|
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury Transit from TRACE (
…
| Title |
Mercury Transit from TRACE (White Light) |
| Abstract |
This is a view of the planet Mercury (a black dot) as seen by TRACE through its white light optical telescope. Because the TRACE field-of-view is much smaller than the solar disk, the spacecraft is repointed three times during the transit (creating the position jumps of the movie). This movie was generated from telemetry which has undergone a minimum of processing (to deliver quickly for the media) so data dropouts and other quick-processing artifacts may be visible. Special thanks to Dawn Myers of the TRACE project for this effort. |
| Completed |
2006-11-14 |
|
STEREO Coronal Mass Ejection
…
| Title |
STEREO Coronal Mass Ejection: From the EUVI to HI-2 |
| Abstract |
This movie collects imagery from SOHO and STEREO-A of a coronal mass ejection (CME) during January of 2007. The instruments in this view, from left to right, are STEREO/HI-1, STEREO/HI-2, SOHO/LASCO/C3, SOHO/LASCO/C2, and STEREO/EUVI. The Heliospheric Imager, HI-2, shows some of the tail of comet McNaught. The dark trapezoidal shape on the left edge of the image in HI-2 is the Earth occulter which will block out the disk of the Earth when it moves into view (since the planet will appear so bright as to saturate the detectors). Due to ongoing work with the STEREO coronagraphs, COR1 and COR2, the SOHO/LASCO coronagraphs are used for this movie. The blue Sun in the center of the coronagraphs is STEREO/EUVI ultraviolet images. There is a 22 hour gap in the data coverage for HI-2 which creates the appearance of a jump in the playback. These are not standard images but are called `running difference' images which highlight changes in the view. White pixels correspond to increases in brightness, while dark pixels reflect a decrease in brightness, with respect to the immediately previous image. 'Running differencing' generates some unusual effects. For example, the mottled background is created by the motion of the stars through the field-of-view as the spacecraft pointing direction slowly changes (the Andromeda galaxy is the oblong 'smudge' near the upper left corner). The planets Venus (right edge of HI-2) and Mercury are visible (near center of HI-1), their column of pixels saturated due to their brightness. * STEREO: Solar TErrestrial RElations Observatory * SOHO: SOlar Heliospheric Observatory * LASCO: Large Angle and Spectrometric Coronagraph * EUVI: Extreme UltraViolet Imager |
| Completed |
2007-02-26 |
|
STEREO Coronal Mass Ejection
…
| Title |
STEREO Coronal Mass Ejection: From the EUVI to HI-2 |
| Abstract |
This movie collects imagery from SOHO and STEREO-A of a coronal mass ejection (CME) during January of 2007. The instruments in this view, from left to right, are STEREO/HI-1, STEREO/HI-2, SOHO/LASCO/C3, SOHO/LASCO/C2, and STEREO/EUVI. The Heliospheric Imager, HI-2, shows some of the tail of comet McNaught. The dark trapezoidal shape on the left edge of the image in HI-2 is the Earth occulter which will block out the disk of the Earth when it moves into view (since the planet will appear so bright as to saturate the detectors). Due to ongoing work with the STEREO coronagraphs, COR1 and COR2, the SOHO/LASCO coronagraphs are used for this movie. The blue Sun in the center of the coronagraphs is STEREO/EUVI ultraviolet images. There is a 22 hour gap in the data coverage for HI-2 which creates the appearance of a jump in the playback. These are not standard images but are called `running difference' images which highlight changes in the view. White pixels correspond to increases in brightness, while dark pixels reflect a decrease in brightness, with respect to the immediately previous image. 'Running differencing' generates some unusual effects. For example, the mottled background is created by the motion of the stars through the field-of-view as the spacecraft pointing direction slowly changes (the Andromeda galaxy is the oblong 'smudge' near the upper left corner). The planets Venus (right edge of HI-2) and Mercury are visible (near center of HI-1), their column of pixels saturated due to their brightness. * STEREO: Solar TErrestrial RElations Observatory * SOHO: SOlar Heliospheric Observatory * LASCO: Large Angle and Spectrometric Coronagraph * EUVI: Extreme UltraViolet Imager |
| Completed |
2007-02-26 |
|
STEREO Coronal Mass Ejection
…
| Title |
STEREO Coronal Mass Ejection: From the EUVI to HI-2 |
| Abstract |
This movie collects imagery from SOHO and STEREO-A of a coronal mass ejection (CME) during January of 2007. The instruments in this view, from left to right, are STEREO/HI-1, STEREO/HI-2, SOHO/LASCO/C3, SOHO/LASCO/C2, and STEREO/EUVI. The Heliospheric Imager, HI-2, shows some of the tail of comet McNaught. The dark trapezoidal shape on the left edge of the image in HI-2 is the Earth occulter which will block out the disk of the Earth when it moves into view (since the planet will appear so bright as to saturate the detectors). Due to ongoing work with the STEREO coronagraphs, COR1 and COR2, the SOHO/LASCO coronagraphs are used for this movie. The blue Sun in the center of the coronagraphs is STEREO/EUVI ultraviolet images. There is a 22 hour gap in the data coverage for HI-2 which creates the appearance of a jump in the playback. These are not standard images but are called `running difference' images which highlight changes in the view. White pixels correspond to increases in brightness, while dark pixels reflect a decrease in brightness, with respect to the immediately previous image. 'Running differencing' generates some unusual effects. For example, the mottled background is created by the motion of the stars through the field-of-view as the spacecraft pointing direction slowly changes (the Andromeda galaxy is the oblong 'smudge' near the upper left corner). The planets Venus (right edge of HI-2) and Mercury are visible (near center of HI-1), their column of pixels saturated due to their brightness. * STEREO: Solar TErrestrial RElations Observatory * SOHO: SOlar Heliospheric Observatory * LASCO: Large Angle and Spectrometric Coronagraph * EUVI: Extreme UltraViolet Imager |
| Completed |
2007-02-26 |
|
STEREO Coronal Mass Ejection
…
| Title |
STEREO Coronal Mass Ejection: From the EUVI to HI-2 |
| Abstract |
This movie collects imagery from SOHO and STEREO-A of a coronal mass ejection (CME) during January of 2007. The instruments in this view, from left to right, are STEREO/HI-1, STEREO/HI-2, SOHO/LASCO/C3, SOHO/LASCO/C2, and STEREO/EUVI. The Heliospheric Imager, HI-2, shows some of the tail of comet McNaught. The dark trapezoidal shape on the left edge of the image in HI-2 is the Earth occulter which will block out the disk of the Earth when it moves into view (since the planet will appear so bright as to saturate the detectors). Due to ongoing work with the STEREO coronagraphs, COR1 and COR2, the SOHO/LASCO coronagraphs are used for this movie. The blue Sun in the center of the coronagraphs is STEREO/EUVI ultraviolet images. There is a 22 hour gap in the data coverage for HI-2 which creates the appearance of a jump in the playback. These are not standard images but are called `running difference' images which highlight changes in the view. White pixels correspond to increases in brightness, while dark pixels reflect a decrease in brightness, with respect to the immediately previous image. 'Running differencing' generates some unusual effects. For example, the mottled background is created by the motion of the stars through the field-of-view as the spacecraft pointing direction slowly changes (the Andromeda galaxy is the oblong 'smudge' near the upper left corner). The planets Venus (right edge of HI-2) and Mercury are visible (near center of HI-1), their column of pixels saturated due to their brightness. * STEREO: Solar TErrestrial RElations Observatory * SOHO: SOlar Heliospheric Observatory * LASCO: Large Angle and Spectrometric Coronagraph * EUVI: Extreme UltraViolet Imager |
| Completed |
2007-02-26 |
|
STEREO Coronal Mass Ejection
…
| Title |
STEREO Coronal Mass Ejection: From the EUVI to HI-2 |
| Abstract |
This movie collects imagery from SOHO and STEREO-A of a coronal mass ejection (CME) during January of 2007. The instruments in this view, from left to right, are STEREO/HI-1, STEREO/HI-2, SOHO/LASCO/C3, SOHO/LASCO/C2, and STEREO/EUVI. The Heliospheric Imager, HI-2, shows some of the tail of comet McNaught. The dark trapezoidal shape on the left edge of the image in HI-2 is the Earth occulter which will block out the disk of the Earth when it moves into view (since the planet will appear so bright as to saturate the detectors). Due to ongoing work with the STEREO coronagraphs, COR1 and COR2, the SOHO/LASCO coronagraphs are used for this movie. The blue Sun in the center of the coronagraphs is STEREO/EUVI ultraviolet images. There is a 22 hour gap in the data coverage for HI-2 which creates the appearance of a jump in the playback. These are not standard images but are called `running difference' images which highlight changes in the view. White pixels correspond to increases in brightness, while dark pixels reflect a decrease in brightness, with respect to the immediately previous image. 'Running differencing' generates some unusual effects. For example, the mottled background is created by the motion of the stars through the field-of-view as the spacecraft pointing direction slowly changes (the Andromeda galaxy is the oblong 'smudge' near the upper left corner). The planets Venus (right edge of HI-2) and Mercury are visible (near center of HI-1), their column of pixels saturated due to their brightness. * STEREO: Solar TErrestrial RElations Observatory * SOHO: SOlar Heliospheric Observatory * LASCO: Large Angle and Spectrometric Coronagraph * EUVI: Extreme UltraViolet Imager |
| Completed |
2007-02-26 |
|
STEREO Coronal Mass Ejection
…
| Title |
STEREO Coronal Mass Ejection: From the EUVI to HI-2 |
| Abstract |
This movie collects imagery from SOHO and STEREO-A of a coronal mass ejection (CME) during January of 2007. The instruments in this view, from left to right, are STEREO/HI-1, STEREO/HI-2, SOHO/LASCO/C3, SOHO/LASCO/C2, and STEREO/EUVI. The Heliospheric Imager, HI-2, shows some of the tail of comet McNaught. The dark trapezoidal shape on the left edge of the image in HI-2 is the Earth occulter which will block out the disk of the Earth when it moves into view (since the planet will appear so bright as to saturate the detectors). Due to ongoing work with the STEREO coronagraphs, COR1 and COR2, the SOHO/LASCO coronagraphs are used for this movie. The blue Sun in the center of the coronagraphs is STEREO/EUVI ultraviolet images. There is a 22 hour gap in the data coverage for HI-2 which creates the appearance of a jump in the playback. These are not standard images but are called `running difference' images which highlight changes in the view. White pixels correspond to increases in brightness, while dark pixels reflect a decrease in brightness, with respect to the immediately previous image. 'Running differencing' generates some unusual effects. For example, the mottled background is created by the motion of the stars through the field-of-view as the spacecraft pointing direction slowly changes (the Andromeda galaxy is the oblong 'smudge' near the upper left corner). The planets Venus (right edge of HI-2) and Mercury are visible (near center of HI-1), their column of pixels saturated due to their brightness. * STEREO: Solar TErrestrial RElations Observatory * SOHO: SOlar Heliospheric Observatory * LASCO: Large Angle and Spectrometric Coronagraph * EUVI: Extreme UltraViolet Imager |
| Completed |
2007-02-26 |
|
Earth and Moon as Viewed fro
…
| Title |
Earth and Moon as Viewed from Mars |
| Description |
This is the first image of Earth ever taken from another planet that actually shows our home as a planetary disk. Because Earth and the Moon are closer to the Sun than Mars, they exhibit phases, just as the Moon, Venus, and Mercury do when viewed from Earth. As seen from Mars by the NASA Mars Global Surveyor on May 8, 2003, at 13:00 GMT (6:00 a.m. PDT), Earth and the Moon appeared in the evening sky. This Earth/Moon image has been specially processed to allow both Earth (with an apparent magnitude of -2.5) and the much darker Moon (with an apparent magnitude of +0.9) to be visible together. The bright area at the top of the image of Earth is cloud cover over central and eastern North America. Below that, a darker area includes Central America and the Gulf of Mexico. The bright feature near the center right of the crescent Earth consists of clouds over northern South America. The image also shows the Earth-facing hemisphere of the Moon, since the Moon was on the far side of Earth as viewed from Mars. The slightly lighter tone of the lower portion of the image of the Moon results from the large and conspicuous ray system associated with the crater Tycho. A note about the coloring process: The Mars Global Surveyor Mars Orbital Camera (MOC, a high-resolution camera) only takes grayscale (black-and-white) images. To "colorize" the image, a Mariner 10 Earth/Moon image taken in 1973 was used to color this Earth and Moon picture. The procedure used was as follows: the Mariner 10 image was converted from 24-bit color to 8-bit color using a JPEG to GIF conversion program. The 8-bit color image was converted to 8-bit grayscale and an associated lookup table mapping each gray value of the image to a red-green-blue color triplet (RGB). Each color triplet was root-sum-squared (RSS), and sorted in increasing RSS values. These sorted lists were brightness-to-color maps for the images. Each brightness-to-color map was then used to convert the 8-bit grayscale MOC image to an 8-bit color image. This 8-bit color image was then converted to a 24-bit color image. The color image was edited to return the background to black. Image courtesy NASA/JPL/Malin Space Science Systems [ http://www.msss.com/ ] |
|
Astronomy From An F-18
| Title |
Astronomy From An F-18 |
| Explanation |
In an era of blossoming [ http://antwrp.gsfc.nasa.gov/apod/ap991228.html ] ground and space-based observatories, astronomers are also pushing the envelope with airborne instrumentation - successfully capturing an asteroid occultation [ http://www.boulder.swri.edu/swuis/polyxo.html ] from a high performance jet aircraft. This blinking animation represents two digitized frames from inflight data of asteroid number 308 [ http://pluto.harvard.edu/iau/lists/NumberedMPs00001.html ], Polyxo, passing in front of or occulting [ http://antwrp.gsfc.nasa.gov/apod/ap990802.html ] a faint star near the center of the field. The camera used, known as the SouthWest Ultraviolet Imaging System (SWUIS) -A [ http://www.boulder.swri.edu/~durda/eosarticle.html ], was mounted in the cockpit [ http://www.boulder.swri.edu/~durda/swuis.html ] of a NASA F/A-18 jet [ http://www.dfrc.nasa.gov/Projects/SRA/ ] (inset lower left). A former US Navy fighter aircraft, the F/A-18 [ http://www.dfrc.nasa.gov/gallery/ photo/F-18SRA/Medium/EC95-42988-5.jpg ] was able to maneuver to the precise position to record the occultation while cruising above clouds and much of Earth's obscuring atmosphere. Using the SWUIS-A data to time the occultation will reveal [ http://www.boulder.swri.edu/~durda/research.html ] the size of the asteroid which is otherwise too small to be imaged by even the orbiting Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap000105.html ]. Future SWUIS-A airborne missions [ http://www.boulder.swri.edu/swuis/swuis.instr.html ] may include a hunt for Vulcanoids, a suspected population of small asteroids [ http://www.seds.org/nineplanets/nineplanets/asteroids.html ] circling [ http://near.jhuapl.edu/ ] the Sun inside the orbit of Mercury. |
|
Southwest Mercury
| Title |
Southwest Mercury |
| Explanation |
The planet Mercury resembles a moon. Mercury [ http://www.seds.org/nineplanets/nineplanets/mercury.html ]'s old surface is heavily cratered [ http://liftoff.msfc.nasa.gov/Academy/SPACE/SolarSystem/Meteors/Craters.html ] like many moons. Mercury [ http://www.solarviews.com/eng/mercury.htm ] is larger than most moons but smaller than Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap990806.html ]'s moon Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap990304.html ] and Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap960717.html ]'s moon Titan [ http://antwrp.gsfc.nasa.gov/apod/ap990207.html ]. Mercury is much denser and more massive than any moon, though, because it is made mostly of iron. In fact, the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990131.html ] is the only planet more dense. A visitor to Mercury's surface [ http://antwrp.gsfc.nasa.gov/apod/ap960121.html ] would see some strange sights. Because Mercury [ http://www.oulu.fi/~spaceweb/textbook/mercury.html ] rotates exactly three times every two orbits around the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap951004.html ], and because Mercury [ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mercury.html ]'s orbit is so elliptical, a visitor to Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap990102.html ] might see the Sun [ http://antwrp.gsfc.nasa.gov/htmltest/gifcity/interv.html ] rise, stop in the sky, go back toward the rising horizon [ http://antwrp.gsfc.nasa.gov/apod/ap990619.html ], stop again, and then set quickly over the other horizon. From Earth [ http://antwrp.gsfc.nasa.gov/apod/ap980530.html ], Mercury's proximity to the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ] cause it to be visible only for a short time just after sunset or just before sunrise. |
|
Sky and Planets
| Title |
Sky and Planets |
| Explanation |
On February 10th, an evocative [ http://www.jps.net/ssumner/ ] evening sky above Rocklin, California, USA inspired astrophotographer Steve Sumner to record this remarkable sight - five planets and the Moon. Near its first quarter phase, the bright Moon [ http://lunar.arc.nasa.gov/ ] was intentionally overexposed but Saturn [ http://www.jpl.nasa.gov/cassini/ ], Jupiter [ http://galileo.jpl.nasa.gov/ ], Mars [ http://mars.jpl.nasa.gov/ ], and Mercury [ http://sd-www.jhuapl.edu/MESSENGER/ ] (and, of course, planet Earth's [ http://www.earth.nasa.gov/ ] horizon) are all clearly visible in the deepening twilight. Notably absent in this grouping of naked-eye planets is Venus [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html ] which is still putting in an early appearance as the morning star [ http://ispec.scibernet.com/station/morn_star.html ]. This month, Mercury has joined Venus in the dawn twilight while Saturn, Jupiter, and Mars still shine brightly in the western sky at nightfall [ http://www.skypub.com/sights/sights.shtml ] making another gorgeous close grouping with the crescent Moon [ http://www.inconstantmoon.com/ ]. |
|
Mercury on the Horizon
| Title |
Mercury on the Horizon |
| Explanation |
Have you ever seen the planet Mercury? Because Mercury [ http://www.seds.org/nineplanets/nineplanets/mercury.html ] orbits so close to the Sun, it is never seen far from the Sun, and so is only visible near sunrise [ http://antwrp.gsfc.nasa.gov/apod/ap990817.html ] or sunset [ http://antwrp.gsfc.nasa.gov/apod/ap990619.html ]. If trailing the Sun, Mercury [ http://antwrp.gsfc.nasa.gov/apod/mercury.html ] will be visible for several minutes before it follows the Sun [ http://antwrp.gsfc.nasa.gov/apod/sun.html ] behind the Earth [ http://antwrp.gsfc.nasa.gov/apod/earth.html ]. If leading the Sun, Mercury [ http://www.solarviews.com/eng/mercury.htm ] will be visible [ http://www.skypub.com/sights/northern/0003skyn.html ] for only several minutes before the Sun [ http://www.seds.org/nineplanets/nineplanets/sol.html ] rises and hides it with increasing glare. An informed skygazer [ http://www.skypub.com/sights/northern/0003skyn.html ] can usually pick Mercury out of a dark horizon glow [ http://antwrp.gsfc.nasa.gov/apod/ap991110.html ] with little more than determination. Above, a lot of determination has been combined with a little digital trickery [ http://www.astropix.com/HTML/J_DIGIT/ETHICS.HTM ] to show [ http://www.galeon.com/eclipses/indexi.htm ] Mercury's successive positions during the middle of last month. Each picture was taken from the same location in Spain when the Sun was 10 degrees below the horizon [ http://antwrp.gsfc.nasa.gov/apod/ap970909.html ] and superposed on the single most photogenic sunset [ http://antwrp.gsfc.nasa.gov/apod/ap980526.html ]. |
|
The Very Large Array of Radi
…
| Title |
The Very Large Array of Radio Telescopes |
| Explanation |
The most photogenic array of radio telescopes [ http://csep10.phys.utk.edu/astr162/lect/light/radio.html ] in the world has also been one of the most productive. Each of the 27 radio telescopes [ http://www.r-clarke.org.uk/astrolinks_radio.htm ] in the Very Large Array [ http://en.wikipedia.org/wiki/Very_Large_Array ] (VLA) is the size of a house [ http://www.msue.msu.edu/msue/imp/mod02/master02.html ] and can be moved on train tracks. The above pictured [ http://www.aoc.nrao.edu/intro/vlapix/vlaviews.index.html ] VLA [ http://antwrp.gsfc.nasa.gov/apod/ap990620.html ], inaugurated in 1980 is situated in New Mexico [ http://www.state.nm.us/ ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ]. The VLA [ http://www.vla.nrao.edu/ ] has been used to discover water on planet Mercury [ http://www.nrao.edu/pr/2000/vla20/background/mercuryice/ ], radio-bright coronae around ordinary stars [ http://www.nrao.edu/pr/2000/vla20/background/radiostars/ ], micro-quasars in our Galaxy [ http://www.nrao.edu/pr/2000/vla20/background/superlum/ ], gravitationally-induced Einstein rings around distant galaxies [ http://www.nrao.edu/pr/2000/vla20/background/ering/ ], and radio counterparts to cosmologically distant gamma-ray bursts [ http://www.nrao.edu/pr/1998/grb/ ]. The vast size of the VLA [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?VLA ] has allowed astronomers to study the details of super-fast cosmic jets [ http://www.nrao.edu/pr/2000/vla20/background/jets/ ], and even map the center [ http://www.nrao.edu/pr/2000/vla20/background/galcenter/ ] of our Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap020521.html ]. An upgrade of the VLA [ http://www.aoc.nrao.edu/evla/ ] is being planned. |
|
Pleiades, Planets, And Hot P
…
| Title |
Pleiades, Planets, And Hot Plasma |
| Explanation |
Bright stars of the Pleiades, four planets, and erupting solar plasma are all captured in this spectacular image [ http://sohowww.nascom.nasa.gov/hotshots/ ] from the space-based SOlar and Heliospheric Observatory (SOHO). In the foreground of the 15 degree wide field of view, a bubble of hot plasma, called a Coronal Mass Ejection (CME [ http://antwrp.gsfc.nasa.gov/apod/ap000309.html ]), is blasting away from the active Sun [ http://www.spaceweather.com/ ] whose position and relative size is indicated by the central white circle. Beyond [ http://sohowww.nascom.nasa.gov/hotshots/2000_05_03/ diagram1.jpg ] appear four of the five [ http://antwrp.gsfc.nasa.gov/apod/ap000505.html ] naked-eye planets [ http://sse.jpl.nasa.gov/features/planets/ planetsfeat.html ] -- courtesy [ http://www.badastronomy.com/bad/misc/planets.html ] of the planetary alignment [ http://science.nasa.gov/headlines/y2000/ ast30mar_1m.htm#alignments ] which did not destroy the world! In the background are distant stars and the famous Pleiades [ http://www.seds.org/messier/m/m045.html ] star cluster, also easily visible to the unaided eye when it shines in the night sky [ http://antwrp.gsfc.nasa.gov/apod/ap000504.html ]. Distances for these familiar [ http://www.seds.org/nineplanets/nineplanets/ nineplanets.html ] celestial objects are, the Sun [ http://helios.gsfc.nasa.gov/sun.html ], 150 million kilometers away, Mercury, Venus, Jupiter, and Saturn, about 58, 110, 780, and 1,400 million kilometers beyond the Sun respectively, and the Pleiades [ http://www.ras.ucalgary.ca/~gibson/pleiades/ ] star cluster at a mere 3,800 trillion kilometers (400 light-years). SOHO itself orbits 1.5 million kilometers sunward of planet Earth. The image [ http://sohowww.nascom.nasa.gov/data/latestimages.html ] was recorded by the Large Angle and Spectrometric COronagraph (LASCO) instrument on board SOHO on Monday, May 15 at 10:42 UT. |
|
Planets In The Sun
| Title |
Planets In The Sun |
| Explanation |
Today [ http://science.nasa.gov/headlines/y2000/ast02may_1.htm ], all five naked-eye planets [ http://www.seds.org/nineplanets/nineplanets/ ] (Mercury, Venus, Mars, Jupiter, Saturn) plus the Moon and the Sun [ http://helios.gsfc.nasa.gov/ sun.html ] will at least approximately line-up. As viewed [ http://drumright.ossm.edu/astronomy/conjunctions.html ] from planet Earth, they will be clustered within about 26 degrees, the closest alignment for all these celestial bodies [ http://science.nasa.gov/headlines/y2000/ ast30mar_1m.htm#alignments ] since February 1962, when there was a solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap990818.html ]! Such planetary alignments [ http://www.griffithobs.org/SkyAlignments.html ] are not dangerous, except of course that the Sun might hurt your eyes when you look at it [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ]. So it might be easier [ http://sohowww.nascom.nasa.gov/hotshots/ ] to appreciate today's solar system [ http://space.jpl.nasa.gov/ ] spectacle if |
|
Ganymede: The Largest Moon i
…
| Title |
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 ]. |
|
The Very Large Array Turns T
…
| Title |
The Very Large Array Turns Twenty |
| Explanation |
The most photogenic array of radio telescopes [ http://csep10.phys.utk.edu/astr162/lect/light/radio.html ] in the world has also been one of the most productive. Each of the 27 radio telescopes [ http://www.r-clarke.org.uk/astrolinks_radio.htm ] in the Very Large Array [ http://info.aoc.nrao.edu/doc/vla/html/VLAintro.shtml ] (VLA) is the size of a house [ http://www.msue.msu.edu/msue/imp/mod02/master02.html ] and can be moved on train tracks. The VLA [ http://antwrp.gsfc.nasa.gov/apod/ap990620.html ], celebrating its twentieth year [ http://www.aoc.nrao.edu/pr/vla20/vla20.html ] of operation, is pictured above [ http://www.aoc.nrao.edu/intro/vlapix/vlaviews.index.html ] in a compact formation in front of Tres Montosas [ http://angeleschapter.org/sps/summits/nm/socorro.htm ], New Mexico [ http://www.state.nm.us/ ], USA [ http://www.odci.gov/cia/publications/factbook/us.html ]. The VLA [ http://info.aoc.nrao.edu/vla/html/VLAhome.shtml ] has been used to discover water on planet Mercury [ http://www.aoc.nrao.edu/pr/vla20/mercury.ice.html ], radio-bright coronae around ordinary stars [ http://www.aoc.nrao.edu/pr/vla20/radiostars.html ], micro-quasars in our Galaxy [ http://www.aoc.nrao.edu/pr/vla20/superlum.html ], gravitationally-induced Einstein rings around distant galaxies [ http://www.aoc.nrao.edu/pr/vla20/einstein.ring.html ], and radio counterparts to cosmologically distant gamma-ray bursts [ http://www.aoc.nrao.edu/pr/vla20/grb.html ]. The vast size of the VLA [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?VLA ] has allowed astronomers to study the details of super-fast cosmic jets [ http://www.aoc.nrao.edu/pr/vla20/jets.html ], and even map the center of our Galaxy [ http://www.aoc.nrao.edu/pr/vla20/galcenter.html ]. An upgrade of the VLA [ http://www.aoc.nrao.edu/pr/evla.decadereview.html ] is being planned [ http://info.aoc.nrao.edu/vla/html/Upgrade/Upgrade_home.shtml ]. |
|
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. |
|
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. |
|
3D Mercury Transit
| Title |
3D Mercury Transit |
| Explanation |
Mercury is now [ http://www.astronomy.com/ASY/CS/forums/314872/ ShowPost.aspx ] visible shortly before dawn, the brightest "star" just above the eastern horizon. But almost two weeks ago Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap061114.html ] actually crossed the face of the Sun for the second time in the 21st century. Viewed with red/blue glasses [ http://photojournal.jpl.nasa.gov/Help/VendorList.html ], this stereo anaglyph combines space-based images of the Sun and innermost planet in a just-for-fun 3D [ http://www.sungazer.net/3dtransit.html ] presentation of the Mercury transit [ http://www.transitofvenus.org/mercury.htm ]. The solar disk image is from Hinode [ http://solarb.msfc.nasa.gov/index.html ]. (sounds like "hee-no-day", means sunrise). A sun-staring observatory, Hinode was launched from Uchinoura Space Center and viewed the transit [ http://solar-b.nao.ac.jp/news_e/20061109_e.shtml ] from Earth orbit. Superimposed on Mercury's dark silhouette is a detailed image [ http://antwrp.gsfc.nasa.gov/apod/ap011124.html ] of the planet's rugged surface based on data from the Mariner 10 [ http://nssdc.gsfc.nasa.gov/nmc/tmp/1973-085A.html ] probe that flew by Mercury in 1974 and 1975. |
|
Children of the Sun
| Title |
Children of the Sun |
| Explanation |
For a moment [ http://photojournal.jpl.nasa.gov/index.html ], planets Jupiter [ http://kids.nineplanets.org/jupiter.htm ], Venus [ http://kids.nineplanets.org/venus.htm ], Mars [ http://kids.nineplanets.org/mars.htm ], and Mercury [ http://kids.nineplanets.org/mercury.htm ] all posed near their parent star in this Sun-centered view, recorded on November 11. The picture, from a coronograph onboard the space-based SOlar Heliospheric Observatory [ http://sohowww.nascom.nasa.gov/ ], spans 15 degrees with the Sun's size and position indicated by the white circle. Background stars are also visible as the otherwise overwhelming sunlight is blocked by the coronograph's [ http://lasco-www.nrl.navy.mil/index.php?p=content/ about_lasco ] occulting disk. But the planets themselves, in particular Jupiter and Venus, are still bright enough to cause significant horizontal streaks in the image. Mercury is actually moving most rapidly (left to right) through the field and days earlier [ http://sohowww.nascom.nasa.gov/hotshots/2006_11_06/ ] was seen to cross in front [ http://www.spaceweather.com/eclipses/gallery_08nov06.htm ] of the solar disk. So what's that bright double star to the left of Mars? Zubenelgenubi [ http://antwrp.gsfc.nasa.gov/apod/ap040514.html ], of course. |
|
Hand Drawn Transit
| Title |
Hand Drawn Transit |
| Explanation |
The sight [ http://astroday.net/MercTransit06.html ] of Mercury's tiny round disk drifting slowly across the face of the Sun inspired [ http://www.transitofvenus.org/mercury.htm ] and entertained [ http://www.rasnz.org.nz/Events2006.htm#Transit ] many denizens [ http://en.wikipedia.org/wiki/Image: Georges_Seurat_-_Un_dimanche_apr%C3%A8s-midi_%C3%A0_l%27%C3%8Ele_de_la_Grande_Jatte.jpg ] of planet Earth last week. In fact, artist and astronomer Mark Seibold viewed both the 1999 [ http://antwrp.gsfc.nasa.gov/apod/ap991119.html ] and 2006 [ http://antwrp.gsfc.nasa.gov/apod/ap061114.html ] transits of the solar system's innermost planet through solar filtered [ http://www.spaceweather.com/eclipses/ gallery_08nov06_page2.htm ] telescopes and composed this rendering [ http://s10.photobucket.com/albums/a109/ markseibold/?action=view¤t=transitmercurytoday-1.jpg ] of Mercury "hovering in the photosphere" near the edge of an enormous solar disk. The original work is a 23 by 17 inch pastel sketch. While the artist's hand [ http://www.etropolis.com/escher/hands.htm ] is creatively superimposed, Seibold concentrated on offering an impression of Mercury's silhouette, surrounded by shadings reflecting his visual experience that are not easily captured in photographic exposures. Of course, before the age of cameras drawings [ http://antwrp.gsfc.nasa.gov/apod/ap031025.html ] were more widely used to record telescopic observations of sunspots [ http://www.astro.ucla.edu/~obs/resource.html ] and planetary transits [ http://star.arm.ac.uk/history/ transit.html ]. |
|
Mercury and the Chromosphere
| Title |
Mercury and the Chromosphere |
| Explanation |
Enjoying [ http://www.spaceweather.com/eclipses/ gallery_08nov06.htm ] Wednesday's transit of Mercury [ http://sohowww.nascom.nasa.gov/hotshots/2006_11_06/ ] from Dallas, Texas, astronomer Phil Jones recorded this detailed image [ http://www.visualuniverse.org/ solar_mercury_transit.shtml ] of the Sun. Along with a silhouette of the innermost planet, a network of cells and dark filaments [ http://solar.physics.montana.edu/YPOP/Program/ hfilament.html ] can be seen against a bright solar disk with spicules and prominences [ http://antwrp.gsfc.nasa.gov/apod/ap030418.html ] along the Sun's edge. The composited image was taken through a telescope equiped with an H-alpha filter that narrowly transmits only the red light from hydrogen atoms. Such images emphasize the solar chromosphere [ http://solar.physics.montana.edu/YPOP/Program/ chromosphere.html ], the region of the Sun's atmosphere immediately above its photosphere or normally visible surface. Left of center, the tiny disk of Mercury seems to be imitating a small sunspot that looks a little too round. But in H-alpha pictures [ http://www.spaceweathercenter.org/living_with_a_star/01/ solarvision.html ], sunspot regions are usually dominated by bright splotches (called plages [ http://csep10.phys.utk.edu/astr162/lect/sun/ prominences.html ]) on the solar chromosphere. |
|
Mercury's Transit: An Unusua
…
| Title |
Mercury's Transit: An Unusual Spot on the Sun |
| Explanation |
What's that dot on the Sun? [ http://www.davidcortner.com/astro/mtransit/ ] If you look closely, it is almost perfectly round. The dot is the result of an unusual type of solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap060404.html ] that occurred last week. Usually it is the Earth's Moon [ http://www.windows.ucar.edu/tour/link=/earth/ moons_and_rings.html ] that eclipses the Sun. Last week, for the first time in over three years, the planet Mercury [ http://en.wikipedia.org/wiki/Mercury_%28mythology%29 ] took a turn. Like the approach to New Moon before a solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap040926.html ], the phase of Mercury became a continually thinner crescent [ http://antwrp.gsfc.nasa.gov/apod/ap061030.html ] as the planet progressed toward an alignment with the Sun. Eventually the phase of Mercury dropped [ http://antwrp.gsfc.nasa.gov/apod/ap040606.html ] to zero and the dark spot of Mercury crossed our parent star. The situation could technically be labeled a Mercurian annular eclipse [ http://www.mreclipse.com/Special/SEprimer.html ] with an extraordinarily large ring of fire [ http://antwrp.gsfc.nasa.gov/apod/ap020610.html ]. From above the cratered planes [ http://antwrp.gsfc.nasa.gov/apod/ap040912.html ] of the night side of Mercury, the Earth appeared in its fullest phase. Hours later, as Mercury continued in its orbit, a slight crescent phase appeared again. The next Mercurian solar eclipse [ http://en.wikipedia.org/wiki/ Transit_of_Mercury_from_Earth ] will occur in 2016. |
|
Simulated Transit of Mercury
| Title |
Simulated Transit of Mercury |
| Explanation |
Mercury, the solar system's innermost planet, will spend about five hours crossing in front of the Sun today [ http://science.nasa.gov/headlines/y2006/ 20oct_transitofmercury.htm ] - beginning at 1912 UT [ http://aa.usno.navy.mil/faq/docs/UT.html ] (2:12pm EST), November 8. Specially equipped telescopes are highly recommended to safely spot the planet's [ http://antwrp.gsfc.nasa.gov/apod/ap991210.html ] diminutive silhouette however, as Mercury should appear about 200 times smaller than the enormous solar disk. This simulated view [ http://www.sungazer.net/transitsim.html ] is based on a filtered solar image recorded on November 3rd. It shows active regions and the Mercury transit [ http://sunearth.gsfc.nasa.gov/eclipse/OH/transit06.html ] across the Sun at six positions from lower left to middle right [ http://www.sungazer.net/transit110806a.html ]. Depending on your location [ http://sunearth.gsfc.nasa.gov/eclipse/OH/ image1/TM2006Nov08-Fig2.GIF ], the Sun may not be above the horizon during the entire transit, but webcasts of the event [ http://www.exploratorium.edu/transit/ ] are planned - including one using images from the sun-staring SOHO [ http://sohowww.nascom.nasa.gov/hotshots/ 2006_11_06/ ] spacecraft. This is the second of 14 transits of Mercury during the 21st century. The next similar event will be a transit of Venus in June of 2012. |
|
A Big Dish at the VLA Radio
…
| Title |
A Big Dish at the VLA Radio Observatory |
| Explanation |
They are so large, they are almost unreal. The radio dishes of the Very Large Array [ http://www.vla.nrao.edu/ ] (VLA) of radio telescopes [ http://csep10.phys.utk.edu/astr162/lect/light/radio.html ] might appear to some as a strange combination of a dinosaur skeleton [ http://www.bbc.co.uk/sn/prehistoric_life/games/skeleton_jigsaw/skeletal_jigsaws/index.shtml ] and common satellite-TV receiving dish [ http://en.wikipedia.org/wiki/Satellite_dish ]. Together, the 27 dishes of the VLA [ http://en.wikipedia.org/wiki/Very_Large_Array ] combine high sensitivity with high resolution, enabling a series of important astronomical discoveries, including water ice on planet Mercury [ http://www.nrao.edu/pr/2000/vla20/background/mercuryice/ ], micro-quasars in our Galaxy [ http://www.nrao.edu/pr/2000/vla20/background/superlum/ ], gravitationally-induced Einstein rings around distant galaxies [ http://www.nrao.edu/pr/2000/vla20/background/ering/ ], and radio counterparts to cosmologically distant gamma-ray bursts [ http://www.nrao.edu/pr/1998/grb/ ]. Pictured above, a dish from the VLA was photographed last week near Socorro [ http://en.wikipedia.org/wiki/Socorro%2C_New_Mexico ], New Mexico [ http://en.wikipedia.org/wiki/New_Mexico ], USA [ https://www.odci.gov/cia/publications/factbook/geos/us.html ]. |
|
Three Planets in Dawn Skies
| Title |
Three Planets in Dawn Skies |
| Explanation |
Three children of the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap061116.html ] rise in the east in this peaceful dawn skyview recorded December 7th near Bolu, Turkey. Inner planet Mercury [ http://kids.nineplanets.org/mercury.htm ], fresh from its second transit [ http://antwrp.gsfc.nasa.gov/apod/ap061114.html ] of the 21st century, stands highest in the bright sky at the top right. Gas giant Jupiter [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ jupiterfact.html ] lies below the cloud bank near picture center. A newsworthy Mars [ http://www.nasa.gov/mission_pages/mars/news/ mgs-20061206.html ] is also visible, right of Jupiter and just above the dark cloud bank. On Sunday, these planets will form a much tighter grouping [ http://skytonight.com/observing/ataglance ] before sunrise [ http://niteskys.com/mercury_mars_jupiter_120806.html ], while in the coming days the western sky after sunset will be ruled by brilliant planet Venus [ http://www.esa.int/SPECIALS/Venus_Express/ ], also known as the evening star. |
|
The Ecliptic Plane
| Title |
The Ecliptic Plane |
| Explanation |
The Plane of the Ecliptic is well illustrated in this picture from the 1994 lunar prospecting Clementine spacecraft. Clementine's star tracker camera image reveals (from right to left) the Moon [ http://lunar.arc.nasa.gov/ ] lit by Earthshine, the Sun's corona [ http://antwrp.gsfc.nasa.gov/apod/ap960530.html ] rising over the Moon's dark limb, and the planets Saturn [ http://www.jpl.nasa.gov/cassini/ ], Mars [ http://mars.jpl.nasa.gov/ ], and Mercury [ http://sd-www.jhuapl.edu/MESSENGER/ ]. The ecliptic plane is defined as the imaginary plane containing the Earth's orbit around the Sun. In the course of a year, the Sun's apparent path [ http://www.astro.wisc.edu/~dolan/constellations/extra/Zodiac.html ] through the sky lies in this plane. The Solar System's [ http://space.jpl.nasa.gov/ ] planetary bodies all tend to lie near this plane, since they were formed from the Sun's spinning, flattened, proto-planetary disk [ http://antwrp.gsfc.nasa.gov/apod/ap990611.html ]. The snapshot above nicely captures a momentary line-up looking out along this fundamental plane of our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap990505.html ]. |
|
Comet Over Krakow
| Title |
Comet Over Krakow |
| Explanation |
Bright Comet [ http://antwrp.gsfc.nasa.gov/apod/ap070109.html ] McNaught (C/2006 P1) graced the twilight this week, seen by many [ http://spaceweather.com/comets/gallery_mcnaught_page5.htm ] and often described with superlatives. Watching the skies over Krakow [ http://www.google.com/maps?f=q&hl=en&q=krakow,+poland&sll=37.0625,-95.677068&sspn=80.335305,76.816406&ie=UTF8&z=13&ll=50.065845,19.940186&spn=0.066224,0.131321&t=k&om=1 ], Poland, Andrzej Sawow recorded this view on Wednesday - with an ordinary handheld digital camera. He notes that "... astronomy is really for everyone who loves to look at the night sky. And fortunately (sometimes) the sky generously rewards its observer". Now very close to the Sun, Comet McNaught [ http://cometography.com/lcomets/2006p1.html ] (along with Mercury) is visible in realtime images from the SOHO spacecraft [ http://sohowww.nascom.nasa.gov/data/ realtime/c3/512/ ]. Otherwise, skywatchers will find the comet hard to see this weekend. But southern hemisphere observers could be rewarded next week as Comet McNaught begins to climb higher in southern skies [ http://skytonight.com/observing/highlights/5133461.html ]. |
|
Comet McNaught Heads for the
…
| Title |
Comet McNaught Heads for the Sun |
| Explanation |
Early morning risers with a clear and unobstructed eastern horizon can enjoy the sight of Comet McNaught (C/2006 P1) in dawn skies over the next few days. Discovered in August by R. H. McNaught (Siding Spring Survey [ http://www.mso.anu.edu.au/~rmn/ ]) the comet has grown bright enough to see with the unaided eye but will soon be lost in the glare of the Sun. Still, by January 11 sun-staring spacecraft SOHO should be able to offer web-based views [ http://sohowww.nascom.nasa.gov/data/realtime/c3/ 512/ ] as the comet heads toward [ http://neo.jpl.nasa.gov/cgi-bin/db_shm?name=c/2006+P1 ] a perihelion [ http://www.windows.ucar.edu/tour/ link=/physical_science/physics/mechanics/orbit/ perihelion_aphelion.html&edu=high ] passage inside the orbit of Mercury. This image captures [ http://www.astrostudio.at/Astrofotos/astrofotos.php?k_id=71 ] the new naked-eye comet [ http://www.nasa.gov/worldbook/comet_worldbook.html ] at about 2nd magnitude [ http://en.wikipedia.org/wiki/Apparent_magnitude ] in twilight skies near sunset on January 3rd. After rounding the Sun [ http://www.shadowandsubstance.com/ ] and emerging from the solar glare later this month, Comet McNaught [ http://www.aerith.net/comet/catalog/2006P1/2006P1.html ] could be even brighter. |
|
Comet McNaught Over Cataloni
…
| Title |
Comet McNaught Over Catalonia |
| Explanation |
This past weekend Comet McNaught peaked at a brightness that surpassed even Venus. Fascinated sky enthusiasts in the Earth's northern hemisphere were treated to an instantly visible [ http://antwrp.gsfc.nasa.gov/apod/ap070113.html ] comet head and a faint elongated tail near sunrise and sunset. Recent brightness estimates [ http://cfa-www.harvard.edu/icq/CometMags.html#2006P1 ] had Comet McNaught [ http://en.wikipedia.org/wiki/Comet_McNaught ] brighter than magnitude [ http://csep10.phys.utk.edu/astr162/lect/stars/magnitudes.html ] -5 (minus five) over this past weekend, making it the brightest comet [ http://cfa-www.harvard.edu/icq/brightest.html ] since Comet Ikeya-Seki [ http://en.wikipedia.org/wiki/Ikeya-Seki ] in 1965, which was recorded at -7 (minus seven). The Great Comet [ http://en.wikipedia.org/wiki/Great_Comet ] of 2007 reached its brightest as it rounded the Sun well inside the orbit of Mercury. Over the next week Comet McNaught [ http://cometography.com/lcomets/2006p1.html ] will begin to fade as it moves south and away from the Sun. The unexpectedly bright comet should remain visible [ http://cfa-www.harvard.edu/iau/Ephemerides/Comets/2006P1_1.html ] to observers in the southern hemisphere [ http://www.assa.org.au/sig/comets/mcnaught.asp ] with unaided eyes for the rest of January. The above image, vertically compressed, was taken at sunset last Friday from mountains above Catalonia [ http://en.wikipedia.org/wiki/Catalonia ], Spain [ http://en.wikipedia.org/wiki/Spain ]. |
|
SOHO: Comet McNaught Movie
| Title |
SOHO: Comet McNaught Movie |
| Explanation |
This frame from a spectacular time lapse movie [ http://soho.nascom.nasa.gov/ hotshots/ ] shows Comet McNaught [ http://skytonight.com/observing/highlights/5252006.html ] - the Great Comet of 2007 [ http://www.space.com/spacewatch/ 070112_ns_comet_mcnaught.html#mcn ] - sweeping through [ http://www.shadowandsubstance.com/ ] the inner solar system. The movie frames were recorded from January 12 through Jan 16 by a coronograph onboard [ http://lasco-www.nrl.navy.mil/ index.php?p=content/about_lasco ] the sun-staring SOHO spacecraft. Bright planet Mercury also glides dramatically through the field of view but the Sun itself remains fixed, hidden behind the coronograph's central occulting disk. The broad-tailed comet is [ http://www.nineplanets.org/comets.html ] so bright it almost overwhelms SOHO's sensitive camera designed to explore the fainter structures [ http://antwrp.gsfc.nasa.gov/apod/ap021213.html ] in the Sun's outer atmosphere. Comet McNaught's [ http://antwrp.gsfc.nasa.gov/apod/ap070119.html ] closest approach to the Sun (perihelion on January 12) was only 0.17 astronomical units [ http://en.wikipedia.org/wiki/Astronomical_unit ], or about half the distance between the Sun and Mercury. ("Note: To download the movie file, click on the picture.") |
|
McNaught's Matinee
| Title |
McNaught's Matinee |
| Explanation |
Comets grow bright when they're close to the Sun, basking [ http://antwrp.gsfc.nasa.gov/apod/ap020111.html ] in the intense solar radiation. Of course, they're also usually impossible to see against [ http://www.wonderquest.com/daylight-stars.htm ] the overwhelming scattered sunlight [ http://math.ucr.edu/home/baez/physics/ General/BlueSky/blue_sky.html ]. But surprising Comet McNaught - whose January 12 closest approach to the Sun (perihelion [ http://www.windows.ucar.edu/tour/ link=/physical_science/physics/mechanics/orbit/ perihelion_aphelion.html&edu=high ] passage) was well inside the orbit [ http://www.shadowandsubstance.com/ ] of Mercury - gave an enjoyable performance [ http://www.spaceweather.com/comets/ gallery_mcnaught_page7.htm ] in bright blue daytime skies. In fact, comet expert David Levy captured this remarkable inset (upper left) telescopic view of McNaught within an hour of perihelion, with the comet in broad daylight only about 7 degrees away from the Sun's position [ http://sohowww.nascom.nasa.gov/hotshots/ ]. Stefan Seip's wider daytime view [ http://www.photomeeting.de/astromeeting/comets/ 070113b_d.htm ] of the comet and fluffy clouds was recorded approximately a day later. Seip used a polarizing filter and a telescope/camera set up near Stuttgart, Germany. No longer visible in broad daylight, Comet McNaught [ http://en.wikipedia.org/wiki/Comet_McNaught ] is now touring twilight southern skies [ http://www.yp-connect.net/~mmatti/ ]. |
|
Degas Ray Crater on Mercury
| Title |
Degas Ray Crater on Mercury |
| Explanation |
Like the Earth's Moon, Mercury is [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html ] scarred with craters testifying to an intense bombardment during the early history [ http://antwrp.gsfc.nasa.gov/apod/ap990326.html ] of the Solar System. In 1974, the Mariner 10 [ http://pds.jpl.nasa.gov/planets/welcome/m10.htm ] spacecraft surveyed this innermost planet [ http://nssdc.gsfc.nasa.gov/imgcat/html/mission_page/ MC_Mariner_10_page1.html ] up close, producing the only detailed images of its tortured surface. In the above mosaic [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/ m10_aom_3_e.html ] the bright rays emanating from the 45 kilometer wide Degas crater almost appear to be painted on [ http://sunsite.unc.edu/wm/paint/auth/degas/ ]. The rays consist of light colored material blasted out during the crater's formation. Craters [ http://www.lpi.usra.edu/expmoon/science/ craterstructure.html ] older than Degas are covered by the ray material while younger craters are seen superimposed on the rays. Mercury's [ http://www.seds.org/nineplanets/nineplanets/ mercury.html ] gravity and density are about [ http://www.whfreeman.com/ENVIRONMENTALGEOLOGY/EXMOD36/ PLANET.HTM ] twice that of Earth's [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ planet_table_ratio.html ] Moon so such bright ray craters [ http://www.sunlink.net/~torff/bwlunar10.html ] on the lunar surface tend to be much larger. NASA plans to launch MESSENGER [ http://sd-www.jhuapl.edu/ MESSENGER/ ] to the least explored [ http://www.soest.hawaii.edu/PSRdiscoveries/Jan97/ MercuryUnveiled.html ] terrestrial planet in 2004. |
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Atmospheres Detected for Two
…
| Title |
Atmospheres Detected for Two Extrasolar Planets |
| Explanation |
Do extrasolar planets have water? In an attempt to find out, the orbiting Spitzer Space Telescope [ http://www.spitzer.caltech.edu/about/index.shtml ] made detailed observations of the atmospheres of two planets that orbit stars other than our Sun. Unfortunately, water vapor [ http://en.wikipedia.org/wiki/Water_vapor ] was not detected in either exoplanet. Spitzer watched star systems HD 209458b [ http://en.wikipedia.org/wiki/Osiris_(planet) ] and HD 189733b [ http://en.wikipedia.org/wiki/HD_189733b ] closely in infrared light both before and after the parent stars eclipsed their known planets. By comparing eclipsed [ http://csep10.phys.utk.edu/astr161/lect/time/eclipse_anim.html ] and uneclipsed spectra very closely, astronomers could deduce bright light-emitting atmospheric gasses that were being blocked during eclipse. Were water vapor one of these atmospheric gases, a new indication that life [ http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=2250 ] might exist outside of our Solar System [ http://www.nationalgeographic.com/solarsystem/ ] would have been found. The planets being analyzed are known as hot Jupiters [ http://en.wikipedia.org/wiki/Hot_Jupiter ] -- they have sizes close to Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap050911.html ] but orbits closer to the distance of Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap061114.html ]. The above illustration [ http://www.spitzer.caltech.edu/Media/releases/ssc2007-04/ssc2007-04d.shtml ] shows an artist's depiction of one of these dry worlds. Although no water vapor was detected this time, the techniques of measuring exoplanet [ http://exoplanet.eu/ ] atmospheres are quite promising, and the search for distant water and other biomarkers [ http://planetquest.jpl.nasa.gov/TPF/tpf_signsOfLife.cfm ] is just beginning. |
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Nashville Four Planet Skylin
…
| Title |
Nashville Four Planet Skyline |
| Explanation |
So far this February, evening skies [ http://antwrp.gsfc.nasa.gov/apod/ap000504.html ] have been blessed with a glorious Moon and three bright planets, Venus [ http://www.library.utoronto.ca/utel/rp/poems/ longfe10.html ], Jupiter, and Saturn. But just last week, on January 30th, an extreme wide-angle lens allowed astrophotographer Larry Koehn to capture this twilight view of Moon and four planets above [ http://www.seds.org/nineplanets/nineplanets/ see.html ] Nashville, Tennessee, USA. These major solar system [ http://space.jpl.nasa.gov/ ] bodies lie along the ecliptic plane [ http://antwrp.gsfc.nasa.gov/apod/ap001014.html ] and so follow a diagonal line through the picture. Starting near the upper left corner is bright Jupiter [ http://starchild.gsfc.nasa.gov/docs/StarChild/ solar_system_level2/jupiter.html ], which takes on a slightly triangular shape due to the lens distortion. Just below and right of Jupiter is Saturn [ http://www.jpl.nasa.gov/cassini/english/kids/ saturn_in_sky.html ]. Continuing along the diagonal toward the lower right is an overexposed, six day old Moon [ http://www.inconstantmoon.com/ ] and brilliant Venus seemingly embedded in clouds. The fourth planet pictured is Mercury. Notoriously hard to see from planet Earth because it never wanders far from the Sun, Mercury is [ http://antwrp.gsfc.nasa.gov/apod/ap991111.html ] visible just above the lower right corner. The line from Jupiter to Mercury spans about 92 degrees across the Nashville sky. |
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Water Claimed in Evaporating
…
| Title |
Water Claimed in Evaporating Planet HD 209458b |
| Explanation |
Planet HD 209458b [ http://antwrp.gsfc.nasa.gov/apod/ap991115.html ] is evaporating. It is so close to its parent star that its heated atmosphere is simply expanding away into space. Some astronomers studying this distant planetary system now believe they have detected water vapor among the gases being liberated. This controversial claim [ http://lanl.arxiv.org/abs/0704.1114 ], if true, would mark the first instance of planetary water beyond our Solar System, and indicate anew that life might be sustainable elsewhere in the universe. HD 209458 [ http://antwrp.gsfc.nasa.gov/apod/ap011128.html ]b is known as a hot Jupiter [ http://www.physorg.com/news11909.html ] type system because it involves a Jupiter-type planet in a Mercury-type orbit. Although spectroscopic [ http://en.wikipedia.org/wiki/Spectroscopy ] observations from the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap010806.html ] are the basis for the water detection claim, the planetary system is too small and faint to image. Therefore, an artist's impression of the HD 209458b system is shown above [ http://www.spacetelescope.org/images/html/heic0303b.html ]. Research into the atmospheric composition of HD 209458b [ http://en.wikipedia.org/wiki/HD_209458_b ] and other extrasolar planets [ http://en.wikipedia.org/wiki/Extrasolar_planet ] is continuing. |
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Bright Venus
| Title |
Bright Venus |
| Explanation |
Have you seen a bright evening star [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html ] in the western sky lately? That's no star, that's planet Venus the second "rock" from the Sun [ http://space.jpl.nasa.gov/ ]. Blazing at -4.6 magnitude [ http://liftoff.msfc.nasa.gov/academy/universe/ MAG.HTML ], Venus, after the Sun and Moon, is the third brightest celestial body in planet Earth's sky [ http://www.skypub.com/sights/sights.shtml ]. Venus is closer [ http://antwrp.gsfc.nasa.gov/apod/ap990612.html ] to the Sun than Earth and as Venus orbits [ http://astrosun.tn.cornell.edu/courses/astro201/ venus_phase.htm ] the Sun it is seen to go through phases [ http://euclid.sms.port.ac.uk/students/astrowise/ venus/demo1.html ] similar to the Moon. But unlike the Moon, as Venus waxes and wanes [ http://www.badastronomy.com/bitesize/ venus_phase.html ] its distance from Earth and hence its apparent size changes drastically. This causes Venus to look brighter [ http://www.science.nasa.gov/newhome/headlines/ ast14jun99_1.htm ] as it looms large in its crescent phases than when it is smaller and nearly full. Taken on January 28th, this dramatic picture finds a crescent Venus near its brightest to the right of a crescent Moon. The brilliant rivals seem poised above a satellite dish of the Scripps Satellite Oceanography Facility [ http://www.sio.ucsd.edu/about_scripps/scripps_tour/ siotour18.htm ]. Closer to the horizon, just below and to the right of the satellite dish, Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap000320.html ] pierces the twilight glow. |
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Sunrise from the Surface of
…
| Title |
Sunrise from the Surface of Gliese 581c |
| Explanation |
How might a sunrise appear on Gliese 581c? One artistic guess is shown above. Gliese 581c [ http://en.wikipedia.org/wiki/Gliese_581c ] is the most Earth-like planet [ http://eso.org/outreach/press-rel/pr-2007/pr-22-07.html ] yet discovered and lies a mere 20 light-years [ http://chandra.harvard.edu/photo/cosmic_distance.html ] distant. The central red dwarf [ http://antwrp.gsfc.nasa.gov/apod/ap991120.html ] is small and redder than our Sun [ http://www.nineplanets.org/sol.html ] but one of the orbiting planets has recently been discovered to be in the habitable zone [ http://www.pbs.org/lifebeyondearth/alone/habitable.html ] where liquid water could exist on its surface. Although this planet is much different from Earth [ http://antwrp.gsfc.nasa.gov/apod/ap070325.html ], orbiting much closer than Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap040912.html ] and containing five times the mass of Earth, it is now a candidate to hold not only oceans but life [ http://www.windows.ucar.edu/tour/link=/life/ocean_life.html ] enabled by the oceans. Were future observations to confirm liquid water, Gliese 581c [ http://antwrp.gsfc.nasa.gov/apod/ap070426.html ] might become a worthy destination or way station for future interstellar travelers [ http://www.strangehorizons.com/2004/20040621/travel.shtml ] from Earth. Drawn above in the hypothetical, the red dwarf star Gliese 581 [ http://en.wikipedia.org/wiki/Gliese_581 ] rises through clouds above a calm ocean [ http://antwrp.gsfc.nasa.gov/apod/ap061017.html ] of its planet Gliese 581c. |
|
Shepard Flies Freedom 7
| Title |
Shepard Flies Freedom 7 |
| Explanation |
Forty years ago today (May 5, 1961 [ http://www.thespaceplace.com/history/mercury/ mercury03.html ]), at the dawn of the space age [ http://www.hq.nasa.gov/office/pao/History/sputnik/ index.html ], NASA controllers "lit the candle" and sent Alan Shepard arcing into space atop a Redstone rocket [ http://antwrp.gsfc.nasa.gov/apod/ap980404.html ]. The picture shows the pressure-suited Shepard before launch in his cramped space capsule [ http://www.hq.nasa.gov/office/pao/History/diagrams/ mercury.html ] dubbed "Freedom 7" [ http://images.jsc.nasa.gov/images/pao/MR3/ 10073523.htm ]. Broadcast live to a global television audience, the flight of Freedom 7 [ http://www.nasm.edu/galleries/attm/nojs/rm.ey.f7.1.html ] - the first space flight by an American - followed less than a month after the first human venture into space by Soviet Cosmonaut Yuri Gagarin [ http://antwrp.gsfc.nasa.gov/apod/ap010414.html ]. Freedom 7's historic flight [ http://www.hq.nasa.gov/office/pao/History/40thmerc7/ intro.htm ] was suborbital, lasting only about 15 minutes, but during it Shepard demonstrated manual control of his capsule. Naval aviator [ http://www.hq.nasa.gov/office/pao/History/40thmerc7/ shepard.htm ] Shepard was chosen as one of the original seven Mercury Program [ http://www.hq.nasa.gov/office/pao/History/SP-4201/ toc.htm ] astronauts. He considered this first flight [ http://www.hq.nasa.gov/office/pao/History/SP-4201/ch11-4.htm ] the greatest challenge and actively sought the assignment. Shepard's career as an astronaut spanned a remarkable period in human achievement and in 1971 he walked on the moon [ http://www.hq.nasa.gov/office/pao/History/alsj/a14/ a14.crew.html ] as commander of the Apollo 14 mission. A true pioneer and intrepid explorer, Alan Shepard died in 1998 [ http://www.nasa.gov/shepard.html ] at age 74. |
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Comet Encke's Tail Ripped Of
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| Title |
Comet Encke's Tail Ripped Off |
| Explanation |
Swinging inside the orbit of Mercury, on April 20th periodic comet Encke [ http://cometography.com/pcomets/002p.html ] encountered a blast from the Sun in the form of a Coronal Mass Ejection [ http://solarscience.msfc.nasa.gov/CMEs.shtml ] (CME). When CMEs, enormous clouds of energetic particles ejected from the Sun, slam into Earth's magnetosphere, they often trigger auroral displays [ http://antwrp.gsfc.nasa.gov/apod/ap050916.html ]. But in this case, the collison carried the tail of the comet away. The tail was [ http://science.nasa.gov/headlines/y2007/ 01oct_encke.htm ] likely ripped off by interacting magnetic fields rather than the mechanical pressure of the collision [ http://secchi.nrl.navy.mil/Publications/ Vourlidas_encke_07.pdf ]. Clicking on the two panel image will play a movie gif of the remarkable event as recorded by the Heliospheric Imager [ http://www.stereo.rl.ac.uk/science/project/ index.shtml ] onboard the STEREO A spacecraft [ http://www.nasa.gov/mission_pages/stereo/main/ index.html ]. In the movie, the time between frames is about 45 minutes, while the frames span about 14x20 million kilometers at the distance of the comet. Of course, similar collisions have happened before as the ancient comet loops [ http://antwrp.gsfc.nasa.gov/apod/ap031223.html ] through its 3.3 year solar orbit [ http://antwrp.gsfc.nasa.gov/apod/ap051115.html ]. So don't worry, Encke's tail grows [ http://www.ifa.hawaii.edu/~jewitt/tail.html ] back! |
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Mercury: A Cratered Inferno
| Title |
Mercury: A Cratered Inferno |
| Explanation |
Mercury's surface looks similar to our Moon's. Each is heavily cratered [ http://antwrp.gsfc.nasa.gov/apod/ap960906.html ] and made of rock. Mercury [ http://www.nineplanets.org/mercury.html ]'s diameter is about 4800 km, while the Moon [ http://antwrp.gsfc.nasa.gov/apod/moon.html ]'s is slightly less at about 3500 km (compared with about 12,700 km for the Earth [ http://antwrp.gsfc.nasa.gov/apod/earth.html ]). But Mercury [ http://www.oulu.fi/~spaceweb/textbook/mercury.html ] is unique in many ways. Mercury [ http://www.hawastsoc.org/solar/eng/mercury.htm ] is the closest planet to the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap960518.html ], orbiting at about 1/3 the radius of the Earth's orbit [ http://aa.usno.navy.mil/faq/docs/seasons_orbit.html ]. As Mercury [ http://pds.jpl.nasa.gov/planets/welcome/mercury.htm ] slowly rotates, its surface temperature varies from an unbearably "cold" -180 degrees Celsius [ http://www.athena.ivv.nasa.gov/curric/weather/fahrcels.html ] to an unbearably hot 400 degrees Celsius [ http://www.astro.uu.se/history/Celsius_eng.html ]. The place nearest the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap980830.html ] in Mercury [ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mercury.html ]'s orbit changes slightly each orbit - a fact used by Albert Einstein [ http://antwrp.gsfc.nasa.gov/apod/ap000108.html ] to help verify the correctness of his then newly discovered theory of gravity: General Relativity [ http://www-groups.dcs.st-andrews.ac.uk/~history/HistTopics/General_relativity.html ]. The above picture [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/m10_aom_18.html ] was taken by the only spacecraft ever to pass Mercury [ http://antwrp.gsfc.nasa.gov/apod/mercury.html ]: Mariner 10 [ http://www.hawastsoc.org/solar/eng/marin10.htm ] in 1974. |
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The Earth and Moon Planetary
…
| Title |
The Earth and Moon Planetary System |
| Explanation |
How similar in size are the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap010204.html ] and the Moon [ http://antwrp.gsfc.nasa.gov/apod/ap000113.html ]? A dramatic visual answer [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02441 ] to this question is found by combining photographs taken by the Mariner 10 spacecraft [ http://nssdc.gsfc.nasa.gov/nmc/tmp/1973-085A.html ] that headed out toward Venus [ http://www.nineplanets.org/venus.html ] and Mercury [ http://www.solarviews.com/eng/mercury.htm ] in 1973. The Moon [ http://www.nineplanets.org/luna.html ] can be seen to have a diameter over one quarter that of Earth [ http://antwrp.gsfc.nasa.gov/apod/earth.html ], relatively large compared to its planetary companion [ http://antwrp.gsfc.nasa.gov/apod/ap991231.html ]. In our Solar System [ http://www.nineplanets.org/overview.html ], only Pluto and Charon [ http://antwrp.gsfc.nasa.gov/apod/ap980708.html ] are closer together in size. Striking features of the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap001127.html ] visible to the passing spacecraft include blue oceans [ http://seawifs.gsfc.nasa.gov/ocean_planet.html ] and white clouds [ http://vortex.plymouth.edu/clouds.html ], showing the Earth [ http://earthobservatory.nasa.gov/ ] to be truly a water world [ http://antwrp.gsfc.nasa.gov/apod/ap980530.html ]. |
|
Mariner's Mercury
| Title |
Mariner's Mercury |
| Explanation |
Mercury [ http://www.seds.org/nineplanets/nineplanets/ mercury.html ], the closest planet to the Sun, remains the most mysterious [ http://wwwflag.wr.usgs.gov/USGSFlag/Space/wall/ mercury.html ] of the Solar System's inner planets. Hiding in the Sun's glare [ http://antwrp.gsfc.nasa.gov/apod/ap991119.html ] it is a difficult target [ http://www.bu.edu/csp/imaging_science/planetary/mercury/ ] for Earth bound observers. The only spacecraft to explore Mercury [ http://www.psrd.hawaii.edu/Jan97/ MercuryUnveiled.html ] close-up was Mariner 10 [ http://sse.jpl.nasa.gov/missions/merc_missns/ merc-m10.html ] which executed three flybys of [ http://nssdc.gsfc.nasa.gov/nmc/tmp/ 1973-085A-traj.html ] Mercury in 1974 and 1975, surveying approximately 45 percent of its surface. Mariner 10 [ http://nssdc.gsfc.nasa.gov/nmc/tmp/1973-085A.html ] deftly manuevered to photograph part of the sunlit hemisphere during each approach, passed behind the planet, and continued to image the sun-facing side as the spacecraft receded. Its highest resolution photographs [ http://nssdc.gsfc.nasa.gov/imgcat/html/mission_page/ MC_Mariner_10_page1.html ] recorded features approximately a mile across. A reprocessing of the Mariner 10 data [ http://www.earth.nwu.edu/people/robinson/merc.html ] has resulted in this dramatic mosaic. Like the Earth's Moon, Mercury's surface [ http://antwrp.gsfc.nasa.gov/apod/ap010819.html ] shows the scars of impact [ http://antwrp.gsfc.nasa.gov/apod/ap990326.html ] cratering - the smooth vertical band and patches visible above represent regions where no image information is available. |
|
A Leonids Star Field
| Title |
A Leonids Star Field |
| Explanation |
As meteor after meteor streaked across a moonless sky, photographers [ http://leonids.hq.nasa.gov/leonids/gallery/date/all.html ] across the world snapped pictures [ http://SpaceWeather.com/meteors/gallery_18nov01.html ] of the 2001 Leonids Meteor Shower [ http://comets.amsmeteors.org/meteors/showers/leonidhistory.html ]. Many recognized this as the best meteor shower they had ever seen. In fact, the 2001 Leonids [ http://science.nasa.gov/headlines/y2001/ast15nov_1.htm ] was the most active meteor [ http://www.nineplanets.org/meteorites.html ] shower since the mid-1960s. The above photo captures three Leonid meteors [ http://antwrp.gsfc.nasa.gov/apod/ap011104.html ] crossing a photogenic star-field [ http://antwrp.gsfc.nasa.gov/apod/ap000929.html ]. On the far right is the Pleiades [ http://antwrp.gsfc.nasa.gov/apod/ap010506.html ] star cluster [ http://antwrp.gsfc.nasa.gov/apod/open_clusters.html ]. The brightest meteor [ http://antwrp.gsfc.nasa.gov/apod/ap011119.html ] crosses right in front of the Hyades star cluster [ http://www.aspsky.org/mercury/mercury/9803/hyades.html ], situated below the image center. Just left of center is the bright planet Saturn [ http://antwrp.gsfc.nasa.gov/apod/saturn.html ], and the bright star below Saturn is Aldebaran [ http://www.astro.uiuc.edu/~kaler/sow/aldebaran.html ]. The ten-minute exposure was taken near Victoria [ http://www.city.victoria.bc.ca/ ], British Columbia [ http://www.gov.bc.ca/ ], Canada [ http://www.cia.gov/cia/publications/factbook/geos/ca.html ] at 2:45 am PST [ http://atm.geo.nsf.gov/ieis/time.html ] on 2001 November 18. |
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