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Moon and moon of Goddard Space Flight Center (GSFC)
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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Earth, Moon, Hubble
| Title |
Earth, Moon, Hubble |
| Explanation |
The Space Shuttle Discovery Crew [ http://spaceflight.nasa.gov/shuttle/archives/sts-103/crew/ ] was fortunate enough to witness one of the brighter full moon's from orbit two weeks ago during their mission to fix the Hubble Space Telescope [ http://www.stsci.edu/hst/ ]. Pictured on the left [ http://spaceflight.nasa.gov/gallery/images/shuttle/sts-103/html/s103e5252.html ], the horizon of the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990619.html ] is visible below this full Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ], which is below the edge of the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ]. The full Moon on this day, last December 22 [ http://antwrp.gsfc.nasa.gov/apod/ap991222.html ], was a few percent brighter than average [ http://www.skypub.com/news/pr_991217brightmoon.html ] because it was full at nearly the same time it was at its closest to the Earth, which comes at a time when the Earth is relatively close to the Sun. The Shuttle Crew successfully showered [ http://spaceflight.nasa.gov/spacenews/reports/sts103/STS-103-13.html ] Hubble with needed holiday gifts, including six new gyroscopes [ http://hubble.gsfc.nasa.gov/sm3a_fact_sheets.html#gyroscopes ], a new computer [ http://hubble.gsfc.nasa.gov/sm3a_fact_sheets.html#advanced ], and new batteries [ http://www.howstuffworks.com/battery.htm ]. |
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A Skygazer's Full Moon
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A Skygazer's Full Moon |
| Explanation |
This dramatically sharp picture [ http://www.geocities.com/CapeCanaveral/Hall/6432/ Einstein.html ] of the full moon was recorded on 22 December, 1999 by astroimager Rob Gendler [ http://www.geocities.com/CapeCanaveral/Hall/6432/homepage.html ]. Big, beautiful, bright, and evocative [ http://205.121.65.141/Millville/teachers/carles/carles96_97/ writing/moonpoems.htm ], it was the last full moon of the Y1.9Ks, pleasing and inspiring even casual skygazers. December's moon was special [ http://www.magna.com.au/~prfbrown/i_asimov.html ] for another reason, as the full phase [ http://www.ac.wwu.edu/~stephan/phases.html ] occurred on the day of the winter solstice and within hours of lunar perigee [ http://antwrp.gsfc.nasa.gov/apod/ap991222.html ]. The first full moon of the year 2000 will bring a special treat [ http://www.bibliography.com/moon/ ] as well, presenting denizens of planet Earth with a total lunar eclipse [ http://sunearth.gsfc.nasa.gov/eclipse/SEextra/TLE2000Jan20.html ]. On Thursday evening, January 20, the moon will encounter the dark edge of Earth's shadow at 10:01 PM Eastern Time [ http://tycho.usno.navy.mil/zones.html ] with the total eclipse phase beginning at 11:05 PM and lasting for 77 minutes. This lunar eclipse will be visible from North and South America and Western Europe (total phase begins at 4:05 AM GMT January 21). |
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Hubble Resolves Expiration D
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Hubble Resolves Expiration Date For Green Cheese Moon |
| Explanation |
Using the new camera on the Hubble Space Telescope [ http://hubblesite.org/reference_desk/faq/ answer.php.id=77&cat=topten ], astronomers have been able to confirm that the Moon is made of green cheese [ http://www.planetfusion.co.uk/~pignut/cheese.html ]. The telling clue was the resolution of a marked date after which the Moon [ http://www.nineplanets.org/luna.html ] may go bad. Controversy [ http://peace.saumag.edu/faculty/Kardas/Courses/ GPWeiten/C1Intro/GreenCheese.html ] still exists, however, over whether the date resolved is truly an expiration date [ http://www.consumeraffairs.com/nutrition/ expiration_dates.htm ] or just a "sell by" date. "To be cautious, we should completely devour the Moon by tomorrow," a spokesperson advised. Happy April Fool's Day from the folks at APOD [ http://antwrp.gsfc.nasa.gov/apod/ap050616.html ]. The above image [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/ ra9_b001.html ] (slightly altered) was actually taken in 1965 by the Ranger 9 [ http://nssdc.gsfc.nasa.gov/database/ MasterCatalog?sc=1965-023A ] probe minutes before impact. The popular Moon is made of Green Cheese [ http://www.straightdope.com/classics/a990723a.html ] myth can be traced back almost 500 years. It has been used historically in context to indicate a claim so clearly false that no one -- not even April Fools [ http://wilstar.com/holidays/aprilfool.htm ] -- will believe it. |
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Zal Patera on Jupiter's Moon
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Zal Patera on Jupiter's Moon Io |
| Explanation |
The Galileo orbiter [ http://www.jpl.nasa.gov/galileo/mission.html ]'s flyby of Io [ http://www.seds.org/nineplanets/nineplanets/io.html ] last November captured an unusual part of Jupiter [ http://antwrp.gsfc.nasa.gov/apod/jupiter.html ]'s volcanic moon. From 26,000 kilometers away, Zal Patera [ http://wwwflag.wr.usgs.gov/USGSFlag/Space/nomen/append5.html ] was found to be a cauldron of flowing lava [ http://antwrp.gsfc.nasa.gov/apod/ap991220.html ], gaseous vents [ http://antwrp.gsfc.nasa.gov/apod/ap970428.html ], and tremendous peaks [ http://antwrp.gsfc.nasa.gov/apod/ap960805.html ]. Red lava can be seen in the above picture [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02527 ] erupting along the base of the volcanic caldera, while cooling black lava lines the edge of a volcanic plateau. Shadow lengths indicate that the top of Zal Patera [ http://antwrp.gsfc.nasa.gov/apod/ap990513.html ] towers nearly 5 kilometers over Io [ http://galileo.jpl.nasa.gov/moons/io.html ]'s molten surface. Galileo zoomed past Io again last month [ http://galileo.jpl.nasa.gov/news/status/status000225.html ], and has begun beaming back images taken only 200 kilometers over Io's surface [ http://antwrp.gsfc.nasa.gov/apod/ap990920.html ]. |
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Venus, Moon, and Neighbors
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Venus, Moon, and Neighbors |
| Explanation |
Rising before the Sun on February 2nd, astrophotographer [ http://pages.prodigy.net/pam.orman/JoeGallery.html ] Joe Orman anticipated [ http://pages.prodigy.net/pam.orman/JoeAlmanac2000.html ] this apparition of the bright morning star [ http://ispec.scibernet.com/station/morn_star.html ] Venus near a lovely crescent Moon above a neighbor's house in suburban Phoenix, Arizona, USA. Fortunately, the alignment of bright planets and the Moon is one of the most inspiring sights in the night sky [ http://www.skypub.com/sights/skyevents/0004skyevents.html ] and one that is often easy to enjoy and share without any special equipment. Take tonight [ http://spacescience.com/headlines/y2000/ast30mar_1m.htm ], for example. Those blessed with clear skies can simply step outside near sunset and view a young crescent Moon very near three bright planets in the west Jupiter [ http://galileo.jpl.nasa.gov/ ], Mars [ http://mars.jpl.nasa.gov/mgs/ ], and Saturn [ http://www.jpl.nasa.gov/cassini/ ]. Jupiter will be the unmistakable brightest star near the Moon with a reddish Mars just to Jupiter's north and pale yellow Saturn directly above. Of course, these sky shows [ http://drumright.ossm.edu/astronomy/conjunctions.html ] create an evocative picture [ http://antwrp.gsfc.nasa.gov/apod/ap000310.html ] but the planets and Moon just appear to be near each other -- they are actually only approximately lined up and lie in widely separated orbits. Unfortunately, next month's highly publicized alignment of planets [ http://www.griffithobs.org/SkyAlignments.html ] on May 5th will be lost from view in the Sun's glare but such planetary alignments [ http://www.skypub.com/news/special/whypanic.html ] occur repeatedly and pose no danger [ http://www.badastronomy.com/bad/misc/planets.html ] to planet Earth. |
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Gamma-Ray Moon
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Gamma-Ray Moon |
| Explanation |
If you could see gamma rays [ http://antwrp.gsfc.nasa.gov/apod/ap000722.html ] - photons with a million or more times the energy of visible light - the Moon would appear brighter than the Sun! The startling notion is demonstrated by this image of the Moon from the Energetic Gamma Ray Experiment Telescope (EGRET [ http://cossc.gsfc.nasa.gov/docs/cgro/cgro/egret.html ]) in orbit on NASA's Compton Gamma Ray Observatory [ http://cossc.gsfc.nasa.gov/docs/cgro/index.html ] from April 1991 to June 2000. Then, the most sensitive instrument of its kind, even EGRET could not see the quiet Sun which is extremely faint at gamma-ray energies. So why [ http://www.aas.org/publications/baas/v28n4/aas189/abs/ S025002.html ] is the Moon bright? High energy charged particles, known as cosmic rays [ http://imagine.gsfc.nasa.gov/docs/features/topics/snr_group/ cosmic_rays.html ], constantly bombard the unprotected lunar surface generating gamma-ray photons. EGRET's gamma-ray vision [ http://cossc.gsfc.nasa.gov/docs/cgro/epo/vu/ index.html ] was not sharp enough to resolve a lunar disk or any surface features, but its sensitivity reveals the induced gamma-ray [ http://antwrp.gsfc.nasa.gov/apod/ap050331.html ] moonglow. So far unique [ http://glast.gsfc.nasa.gov/ ], the image was generated from eight exposures made during 1991-1994 and covers a roughly 40 degree wide field of view with gamma-ray intensity represented in false color. |
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The Belt of Venus over the V
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The Belt of Venus over the Valley of the Moon |
| Explanation |
Although you've surely seen it, you might not have noticed it. During a cloudless twilight [ http://www.hyperdictionary.com/dictionary/twilight ], just before sunrise [ http://antwrp.gsfc.nasa.gov/apod/ap030320.html ] or after sunset [ http://antwrp.gsfc.nasa.gov/apod/ap030412.html ], part of the atmosphere above the horizon appears slightly off-color, slightly pink. Called the Belt of Venus [ http://www.weather-photography.com/Photos/gallery.php?cat=optics&subcat=venus_belt ], this off-color band between the dark eclipsed [ http://antwrp.gsfc.nasa.gov/apod/ap030822.html ] sky and the blue sky [ http://www.sciencemadesimple.com/sky_blue.html ] can be seen in nearly every direction including that opposite the Sun. Straight above, blue sky [ http://www.why-is-the-sky-blue.org/why-is-the-sky-blue.html ] is normal sunlight reflecting off the atmosphere. In the Belt of Venus [ http://epod.usra.edu/archive/epodviewer.php3?oid=158080 ], however, the atmosphere reflects light from the setting (or rising) Sun which appears more red. The Belt of Venus [ http://en.wikipedia.org/wiki/Belt_of_Venus ] can be seen from any location with a clear horizon. Pictured above, the Belt of Venus was photographed above morning fog [ http://antwrp.gsfc.nasa.gov/apod/ap021122.html ] in the Valley of the Moon [ http://www.vmoa.kenwood.ca.us/ ], a famous wine-producing region in northern California [ http://en.wikipedia.org/wiki/California ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ]. The belt is frequently [ http://antwrp.gsfc.nasa.gov/apod/ap011209.html ] caught [ http://antwrp.gsfc.nasa.gov/apod/ap010601.html ] by [ http://antwrp.gsfc.nasa.gov/apod/ap010308.html ] accident [ http://antwrp.gsfc.nasa.gov/apod/ap990418.html ] in [ http://antwrp.gsfc.nasa.gov/apod/ap990325.html ] other [ http://antwrp.gsfc.nasa.gov/apod/ap990308.html ] photographs [ http://antwrp.gsfc.nasa.gov/apod/ap010501.html ]. |
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A Halo Around the Moon
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A Halo Around the Moon |
| Explanation |
Have you ever seen a halo around the Moon? This fairly common sight occurs when high thin clouds [ http://ww2010.atmos.uiuc.edu/(Gh)/wwhlpr/cirrus.rxml?hret=/guides/mtr/opt/ice/halo/22.rxml ] containing millions of tiny ice crystals [ http://dspace.dial.pipex.com/lc/halo/crystals.htm ] cover much of the sky. Each ice crystal [ http://kristall.uni-mki.gwdg.de/homep1.htm ] acts like a miniature lens. Because most [ http://dspace.dial.pipex.com/lc/halo/xtalreal.htm ] of the crystals have a similar elongated hexagonal shape, light entering one crystal face and exiting through the opposing face refracts 22 degrees, which corresponds to the radius of the Moon Halo [ http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/ice/halo/22.rxml ]. A similar Sun Halo [ http://antwrp.gsfc.nasa.gov/apod/ap990823.html ] may be visible during the day. The town in the foreground of the above picture [ http://www.skylook.net/album/fenatm/fat3i.htm ] is San Sebastian [ http://www.donsnsn.es/icaste.htm ], Spain [ http://www.odci.gov/cia/publications/factbook/sp.html ]. The distant planet Jupiter [ http://antwrp.gsfc.nasa.gov/apod/jupiter.html ] appears by chance on the halo [ http://dspace.dial.pipex.com/lc/halo/halfeat.htm ]'s upper right. Exactly how ice-crystals form [ http://www.public.iastate.edu/~skrentz/ice_crystal.htm ] in clouds remains under investigation [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1995dri..rept.....H ]. |
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Ganymede: The Largest Moon i
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Ganymede: The Largest Moon in the Solar System |
| Explanation |
If Ganymede orbited the Sun, it would be considered a planet. The reason is that Jupiter [ http://galileo.jpl.nasa.gov/jupiter/jupiter.html ]'s moon Ganymede [ http://www.seds.org/nineplanets/nineplanets/ganymede.html ] is not only the largest moon in the Solar System [ http://www.seds.org/nineplanets/nineplanets/datamax.html ], it is larger than planets Mercury [ http://www.seds.org/nineplanets/nineplanets/mercury.html ] and Pluto [ http://dosxx.colorado.edu/plutohome.html ]. The robot spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/overview.html ] currently orbiting Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] has been able to zoom by Ganymede [ http://www.solarviews.com/eng/ganymede.htm ] several times and snap many close-up pictures. Ganymede, shown above [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA00716 ] in its natural colors, sports a large oval dark region known as Galileo Regio [ http://www.jpl.nasa.gov/galileo/ganymede/121896.html ]. In general, the dark regions on Ganymede [ http://sse.jpl.nasa.gov/features/planets/jupiter/ganymede.html ] are heavily cratered, implying they are very old, while the light regions are younger and dominated by unusual grooves [ http://antwrp.gsfc.nasa.gov/apod/ap960711.html ]. The origin of the grooves is still under investigation [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998Icar..135..317P ]. |
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Up Close to Jupiter's Moon I
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Up Close to Jupiter's Moon Io |
| Explanation |
Above is the highest resolution photograph [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02556 ] yet taken of the Solar System [ http://www.seds.org/nineplanets/nineplanets/overview.html ]'s strangest moon. The surface of Jupiter [ http://www.solarviews.com/eng/jupiter.htm ]'s moon Io [ http://galileo.jpl.nasa.gov/moons/io.html ] is home to violent volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap000606.html ] that are so active they turn the entire moon inside out. The above photograph [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02556 ] shows a region four kilometers across and resolves features only five meters [ http://www.twenj.com/measures.htm ] across. Many revealed details are not well understood. In general, the bright areas are higher terrain than the darker areas, but some areas of the surface appear eroded [ http://www.qub.ac.uk/geosci/teaching/postgrad/workshop1/erosion1.html ] by an unknown process. Although the parts of Io's surface [ http://antwrp.gsfc.nasa.gov/apod/ap970321.html ] near erupting volcanoes are hot enough to melt rock, most of Io [ http://antwrp.gsfc.nasa.gov/apod/ap990920.html ] has cooled well below the freezing point of water [ http://www.nyu.edu/pages/mathmol/modules/water/info_water.html ]. The robot spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/overview.html ] during its most recent flyby [ http://galileo.jpl.nasa.gov/news/release/press000531.html ] of Io [ http://www.seds.org/nineplanets/nineplanets/io.html ] took the above image in 2000 February. |
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The Last Moon Shot
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The Last Moon Shot |
| Explanation |
In 1865 Jules Verne [ http://www.interlog.com/~anash/najvs.html ] predicted the invention of a space capsule that could carry people. In his science fiction story "From the Earth to the Moon" [ http://JV.Gilead.org.il/pg/moon/ ], he outlined his vision of a cannon in Florida so powerful that it could shoot a "Projectile-Vehicle" [ http://www.nasm.edu/galleries/gal109/NEWHTF/ITM6201.HTM ] carrying three adventurers to the Moon [ http://www.hq.nasa.gov/office/pao/History/ ap11ann/eagle.html ]. Over 100 years later, NASA [ http://www.hq.nasa.gov/pao/History/history.html ], guided by Wernher Von Braun [ http://history.msfc.nasa.gov/vonbraun/index.html ]'s vision, produced the Saturn V rocket [ http://www.apollosaturn.com/ ]. From a spaceport in Florida [ http://www.ksc.nasa.gov/ksc.html ], this rocket turned Verne's fiction into fact, launching 9 Apollo Lunar missions and allowing 12 astronauts to walk on the Moon [ http://www.hq.nasa.gov/office/pao/History/alsj/ ]. Pictured [ http://images.jsc.nasa.gov/images/pao/AS17/10075937.htm ] is the last moon shot, Apollo 17 [ http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo17info.html ], awaiting a night launch in December of 1972. Spotlights play on the rocket and launch pad while the full Moon looms [ http://cass.jsc.nasa.gov/moon.html ] in the background. Humans have not walked on [ http://www.hq.nasa.gov/office/pao/History/alsj/ apollo.epilog.html ] on the lunar surface since. [ http://ilewg.jsc.nasa.gov/ ] |
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A Continuous Eruption on Jup
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A Continuous Eruption on Jupiter's Moon Io |
| Explanation |
A volcano on Jupiter's moon Io [ http://www.seds.org/nineplanets/nineplanets/io.html ] has been photographed recently during an ongoing eruption. Hot glowing lava is visible on the left on this representative-color image [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02550 ]. A glowing landscape of plateaus and valleys covered in sulfur [ http://pearl1.lanl.gov/periodic/elements/16.html ] and silicate rock [ http://windows.ivv.nasa.gov/cgi-bin/tour_def/glossary/silicate_rock.html ] surrounds the active volcano [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/Io/Overview.html ]. Many features including several of the dark spots [ http://antwrp.gsfc.nasa.gov/apod/ap971110.html ] have evolved between February 2000, when the robot spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/spacecraft.html ] currently orbiting Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] took this picture, and November 1999. Io [ http://cass.jsc.nasa.gov/pub/research/outerp/io.html ] is slightly larger than Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ] and is the closest large moon to Jupiter [ http://galileo.jpl.nasa.gov/jupiter/jupiter.html ]. The above image [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02550 ] shows a region about 250 kilometers across. How the internal structure of Io [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1990Icar...85..309R ] creates these active volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap961027.html ] remains under investigation. |
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Ultraviolet Earth from the M
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Ultraviolet Earth from the Moon |
| Explanation |
Here's a switch: the above picture is of the " Earth " taken from a " lunar " observatory! [ http://antwrp.gsfc.nasa.gov/apod/ap960608.html ] This false color picture [ http://images.jsc.nasa.gov/images/pao/AS16/10075878.htm ] shows how the Earth [ http://antwrp.gsfc.nasa.gov/apod/earth.html ] glows in ultraviolet [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#uv ] (UV) light. UV light is so blue humans can't see it. Very little UV light [ http://titan.srrb.noaa.gov/UV/ ] is transmitted through the Earth's atmosphere but what sunlight does make it through can cause a sunburn [ http://uhs.bsd.uchicago.edu/uhs/infoline/sunburn.htm ]. The Far UV Camera / Spectrograph [ http://cass.jsc.nasa.gov/pub/expmoon/Apollo16/A16_Experiments_UVC.html ] deployed and left on the Moon by the crew of Apollo 16 [ http://antwrp.gsfc.nasa.gov/apod/ap000319.html ] took the above picture. The part of the Earth facing the Sun [ http://antwrp.gsfc.nasa.gov/apod/sun.html ] reflects much UV light, but perhaps more interesting is the side facing away from the Sun. Here bands of UV emission [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/emspectrum.html ] are also apparent. These bands [ http://antwrp.gsfc.nasa.gov/apod/ap970402.html ] are the result of aurorae [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_ts?aurora ] and are caused by charged particles [ http://www-spof.gsfc.nasa.gov/Education/Intro.html ] expelled by the Sun. |
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Eclipsed Moon Rising Over En
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| Title |
Eclipsed Moon Rising Over England |
| Explanation |
Last Thursday, part of our Moon turned dark. The cause, this time, was not a partial lunar phase [ http://antwrp.gsfc.nasa.gov/apod/ap051113.html ] -- the Moon was full -- but rather that part of the Moon went into Earth's shadow. The resulting partial lunar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap041103.html ] was visible from the eastern Atlantic Ocean [ https://www.cia.gov/cia/publications/factbook/geos/zh.html ] through Europe [ http://antwrp.gsfc.nasa.gov/apod/ap051207.html ], Africa [ http://en.wikipedia.org/wiki/Africa ], and Asia [ http://en.wikipedia.org/wiki/Asia ] and into the western Pacific Ocean [ https://www.cia.gov/cia/publications/factbook/geos/zn.html ]. The darkest part of the lunar eclipse, when part of the Moon was completely shielded from sunlight [ http://antwrp.gsfc.nasa.gov/apod/ap060909.html ], lasted about 90 minutes. Pictured above, a partially eclipsed Moon is seen rising over an estate in Huddersfield [ http://en.wikipedia.org/wiki/Huddersfield_%28UK_Parliament_constituency%29 ], England [ http://en.wikipedia.org/wiki/British_Isles_%28terminology%29 ]. The above image was taken far away from the house in the foreground, as only this would allow it to appear as angularly small as the half-degree Moon [ http://antwrp.gsfc.nasa.gov/apod/ap031011.html ] far in the background. A setting twilight Sun lit the foreground. The next eclipse [ http://mreclipse.com/Special/LEnext.html ] of the Moon will occur in March 2007. |
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Bright Cliffs Across Saturn'
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| Title |
Bright Cliffs Across Saturn's Moon Dione |
| Explanation |
What causes the bright streaks on Dione? Recent images of this unusual moon by the robot Cassini spacecraft [ http://saturn.jpl.nasa.gov/overview/mission.cfm ] now orbiting Saturn [ http://www.nineplanets.org/saturn.html ] are helping to crack the mystery. Close inspection of Dione's trailing hemisphere, pictured above [ http://photojournal.jpl.nasa.gov/catalog/PIA08256 ], indicates that the white wisps are composed of deep ice cliffs [ http://antwrp.gsfc.nasa.gov/apod/ap051026.html ] dropping hundreds of meters. The cliffs may indicate that Dione has undergone some sort of tectonic surface [ http://www.seismo.unr.edu/ftp/pub/louie/class/100/plate-tectonics.html ] displacements in its past. The bright ice-cliffs run across some of Dione [ http://en.wikipedia.org/wiki/Dione_%28moon%29 ]'s many craters, indicating that the process [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1984Icar...59..205M ] that created them occurred later than the impacts [ http://antwrp.gsfc.nasa.gov/apod/ap010428.html ] that created those craters. Dione [ http://www.nineplanets.org/dione.html ] is made of mostly water ice but its relatively high density indicates that it contains much rock [ http://en.wikipedia.org/wiki/Rock_and_roll ] inside. Giovanni Cassini [ http://www.seds.org/messier/xtra/Bios/cassini.html ] discovered Dione in 1684. The above image [ http://photojournal.jpl.nasa.gov/catalog/PIA08256 ] was taken at the end of July from a distance of about 263,000 kilometers. Other high resolution image [ http://antwrp.gsfc.nasa.gov/apod/ap951009.html ]s of Dione were taken by the passing Voyager spacecraft [ http://nssdc.gsfc.nasa.gov/planetary/voyager.html ] in 1980. |
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Colorful Moon Mosaic
| Title |
Colorful Moon Mosaic |
| Explanation |
No single exposure can easily capture faint stars along with the subtle colors [ http://www.atalaia.org/filipe/moon/colorofthemoon.htm ] of the Moon. But this dramatic composite view highlights both. The mosaic digitally stitches together fifteen carefully exposed [ http://ncarboni.home.att.net/Astrophotography.html ] high resolution images of a bright, gibbous [ http://www.earthsky.com/skywatching/tips_moonphases.php ] Moon and a representative background star field. The fascinating color [ http://antwrp.gsfc.nasa.gov/apod/ap060216.html ] differences along the lunar surface are real, though highly exaggerated, corresponding to regions with different chemical compositions [ http://www.psrd.hawaii.edu/Dec04/LunarCrust.html ]. And while these color differences are not visible to the eye even with [ http://antwrp.gsfc.nasa.gov/apod/ap010428.html ] a telescope, moon watchers can still see a dramatic lunar presentation [ http://www.shadowandsubstance.com/ ] tonight. A partial eclipse of the Moon [ http://sunearth.gsfc.nasa.gov/eclipse/OH/ OH2006.html#2006Sep07P ] will be visible from Europe, Africa, Asia, and Australia. |
|
Sirius, Sun, Moon, and South
…
| Title |
Sirius, Sun, Moon, and Southern Cross |
| Explanation |
From left to right are the enclosures of Yepun ("ye-poon", Sirius [ http://antwrp.gsfc.nasa.gov/apod/ap000611.html ]), Antu ("an-too", Sun [ http://antwrp.gsfc.nasa.gov/apod/ap000621.html ]), Kueyen ("qua-yen", Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991222.html ]), and Melipal ("me-li-pal", Southern Cross [ http://antwrp.gsfc.nasa.gov/apod/ap000618.html ]), pictured here as night falls at Paranal Observatory [ http://www.eso.org/outreach/press-rel/pr-2000/ phot-15B-00.html ] in northern Chile. These are the four 8.2 meter wide telescope units of the European Southern Observatory's Very Large Telescope [ http://www.eso.org/outreach/press-rel/pr-2000/ phot-15-00.html ] (VLT). ESO astronomers and engineers plan to combine the light [ http://www.eso.org/projects/vlt/ ] of the individual units, achieving an equivalent aperture [ http://www.seds.org/billa/bigeyes.html ] of 16.4 meters which will, for a while [ http://nastol.astro.lu.se/~torben/50m/50m.html ], constitue the biggest [ http://www.sciam.com/specialissues/1299engineering/ 1299musserbox2.html ] telescope on planet Earth [ http://www.sciam.com/specialissues/1299engineering/ 1299musser.html ]. Of course, the individual telescopes also function independently. Antu, Kueyen, and Melipal have already achieved first light with Yepun expected to operate in 2001. The telescope names [ http://www.eso.org/outreach/info-events/ut1fl/names.html ] come from the Mapuche [ http://www.uchile.cl/cultura/mapa/ artesamapuche/ingles/index.htm ] language [ http://www-linguistics.stanford.edu/~arnold/mapuche/ mapudungun.html ]. They were unanimously chosen based on the winning "name-the-telescopes" essay by 17-year old Jorssy Albanez Castilla from Chuquicamata near the city of Calama. |
|
Moon And Venus Share The Sky
| Title |
Moon And Venus Share The Sky |
| Explanation |
July is drawing to a close and in the past few days, some early morning risers [ http://antwrp.gsfc.nasa.gov/apod/ap990714.html ] could have looked east and seen a crescent Moon sharing the pre-dawn [ http://science.nasa.gov/headlines/y2000/ast25jul_1m.htm ] skies with planets Jupiter and Saturn. Planet Mercury will also pass about 2 degrees from the thin waning crescent Moon [ http://aa.usno.navy.mil/AA/faq/docs/moon_phases.html ] just before sunrise near the eastern horizon on Saturday, July 29. And finally, on the evening of July 31st, Venus will take its turn near the crescent Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ]. But this time it will be a day-old crescent Moon near the western horizon, shortly after sunset [ http://antwrp.gsfc.nasa.gov/apod/ap000507.html ]. In fact [ http://pages.prodigy.net/pam.orman/JoeAlmanac2000.html ], on July 31 (August 1 Universal Time) the Moon will occult [ http://www.skypub.com/sights/occultations/lunar/ 0001lunarocc.html ] (pass in front of) Venus for northwestern observers [ http://www.skypub.com/sights/images2000/ 0008moonvenus_big.jpg ] in North America. This telescopic picture taken on 31 December 1997, shows a lovely young crescent Moon and brilliant crescent Venus in [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html ] the early evening sky near Bursa, Turkey [ http://www.mersina.com/Turkey/Marmara/Bursa/index.html ]. And what about the Sun? On Sunday, July 30, a partial eclipse of the Sun [ http://sunearth.gsfc.nasa.gov/eclipse/extra/ PSE2000Jul31.html ] will be visible from some locations [ http://sunearth.gsfc.nasa.gov/eclipse/OH/ PSE2000Jul.gif ] in North America. |
|
Crescent Venus and Moon
| Title |
Crescent Venus and Moon |
| Explanation |
There's something behind these clouds. Those faint graceful arcs, upon inspection, are actually far, far in the distance. They are the Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap060907.html ] and the planet Venus [ http://en.wikipedia.org/wiki/Planet_Venus ]. Both the Moon and Venus [ http://antwrp.gsfc.nasa.gov/apod/ap050913.html ] are bright enough to be seen during the day, and both are quite capable of showing a crescent phase [ http://antwrp.gsfc.nasa.gov/apod/ap060618.html ]. To see Venus, which appears quite small, in a crescent phase [ http://antwrp.gsfc.nasa.gov/apod/ap060110.html ] requires binoculars [ http://en.wikipedia.org/wiki/Binoculars ] or a telescope. In the above dramatic daytime image [ http://eder.csillagaszat.hu/digital/venus_fedes/Ven_fed.html ] taken from Budapest [ http://en.wikipedia.org/wiki/Budapest ], Hungary [ http://en.wikipedia.org/wiki/Hungary ], the Moon and Venus [ http://antwrp.gsfc.nasa.gov/apod/ap060723.html ] shared a similar crescent phase a few minutes before the Moon eclipsed [ http://www.astronomy.no/venus080604/venusocc/images.html ] the larger but more distant world. About an hour later, Venus reappeared. |
|
X-Ray Moon
| Title |
X-Ray Moon |
| Explanation |
This x-ray image [ http://heasarc.gsfc.nasa.gov/docs/rosat/gallery/ misc_moon2.html ] of the Moon [ http://antwrp.gsfc.nasa.gov/apod/ap960919.html ] was made by the orbiting ROSAT [ http://heasarc.gsfc.nasa.gov/docs/rosat/rhp_geninfo.html ] (Röntgensatellit [ http://heasarc.gsfc.nasa.gov/docs/rosat/gallery/ wilhelm.html ]) Observatory in 1990. In this digital picture, pixel brightness corresponds to x-ray intensity. Consider the image in three parts: the bright hemisphere of the x-ray moon, the darker half of the moon, and the x-ray sky [ http://antwrp.gsfc.nasa.gov/apod/ap000819.html ] background. The bright lunar hemisphere shines in x-rays [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/ history1_xray.html ] because it reflects x-rays emitted by the sun ... just as it shines at night [ http://antwrp.gsfc.nasa.gov/apod/ap000113.html ] by reflecting visible sunlight. The background [ http://heasarc.gsfc.nasa.gov/docs/objects/ background/background.html ] sky has an x-ray glow in part due to the myriad of distant, powerful active galaxies, unresolved in the ROSAT picture but recently detected in Chandra Observatory x-ray images [ http://antwrp.gsfc.nasa.gov/apod/ap000114.html ]. But why isn't the dark half of the moon completely dark? It's true that the dark lunar face is in shadow [ http://antwrp.gsfc.nasa.gov/apod/ap980312.html ] and so is not reflecting solar x-rays [ http://antwrp.gsfc.nasa.gov/apod/ap981221.html ]. Still, the few x-ray photons which seem to come from the moon's dark half are currently thought to be caused by energetic particles in the solar wind [ http://www-spof.gsfc.nasa.gov/Education/wsolwind.html ] bombarding the lunar surface. |
|
Full Moon Crossing
| Title |
Full Moon Crossing |
| Explanation |
On October 6th, a nearly full perigee [ http://antwrp.gsfc.nasa.gov/apod/ap041021.html ] Moon shone in Earth's night sky. The bright moonlight [ http://science.nasa.gov/headlines/y2006/ 28sep_strangemoonlight.htm ], accurate planning, and proper equipment resulted in this amazing composite [ http://pictures.ed-morana.com/ISSTransits/ ] featuring sharp silhouettes of the International Space Station (ISS) as it rapidly crossed (right to left) in front [ http://antwrp.gsfc.nasa.gov/apod/ap060921.html ] of the lunar disk. The picture was constructed using six video frames recorded from a site just outside Tracy, California, USA. Sporting newly deployed solar arrays, the ISS [ http://antwrp.gsfc.nasa.gov/apod/ap060920.html ] was at a range of about 260 miles from the telescope/video camera setup. In the background, about a thousand times more distant than the ISS, lies bright lunar ray crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap050305.html ]. |
|
X-Ray Moon and X-Ray Star
| Title |
X-Ray Moon and X-Ray Star |
| Explanation |
An x-ray star [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/binaries.html ] winks out behind the Moon in these [ http://heasarc.gsfc.nasa.gov/docs/rosat/gallery/ misc_gx5-1_moon_occult.html ] before (left) and after views of a lunar occultation [ http://www.skypub.com/sights/occultations/occultations.shtml ] of the galactic x-ray source designated GX5-1 [ http://antwrp.gsfc.nasa.gov/apod/ap000909.html http://adsabs.harvard.edu/cgi-bin/ nph-bib_query?bibcode=1997PASJ...49..589K&db_key=AST&high=3899d8d98228744 ]. The false color images were made using data from the ROSAT [ http://heasarc.gsfc.nasa.gov/docs/rosat/rosat3.html ] (ROentgen SATellite), orbiting observatory. They show high energy x-rays in yellow (mostly from GX5-1), and lower energy x-rays in red (the Moon reflecting x-rays [ http://antwrp.gsfc.nasa.gov/apod/ap000902.html ] from the Sun). GX5-1 is a binary system [ http://heasarc.gsfc.nasa.gov/docs/binary.html ] consisting of a neutron star [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#ns ] and a companion star in mutual orbit about the system's center of mass. The gas in the companion star's outer envelope falls toward the neutron star and accumulates in a disk [ http://antwrp.gsfc.nasa.gov/apod/ap991219.html ] around it. This disk material swirls deeper in to the neutron star's gravitational well [ http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html ], and is finally dumped onto its surface - in the process creating tremendous temperatures and generating the high energy x-rays. |
|
Janus: Potato Shaped Moon of
…
| Title |
Janus: Potato Shaped Moon of Saturn |
| Explanation |
Janus is one of the stranger moons of Saturn. First, Janus [ http://www.planetary.org/explore/topics/saturn/janus.html ] travels in an unusual orbit around Saturn where it periodically trades places with its sister moon Epimetheus [ http://antwrp.gsfc.nasa.gov/apod/ap050429.html ], which typically orbits about 50 kilometers away. Janus [ http://en.wikipedia.org/wiki/Janus_%28moon%29 ], although slightly larger than Epimetheus [ http://antwrp.gsfc.nasa.gov/apod/ap050824.html ], is potato [ http://en.wikipedia.org/wiki/Potato ]-shaped and has a largest diameter of about 190 kilometers. Next, Janus is covered with large craters but strangely appears to lack small craters. One possible reason for this is a fine dust that might cover the small moon, a surface also hypothesized for Pandora [ http://antwrp.gsfc.nasa.gov/apod/ap051123.html ] and Telesto [ http://antwrp.gsfc.nasa.gov/apod/ap060222.html ]. Pictured above [ http://photojournal.jpl.nasa.gov/catalog/PIA08296 ], Janus was captured in front of the cloud tops [ http://antwrp.gsfc.nasa.gov/apod/ap051010.html ] of Saturn [ http://en.wikipedia.org/wiki/Saturn ] in late September. |
|
Eclipse Moon Trail
| Title |
Eclipse Moon Trail |
| Explanation |
Tonight, Friday the 13th, October's big, bright, beautiful full Moon [ http://antwrp.gsfc.nasa.gov/apod/ap000113.html ] will be in the sky, rising as the sun sets. A time exposure of this evening's full Moon would show a brilliant circular arc or Moon trail tracing its celestial path. In fact, this single [ http://pages.prodigy.net/pam.orman/joemoon/ MoonPlanets_000120_2.html ], four hour long exposure from the evening of January 20 shows a full Moon trailing through hazy skies above [ http://pages.prodigy.net/pam.orman/ JoeGallery.html ] Phoenix, Arizona, USA. Of course, the picture also shows something you won't see tonight -- a total lunar eclipse [ http://www.mreclipse.com/Special/LEprimer.html ]. A lunar eclipse is caused when the full moon enters Earth's shadow [ http://image.gsfc.nasa.gov/poetry/ask/q2806.html ] and as the eclipsed Moon's light grows steadily fainter, the Moon trail becomes narrow and dim. The total eclipse phase, when the Moon passes completely within Earth's shadow [ http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=3&vbody=103& month=1&day=21¢ury=20&decade=0&year=0&hour=04&minute=0& rfov=30&fovmul=-1&bfov=30 ], occurs near the middle of this Moon trail arc [ http://antwrp.gsfc.nasa.gov/apod/ap000905.html ]. But even during totality, the Moon trail is visible and noticeably red. Normally illuminated by sunlight which falls directly on its surface, during a total lunar eclipse the Moon is still illuminated [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ] by sunlight filtered and refracted through Earth's atmosphere. The refracted light lends the eclipsed Moon [ http://www.mreclipse.com/ ] a dim and reddish appearance. |
|
The Averted Side Of The Moon
| Title |
The Averted Side Of The Moon |
| Explanation |
This vintage 60-kopek stamp celebrates a dramatic achievement. On the 7th of October, 1959 [ http://nssdc.gsfc.nasa.gov/planetary/lunar/lunartimeline.html ] (7/X/1959), the Soviet interplanetary station which has come to be called "Luna 3" [ http://nssdc.gsfc.nasa.gov/cgi-bin/database/www-nmc?59-008A ] successfully photographed the far side [ http://antwrp.gsfc.nasa.gov/apod/ap981008.html ] of the moon giving denizens of planet Earth their first ever view [ http://antwrp.gsfc.nasa.gov/apod/ap950914.html ] of this hidden [ http://www.badastronomy.com/bad/misc/dark_side.html ] hemisphere [ http://www.badastronomy.com/bad/misc/moon_spin.html ]. Lacking the digital image technology [ http://willmclaughlin.astrodigitals.com/ ] familiar now, Luna 3 took the pictures on 35mm film which was automatically developed on board. The pictures were then scanned and the signal transmitted [ http://www.users.wineasy.se/svengrahn/trackind/ jodrell/jodrole1.htm#luna3fars ] to Earth days later in what was perhaps also the first interplanetary fax. In all, seventeen pictures [ http://nssdc.gsfc.nasa.gov/cgi-bin/database/www-nmc?59-008A-01 ] were received providing enough coverage and resolution to construct a far side map and identify a few major features. Depicted on [ http://vesuvius.jsc.nasa.gov/er/seh/stamps.html ] the stamp are regions dubbed the Sea of Moscow, the Soviet Mountains, the Bay of Astronauts, and the Sea of Dreams. |
|
Phobos: Doomed Moon of Mars
| Title |
Phobos: Doomed Moon of Mars |
| Explanation |
This moon is doomed. Mars [ http://mars.jpl.nasa.gov/extreme/index.html ], the red planet named for the Roman god of war [ http://www.pantheon.org/articles/m/mars.html ], has two tiny moons, Phobos [ http://www.nineplanets.org/phobos.html ] and Deimos [ http://www.nineplanets.org/deimos.html ], whose names are derived from the Greek for Fear and Panic. These martian moons [ http://antwrp.gsfc.nasa.gov/apod/ap031024.html ] may well be captured asteroids [ http://www.solarviews.com/eng/asteroid.htm ] originating in the main asteroid belt between Mars and Jupiter [ http://www.jpl.nasa.gov/galileo/jupiter/ jupiter.html ] or perhaps from even more distant reaches of the Solar System. The larger moon, Phobos [ http://antwrp.gsfc.nasa.gov/apod/ap030329.html ], is indeed seen to be a cratered, asteroid-like object in this stunning color image [ http://www.esa.int/SPECIALS/Mars_Express/ SEM21TVJD1E_0.html ] from the Mars Express spacecraft, recorded at a resolution of about seven meters per pixel. But Phobos orbits so close to Mars - about 5,800 kilometers above the surface compared to 400,000 kilometers for our Moon [ http://antwrp.gsfc.nasa.gov/apod/ap020504.html ] - that gravitational tidal forces [ http://csep10.phys.utk.edu/astr161/lect/moon/ tidal.html ] are dragging it down. In 100 million years or so it will likely crash into the surface or be shattered by stress caused by the relentless [ http://www.badastronomy.com/bad/misc/tides.html ] tidal forces, the debris forming a ring around Mars. |
|
Moon Over Andromeda
| Title |
Moon Over Andromeda |
| Explanation |
The Great Spiral Galaxy in Andromeda [ http://antwrp.gsfc.nasa.gov/apod/ap051222.html ] (aka M31), a mere 2.5 million light-years distant [ http://arxiv.org/abs/astro-ph/0511045 ], is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small, faint, fuzzy patch, but because its surface brightness is so low, casual skygazers [ http://www.physics.ucla.edu/~huffman/m31.html ] can't appreciate the galaxy's impressive extent in planet Earth's sky. This entertaining composite image compares the angular size [ http://chandra.harvard.edu/photo/scale.html ] of the nearby galaxy to a brighter, more familiar celestial sight. In it, a deep exposure of Andromeda [ http://www.caelumobservatory.com/gallery/m31abtp.shtml ], tracing beautiful blue star clusters in spiral arms far beyond the bright yellow core, is combined with a typical view of a nearly full Moon. Shown at the same angular scale, the Moon covers about 1/2 degree on the sky, while the galaxy is clearly [ http://www.regulusastro.com/regulus/papers/ m31/ ] several times that size. The deep Andromeda exposure also includes two bright satellite galaxies, M32 [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html ] and M110 [ http://antwrp.gsfc.nasa.gov/apod/ap060908.html ] (bottom). |
|
Solar Eclipse from the Moon
| Title |
Solar Eclipse from the Moon |
| Explanation |
Parts of Saturday's (March 3) lunar eclipse [ http://sunearth.gsfc.nasa.gov/eclipse/OH/OH2007.html ] will be widely visible. For example, skywatchers [ http://www.xs4all.nl/~carlkop/maaneclips2007/ leclips2007.html ] in Europe, Africa, and western Asia will be able to see the entire spectacle of the Moon gliding through Earth's shadow, but in eastern North America the Moon will rise already in its total eclipse phase [ http://www.mreclipse.com/Special/LEprimer.html ]. Of course if you traveled to the Moon's near side [ http://science.nasa.gov/headlines/y2007/ 12feb_lunareclipse.htm ], you could see the same event as a solar eclipse, with the disk of our fair planet Earth [ http://earthobservatory.nasa.gov/Newsroom/BlueMarble/ ] completely blocking out the Sun. For a moon-based observer's view, graphic artist Hana Gartstein (Haifa, Israel [ http://maps.google.com/maps?f=q&hl=en&q=haifa,+israel &layer=&ie=UTF8&om=1&z=7&ll=33.027088,34.865112 &spn=6.83228,13.886719&t=k ]) offers this composite illustration. In the cropped version of her picture, an Apollo 17 [ http://antwrp.gsfc.nasa.gov/apod/ap051210.html ] image of Earth is surrounded with a red-tinted haze as sunlight streams [ http://antwrp.gsfc.nasa.gov/apod/ap031121.html ] through the planet's dusty atmosphere. Earth's night [ http://antwrp.gsfc.nasa.gov/apod/ap050611.html ] side remains faintly visible, still illuminated by the dark, reddened Moon, but the disk of the Earth would appear almost four times the size of the Sun's disk, so the faint corona surrounding the Sun would be largely obscured. At the upper left, the Sun itself [ http://antwrp.gsfc.nasa.gov/apod/ap060330.html ] is just disappearing [ http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=399&vbody=301 &month=3&day=3&year=2007&hour=22&minute=05&rfov=2 &fovmul=-1&bfov=30&porbs=1&showsc=1 ] behind the Earth's limb. |
|
Oceans Under Jupiter's Moon
…
| Title |
Oceans Under Jupiter's Moon Ganymede? |
| Explanation |
The search for extraterrestrial [ http://www.seti.org/ ] life came back into our own Solar System [ http://www.seds.org/nineplanets/nineplanets/overview.html ] last week with the announcement [ http://www.jpl.nasa.gov/releases/2000/aguganymederoundup.html ] that there may be liquid oceans under the surface of Jupiter [ http://antwrp.gsfc.nasa.gov/apod/jupiter.html ]'s moon Ganymede [ http://www.jpl.nasa.gov/galileo/moons/ganymede.html ]. Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap000620.html ] now joins Callisto [ http://www.jpl.nasa.gov/galileo/news32.html ] and Europa [ http://www.jpl.nasa.gov/galileo/moons/europa.html ] as moons of Jupiter [ http://www.solarviews.com/eng/jupiter.htm ] that may harbor seas of liquid water under layers of surface ice [ http://antwrp.gsfc.nasa.gov/apod/ap980722.html ]. The ocean hypothesis surfaced as an explanation for Ganymede's unusually strong magnetic field [ http://www.igpp.ucla.edu/galileo/doc/n384/text.htm ]. Ganymede, the largest moon in the Solar System, also has the largest measured magnetic field [ http://www-spof.gsfc.nasa.gov/Education/Imagnet.html ] of any moon. Some exobiologists [ http://exobiology.nasa.gov/ssx/exobiology.html ] hypothesize that life may be able to emerge [ http://www.etext.org/Zines/Quanta/life.html ] in such an ocean, much as it did in the oceans of ancient Earth [ http://wwwcatsic.ucsc.edu/~eart1/Notes/Lec1.html ]. Above [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02583 ], a frame from a computer simulation [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenDownloadOpts.pl?PIA02583 ] shows what it would look like to fly over [ http://antwrp.gsfc.nasa.gov/apod/ap961025.html ] the surface of Ganymede, as extrapolated from photographs of the grooved moon [ http://antwrp.gsfc.nasa.gov/apod/ap960711.html ] taken by the robot spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/mission.html ] currently orbiting Jupiter. |
|
The Far Side of the Moon
| Title |
The Far Side of the Moon |
| Explanation |
Does this moon look familiar? Possibly not, even though it is Earth's Moon. Locked in synchronous rotation, the Moon [ http://www.nineplanets.org/luna.html ] always presents its well-known near side to Earth. But from lunar orbit, Apollo astronauts [ http://www.hq.nasa.gov/office/pao/History/SP-4204/cover.html ] also grew to know the Moon's far side. This sharp picture [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/a16_m_3021.html ] from Apollo 16 [ http://en.wikipedia.org/wiki/Apollo_16 ]'s mapping camera shows the eastern edge of the familiar near side [ http://antwrp.gsfc.nasa.gov/apod/ap040829.html ] (top) and the strange and heavily cratered far side [ http://en.wikipedia.org/wiki/The_Far_Side ] of the Moon. Surprisingly, the rough and battered surface [ http://antwrp.gsfc.nasa.gov/apod/ap061210.html ] of the far side looks very different [ http://en.wikipedia.org/wiki/Far_side_of_the_Moon ] from the near side which is covered with smooth dark lunar maria [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/lunar/mare/mlm.html ]. The likely explanation is that the far side [ http://antwrp.gsfc.nasa.gov/apod/ap070225.html ap950914.html ] crust is thicker, making it harder for molten material from the interior to flow to the surface and form the smooth maria [ http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=800 ]. |
|
Eclipsed Moon and Stars
| Title |
Eclipsed Moon and Stars |
| Explanation |
This dramatic image [ http://panther-observatory.com/gallery/moon/doc/ Mofi_03032007_cass.htm ] features a dark red Moon during a total lunar eclipse -- celestial shadow play [ http://antwrp.gsfc.nasa.gov/apod/ap060909.html ] enjoyed by many denizens of planet Earth [ http://spaceweather.com/eclipses/gallery_03mar07.htm ] last Saturday. Recorded near Wildon, Austria, the picture is a composite of two exposures, a relatively short exposure to feature the lunar surface and a longer exposure to capture background stars in the constellation Leo [ http://www.seds.org/Maps/Stars_en/Fig/leo.html ]. Completely immersed in Earth's cone-shaped shadow during the total eclipse [ http://www.inconstantmoon.com/cyc_ecl1.htm ] phase, the lunar surface is still illuminated by sunlight, reddened and [ http://antwrp.gsfc.nasa.gov/apod/ap031121.html ] refracted into the dark shadow region by a dusty atmosphere. As a result, familiar [ http://antwrp.gsfc.nasa.gov/apod/ap031212.html ] details of the Moon's nearside are easy to pick out, including the smooth lunar mare and the large ray crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap050305.html ]. In this telescopic view, the background stars are faint and most would be invisible to the naked eye. |
|
Moon Mare and Montes
| Title |
Moon Mare and Montes |
| Explanation |
This arresting [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ] image of the third quarter moon in the excellent skies above the Pine Crest Farm Observatory, Dell Prairie, Wisconsin, was recorded [ http://www.scancam.com/ ] with a 24 inch telescope and digital camera on October 19. Marvelously detailed [ http://www.seds.org/billa/psc/lunam.html ], especially along the terminator or shadow line between lunar night [ http://antwrp.gsfc.nasa.gov/apod/ap960919.html ] and day, this cropped version of the full mosaicked image shows the cratered north polar region (top) and the broad smooth Mare Imbrium [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/lunar/ mare/mlm.html ]. Notable at the northern edge [ http://www.arval.org.ve/MoonMapen.htm ] of the Mare Imbrium (Sea of Rains) is the 95 kilometer wide dark crater Plato, while the dramatic straight "cut" to the right of Plato, (toward the terminator) is the Vallis Alpes (Alpine Valley). The long, graceful arc of the lunar [ http://www.tiac.net/users/richarde/ ] Montes Apenninus (Apennine Mountains) in the lower portion of the image sweeps southward along the boundary of the mare toward the left and ends near the bright ray crater [ http://antwrp.gsfc.nasa.gov/apod/ap001216.html ] Copernicus [ http://cass.jsc.nasa.gov/expmoon/orbiter/ orbiter-craters.html#COPER ] at the picture's edge. In 1971, Apollo 15 [ http://www.hq.nasa.gov/alsj/a15/a15j.html ] landed near the gap beyond the opposite (northern) end of the Montes Apenninus arc. |
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Triton: Neptune's Largest Mo
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| Title |
Triton: Neptune's Largest Moon |
| Explanation |
In October of 1846, William Lassell [ http://en.wikipedia.org/wiki/William_Lassell ] was observing the newly discovered planet Neptune [ http://www.seds.org/nineplanets/nineplanets/neptune.html ]. He was attempting to confirm his observation, made just the previous week, that Neptune [ http://en.wikipedia.org/wiki/Neptune ] had a ring. But this time he discovered that Neptune had a satellite as well. Lassell soon proved that the ring was a product of his new telescope's distortion, but the satellite Triton [ http://www.seds.org/nineplanets/nineplanets/triton.html ] remained. The above picture [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/vg2_p34764.html ] of Triton [ http://en.wikipedia.org/wiki/Triton_%28moon%29 ] was taken in 1989 by the only spacecraft ever to pass Triton [ http://antwrp.gsfc.nasa.gov/apod/ap950805.html ]: Voyager [ http://antwrp.gsfc.nasa.gov/apod/ap020831.html ] 2. Voyager 2 found fascinating terrain [ http://nssdc.gsfc.nasa.gov/photo_gallery/caption/triton_close.txt ], a thin atmosphere, and even evidence for ice volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap010629.html ] on this world of peculiar orbit and spin. Ironically, Voyager 2 also confirmed the existence of complete thin rings [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/vg2_1135023.html ] around Neptune - but these would have been quite invisible [ http://www.youtube.com/watch?v=OQWxIrSRDQQ ] to Lassell! |
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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. |
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Eiffel Moon
| Title |
Eiffel Moon |
| Explanation |
Celestial and terrestrial lights are featured in this stunning image that includes the Moon in phases of the total lunar eclipse of March 3rd [ http://www.xs4all.nl/~carlkop/ maaneclips2007/leclips2007.html ]. In the foreground, the distinctively-shaped Eiffel Tower [ http://www.tour-eiffel.fr/teiffel/uk/ ], over 300 meters tall, is a well-known tourist destination [ http://maps.google.com/ maps?ie=UTF8&z=17&ll=48.8583,2.2945&spn=0.00324,0.007296&t=k&om=1 ] and one of the most visited buildings in the world. Of course the Moon is even more [ http://en.wikipedia.org/wiki/Moon_in_art_and_literature ] recognizable, but harder to visit [ http://en.wikipedia.org/wiki/A_Grand_Day_Out ]. The last lunar tour was undertaken nearly 35 years ago, during the Apollo 17 mission [ http://antwrp.gsfc.nasa.gov/apod/ap060826.html ]. |
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A Blue Crescent Moon from Sp
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| Title |
A Blue Crescent Moon from Space |
| Explanation |
What's happening to the Moon? Drifting around the Earth in 2006 July, astronauts from the International Space Station [ http://antwrp.gsfc.nasa.gov/apod/ap060920.html ] (ISS) captured a crescent Moon [ http://antwrp.gsfc.nasa.gov/apod/ap060618.html ] floating far beyond the horizon. The captured above image [ http://eobadmin.gsfc.nasa.gov/Newsroom/NewImages/images.php3?img_id=17542 ] is interesting because part of the Moon appears blue [ http://antwrp.gsfc.nasa.gov/apod/ap040731.html ], and because part of the moon appears missing. Both effects are created by the Earth's atmosphere [ http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html ]. Air molecules [ http://en.wikipedia.org/wiki/Molecules ] more efficiently scatter increasingly blue light, making the clear day sky blue [ http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html ] for ground observers, and the horizon blue for astronauts. Besides reflecting sunlight, these atmospheric molecules [ http://en.wikipedia.org/wiki/Air ] also deflect moonlight, making the lower part of the moon appear to fade away. As one looks higher in the photograph [ http://eol.jsc.nasa.gov/scripts/sseop/photo.pl?mission=ISS013&roll=E&frame=54329 ], the increasingly thin atmosphere appears to fade to black [ http://antwrp.gsfc.nasa.gov/apod/ap000913.html ]. |
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