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Venus and Comet Pojmanski
| Title |
Venus and Comet Pojmanski |
| Explanation |
Shining brightly in the east at dawn, Venus [ http://antwrp.gsfc.nasa.gov/apod/ap060201.html ] dominates the sky in this view over a suburban landscape from Bursa, Turkey. An otherwise familiar scene for astronomer Tunc Tezel, his composite picture of the morning sky recorded on March 2nd also includes a surprise visitor to the inner solar system, Comet [ http://www.windows.ucar.edu/tour/link=/comets/ comets.html&edu=high ] Pojmanski. Cataloged as C/2006 A1 [ http://www.aerith.net/comet/catalog/2006A1/ 2006A1.html ], the comet was discovered on January 2nd by Grzegorz Pojmanski of Warsaw University Astronomical Observatory [ http://www.astrouw.edu.pl/ ] in Poland. At the time very faint [ http://www.aerith.net/pictures/comet.html#2006A1 ] and tracking through southern skies [ http://www.yp-connect.net/~mmatti/ ], the comet has now moved north and grown just bright enough to be a good target for early-rising [ http://astroblogger.blogspot.com/2006/02/ hunting-comet-pojmanski.html ] skygazers with binoculars. Enhanced and framed in this picture, the comet's tail [ http://antwrp.gsfc.nasa.gov/apod/ap000413.html ] has also grown to a length of several degrees. The comet will be at its closest approach to planet Earth, just over 100 million kilometers away, on March 5. For northern hemisphere observers in the next few days, the beginning of morning twilight really will be the best time to spot Comet Pojmanski [ http://skyandtelescope.com/observing/objects/comets/ article_1684_1.asp ]. |
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Crumbling Comet
| Title |
Crumbling Comet |
| Explanation |
This false-color mosaic [ http://www.spitzer.caltech.edu/Media/releases/ssc2006-13/ release.shtml ] of crumbling comet Schwassmann-Wachmann 3 [ http://skyandtelescope.com/observing/objects/comets/ article_1704_1.asp ] spans about 6 degrees (12 full moons) along the comet's orbit. Recorded on May 4-6 by an infrared camera on board the Spitzer Space Telescope, the picture captures about 45 of the 60 or more alphabetically [ http://neo.jpl.nasa.gov/cgi-bin/db?name=73P ] cataloged large comet fragments. The brightest fragment at the upper right of the track is Fragment C [ http://antwrp.gsfc.nasa.gov/apod/ap060512.html ]. Bright Fragment B [ http://antwrp.gsfc.nasa.gov/apod/ap060504.html ] is below and left of center. Looking for clues to how the comet broke up, Spitzer's infrared view [ http://coolcosmos.ipac.caltech.edu/ image_galleries/ir_zoo/ ] also captures the trail of dust left over as the comet deteriorated during previous passes [ http://cometography.com/pcomets/073p.html ]. Emission from the dust particles warmed by sunlight appears to fill the space along the cometary orbit. The fragments are near their closest approach in the coming days [ http://www.skyhound.com/sh/73P.html ], about 10 million kilometers away, and none pose any danger [ http://www.nasa.gov/mission_pages/hubble/Comet_73P.html ] to our fair planet. |
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Crumbling Comet Schwassmann-
…
| Title |
Crumbling Comet Schwassmann-Wachmann 3 Approaches |
| Explanation |
A crumbling comet will soon pass near the Earth. Comet 73P/Schwassmann-Wachmann 3 [ http://science.nasa.gov/headlines/y2006/24mar_73p.htm ] is brightening and may even be visible to the unaided eye [ http://webvision.med.utah.edu/anatomy.html ] when the fragmented comet [ http://antwrp.gsfc.nasa.gov/apod/ap040724.html ] zooms past Earth during the middle of next month. Still, the small comet poses no Earth hazard [ http://liftoff.msfc.nasa.gov/Academy/SPACE/SolarSystem/Meteors/ImpactHazard.html ], since it will pass the Earth at about 25 times the distance of the Moon. Exactly how bright Comet Schwassman-Wachmann 3 [ http://en.wikipedia.org/wiki/73P/Schwassmann-Wachmann ] will get is unknown. It is even possible, althought unlikely, that debris from the comet [ http://cometography.com/pcomets/073p.html ] will have spread out enough to cause a notable meteor shower [ http://antwrp.gsfc.nasa.gov/apod/ap031116.html ]. Pictured above [ http://www.eso.org/outreach/press-rel/pr-2006/phot-15-06.html ], Fragment B of Comet Schwassman-Wachmann 3 [ http://www.eso.org/outreach/press-rel/pr-2006/pr-15-06.html ] was photographed two nights ago by a 8.2-meter Very Large Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap990309.html ] in Chile [ http://en.wikipedia.org/wiki/Chile ]. Visible [ http://antwrp.gsfc.nasa.gov/apod/ap060426.html http://www.space.com/spacewatch/060414_night_sky.html ] to the lower right of the large B fragment are many mini-comets that have broken off and now orbit the Sun separately. Each mini-comet itself sheds gas and dust and so appears to have its own hazy coma. The comet [ http://skyandtelescope.com/observing/objects/comets/article_1704_1.asp ] will pass closest to the Sun on June 7. |
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Comet Meets Ring Nebula: Par
…
| Title |
Comet Meets Ring Nebula: Part II |
| Explanation |
Moving rapidly through planet Earth's night sky, Fragment C of crumbling [ http://www.spitzer.caltech.edu/Media/releases/ ssc2006-13/index.shtml ] comet 73P/Schwassmann-Wachmann 3 [ http://skyandtelescope.com/observing/objects/comets/ article_1704_1.asp ] passed almost directly in front of M57 [ http://seds.lpl.arizona.edu/messier/m/m057.html ] - the Ring Nebula, and faint spiral galaxy IC 1296 [ http://www.skyhound.com/sh/archive/jul/IC_1296.html ] on May 8. In fact, in this gorgeous view [ http://www.masil-astro-imaging.com/ Latest_Images.html ], the bright head of Fragment C is separated by only about 0.1 degrees from M57, with the tail apparently engulfing nebula and galaxy. Recorded from Elizabeth, Illinois, USA, this picture corresponds to the cosmic scene only 30 minutes after yesterday's picture [ http://antwrp.gsfc.nasa.gov/apod/ap060511.html ] of the approaching alignment. The relative motion of the comet [ http://www.galacticimages.com/astronomical_events.html ] against the background stars and nebulae is easy to see when comparing the two images. This comet's fragments [ http://www.skyhound.com/sh/73P.html ] will be near their closest approach in the coming days, about 10 million kilometers away, and none pose any danger [ http://www.nasa.gov/mission_pages/hubble/ Comet_73P.html ] to our fair planet. |
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Comet Meets Ring Nebula: Par
…
| Title |
Comet Meets Ring Nebula: Part I |
| Explanation |
As dawn approached on May 8, astronomer Stefan Seip carefully watched Fragment C of broken [ http://neo.jpl.nasa.gov/cgi-bin/db?name=73P ] comet 73P/Schwassmann-Wachmann 3 [ http://skyandtelescope.com/observing/objects/comets/ article_1704_1.asp ] approach M57 [ http://seds.lpl.arizona.edu/messier/m/m057.html ] - the Ring Nebula, and faint spiral galaxy IC 1296 [ http://www.skyhound.com/sh/archive/jul/IC_1296.html ]. Of course, even though the trio seemed to come close together in a truly cosmic photo opportunity, the comet [ http://antwrp.gsfc.nasa.gov/apod/ap060504.html ] is in the inner part of our solar system, a mere 0.5 light-minutes [ http://en.wikipedia.org/wiki/Light-minute ] or so from Seip's telescope located near Stuttgart, Germany, planet Earth [ http://science.nasa.gov/headlines/y2006/ 24mar_73p.htm?list237669 ]. The Ring Nebula (upper right) is more like 2,000 light-years distant, well within our own Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap050825.html ]. At a distance of 200 million light-years, IC 1296 (between comet and ring) is beyond even the Milky Way's boundaries. Because the comet is so close, it appears to move relatively rapidly against the distant stars. This dramatic telescopic view [ http://www.photomeeting.de/astromeeting/comets/ 060508SchwWas_a_d.htm ] was composited from two sets of images, one compensating [ http://www.ewellobservatory.com/ccd/ comet.cfm ] for the comet's apparent motion and one recording the background stars and nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap030516.html ]. |
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Exploring Comet Tails
| Title |
Exploring Comet Tails |
| Explanation |
Comets [ http://seds.lpl.arizona.edu/billa/tnp/comets.html ] are known for their tails. In the spring [ http://antwrp.gsfc.nasa.gov/apod/ap970320.html ] of 1997 and 1996 Comet Hale-Bopp [ http://encke.jpl.nasa.gov/hale_bopp_info.html ] (above) and Comet Hyakutake [ http://encke.jpl.nasa.gov/comets_long/96B2.html ] gave us stunning examples [ http://pages.prodigy.net/pam.orman/JoeGallery.html ] as they passed near the Sun. These extremely active comets [ http://antwrp.gsfc.nasa.gov/apod/ap980410.html ] were bright, naked-eye spectacles offering researchers an opportunity to telescopically [ http://encke.jpl.nasa.gov/ ] explore the composition of primordial chunks of our solar system by studying their long and beautiful tails. But it has only recently been discovered that surprising readings [ ftp://ftp.hq.nasa.gov/pub/pao/pressrel/2000/00-055.txt ] from experiments on-board the interplanetary Ulysses probe [ http://ulysses.jpl.nasa.gov ] which lasted for several hours on May 1, 1996, indicate the probe passed through [ http://www.sp.ph.ic.ac.uk/Ulysses/comet/ ] comet Hyakutake's tail! Ulysses experiments were intended [ http://ulysses.jpl.nasa.gov/science/objectives.html ] to study the Sun and solar wind and the spacecraft-comet [ http://stardust.jpl.nasa.gov/ ] encounter was totally unanticipated. Relative positions of Ulysses [ http://ulysses-ops.jpl.esa.int/ulysses/ ] and Hyakutake on that date indicate that this comet's ion tail [ http://antwrp.gsfc.nasa.gov/apod/ap960319.html ] stretched an impressive 360 million miles or about four times the Earth-Sun distance [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ]. This makes Hyakutake's tail the longest ever recorded [ http://heasarc.gsfc.nasa.gov/docs/heasarc/missions/isee3.html ] and suggests that comet tails [ http://antwrp.gsfc.nasa.gov/apod/ap960327.html ] are much longer than previously believed. |
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Comet Schwassmann-Wachmann 3
…
| Title |
Comet Schwassmann-Wachmann 3 Passes the Earth |
| Explanation |
Rarely does a comet pass this close to Earth. Last week, dedicated astrofilmographers were able to take advantage of the close approach of crumbling 73P / Comet Schwassmann-Wachmann 3 [ http://en.wikipedia.org/wiki/Comet_73P ] to make time-lapse movies of the fast-moving comet. Large comet fragments passed about 25 times the Moon's distance from the Earth. The above time lapse movie of Fragment B [ http://antwrp.gsfc.nasa.gov/apod/ap060504.html ] of Comet Schwassmann-Wachmann 3 [ http://antwrp.gsfc.nasa.gov/apod/ap060511.html ] over Colorado [ http://en.wikipedia.org/wiki/Colorado ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ] was taken during a single night, May 16, with 83 consecutive 49-second exposures. Some observers report being able to perceive the slight motion of the comet with respect to the background stars using only their binoculars [ http://www.yesmag.bc.ca/Questions/binoculars.html ] and without resorting to the creation of fancy digital time-lapse movies. Fragment B of Comet Schwassmann-Wachmann 3 [ http://www.eso.org/outreach/press-rel/pr-2006/pr-15-06.html ] became just barely visible to the unaided eye two weeks ago but now is appearing to fade as the comet has moved past the Earth and nears the Sun. Many sky enthusiasts [ http://antwrp.gsfc.nasa.gov/apod/ap040808.html ] will be on the watch for a particularly active meteor shower tonight as the Earth made its closest approach to orbit of Comet Schwassmann-Wachmann 3 [ http://skyandtelescope.com/observing/objects/comets/article_1704_1.asp ] late yesterday. |
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Comet Dust over Colorado
| Title |
Comet Dust over Colorado |
| Explanation |
The rock formation in the foreground of this night view was recorded on August 10, illuminated by light from a waning gibbous Moon. Even though [ http://antwrp.gsfc.nasa.gov/apod/ap060811.html ] the sky above also scatters the bright moonlight, a brilliant meteor was captured as it flashed across the scene [ http://spaceweather.com/meteors/gallery_12aug06.htm ] during the 30 second long exposure. Of course, the meteor was part of the annual rain [ http://antwrp.gsfc.nasa.gov/apod/ap050806.html ] of dust from periodic Comet Swift-Tuttle [ http://antwrp.gsfc.nasa.gov/apod/ap960219.html ] known as the Perseid Meteor Shower [ http://comets.amsmeteors.org/meteors/showers/ perseidhistory.html ]. Leaving trails that point back to a radiant [ http://comets.amsmeteors.org/meteors/showers/ perseids.html ] in the constellation Perseus, the ancient dust [ http://stardustathome.ssl.berkeley.edu/ about.php ] particles are vaporized as they enter the atmosphere at about 60 kilometers per second, their visible streaks beginning at altitudes of around 100 kilometers. And though it looks like the knuckles of a giant hand, the curious rock formation can be found in Colorado National Monument park, USA, planet Earth [ http://www.nps.gov/colm/ ]. |
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The Comet and the Galaxy
| Title |
The Comet and the Galaxy |
| Explanation |
The Moon almost ruined this photograph. During late March and early April 1997, Comet Hale-Bopp [ http://www.jpl.nasa.gov/comet/ ] passed nearly in front of the Andromeda Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap040718.html ]. Here the Great Comet of 1997 [ http://cometography.com/lcomets/1995o1.html ] and the Great Galaxy in Andromeda [ http://www.seds.org/messier/m/m031.html ] were photographed together [ http://antwrp.gsfc.nasa.gov/apod/ap970401.html ] on 1997 March 24th. The problem was the brightness of the Moon [ http://antwrp.gsfc.nasa.gov/apod/ap970924.html ]. The Moon [ http://www.seds.org/nineplanets/nineplanets/luna.html ] was full that night and so bright that long exposures meant to capture the tails of Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap970416.html ] and the disk of M31 [ http://antwrp.gsfc.nasa.gov/apod/ap961011.html ] would capture instead only moonlight reflected off the Earth's atmosphere. By the time the Moon would set, this opportunity would be gone. That's why this picture was taken during a total lunar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap960926.html ]. |
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M27: Not A Comet
| Title |
M27: Not A Comet |
| Explanation |
While searching the skies above 18th century France for comets, astronomer Charles Messier [ http://www.seds.org/messier/xtra/history/biograph.html ] diligently recorded this object as number 27 on his list of things which are definitely not comets [ http://antwrp.gsfc.nasa.gov/apod/ap960626.html ]. So what is it? Well, 20th century astronomers would classify it as a Planetary Nebula [ http://www.seds.org/messier/planetar.html ] ... but it's not a planet either, even though it may appear round [ http://antwrp.gsfc.nasa.gov/apod/ap030614.html ] and planet-like in a small telescope. Messier 27 (M27) is now known to be an excellent example of a gaseous emission nebula [ http://www.astro.washington.edu/balick/WFPC2/ ] created as a sun-like star runs out [ http://antwrp.gsfc.nasa.gov/apod/ap050123.html ] of nuclear fuel in its core. The nebula forms as the star's outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star's intense but invisible ultraviolet light [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/ emspectrum.html ]. Known by the popular name of the Dumbbell Nebula [ http://www.seds.org/messier/m/m027.html ], the beautifully symmetric interstellar gas cloud is about 1,200 light-years away in the constellation Vulpecula [ http://hawastsoc.org/deepsky/vul/index.html ]. This intriguing color composite view [ http://www.ricksastro.com/DSOs/m27HaOiii.shtml ] was recorded through narrow band filters sensitive to emission from hydrogen atoms (shown in red) and oxygen atoms (shown in blue/green). |
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Comet LINEAR Extends
| Title |
Comet LINEAR Extends |
| Explanation |
Comet LINEAR's tail appears to be extending. Many sky watchers are closely following Comet C/1999 S4 LINEAR [ http://antwrp.gsfc.nasa.gov/apod/ap000704.html ] and wondering if it will develop an impressive tail [ http://antwrp.gsfc.nasa.gov/apod/ap980717.html ] or become visible to the naked eye later this month. So far, the unpredictable comet is moving oddly indicating that exploding caverns [ http://antwrp.gsfc.nasa.gov/apod/ap970213.html ] of heated gas are causing the comet [ http://www.cometlinear.com/ ] to shift slightly in its orbit [ http://encke.jpl.nasa.gov/whats_visible.html#1999S4 ] around the Sun [ http://www.seds.org/nineplanets/nineplanets/sol.html ]. This volatility contributes to Comet LINEAR [ http://www.skypub.com/sights/comets/0007linearS4.html ] newly visible two-degree tail, discernable in the above photograph [ http://www.comet-track.com/s4/s4.html ]ic negative taken Friday from California [ http://www.state.ca.us/ ]. Current brightness estimates [ http://cfa-www.harvard.edu/iau/Ephemerides/Comets/1999S4_1.html ] indicate that Comet LINEAR [ http://science.nasa.gov/headlines/y2000/ast05jul_1m.htm ] will just barely become visible without binoculars in northern skies in the days surrounding July 23 during the early evening hours. |
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Comet LINEAR Approaches
| Title |
Comet LINEAR Approaches |
| Explanation |
Just possibly, a new comet [ http://www.seds.org/nineplanets/nineplanets/comets.html ] may become bright enough to see without binoculars later this month. Comet C/1999 S4 LINEAR [ http://www.skypub.com/sights/comets/0007linearS4.html ] is rapidly approaching both the Earth [ http://antwrp.gsfc.nasa.gov/apod/earth.html ] and the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap000522.html ] from the outer Solar System [ http://www.exploratorium.edu/ronh/solar_system/ ], and should be at its brightest around 2000 July 25 in the early evening sky of northern observers. The comet was discovered [ http://www.swisr.org/newcomet.html ] by chance by project LINEAR [ http://www.ll.mit.edu/LINEAR/ ] last September. The above time-lapse sequence [ http://www.astrophotographer.com/C1999-S4_1Jul2000.html ] of Comet LINEAR [ http://encke.jpl.nasa.gov/whats_visible.html#1999S4 ] was taken on 2000 July 2 from Arizona [ http://www.state.az.us/ ] and shows the comet's movement over only 19 minutes. Although Comet LINEAR [ http://cfa-www.harvard.edu/iau/Ephemerides/Comets/1999S4.html ]'s positions will be known quite accurately, the comet's future brightness and tail [ http://antwrp.gsfc.nasa.gov/apod/ap000413.html ] length can only be guessed, and it is quite possible that neither will become very impressive. |
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Tails Of Comet LINEAR
| Title |
Tails Of Comet LINEAR |
| Explanation |
Comet C/1999 S4 LINEAR is only one of many [ http://www.ll.mit.edu/LINEAR/neos.html ] comets discovered with the Lincoln Near Earth Asteroid Research [ http://www.ll.mit.edu/LINEAR/ ] (LINEAR) telescope operating near Soccoro, New Mexico, USA. Traveling steadily southward through Earth's night sky, C/1999 S4 passed perihelion (closest approach to the Sun) yesterday on what is likely its first trip [ http://www.skypub.com/sights/comets/0007linearS4.html ] through the inner solar system. Now fading, comet LINEAR [ http://www.swisr.org/newcomet.html#Anchor Latest ] became no brighter than about 6th magnitude, but is still easily visible with binoculars in northern hemisphere skies. While the memorable comets Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap970320.html ] and Hyakutake [ http://antwrp.gsfc.nasa.gov/apod/ap980717.html ] were much brighter, comet LINEAR [ http://antwrp.gsfc.nasa.gov/apod/ap000704.html ] is displaying [ http://cfa-www.harvard.edu/iauc/07400/07461.html#Item2 ] delightful tails evident in this false-color composite image from [ http://www.fiz.uni-lj.si/astro/comets/images/99s4.html ] the Crni Vrh Observatory [ http://www.fiz.uni-lj.si/astro/comets/cvobs.html ] in Slovenia. The combined series of exposures made on July 22nd are registered on the comet. In the resulting picture, stars appear as rows of dots, but the faint structures in the comet's tail are beautifully recorded. Presently seen moving from Ursa Major to Leo [ http://www.astro.wisc.edu/~dolan/constellations/ constellations.html ] this comet LINEAR [ http://encke.jpl.nasa.gov/whats_visible.html#1999S4 ] will begin to shine in southern hemisphere skies in August. |
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Fragments of Comet LINEAR
| Title |
Fragments of Comet LINEAR |
| Explanation |
What do you call [ http://www.ojohaven.com/collectives/ ] a bunch [ http://antwrp.gsfc.nasa.gov/apod/ap990814.html ] of comet fragments anyway ... a flock, a covey, a swarm? The question is definitely relevant to comet LINEAR [ http://www.cometlinear.com ] (C/1999 S4 LINEAR) whose nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap000805.html ] apparently fragmented late last month [ http://www.ing.iac.es/PR/press/ing300.html ] during its first trip [ http://meteors.com/cometlinear/images.html ] through the inner solar system. This computer enhanced composite [ http://www.eso.org/outreach/press-rel/pr-2000/ phot-20-00.html ] image shows faint stars as trails [ http://pages.prodigy.net/pam.orman/JoeTrails.html ] and the remnants of LINEAR's nucleus as a flock of "mini-comets" embedded in a cloud of gas and dust. It was recorded by astronomers using the European Southern Observatory's Antu telescope [ http://antwrp.gsfc.nasa.gov/apod/ap000707.html ] about a day after the Hubble Space Telescope (HST) was also able to image the covey of condensations [ http://antwrp.gsfc.nasa.gov/apod/ap000808.html ]. A comparison of the HST and the subsequent Antu images reveals that the swarm of cometary debris has changed markedly in 24 hours demonstrating the very dynamic behavior of comet LINEAR's remains. Astronomers intend [ http://stardust.jpl.nasa.gov/comets/deepimpact.html ] to keep watching [ http://user.icx.net/~mfleenor/ccd/ 07032000_0800ani.html ] as comet LINEAR's fragments continue to lose dust and gas and fade from view. As a result, LINEAR's legacy may well be insight into the make-up of a primordial piece [ http://stardust.jpl.nasa.gov/ ] of our solar system. If pictures of comet LINEAR have piqued your curiosity about fragments of a comet, why not watch the Perseid meteor shower [ http://spacescience.com/headlines/y2000/ ast08aug_1.htm ] this weekend? |
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Comet LINEAR Disperses
| Title |
Comet LINEAR Disperses |
| Explanation |
What's happened to the nucleus of Comet LINEAR? The brightest comet [ http://www.seds.org/nineplanets/nineplanets/comets.html ] this year has unexpectedly broken up [ http://antwrp.gsfc.nasa.gov/apod/ap000731.html ] into many smaller pieces. The break-up occurred on or about July 25 and was noted by many astronomers around the world with particularly pioneering work [ http://meteors.com/cometlinear/update2.html ] by Mark Kidger [ http://www.iac.es/galeria/mrk/index.html ] (IAC [ http://www.iac.es/ ]). Since then astronomers [ http://www.iau.org/ ] had been searching [ http://www.ing.iac.es/PR/press/ing300.html ] in vain to find any fragments left of the nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap000805.html ], and watching to see how fast the remaining debris fades. Just three days ago the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ] was maneuvered to photograph the region [ http://oposite.stsci.edu/pubinfo/PR/2000/27/pr-photos.html ] and recovered some of the disintegrating fragments that used to compose Comet LINEAR [ http://antwrp.gsfc.nasa.gov/apod/ap000704.html ]'s nucleus. The above image [ http://oposite.stsci.edu/pubinfo/PR/2000/27/pr.html ] covers only the very tip of an elongated diffuse train [ http://oposite.stsci.edu/pubinfo/PR/2000/27/index.html ] of slowly dispersing gas, dust, ice fragments, and gravel. The largest bits remaining of the badly fractured nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap000805.html ] appear to be less than 30 meters across. This debris train will not collide with the Earth [ http://science.nasa.gov/headlines/y2000/ast31jul_1m.htm ] and so will not cause a meteor shower [ http://comets.amsmeteors.org/ ]. Interested astronomers are now theorizing why Comet LINEAR [ http://encke.jpl.nasa.gov/ ]'s nucleus disintegrated into such small pieces. |
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Comet SWAN Brightens
| Title |
Comet SWAN Brightens |
| Explanation |
A newly discovered comet has brightened enough to be visible this week with binoculars. The picturesque comet [ http://antwrp.gsfc.nasa.gov/apod/ap050904.html ] is already becoming a favored target for northern sky imagers. Pictured above [ http://www.astrostudio.at/Astrofotos/astrofotos.php?k_id=69 ] just last week, Comet SWAN showed a bright blue-green coma and an impressive tail. Comet C/2006 M4 (SWAN) [ http://cometography.com/lcomets/2006m4.html ] was discovered in June in public images from the Solar Wind Anisotropies [ http://www.fmi.fi/research_space/space_7.html ] (SWAN) instrument of NASA and ESA [ http://en.wikipedia.org/wiki/ESA ]'s Sun-orbiting SOHO [ http://sohowww.nascom.nasa.gov/ ] spacecraft. Comet [ http://en.wikipedia.org/wiki/Comet ] SWAN, near magnitude six, will be visible with binoculars in the northeastern sky not far from the Big Dipper over the next few days before dawn. The comet [ http://www.aerith.net/comet/catalog/2006M4/2006M4.html ] is expected to reach its peak brightness this week. Passing its closest to the Sun two days ago, Comet SWAN [ http://ssd.jpl.nasa.gov/sbdb.cgi?ID=dK06M040;orb=1;cov=0#orb ] and will be at its closest to the Earth toward the end of this month. Comet SWAN's unusual orbit [ http://cfa-www.harvard.edu/cfa/ps/mpec/K06/K06S89.html ] appears to be hyperbolic [ http://adsabs.harvard.edu/abs/1992A&A...259..692K ], meaning that it will likely go off into interstellar space [ http://antwrp.gsfc.nasa.gov/apod/ap020210.html ], never to return. |
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Comet LINEAR Breaks Up
| Title |
Comet LINEAR Breaks Up |
| Explanation |
Unexpectedly, Comet LINEAR is breaking up [ http://meteors.com/cometlinear/update.html ]. In retrospect, clues of its demise have been surfacing all month as the new comet [ http://antwrp.gsfc.nasa.gov/apod/ap000727.html ] has been approaching the Sun [ http://www.seds.org/nineplanets/nineplanets/sol.html ] and brightening [ http://spacescience.com/headlines/y2000/ast28jul_1m.htm ] with dramatic flares. Above [ http://oposite.stsci.edu/pubinfo/PR/2000/26/index.html ], the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ] captured Comet C/1999 S4 LINEAR [ http://antwrp.gsfc.nasa.gov/apod/ap000704.html ] early this month blowing off a large piece of its crust. Recent speculation [ http://www.ing.iac.es/PR/press/ing200.html ] holds that the nucleus completely disrupted [ http://spaceweather.com/meteoroutlook/iauc7467.html ] on or about July 24. If true, the elongated train [ http://antwrp.gsfc.nasa.gov/apod/ap990814.html ] of material should continue to ablate and orbit the Sun, but may now fade much more quickly. The break up of a bright comet [ http://www.solarviews.com/eng/comet.htm ] is unusual but not unprecedented, as Comet Shoemaker-Levy 9 [ http://antwrp.gsfc.nasa.gov/apod/ap980804.html ] broke up before it struck Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] in 1994, and Comet Bennett [ http://meteors.com/cometlinear/update.html ] broke apart as it neared the Sun in 1974. Future observations will tell if Comet LINEAR [ http://antwrp.gsfc.nasa.gov/apod/ap000710.html ]'s first trip into the inner Solar System [ http://www.seds.org/nineplanets/nineplanets/overview.html ] is its last. |
|
X-Rays from Comet LINEAR
| Title |
X-Rays from Comet LINEAR |
| Explanation |
Why do comets emit X-rays? First discovered [ http://antwrp.gsfc.nasa.gov/apod/ap960411.html ] during the passing of Comet Hyakutake [ http://antwrp.gsfc.nasa.gov/apod/ap980717.html ] in 1996, the reason a cold comet [ http://comets.amsmeteors.org/ ] would produce hot X-rays [ http://chandra.harvard.edu/xray_astro/xrays.html ] has since remained a mystery. On July 14, however, the orbiting Chandra X-ray Observatory [ http://chandra.harvard.edu/about/axaf_mission.html ] was able to provide an image of passing Comet LINEAR [ http://antwrp.gsfc.nasa.gov/apod/ap000731.html ], shown above [ http://www1.msfc.nasa.gov/NEWSROOM/news/photos/2000/photos00-232.htm ], in enough detail to unravel the mystery. The key to the solution [ http://chandra.harvard.edu/photo/cycle1/c1999s4/index.html ] turns out to be the unusual wind [ http://antwrp.gsfc.nasa.gov/apod/ap000318.html ] of fast ions emitted by our Sun [ http://www.seds.org/nineplanets/nineplanets/sol.html ]. These ions [ http://zebu.uoregon.edu/~js/glossary/ion.html ] apparently collide with gas recently emitted by the comet [ http://antwrp.gsfc.nasa.gov/apod/hale_bopp.html ] and cause some ions to acquire a new electron [ http://zebu.uoregon.edu/~js/glossary/electron.html ]. An electron [ http://www.aip.org/history/electron/ ] that starts in a high-energy state will emit an X-ray [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/history1_xray.html ] as it falls in closer to the ion nucleus [ http://www.dpgraph.com/janine/nucleus.html ]. As other comets move into the inner Solar System [ http://spacelink.nasa.gov/Instructional.Materials/Curriculum.Support/Space.Science/Our.Solar.System/.index.html ], this discovery should allow future study of the continually evolving gas cloud that surrounds comets [ http://stardate.utexas.edu/resources/ssguide/comets.html ] as well as the composition of the solar wind [ http://science.msfc.nasa.gov/ssl/pad/solar/sun_wind.htm ]. |
|
Comet SWAN Outburst
| Title |
Comet SWAN Outburst |
| Explanation |
Near its closest approach to planet Earth, comet SWAN [ http://antwrp.gsfc.nasa.gov/apod/ap0610004.html ] (C/2006 M4) brightened unexpectedly earlier this week [ http://www.spaceweather.com/comets/ gallery_cometswan.html ], becoming visible to naked-eye observers under dark night skies. Telescopic observers also noticed dramatic changes [ http://antwrp.gsfc.nasa.gov/apod/ap061019.html ] in the comet's colorful coma and tail [ http://www.nasa.gov/worldbook/comet_worldbook.html ], seen in this view recorded on October 25th. To make the picture, images totaling eight minutes in exposure time were stacked and centered on the comet as it moved relatively quickly against the background star field. The picture covers about 1 degree on the sky. Northern hemisphere observers should still find the comet [ http://www.skyhound.com/sh/comets.html ] an easy binocular target in the early evening, even though moonlight will increase the overall sky brightness in the next few days. Look toward [ http://skytonight.com/observing/home/4477131.html ] the northwestern horizon and the constellation Hercules. |
|
The Ghostly Tail of Comet SW
…
| Title |
The Ghostly Tail of Comet SWAN |
| Explanation |
What causes the structure in Comet SWAN's tail? Comet SWAN [ http://www.aerith.net/comet/catalog/2006M4/2006M4.html ], which unexpectedly flared up to naked-eye brightness last week, has been showing detail in its ion tail [ http://antwrp.gsfc.nasa.gov/apod/ap050522.html ] that might be described as ghostly [ http://antwrp.gsfc.nasa.gov/apod/ap041031.html ]. The ion tail [ http://www.ifa.hawaii.edu/~jewitt/tail.html ] is made of ionized gas, energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind [ http://csep10.phys.utk.edu/astr162/lect/sun/wind.html ] itself is quite structured and sculpted by the Sun's complex and ever changing magnetic field [ http://www-spof.gsfc.nasa.gov/Education/wmfield.html ]. Following the wind, structure in Comet SWAN's tail [ http://www.nasa.gov/worldbook/comet_worldbook.html ] can be seen to move outward from the Sun even alter its wavy appearance over time. The blue color of the ion tail is dominated by recombining carbon monoxide [ http://en.wikipedia.org/wiki/Carbon_monoxide ] atoms. The color of the coma surrounding the head of the comet is tinged green by slight amounts of the molecule cyanogen [ http://en.wikipedia.org/wiki/Cyanogen ]. The above image was taken last week from California, USA. This week may be the best remaining chance for northern hemisphere observers to see the fading interplanetary snowball [ http://antwrp.gsfc.nasa.gov/apod/ap040512.html ]. SWAN [ http://cometography.com/lcomets/2006m4.html ] has now passed both the Earth and the Sun and will fade as it moves away from the Earth and heads out into the vast space between the stars. |
|
Comet LINEAR: Fade To Black
| Title |
Comet LINEAR: Fade To Black |
| Explanation |
Only last month [ http://antwrp.gsfc.nasa.gov/apod/ap000727.html ] the stage was set for Comet LINEAR [ http://encke.jpl.nasa.gov/whats_visible.html#1999S4 ] (C/1999S4 LINEAR) to become the first "naked-eye" comet of Y2K. It didn't fill that role, of course, but it did turn in a very dramatic performance [ http://meteors.com/cometlinear/ kidger_update.html ]. Closely followed by astronomer Mark Kidger and colleagues with the Isaac Newton Group [ http://www.ing.iac.es/ ] telescopes (La Palma, Canary [ http://antwrp.gsfc.nasa.gov/apod/ap990410.html ] Islands), comet LINEAR's nucleus apparently fragmented extensively on the night of July 25th. A faint fluorescent [ http://www.seds.org/nineplanets/nineplanets/ comets.html ] cloud fading against a background of stars is all that is still visible in this August 21st telescopic view from Loomberah [ http://www.ozemail.com.au/~loomberah/linear.htm ], NSW Australia. Why did comet LINEAR break up? Comets are conglomerates of ice and rock [ http://antwrp.gsfc.nasa.gov/apod/ap000805.html ]. A very plausible scenario is [ http://www.ing.iac.es/PR/press/ing300.html ] that a substantial fraction of LINEAR's icy component was evaporated, leaving too little to hold the rocky material together. In any event, no bright telltale condensations [ http://antwrp.gsfc.nasa.gov/apod/ap000811.html ] remain. So, following its first tour through the inner Solar System, an encore [ http://antwrp.gsfc.nasa.gov/apod/ap000808.html ] from comet LINEAR seems unlikely! |
|
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 ]. |
|
McNaught Now Brightest Comet
…
| Title |
McNaught Now Brightest Comet in Decades |
| Explanation |
The brightest comet in decades [ http://cfa-www.harvard.edu/icq/brightest.html ] is unexpectedly now visible [ http://skytonight.com/observing/highlights/5118926.html ]. The most optimistic predictions have Comet McNaught [ http://cometography.com/lcomets/2006p1.html ] (C/2006 P1) shortly becoming one of the brightest comets of the past century. For the next few days, its short tail and bright coma can be spotted with the unaided eye close to the Sun [ http://www.shadowandsubstance.com/ ] and near the horizon in both evening [ http://spaceweather.com/images2007/08jan07/ skymap_north.gif ] and morning [ http://spaceweather.com/images2007/08jan07/ skymap_north_m.gif ] skies. This dramatic picture of the comet [ http://spaceweather.com/comets/gallery_mcnaught.htm ] shining through cloudy skies [ http://antwrp.gsfc.nasa.gov/apod/ap070105.html ] was taken near sunset on January 7 from Bad Mergentheim, Germany. |
|
Jupiter Swallows Comet Shoem
…
| Title |
Jupiter Swallows Comet Shoemaker Levy 9 |
| Explanation |
What happens when a comet [ http://comets.amsmeteors.org/comets/periodic_comets.html ] encounters a planet? If the planet has a rocky surface, a huge impact feature [ http://antwrp.gsfc.nasa.gov/apod/ap960120.html ] will form. A giant planet like Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ], however, is mostly gas [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ]. When Comet Shoemaker-Levy 9 [ http://www.jpl.nasa.gov/sl9/ ] struck Jupiter in 1994, each piece [ http://antwrp.gsfc.nasa.gov/apod/ap990814.html ] was swallowed [ http://antwrp.gsfc.nasa.gov/apod/ap980728.html ] into the vast Jovian atmosphere [ http://antwrp.gsfc.nasa.gov/apod/ap000429.html ]. Pictured above is a time-lapse sequence of the result of two fragments striking Jupiter [ http://www.hawastsoc.org/solar/eng/jupiter.htm ]. As the comet plunged in, it created large dark marks that gradually faded. The high temperature of gas under Jupiter's cloud tops [ http://antwrp.gsfc.nasa.gov/apod/ap970310.html ] surely caused the comet fragment to melt before it plunged very far. Because Jupiter is much more massive than any comet, the orbit of Jupiter around the Sun [ http://solar-center.stanford.edu/folklore/folklore.html ] did not change noticeably. |
|
Comet McNaught from New STER
…
| Title |
Comet McNaught from New STEREO Satellite |
| Explanation |
The brightest comet of recent decades was a surprising first sight for a new camera in space. The Sun Earth Connection Coronal and Heliospheric Investigation [ http://secchi.nrl.navy.mil/ ] (SECCHI) instrument onboard the Solar TErrestrial RElations Observatory [ http://en.wikipedia.org/wiki/STEREO ] (STEREO) satellite had just opened up on January 11 when it snapped the above image of Comet McNaught [ http://antwrp.gsfc.nasa.gov/apod/ap070115.html ]. Visible was a spectacular view of the ion tail [ http://www.ifa.hawaii.edu/~jewitt/tail.html ] of Comet McNaught [ http://www.planetary.org/blog/article/00000825/ ] being swept away from the Sun by the solar wind [ http://csep10.phys.utk.edu/astr162/lect/sun/wind.html ] in filamentary rays. The comet tail is seen to extend at least seven degrees across the above image [ http://ares.nrl.navy.mil/sungrazer/index.php?p=latest_news ], while the central coma [ http://www.windows.ucar.edu/tour/link=/comets/coma.html ] is so bright it saturates. Comet McNaught [ http://www.badastronomy.com/bablog/2007/01/14/comet-mcnaught-daytime-comet/ ] is now reportedly so bright that it is visible even in broad daylight by blocking out the Sun with your hand. Comet McNaught [ http://cometography.com/lcomets/2006p1.html ] has rounded the Sun and will slowly fade away [ http://cfa-www.harvard.edu/iau/Ephemerides/Comets/2006P1_1.html ] for observers in Earth's Southern Hemisphere [ http://antwrp.gsfc.nasa.gov/apod/ap021222.html ] as it recedes from the Sun. |
|
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 ]. |
|
Southern Comet
| Title |
Southern Comet |
| Explanation |
After a remarkable [ http://www.cortinastelle.it/comete/ 2006P1-mcnaught.htm ] performance in the northern hemisphere, the brightest comet [ http://spaceweather.com/comets/ gallery_mcnaught.htm ] in decades is now showing off in the south [ http://www.yp-connect.net/~mmatti/ ]. Recorded during evening twilight on January 17, this view features the bright coma [ http://www.windows.ucar.edu/tour/ link=/comets/coma.html&edu=high ] and gorgeous, sweeping tail [ http://www.windows.ucar.edu/tour/ link=/comets/tail.html&edu=high ] of Comet McNaught (c/2006 P1) [ http://cometography.com/lcomets/2006p1.html ] over Lake Horowhenua in Levin, a small town on New Zealand's North Island. Astronomer Noel Munford reports that the five second long digital camera exposure comes close to capturing the visual appearance of the comet in a sky coloured by smoke from distant brush fires in Australia. Discovered last summer by R. H. McNaught (Siding Spring Survey [ http://www.mso.anu.edu.au/~rmn/ ]), the comet grew impressively bright [ http://www.mso.anu.edu.au/~rmn/C2006P1.htm ] in early January and has even been sighted in full daylight. In the coming days [ http://www.skyhound.com/sh/comets.html ] Comet McNaught will continue to move south, for now a spectacle in southern skies [ http://www.rasnz.org.nz/Comets/C2006P1.htm ] as it heads for the outer solar system. |
|
The Magnificent Tail of Come
…
| Title |
The Magnificent Tail of Comet McNaught |
| Explanation |
Comet McNaught, the Great Comet of 2007, has grown a long and filamentary tail. The spectacular tail [ http://www.windows.ucar.edu/tour/link=/comets/tail.html&edu=high ] spreads across the sky and is visible to Southern Hemisphere observers just after sunset. The head of the comet [ http://cse.ssl.berkeley.edu/SegWayEd/lessons/cometstale/com.html ] remains quite bright and easily visible [ http://msowww.anu.edu.au/~rmn/C2006P1new.htm ] to even city observers without any optical aide. The amazing tail [ http://antwrp.gsfc.nasa.gov/apod/ap070117.html ] is visible on long exposures and even to the unaided eye from a dark location. Reports [ http://spaceweather.com/comets/gallery_mcnaught_page11.htm ] even have the tail visible just above the horizon after sunset for many northern observers as well. Comet McNaught, estimated [ http://cfa-www.harvard.edu/icq/CometMags.html#2006P1 ] at magnitude [ http://en.wikipedia.org/wiki/Apparent_magnitude ] -2 (minus two), was caught by the comet's discoverer [ http://en.wikipedia.org/wiki/Robert_H._McNaught ] in the above image [ http://msowww.anu.edu.au/~rmn/C2006P1.htm ] just after sunset last Friday from Siding Spring Observatory [ http://en.wikipedia.org/wiki/Siding_Spring_Observatory ] in Australia [ http://en.wikipedia.org/wiki/Australia ]. Comet McNaught, the brightest comet in decades, is now fading [ http://cfa-www.harvard.edu/iau/Ephemerides/Comets/2006P1.html ] as it moves further into southern skies and away from the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap061204.html ] and Earth [ http://antwrp.gsfc.nasa.gov/apod/ap060927.html ]. |
|
Comet McNaught Over New Zeal
…
| Title |
Comet McNaught Over New Zealand |
| Explanation |
Comet McNaught is perhaps the most photogenic comet of our time. After making quite a show [ http://antwrp.gsfc.nasa.gov/apod/ap070115.html ] in the northern hemisphere in mid January, the comet moved south and developed a long and unusual dust tail [ http://antwrp.gsfc.nasa.gov/apod/ap070122.html ] that dazzled southern hemisphere observers [ http://antwrp.gsfc.nasa.gov/apod/ap070205.html ] starting in late January. Comet McNaught [ http://en.wikipedia.org/wiki/Comet_McNaught ] was imaged two weeks ago between Mount Remarkable and Cecil Peak in this spectacular image [ http://homepages.ihug.co.nz/~mkyoneto/star/mcnaught.htm ] taken from Queenstown [ http://en.wikipedia.org/wiki/Queenstown%2C_New_Zealand ], South Island [ http://en.wikipedia.org/wiki/South_Island ], New Zealand [ http://en.wikipedia.org/wiki/New_Zealand ]. The bright comet dominates the right part of the above image, while the central band [ http://antwrp.gsfc.nasa.gov/apod/ap050605.html ] of our Milky Way Galaxy [ http://www.seds.org/messier/more/mw.html ] dominates the left. Careful inspection of the image will reveal a meteor streak [ http://antwrp.gsfc.nasa.gov/apod/ap011111.html ] just to the left of the comet. Comet McNaught [ http://www.spaceweather.com/comets/gallery_mcnaught_page18.php ] continues to move out from the Sun and dim, but should remain visible [ http://cfa-www.harvard.edu/iau/Ephemerides/Comets/2006P1.html ] in southern skies with binoculars through the end of this month. |
|
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.") |
|
Comet Between Fireworks and
…
| Title |
Comet Between Fireworks and Lightning |
| Explanation |
Sometimes the sky itself is the best show in town. On January 26, people from Perth [ http://en.wikipedia.org/wiki/Perth%2C_Western_Australia ], Australia [ http://en.wikipedia.org/wiki/Australia ] gathered on a local beach to watch a sky [ http://antwrp.gsfc.nasa.gov/apod/ap050913.html ] light up with delights near and far. Nearby, fireworks exploded as part of Australia Day [ http://en.wikipedia.org/wiki/Australia_Day ] celebrations. On the far right, lightning [ http://www.nationalgeographic.com/lightning/ ] from a thunderstorm [ http://www.fema.gov/hazard/thunderstorm/index.shtm ] flashed in the distance. Near the image center, though, seen through clouds, was the most unusual sight of all: Comet McNaught [ http://antwrp.gsfc.nasa.gov/apod/ap070122.html ]. The photogenic comet [ http://spaceweather.com/comets/gallery_mcnaught_page21.php ] was so bright that it even remained visible though the din of Earthly flashes. Comet McNaught continues to move out from the Sun and dim, but should remain visible in southern skies [ http://cfa-www.harvard.edu/iau/Ephemerides/Comets/2006P1.html ] with binoculars through the end of this month. The above image [ http://jkemppainen.com/antti/ ] is actually a three photograph panorama digitally processed to reduce red reflections from the exploding firework [ http://people.howstuffworks.com/fireworks.htm ]. |
|
A Comet Tail Horizon
| Title |
A Comet Tail Horizon |
| Explanation |
What's happening over the horizon? Many a sky enthusiast [ http://antwrp.gsfc.nasa.gov/apod/ap040808.html ] who thought they had seen it all had never seen anything like this. To the surprise of many Northern Hemisphere observers, the tail of Comet McNaught [ http://cometography.com/lcomets/2006p1.html ] remained visible even after the comet's head set ahead of the Sun. What's more, visible were bright but extremely rare filamentary striae [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998AGM....14..P02B ] from the comet's expansive dust tail. The cause of dust tail striae are not known for sure, but are possibly related to fragmentation [ http://adsabs.harvard.edu/abs/1998AGM....14..P02B ] of comet's nucleus. The last comet to show prominent striae [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999STIN...0073719S ] was Comet Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap050522.html ] in 1997. Pictured above [ http://spaceweather.com/comets/gallery_mcnaught_page13.htm ], the tail of Comet McNaught [ http://antwrp.gsfc.nasa.gov/apod/ap070122.html ] was caught just after sunset last Friday above the Carnic Alps [ http://en.wikipedia.org/wiki/Carnic_Alps ] of northern Italy [ http://en.wikipedia.org/wiki/Italy ]. |
|
Three Galaxies and a Comet
| Title |
Three Galaxies and a Comet |
| Explanation |
Diffuse starlight and dark nebulae along [ http://antwrp.gsfc.nasa.gov/apod/ap070222.html ] the southern Milky Way [ http://home.arcor-online.de/axel.mellinger/ ] arc over the horizon and sprawl diagonally through this gorgeous nightscape. The breath-taking mosaic [ http://www.zam.fme.vutbr.cz/~druck/Astro/ Mcnaugh/3772-84/0-info.htm ] spans a wide 100 degrees, with the rugged terrain [ http://maps.google.com/maps?f=q&hl=en &q=S+41%C2%B0+11.34%27,+W+71%C2%B0+32.95%27 &layer=&ie=UTF8&om=1&z=8&ll=-41.112469,-71.548462 &spn=1.961703,5.537109&t=h&iwloc=addr ] of the Patagonia, Argentina region in the foreground. Along with the insider's view of our own galaxy, the image features our outside perspective on two irregular satellite galaxies - the Large [ http://antwrp.gsfc.nasa.gov/apod/ap060510.html ] and Small [ http://antwrp.gsfc.nasa.gov/apod/ap050617.html ] Magellanic Clouds. Recorded on January 28, the scene also captures the broad tail [ http://antwrp.gsfc.nasa.gov/apod/ap070201.html ] and bright coma [ http://antwrp.gsfc.nasa.gov/apod/ap070119.html ] of Comet McNaught, The Great Comet of [ http://ssd.jpl.nasa.gov/?great_comets ] 2007. |
|
Hale-Bopp: The Great Comet o
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| Title |
Hale-Bopp: The Great Comet of 1997 |
| Explanation |
Ten short years ago, Comet Hale-Bopp [ http://www.cometography.com/lcomets/1995o1.html ] rounded the Sun and offered a dazzling spectacle in planet Earth's night. This stunning view [ http://www.astropix.com/HTML/SHOWCASE/970401.HTM ], recorded shortly after the comet's perihelion passage on April 1, 1997, features the memorable tails [ http://www.ifa.hawaii.edu/~jewitt/tail.html ] of Hale-Bopp -- a whitish dust tail and blue ion tail. Here, the ion tail extends well over ten degrees across the northern sky, fading near the double star clusters [ http://antwrp.gsfc.nasa.gov/apod/ap060413.html ] in Perseus, while the head of the comet lies near Almach [ http://www.astro.uiuc.edu/~kaler/sow/almach.html ], a bright star in the constellation Andromeda. Do you remember Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap970416.html ]? The photographer's sons do, pictured in the foreground at ages 12 and 15. In all, Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap970328.html ] was reported as visible to the naked eye from roughly late May 1996 through September 1997. |
|
The Iron Tail of Comet McNau
…
| Title |
The Iron Tail of Comet McNaught |
| Explanation |
Outstanding in planet Earth's sky [ http://www.spaceweather.com/comets/ gallery_mcnaught_page23.php ] early this year, Comet McNaught [ http://en.wikipedia.org/wiki/Comet_McNaught ] is captured in this view from the STEREO [ http://stereo.gsfc.nasa.gov/ ] A spacecraft. McNaught's coma [ http://www.nasa.gov/worldbook/comet_worldbook.html ] is so bright, it blooms [ http://www.cs.duke.edu/~parr/photography/ faq.html#blooming ] into the long horizontal stripe at the bottom of the field. Brilliant Venus, near the top left corner, also produces a severe horizontal blemish in the digital image. But the sensitive camera does accurately record the striations in McNaught's famous dust tail [ http://antwrp.gsfc.nasa.gov/apod/ap070201.html ] along a region stretching over 30 million kilometers toward the top right of the field of view. A separate, fainter, arching tail just to the left of the dust tail was initially thought to be an example of a common ion tail [ http://www.ifa.hawaii.edu/~jewitt/tail.html ], formed by electrically charged atoms [ http://www.chem4kids.com/files/atom_ions.html ] carried away from the comet by the solar wind [ http://www.phy6.org/Education/wsolwind.html ]. However, detailed [ http://www.swisseduc.ch/stromboli/pdf/irontail.pdf ] modeling indicates that tail is actually due to neutral iron atoms pushed out by the pressure of sunlight [ http://www.phy6.org/stargaze/Solsail.htm ] -- the first ever detected neutral iron tail from a comet. The iron atoms are thought to originate in dust grains [ http://stardust.jpl.nasa.gov/home/index.html ] from the comet nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap050915.html ] that contain the iron-sulfur mineral troilite [ http://www.mindat.org/min-4029.html ] (FeS). |
|
Comet McNaught-Hartley
| Title |
Comet McNaught-Hartley |
| Explanation |
Outbound and climbing [ http://www.skypub.com/sights/skyevents/ 0103skyevents.shtml ] above the plane [ http://antwrp.gsfc.nasa.gov/apod/ap001014.html ] of our solar system, comet McNaught-Hartley [ http://encke.jpl.nasa.gov/whats_visible.html#1999T1 ] (C/1999 T1) is presently soaring through northern skies. This telescopic picture [ http://www.heavensgloryobservatory.com/ ], a composite of many 30 second exposures made through three color filters, recorded the delicate colors in its diminutive coma [ http://antwrp.gsfc.nasa.gov/apod/ap980410.html ] and faint tail [ http://antwrp.gsfc.nasa.gov/apod/ap970314.html ] on February 26th. Combining the exposures to produce the final image registered on the comet causes stars to appear as "dotted trails", evidence of the comet's [ http://www.seds.org/nineplanets/nineplanets/comets.html ] motion relative to the distant stellar background. Discovered by [ http://www.maa.mhn.de/Comet/Lcomets/1999t1.html ] southern hemisphere observers, this comet's closest approach to the Sun occurred in December last year as it passed just outside planet Earth's orbit. For now the brightest comet in the sky [ http://encke.jpl.nasa.gov/ ], this primordial chunk of [ http://antwrp.gsfc.nasa.gov/apod/ap010302.html ] solar system is crossing from the constellation Hercules [ http://www.allthesky.com/constellations/hercules/ constell.html ] to Draco [ http://www.seds.org/Maps/Stars_en/Fig/draco.html ] and will continue to fade. Never visible [ http://encke.jpl.nasa.gov/will_be_visible.html ] to the unaided eye, McNaught-Hartley is still at about 10th magnitude and can be viewed by comet seekers [ http://stardust.jpl.nasa.gov/classroom/ captaincomet.html ] using small telescopes. |
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Comet Hale-Bopp in the Outer
…
| Title |
Comet Hale-Bopp in the Outer Solar System |
| Explanation |
Whatever became of Comet Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap010326.html http://apod.gsfc.nasa.gov/cgi-bin/apod/apod_search?Comet+Hale-Bopp ]? The brightest comet [ http://www.nineplanets.org/comets.html ] in recent years has continued into the outer Solar System [ http://www.exploratorium.edu/ronh/solar_system/ ] and is now farther from the Sun [ http://www.nineplanets.org/sol.html ] than Saturn [ http://www.solarviews.com/eng/saturn.htm ]. To the surprise of many, Comet Hale-Bopp [ http://www.jpl.nasa.gov/comet/ ] is still active, continuing to spew gas, ice and dust particles out into space. Pictured above earlier this month, Comet Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/hale_bopp.html ] can be seen in the Southern Hemisphere [ http://antwrp.gsfc.nasa.gov/apod/ap001223.html ] with a moderate sized-telescope. The continued activity of Comet Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap001227.html ] may be due to the large size of its nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap000805.html ] - estimated to be about 50 kilometers across. The unusual dotted appearance [ http://www.eso.org/outreach/press-rel/pr-2001/phot-07-01.html#techinfo ] of most stars in the above image [ http://www.eso.org/outreach/press-rel/pr-2001/phot-07-01.html ] is due to the 14 discrete exposures that were centered on the comet and not the stars. |
|
Comet Hale-Bopp Over Val Par
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| Title |
Comet Hale-Bopp Over Val Parola Pass |
| Explanation |
Comet Hale-Bopp became much brighter than any surrounding stars. It was seen even over bright city lights [ http://antwrp.gsfc.nasa.gov/apod/ap970408.html ]. Out away from city lights, however, it put on quite a spectacular show. Here Comet Hale-Bopp was photographed above Val Parola Pass in the Dolomite mountains [ http://www.geocities.com/Yosemite/Trails/6876/ ] surrounding Cortina d'Ampezzo [ http://www.sunrise.it/cortina/ ], Italy [ http://www.cia.gov/cia/publications/factbook/geos/it.html ]. Comet Hale-Bopp's blue ion tail was created when fast moving particles from the solar wind [ http://antwrp.gsfc.nasa.gov/apod/ap000318.html ] struck expelled ions from the comet's nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap000805.html ]. The white dust tail [ http://antwrp.gsfc.nasa.gov/apod/ap001227.html ] is composed of larger particles of dust and ice expelled by the nucleus that orbit behind the comet [ http://www.nineplanets.org/comets.html ]. Observations showed that Comet Hale-Bopp's nucleus spins about once every 12 hours. |
|
Another Comet LINEAR Breaks
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| Title |
Another Comet LINEAR Breaks Up |
| Explanation |
Last year, a "different" comet LINEAR (C/1999 S4) [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?LINEAR+S4 ] broke up. This year, a comet first imaged [ http://cfa-www.harvard.edu/iauc/07500/07564.html ] by the Lincoln Near Asteroid Research [ http://www.ll.mit.edu/LINEAR/ ] (LINEAR) telescope in New Mexico [ http://www.state.nm.us/ ] on 2001 January 3, is also breaking up. This new Comet LINEAR (C/2001 A2) [ http://encke.jpl.nasa.gov/whats_visible.html#2001A2 ] unexpectedly brightened to the edge of naked-eye visiblilty a few weeks ago when its nucleus broke in two. Observations taken just last week [ http://www.eso.org/outreach/press-rel/pr-2001/phot-18-01.html ] now indicate that one of the two remaining nuclear fragments [ http://meteors.com/cometlinear/ ] has again fragmented. The first piece to break off is visible on the upper left of the above false-color image [ http://www.eso.org/outreach/press-rel/pr-2001/phot-18-01.html ] by a Very Large Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap000707.html ], while additional fragmentation is inferred from the brightness and elongation of the spot on the lower right. When a comet nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap000805.html ] splits, new surfaces are exposed and previously trapped ice and gas are released that evaporate and brighten in the energetic sunlight. Comet LINEAR may remain visible with little or no optical aid into early June [ http://www.skypub.com/sights/skyevents/0105skyevents.shtml ]. In contrast, at least two other much dimmer Comet [ http://encke.jpl.nasa.gov/whats_visible.html#1999T2 ] LINEARs [ http://encke.jpl.nasa.gov/whats_visible.html#1999Y1 ] discovered recently appear stable. |
|
A Brighter Comet LINEAR
| Title |
A Brighter Comet LINEAR |
| Explanation |
Brighter than ever expected [ http://www.jarnac.org/ ], comet LINEAR -- you know [ http://www.pha.jhu.edu/~weaver/nova/ naming_convention.html ], the one designated C/2001 A2 [ http://www.qsl.net/ah6l/A2.html ] -- is a sight to see in southern skies. This comet LINEAR [ http://antwrp.gsfc.nasa.gov/apod/ap010531.html ] first brightened impressively in late March as its active nucleus began to fragment [ http://antwrp.gsfc.nasa.gov/apod/ap010521.html ], prompting some speculation that the comet might soon break up [ http://antwrp.gsfc.nasa.gov/apod/ap000913.html ] completely. But still hanging together after its closest approach to the Sun, C/2001 A2 suddenly brightened again and was reported [ http://encke.jpl.nasa.gov/RecentObs.html#01A2 ] last week to have reached nearly 3rd magnitude, easily visible to the unaided eye. This delightful telescopic picture [ http://members.ozemail.com.au/~loomberah/linear.htm ] of the brighter coma of comet LINEAR was recorded from Australia on June 20. Stars seen through the tenuous coma [ http://antwrp.gsfc.nasa.gov/apod/ap980410.html ] and filamentary tail appear as a series of short trails in this three-color composite image registered on the comet [ http://encke.jpl.nasa.gov/ ]. North is up and the scene covers about half the width of the full Moon. Now moving through the constellation Cetus [ http://einstein.stcloudstate.edu/Dome/constellns/ cet.html ], comet LINEAR will be north of the celestial equator by July 4 as it comes into view for eager northern sky-gazers. |
|
C/2001 A2 (LINEAR): Comet !
| Title |
C/2001 A2 (LINEAR): Comet ! |
| Explanation |
Comet C/2001 A2 (LINEAR) [ http://www.skypub.com/news/news.shtml#CometWorldwide ] has crossed the celestial equator and is heading north. Outward bound [ http://antwrp.gsfc.nasa.gov/apod/ap010625.html ], this primordial piece [ http://stardust.jpl.nasa.gov/comets/comets.html ] of the solar system is still just visible to the unaided eye and can now be sighted by northern hemisphere skygazers as it moves through the constellation Pisces. This picture of the comet [ http://www.astrophotographer.com/C2001A2.html ] is a combination of 33 individual one minute exposures made on June 30 with a small telescope and digital camera situated in central Arizona, USA. The composite image brings out faint details in the comet's tail [ http://antwrp.gsfc.nasa.gov/apod/ap010531.html ] which was reported [ http://encke.jpl.nasa.gov/RecentObs.html#01A2 ] to extend for several degrees, beyond the camera's roughly 2 degree field of view. Closely spaced, the combined exposures were registered on the comet so background stars appear trailed. To produce the "punctuation" at the end of each star trail [ http://antwrp.gsfc.nasa.gov/apod/ap980912.html ], two exposures near the end of the sequence were left out. As a result, the final dots nicely reveal the pattern of the background star field. |
|
Comet Encke's Tail Ripped Of
…
| 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! |
|
Comet Holmes' Coma Expands
| Title |
Comet Holmes' Coma Expands |
| Explanation |
Go outside tonight and see Comet Holmes [ http://www.skyandtelescope.com/observing/home/10775326.html ]. No binoculars or telescopes are needed -- just curiosity and a sky map. Last week, Comet 17P/Holmes [ http://antwrp.gsfc.nasa.gov/apod/ap071026.html ] underwent an unusual outburst that vaulted it unexpectedly from obscurity into one of the brightest comets in recent years. Sky enthusiasts [ http://antwrp.gsfc.nasa.gov/apod/ap040808.html ] from the northern hemisphere have been following the comet's progress [ http://www.spaceweather.com/comets/gallery_holmes.html ] closely. In this animation [ http://spaceweather.com/comets/gallery_holmes_page4.htm ] recorded from Quebec [ http://en.wikipedia.org/wiki/Quebec ], Canada [ http://en.wikipedia.org/wiki/Canada ], the coma [ http://www.windows.ucar.edu/tour/link=/comets/coma.html&edu=high ] of Comet Holmes [ http://www.badastronomy.com/bablog/2007/10/28/comet-17p-holmes-update/ ] is seen noticeably expanding over the past few days. Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap050911.html ] has been placed artificially nearby to allow for a comparison of angular sizes [ http://chandra.harvard.edu/photo/scale.html ] and scaled to the size it would appear at the current location of Comet Holmes [ http://en.wikipedia.org/wiki/17P/Holmes ]. How Comet Holmes will further evolve [ http://cometography.com/pcomets/017p.html ] is unknown, with one possibility being that the expanding gas cloud that started from its recent outburst [ http://antwrp.gsfc.nasa.gov/apod/ap071029.html ] will slowly disperse and fade. |
|
A Telescopic View of Eruptin
…
| Title |
A Telescopic View of Erupting Comet Holmes |
| Explanation |
What's happened to Comet Holmes? A normally docile comet discovered over 100 years ago, Comet 17P/Holmes [ http://cometography.com/pcomets/017p.html ] suddenly became nearly one million times brighter last week, possibly over just a few hours. In astronomical terms, the comet brightened from magnitude [ http://csep10.phys.utk.edu/astr162/lect/stars/magnitudes.html ] 17, only visible through a good telescope, to magnitude 3, becoming visible with the unaided eye. Comet Holmes [ http://en.wikipedia.org/wiki/17P/Holmes ] had already passed its closest to the Sun in 2007 May outside the orbit of Mars and was heading back out [ http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=17P;orb=1 ] near Jupiter's orbit when the outburst occurred. The comet's sudden brightening is likely due to some sort of sunlight-reflecting outgassing [ http://antwrp.gsfc.nasa.gov/apod/ap040319.html ] event, possibly related to ice melting over a gas-filled cavern, or possibly even a partial breakup of the comet's nucleus. Pictured above [ http://www.fpsoftlab.com/gallery/solar-system-images.htm ] through a small telescope last Thursday, Comet Holmes [ http://www.skyandtelescope.com/observing/home/10775326.html ] appeared as a fuzzy yellow spot, significantly larger in angular size than Earth-atmosphere blurred distant stars [ http://antwrp.gsfc.nasa.gov/apod/ap000725.html ]. Although Comet Holmes' [ http://www.space.com/spacewatch/071025-comet-holmes.html ] orbit will place it [ http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=17P;orb=1 ] in northern hemisphere skies for the next two years, whether it will best be viewed through a telescope [ http://antwrp.gsfc.nasa.gov/apod/ap060806.html ] or sunglasses [ http://www.youtube.com/watch?v=PXw4qqQqTrY ] remains unknown. |
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Comet Borrelly's Nucleus
| Title |
Comet Borrelly's Nucleus |
| Explanation |
What does a comet nucleus look like? To answer this question, NASA [ http://www.nasa.gov/qanda/studentprograms.html ] controllers drove an aging probe through the hostile environs of a distant comet, expecting that even if comet fragments disabled the spacecraft, it would be worth the risk. The probe, Deep Space 1 [ http://nmp.jpl.nasa.gov/ds1/ ], survived. Pictured above [ http://www.jpl.nasa.gov/images/ds1/ borrelly_caption.html ] is the most detailed image ever taken of a comet [ http://www.nineplanets.org/comets.html ] nucleus, obtained Saturday by Deep Space 1 [ http://nmp.jpl.nasa.gov/ds1/images.html ] and released yesterday by NASA [ http://www.nasa.gov/ ]. Comet Borrelly [ http://cometography.com/pcomets/019p.html ]'s nucleus is seen to be about 8 kilometers long with mountains [ http://antwrp.gsfc.nasa.gov/apod/ap010527.html ], faults [ http://antwrp.gsfc.nasa.gov/apod/ap960121.html ], grooves [ http://antwrp.gsfc.nasa.gov/apod/ap960711.html ], smooth rolling plains [ http://antwrp.gsfc.nasa.gov/apod/ap010129.html ], and materials of vastly different reflectance [ http://antwrp.gsfc.nasa.gov/apod/ap000829.html ]. Light colored regions are present near the center and seem to give rise to dust [ http://antwrp.gsfc.nasa.gov/apod/ap010813.html ] jets seen in Borrelly's coma [ http://antwrp.gsfc.nasa.gov/apod/ap010625.html ], visible in distant images [ http://science.nasa.gov/headlines/y2000/ast11jul_1.htm ] of the comet. Previously, the best image of a comet nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap000805.html ] came from the Giotto mission [ http://nssdc.gsfc.nasa.gov/planetary/giotto.html ] to Comet Halley [ http://csep10.phys.utk.edu/astr161/lect/comets/ halley.html ] in 1986. Deep Space 1 images [ http://www.jpl.nasa.gov/releases/2001/ release_2001_190.html ] of Borrelly add welcomed bedrock [ http://www.state.me.us/doc/nrimc/mgs/bedrock/bedrock.htm ] to understanding Solar System [ http://www.nineplanets.org/overview.html ] history [ http://adsabs.harvard.edu/cgi-bin/ nph-bib_query?bibcode=1993A%26ARv...5...37F ] and to the accurate prediction of future brightness changes of notoriously fickle comet [ http://www.exploratorium.edu/exploring/space/kohoutek.html ]s. |
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Comet Holmes in Outburst
| Title |
Comet Holmes in Outburst |
| Explanation |
Comet 17P/Holmes [ http://cometography.com/pcomets/017p.html ] stunned comet watchers [ http://www.spaceweather.com/comets/ gallery_holmes.html ] across planet Earth earlier this week. On October 24, it increased in brightness over half a million times in a matter of hours. The outburst [ http://www.skyandtelescope.com/observing/home/ 10775326.html ] transformed it from an obscure and faint comet quietly orbiting the Sun with a period of about 7 years to a naked-eye comet rivaling the brighter stars in the constellation Perseus [ http://spaceweather.com/images2007/24oct07/ skymap_north_holmes.gif ]. Recorded on that date, this view from Tehran, Iran highlights the comet's (enhanced and circled) dramatic new visibility in urban skies. The inset (left) is a telescopic image [ http://www.avertedimagination.com/img_pages/ 17P_Holmes102407.html ] from a backyard in Buffalo, New York showing the comet's greatly expanded coma [ http://www.nasa.gov/worldbook/comet_worldbook.html ], but apparent lack of a tail. Holmes' outburst [ http://www.aerith.net/comet/catalog/0017P/ 2007.html ] could be due to a sudden exposure of fresh cometary ice or even the breakup of the comet nucleus [ http://www.ifa.hawaii.edu/~jewitt/nucleus.html ]. The comet may well remain bright in the coming days. |
|
Skyscape with Comet Holmes
| Title |
Skyscape with Comet Holmes |
| Explanation |
This gorgeous skyscape [ http://www.eanet.com/kodama/astro/2007/1102b/ index.htm ] spans some 10 degrees across the heroic constellation Perseus [ http://www.windows.ucar.edu/tour/link=/the_universe/Constellations/ perseus.html&edu=high ], about the size of a generous binocular field of view. The deep exposure includes bright stars, emission nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap050930.html ], star clusters, and, of course, the famous Comet Holmes [ http://www.earthsky.org/article/ see-comet-holmes-this-weekend ]. To identify the celestial landmarks, just place your cursor over the image. The brightest star in view, Alpha Persei, is itself surrounded by a loose cluster of stars - the Alpha Per Moving Cluster [ http://seds.org/messier/xtra/ngc/alphaper.html ] - at a distance of about 600 light-years. But, at a distance of a mere 14 light-minutes [ http://haydenplanetarium.org/universe/duguide/ app_light_travel_time_dista.php ] bright Comet Holmes [ http://spaceweather.com/comets/gallery_holmes_page11.htm ] still dominates the scene with its fluorescing [ http://antwrp.gsfc.nasa.gov/apod/ap060311.html ] greenish coma and foreshortened blue tail. |
|
The Inner Coma of Comet Holm
…
| Title |
The Inner Coma of Comet Holmes |
| Explanation |
What's happening to Comet Holmes? The rare comet remains visible to the unaided eyes of northern observers as an unusual small puff ball [ http://spaceweather.com/comets/gallery_holmes_page13.htm ] in the constellation of Perseus [ http://en.wikipedia.org/wiki/Perseus_(constellation) ]. A high resolution set of images of the comet's inner coma [ http://www.ifa.hawaii.edu/~jewitt/coma.html ], taken last week and shown above, reveals significant detail. Close inspection shows numerous faint streamers that are possibly the result of jets emanating [ http://antwrp.gsfc.nasa.gov/apod/ap970213.html ] from the comet's nucleus. Comet Holmes [ http://antwrp.gsfc.nasa.gov/apod/ap071110.html ] has remained surprisingly bright over the past week, with luminosity estimates [ http://cfa-www.harvard.edu/iau/icq/CometMags.html#0017P ] ranging from between visual magnitude [ http://en.wikipedia.org/wiki/Apparent_magnitude ]s 2 to 3, making it brighter than most stars visible on a dark sky. The above image of Comet Holmes [ http://en.wikipedia.org/wiki/Comet_Holmes ] was made with a small automated 0.38-meter telescope [ http://virtualtelescope.bellatrixobservatory.org/newsetupeng.html ] hirable over the web for a small fee. |
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Golden Comet Holmes
| Title |
Golden Comet Holmes |
| Explanation |
Surprising Comet Holmes remains easily visible as a round, fuzzy cloud in the northern constellation Perseus [ http://antwrp.gsfc.nasa.gov/apod/ap071026.html ]. Skywatchers with telescopes, binoculars, or those that just decide to look up can enjoy [ http://spaceweather.com/comets/gallery_holmes_page7.htm ] the solar system's latest prodigy as it glides [ http://www.shadowandsubstance.com/ ] about 150 million kilometers from Earth, beyond the orbit of Mars. Still expanding [ http://antwrp.gsfc.nasa.gov/apod/ap071030.html ], Holmes now appears to be about 1/3 the size of the Full Moon, and many observers report a yellowish tint to the dusty coma [ http://www.nasa.gov/worldbook/comet_worldbook.html ]. A golden color does dominate this telescopic view [ http://dg-imaging.astrodon.com/gallery/ display.cfm?imgID=104 ] recorded on November 1, showing variations across the coma's bright central region. But where's the comet's tail? Like any good comet, Holmes' [ http://cometography.com/pcomets/017p.html ] tail would tend to point away from the Sun. That direction is nearly along our line-of-sight behind the comet, making its tail very difficult to see. |
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