ http://antwrp.gsfc.nasa.gov/apod/ap010204.html ]. |
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A Solar System Portrait
| Title |
A Solar System Portrait |
| Explanation |
As the Voyager 1 spacecraft [ http://vraptor.jpl.nasa.gov/voyager/vgrfaqs.html ] headed out of our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap980517.html ], it looked back and took a parting family portrait [ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-solarsystem.html ] of the Sun [ http://www.seds.org/nineplanets/nineplanets/sol.html ] and planets. From beyond Pluto [ http://antwrp.gsfc.nasa.gov/apod/ap990213.html ], our Solar System looks like a bright star surrounded by faint dots. In the above picture [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA00451 ], the Sun is so bright it is blocked out for contrast. The innermost dots visible, labeled E and V for Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990131.html ] and Venus [ http://www.nasm.edu/ceps/RPIF/VENUS/rpifvenus.html ], are particularly hard to discern. Gas giants Jupiter [ http://www.jpl.nasa.gov/galileo/Jovian.html ] (J) and Saturn [ http://www.seds.org/nineplanets/nineplanets/saturn.html ] (S) are much more noticeable. The outermost planets visible are Uranus [ http://www.hawastsoc.org/solar/eng/uranus.htm ] (U) and Neptune [ http://antwrp.gsfc.nasa.gov/apod/ap980221.html ] (N). Each planet is shown labeled and digitally enhanced in an inset image. Voyager 1 is only one of four human-made objects to leave our Solar System, the other three being Voyager 2, and Pioneer 10 and Pioneer 11. |
|
Uranus' Moon 18
| Title |
Uranus' Moon 18 |
| Explanation |
The discovery was there for the taking. An image of Uranus [ http://www.seds.org/nineplanets/nineplanets/uranus.html ] taken by Voyager [ http://nssdc.gsfc.nasa.gov/planetary/voyager.html ] 2 as it passed the giant planet 13 years ago apparently recorded a moon that had since gone unnoticed. The image on which Uranus' 18th moon was discovered was freely available [ http://www-pdsimage.JPL.NASA.GOV/PDS/public/jukebox.html ] from NASA. Erich Karkoschka (U. Arizona [ http://science.opi.arizona.edu/ ]) noticed the moon when comparing a 1986 photo to a recent [ http://oposite.stsci.edu/pubinfo/pr/1998/35/index.html ] one taken by the Hubble Space Telescope [ http://www.stsci.edu/hst/ ]. The newly identified moon is hard to see but marked in the above photograph [ http://science.opi.arizona.edu/lasso.acgi?-database=science.fp3&-layout=Fields&-response=%2f%7escience%2fcurrentdetails.htm&-recid=34354&-search ]. Also visible are many other Uranian moons [ http://www.seds.org/nineplanets/nineplanets/uramoons.html ] and background stars. The moon is the 18th known around Uranus [ http://www.hawastsoc.org/solar/eng/uranus.htm ], tying it with Saturn [ http://www.seds.org/nineplanets/nineplanets/saturn.html ] for the most around any planet. |
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