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Comets Kick up Dust in Helix …
Title Comets Kick up Dust in Helix Nebula
Description This infrared image from NASA's Spitzer Space Telescope shows the Helix nebula, a cosmic starlet often photographed by amateur astronomers for its vivid colors and eerie resemblance to a giant eye. The nebula, located about 700 light-years away in the constellation Aquarius, belongs to a class of objects called planetary nebulae. Discovered in the 18th century, these colorful beauties were named for their resemblance to gas-giant planets like Jupiter. Planetary nebulae are the remains of stars that once looked a lot like our sun. When sun-like stars die, they puff out their outer gaseous layers. These layers are heated by the hot core of the dead star, called a white dwarf, and shine with infrared and visible colors. Our own sun will blossom into a planetary nebula when it dies in about five billion years. In Spitzer's infrared view of the Helix nebula, the eye looks more like that of a green monster's. Infrared light from the outer gaseous layers is represented in blues and greens. The white dwarf is visible as a tiny white dot in the center of the picture. The red color in the middle of the eye denotes the final layers of gas blown out when the star died. The brighter red circle in the very center is the glow of a dusty disk circling the white dwarf (the disk itself is too small to be resolved). This dust, discovered by Spitzer's infrared heat-seeking vision, was most likely kicked up by comets that survived the death of their star. Before the star died, its comets and possibly planets would have orbited the star in an orderly fashion. But when the star blew off its outer layers, the icy bodies and outer planets would have been tossed about and into each other, resulting in an ongoing cosmic dust storm. Any inner planets in the system would have burned up or been swallowed as their dying star expanded. So far, the Helix nebula is one of only a few dead-star systems in which evidence for comet survivors has been found. This image is made up of data from Spitzer's infrared array camera and multiband imaging photometer. Blue shows infrared light of 3.6 to 4.5 microns, green shows infrared light of 5.8 to 8 microns, and red shows infrared light of 24 microns.
Comets Kick up Dust in Helix …
Title Comets Kick up Dust in Helix Nebula
Description This infrared image from NASA's Spitzer Space Telescope shows the Helix nebula, a cosmic starlet often photographed by amateur astronomers for its vivid colors and eerie resemblance to a giant eye. The nebula, located about 700 light-years away in the constellation Aquarius, belongs to a class of objects called planetary nebulae. Discovered in the 18th century, these colorful beauties were named for their resemblance to gas-giant planets like Jupiter. Planetary nebulae are the remains of stars that once looked a lot like our sun. When sun-like stars die, they puff out their outer gaseous layers. These layers are heated by the hot core of the dead star, called a white dwarf, and shine with infrared and visible colors. Our own sun will blossom into a planetary nebula when it dies in about five billion years. In Spitzer's infrared view of the Helix nebula, the eye looks more like that of a green monster's. Infrared light from the outer gaseous layers is represented in blues and greens. The white dwarf is visible as a tiny white dot in the center of the picture. The red color in the middle of the eye denotes the final layers of gas blown out when the star died. The brighter red circle in the very center is the glow of a dusty disk circling the white dwarf (the disk itself is too small to be resolved). This dust, discovered by Spitzer's infrared heat-seeking vision, was most likely kicked up by comets that survived the death of their star. Before the star died, its comets and possibly planets would have orbited the star in an orderly fashion. But when the star blew off its outer layers, the icy bodies and outer planets would have been tossed about and into each other, resulting in an ongoing cosmic dust storm. Any inner planets in the system would have burned up or been swallowed as their dying star expanded. So far, the Helix nebula is one of only a few dead-star systems in which evidence for comet survivors has been found. This image is made up of data from Spitzer's infrared array camera and multiband imaging photometer. Blue shows infrared light of 3.6 to 4.5 microns, green shows infrared light of 5.8 to 8 microns, and red shows infrared light of 24 microns.
The Rosette Nebula in Hydrog …
Title The Rosette Nebula in Hydrogen, Oxygen, and Sulfur
Explanation The Rosette Nebula is a large emission nebula [ http://seds.lpl.arizona.edu/billa/twn/types.html#emission ] located 3000 light-years away. The great abundance of hydrogen gas [ http://casswww.ucsd.edu/public/tutorial/Planck.html#atoms ] gives NGC 2237 [ http://seds.lpl.arizona.edu/billa/twn/n2237x.html ] its red color in most photographs [ http://antwrp.gsfc.nasa.gov/apod/ap980214.html ]. The wind [ http://antwrp.gsfc.nasa.gov/apod/ap990208.html ] from the open cluster [ http://antwrp.gsfc.nasa.gov/apod/ap980329.html ] of stars known as NGC 2244 has cleared a hole in the nebula's center. The above photograph [ http://www.noao.edu/image_gallery/html/im0557.html ], however, was taken in the light emitted by three elements of the gas ionized by the energetic central stars. Here green light originating from oxygen [ http://pearl1.lanl.gov/periodic/elements/8.html ] and blue light originating from sulfur [ http://pearl1.lanl.gov/periodic/elements/16.html ] supplements the red from hydrogen. Filaments of dark dust [ http://galileo.mpi-hd.mpg.de/ ] lace run through the nebula's gases. The origin of recently observed fast-moving molecular knots [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998A%26A...334..264C ] in the Rosette Nebula remains under investigation.
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.
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 ].
Star EGGs in the Eagle Nebul …
Title Star EGGs in the Eagle Nebula
Explanation Where do stars form? One place, star forming regions known as "EGGs", are uncovered at the end of this giant pillar [ http://antwrp.gsfc.nasa.gov/apod/ap050424.html ] of gas and dust [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#dust ] in the Eagle Nebula [ http://en.wikipedia.org/wiki/Eagle_Nebula ] (M [ http://antwrp.gsfc.nasa.gov/apod/messier.html ]16). EGGs, short for evaporating gaseous globules [ http://antwrp.gsfc.nasa.gov/apod/ap030816.html ], are dense regions of mostly molecular hydrogen [ http://periodic.lanl.gov/elements/1.html ] gas that fragment and gravitationally collapse to form stars [ http://antwrp.gsfc.nasa.gov/apod/ap060403.html ]. Light from the hottest and brightest of these new stars [ http://antwrp.gsfc.nasa.gov/apod/ap060109.html ] heats the end of the pillar and causes further evaporation of gas - revealing yet more EGGs [ ftp://ftp.hq.nasa.gov/pub/pao/pressrel/1995/95-190.txt ] and more young stars. This picture [ http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/44/image/b ] was taken by the Wide Field and Planetary Camera [ http://www.stsci.edu/instruments/wfpc2/wfpc2_top.html ] on board the Hubble Space Telescope [ http://www.stsci.edu/hst/HST_overview/ ].
IC 4628: The Prawn Nebula
Title IC 4628: The Prawn Nebula
Explanation South of Antares [ http://antwrp.gsfc.nasa.gov/apod/ap060714.html ], in the tail of the nebula-rich [ http://antwrp.gsfc.nasa.gov/apod/ap060628.html ] constellation Scorpius, lies emission nebula IC 4628 [ http://www.aao.gov.au/images/captions/aat105.html ]. Nearby hot, massive stars, millions of years young, radiate the nebula [ http://en.wikipedia.org/wiki/H_II_region ] with invisible ultraviolet light, stripping electrons from atoms. The electrons eventually recombine with the atoms to produce the visible nebular glow [ http://vis.sdsc.edu/research/hayden2.html ]. This narrow band [ http://antwrp.gsfc.nasa.gov/apod/ap060324.html ] image adopts a typical false-color mapping [ http://hubblesite.org/gallery/behind_the_pictures/ meaning_of_color/eagle.shtml ] of the atomic emission, showing hydrogen emission in green hues, sulfur as red and oxygen as blue. At an estimated distance of 6,000 light-years, the region shown is about 250 light-years across. The nebula is also cataloged as [ http://antwrp.gsfc.nasa.gov/apod/ap060519.html ] Gum 56 for Australian astronomer Colin Stanley Gum, but seafood-loving astronomers might know [ http://seds.lpl.arizona.edu/messier/xtra/supp/ d-names.html ] this cosmic cloud as The Prawn Nebula [ http://www.martinpughastrophotography.id.au/ Nebulae/IC4628.htm ].
X-rays and the Eagle Nebula
Title X-rays and the Eagle Nebula
Explanation The premier Chandra X-ray Observatory images of M16 [ http://chandra.harvard.edu/photo/2007/m16/ ], the Eagle Nebula, show many bright x-ray sources in the region. Most of the x-ray sources [ http://chandra.harvard.edu/xray_astro/medxray.html ] are energetic young stars. They are seen here as colored spots superimposed on the Hubble's well-known optical view of M16's light-year long Pillars of Creation [ http://antwrp.gsfc.nasa.gov/apod/ap070218.html ]. For example, a blue source near [ http://chandra.harvard.edu/photo/2007/m16/zoom.html ] the tip of the large pillar at the upper left is estimated to be an embedded young star 4 or 5 times as massive as the Sun [ http://www.sunblock99.org.uk/sb99/fact/ heavy.html ]. Still, most of the x-ray sources are not coincident with the pillars themselves, indicating that embedded stars are not common in the dusty structures. The mostly empty pillars are thought to be an indication [ http://arxiv.org/abs/astro-ph/0610279 ] that star formation actually peaked millions of years ago within [ http://arxiv.org/abs/astro-ph/0201292 ] the Eagle Nebula [ http://seds.lpl.arizona.edu/messier/m/m016.html ].
Dust and the Helix Nebula
Title Dust and the Helix Nebula
Explanation Dust makes this cosmic eye look red. The eerie Spitzer Space Telescope image [ http://www.spitzer.caltech.edu/Media/releases/ ssc2007-03/index.shtml ] shows infrared [ http://coolcosmos.ipac.caltech.edu// ] radiation from the well-studied Helix Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap060112.html ] (NGC 7293) a mere 700 light-years away in the constellation Aquarius [ http://www.seds.org/Maps/Stars_en/Fig/aquarius.html ]. The two light-year diameter shroud of dust and gas around a central white dwarf has long been considered an excellent example of a planetary nebula [ http://www.noao.edu/jacoby/pn_gallery.html ], representing the final stages in the evolution of a sun-like star. But the Spitzer data show the nebula's central star itself is immersed in a surprisingly bright infrared glow. Models [ http://arxiv.org/abs/astro-ph/0702296 ] suggest the glow is produced by a dust debris disk [ http://antwrp.gsfc.nasa.gov/apod/ap041210.html ]. Even though the nebular material was ejected from the star many thousands of years ago, the close-in dust could be generated by collisions in a reservoir of objects analogous to our own solar system's Kuiper Belt [ http://www.ifa.hawaii.edu/faculty/jewitt/kb/kb.con.html ] or cometary Oort cloud [ http://www.windows.ucar.edu/tour/ link=/comets/Oort_cloud.html&edu=high ]. Formed in the distant planetary system, the comet-like bodies have otherwise survived even the dramatic late stages of the star's evolution [ http://en.wikipedia.org/wiki/Stellar_evolution ].
In the Center of Reflection …
Title In the Center of Reflection Nebula NGC 1333
Explanation The dust is so thick in the center of NGC 1333 that you can hardly see the stars forming. Conversely, the very dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ] clouds that hide the stars also reflects their optical light [ http://fuse.pha.jhu.edu/~wpb/spectroscopy/em_spec.html ], giving NGC 1333 [ http://www.robgendlerastropics.com/NGC1333text.html ]'s predominantly blue glow the general designation of a reflection nebula [ http://antwrp.gsfc.nasa.gov/apod/reflection_nebulae.html ]. A highly detailed image of the nebula, shown above [ http://www.noao.edu/image_gallery/html/im1037.html ], was taken recently by the Mayall 4-meter telescope [ http://www.noao.edu/outreach/kptour/mayall.html ] on Kitt Peak [ http://www.noao.edu/kpno/ ] in Arizona [ http://en.wikipedia.org/wiki/Arizona ], USA [ http://en.wikipedia.org/wiki/United_States ] and released to honor astronomer Stephen Strom [ http://www.noao.edu/outreach/press/pr07/pr0706.html ] on his retirement. Visible near the image top are vast blue regions of dust [ http://antwrp.gsfc.nasa.gov/apod/ap061211.html ] predominantly reflecting the light from bright massive stars [ http://antwrp.gsfc.nasa.gov/apod/ap060109.html ]. Visible in the thick central dust are not only newly formed stars but red jets [ http://antwrp.gsfc.nasa.gov/apod/ap070430.html ] and red-glowing gas energized by the light and winds [ http://www-spof.gsfc.nasa.gov/Education/wsolwind.html ] from recently formed young stars. The NGC 1333 [ http://adsabs.harvard.edu/abs/2002ApJ...580..959N ] nebula contains [ http://antwrp.gsfc.nasa.gov/apod/ap061006.html ] hundreds of newly formed stars that are less than one million years old. Reflection nebula [ http://en.wikipedia.org/wiki/Reflection_nebula ] NGC 1333 lies about 1,000 light years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] away toward the constellation of Perseus [ http://chandra.harvard.edu/photo/constellations/perseus.html ].
Hot Stars in the Rosette Neb …
Title Hot Stars in the Rosette Nebula
Explanation Winds and radiation from massive hot stars in the Rosette Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap070214.html ] have cleared the natal gas and dust [ http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ cosmic_reference/dust.html ] from the center of the nearby star-forming region. They also pose a danger to planet forming disks [ http://antwrp.gsfc.nasa.gov/apod/ap041210.html ] around young, cooler stars in the neighborhood. This Spitzer Space Telescope infrared image [ http://gallery.spitzer.caltech.edu/ Imagegallery/image.php?image_name=ssc2007-08b ] of dust clouds near the Rosette's central region, shows the cleared-out cavity. The view spans about 45 light-years at the the nebula's estimated distance of 5,200 light-years. Putting your cursor over the false color picture will highlight the dangerous hot stars, classified as O stars [ http://www.astro.uiuc.edu/~kaler/sow/ spectra.html#classes ] with surface temperatures of 25,000 kelvins [ http://en.wikipedia.org/wiki/Kelvin ] or higher. Astronomers calculate [ http://arxiv.org/abs/astro-ph/0701741 ] that cool stars wandering within about 1.6 light-years of the Rosette's O stars are in danger of having their planet forming disks destroyed [ http://antwrp.gsfc.nasa.gov/apod/ap010504.html ].
NGC 1977: Blue Reflection Ne …
Title NGC 1977: Blue Reflection Nebula in Orion
Explanation The Orion Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap980127.html ] is visible to the unaided eye as a fuzzy patch near the famous belt of three stars [ http://antwrp.gsfc.nasa.gov/apod/ap970820.html ] in the
M57: The Ring Nebula
Title M57: The Ring Nebula
Explanation Except for the rings of Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap000212.html ], the Ring Nebula [ http://seds.lpl.arizona.edu/messier/m/m057.html ] (M57) is probably the most famous celestial band. This planetary nebula's [ http://www.astro.washington.edu/balick/WFPC2/ ] simple, graceful appearance is thought to be due to perspective -- our view from planet Earth [ http://antwrp.gsfc.nasa.gov/apod/earth.html ] looking straight into what is actually a barrel-shaped cloud [ http://www.seds.org/billa/twn/n6720x.html ] of gas shrugged off by a dying central star. Astronomers of the Hubble Heritage Project [ http://heritage.stsci.edu/ ] produced this strikingly sharp image [ http://heritage.stsci.edu/public/jan6/ringbond.html ] from Hubble Space Telescope [ http://www.stsci.edu/hst/ ] observations using natural appearing colors to indicate the temperature of the stellar gas shroud. Hot blue gas near the energizing central star gives way to progressively cooler green and yellow gas at greater distances [ http://antwrp.gsfc.nasa.gov/apod/ap990922.html ] with the coolest red gas along the outer boundary. Dark, elongated structures [ http://antwrp.gsfc.nasa.gov/apod/ap970720.html ] can also be seen near the nebula's edge. The Ring Nebula [ http://seds.lpl.arizona.edu/messier/more/m057_jac.html ] is about one light-year [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] across and 2,000 light-years away in the northern constellation Lyra [ http://www.astro.wisc.edu/~dolan/constellations/ constellations/Lyra.html ].
Cold Dust in the Eagle Nebul …
Title Cold Dust in the Eagle Nebula
Explanation Stars are born in M16's Eagle Nebula [ http://seds.lpl.arizona.edu/messier/m/m016.html ], a stellar nursery 7,000 light-years from Earth toward the constellation Serpens [ http://www.astronomical.org/constellations/ser.html ]. The striking nebula's star forming pillars [ http://antwrp.gsfc.nasa.gov/apod/ap000924.html ] of gas and dust are familiar to astronomers [ http://antwrp.gsfc.nasa.gov/apod/ap970730.html ] from images at visible wavelengths, but this false-color picture [ http://sci.esa.int/content/news/ photorelease.cfm?aid=1&cid=1&oid=28114 ] shows off the nebula in infrared light [ http://imagers.gsfc.nasa.gov/ems/infrared.html ]. Data from ESA's Infrared Space Observatory [ http://www.iso.vilspa.esa.es/users/expl_lib/ mission.html ] satellite (ISO) was used to construct the detailed two color image [ http://www.iso.vilspa.esa.es/galleries/ism/eagle.htm ], dominated by infrared emission from clouds of interstellar material at temperatures below -100 degrees Celsius. Blue colors highlight emission thought to indicate the presence of complex carbon molecules [ http://www.sciam.com/explorations/1999/032299life/ ], known on planet Earth as PAHs [ http://www.chem.ucl.ac.uk/cosmicdust/pah.htm ], while red colors trace emission from cold, microscopic dust grains [ http://science.nasa.gov/headlines/y2000/ ast24apr_1.htm ]. Hot young stars are formed as this frigid material condenses under the influence of gravity [ http://hyperphysics.phy-astr.gsu.edu/hbase/astro/ gravc.html ]. Once begun, the process takes [ http://www.astro.psu.edu/users/carkner/ttauri/ star1.html ] only tens of thousands of years for truly massive stars and up to tens of millions of years for low mass stars like the Sun.
Orion's Horsehead Nebula
Title Orion's Horsehead Nebula
Explanation The black indentation to the red emission nebula [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#emis_neb ] seen just to the right of center of the above photograph is one of the most famous features in any nebulae on the sky. Because of its shape, it is known as the Horsehead Nebula [ http://seds.lpl.arizona.edu/billa/twn/b33x.html ]. The bright star near the center is located in the belt of the familiar constellation of Orion. The horse head feature is dark because it is really a dense dust [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#dust ] cloud which lies in front of the bright nebula and blocks the light. Like clouds in our sky, this cosmic cloud has chanced to assume a recognizable shape. After thousands of years, the internal motions of the cloud will alter its appearance. The emission nebula [ http://zebu.uoregon.edu/textbook/ism.html ]'s red color is caused by electrons recombining with protons to form hydrogen [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ] atoms. Also visible in the picture are blue reflection nebulae [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#refl_neb ]. This type of nebula contains dust which preferentially reflects the blue light of nearby stars.
Cone Nebula Infrared Close-U …
Title Cone Nebula Infrared Close-Up
Explanation After astronauts repaired NICMOS [ http://oposite.stsci.edu/pubinfo/pr/2002/13/ index.html ] - the Near Infrared Camera and Multi-Object Spectrometer - during the latest Hubble Space Telescope servicing mission [ http://antwrp.gsfc.nasa.gov/apod/ap020314.html ], astronomers were quick to turn the sophisticated instrument on the photogenic stellar nursery [ http://antwrp.gsfc.nasa.gov/apod/ap020503.html ] known as the Cone Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap020107.html ]. This remarkable NICMOS [ http://www.stsci.edu/hst/nicmos/ ] close-up of the Cone Nebula [ http://oposite.stsci.edu/pubinfo/pr/2002/13/ fastfacts.html#Cone ] dramatically confirms that the Hubble's infrared vision has been restored [ http://oposite.stsci.edu/pubinfo/pr/2002/13/faq.html ]. Gas and dust clouds at the blunted tip of the cone-shaped star-forming region are seen here [ http://oposite.stsci.edu/pubinfo/pr/2002/13/ pr-photos.html ] in false-color covering an area about half a light-year across. Toward the left hand side of the picture, the four bright stars with diffraction spikes [ http://antwrp.gsfc.nasa.gov/apod/ap010415.html ] are also present in visible light images and are in front of the Cone Nebula, itself 2,500 light-years away. But the fainter stars to their right are embedded in or behind the nebula's obscuring dust clouds and are revealed [ http://oposite.stsci.edu/pubinfo/pr/2002/13/prc/ 0213aw.jpg ] only in this penetrating infrared view [ http://www.ipac.caltech.edu/Outreach/Edu/Regions/ irregions.html ].
Nebula Nova Cygni Turns On
Title Nebula Nova Cygni Turns On
Explanation Old photographs show no evidence of the above nebula. In 1992, a white dwarf star [ http://antwrp.gsfc.nasa.gov/apod/ap000910.html ] toward the constellation [ http://www.astro.wisc.edu/~dolan/constellations/extra/constellations.html ] of Cygnus [ http://www.astronomical.org/constellations/cyg.html ] blew off its outer layers in a classical nova [ http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_4a.html ] explosion: an event called Nova Cygni 1992 [ http://antwrp.gsfc.nasa.gov/apod/ap951227.html ]. Light flooded the local interstellar neighborhood [ http://www-ssg.sr.unh.edu/tof/Outreach/Interstellar/ ], illuminated this existing gas cloud, excited the existing hydrogen [ http://pearl1.lanl.gov/periodic/elements/1.html ], and hence caused the red emission [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ]. The only gas actually expelled by the nova [ http://astrosun.tn.cornell.edu/SC10/ncyg92.html ] can be seen as a small red ball just above the photograph's center. Eventually, light from the nova shell [ http://www.journals.uchicago.edu/ApJ/journal/issues/ApJL/v448n2/5174/sc0.html ] will fade, and this nebula will again become invisible!
Rampaging Fronts of the Veil …
Title Rampaging Fronts of the Veil Nebula
Explanation A supernova explosion [ http://www.ast.cam.ac.uk/RGO/leaflets/supernovae/supernovae.html ] of a high-mass star results in fast moving blast waves. At the front of the waves shown above, ionized gas in the Veil Supernova Remnant [ http://seds.lpl.arizona.edu/billa/twn/cygnusx.html ] rushes out from the explosion, sweeps up material, and breaks up many atoms into constituent ions and electrons. Observations [ file://stsci.edu/stsci/epa/tiff/cloop.txt ] with the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap950810.html ] in 1993 indicate that the blue shock wave was catapult away from the stellar explosion after the red shock wave and has yet to catch up to it in some regions. The Veil supernova remnant's has a very large angular size - six times the diameter of the full moon - and different parts of it are known as the "Cygnus Loop [ http://antwrp.gsfc.nasa.gov/apod/ap950718.html ]" and catalog numbers NGC 6960, NGC 6979, NGC 6992, and NGC 6995.
NGC 2237: The Rosette Nebula
Title NGC 2237: The Rosette Nebula
Explanation Would the Rosette [ http://c.gp.cs.cmu.edu:5103/prog/webster?rosette ] nebula by any other name " look " as sweet [ http://the-tech.mit.edu/Shakespeare/Tragedy/romeoandjuliet/ romeoandjuliet.all.html ]? The bland New General Catalog [ http://www.physics.sfsu.edu/asp/ngc.html ] designation of NGC 2237 [ http://seds.lpl.arizona.edu/billa/twn/n2237x.html ] doesn't appear to diminish the appearance of the this flowery emission nebula [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#emis_neb ]. Inside the nebula lies an open cluster [ http://antwrp.gsfc.nasa.gov/apod/ap960116.html ] of bright young stars designated NGC 2244. These stars recently formed from the nebular material and their stellar "wind" has cleared a hole in the nebula's center, insulated by a layer of dust [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#dust ] and hot gas [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ]. Ultraviolet [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#uv ] light from the hot cluster stars causes the surrounding nebula to glow.
The Keyhole Nebula Near Eta …
Title The Keyhole Nebula Near Eta Carinae
Explanation The dark dusty Keyhole Nebula gets its name from its unusual shape. Designated NGC 3324, the Keyhole Nebula [ http://seds.lpl.arizona.edu/billa/twn/n3324x.html ] is a smaller region superposed on the bright Eta Carina Nebula [ http://seds.lpl.arizona.edu/billa/twn/n3372x.html ]. The Eta Carina Nebula is the largest nebula in angular extent on the sky, larger than the famous Orion Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap951121.html ], but its southerly location makes it less familiar to Northern Hemisphere skywatchers. The star Eta Carinae [ http://antwrp.gsfc.nasa.gov/apod/ap960111.html ] itself is extremely variable and has faded in a mere 150 years - formerly one of the brightest in the sky it is now invisible without a telescope. The nebula created [ http://antwrp.gsfc.nasa.gov/apod/ap950712.html ] by the star's 19th century outburst [ http://www.stsci.edu/pubinfo/gif/WFPCEtaCar.txt ] has been photographed by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap950810.html ].
M17: The Majestic Swan Nebul …
Title M17: The Majestic Swan Nebula
Explanation What unusual eggs have been laid by this majestic swan [ http://www.dnr.ohio.gov/odnr/wildlife/diversity/swan.html ]? The star forming region above, known as Swan Nebula [ http://seds.lpl.arizona.edu/messier/m/m017.html ], is the home of hot red-glowing gas [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ], dark lanes of dust [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#dust ], bright young stars [ http://antwrp.gsfc.nasa.gov/apod/ap960823.html ] and -- what are those? Of the few stars visible in the Swan Nebula [ http://www.seds.org/billa/twn/n6618x.html ], several have quite unusual colors and are hypothesized to be very young stars still shrouded by gas from the cloud that formed them [ http://www.aas.org/ApJ/v448n1/5151/sc0.html ]. The Swan Nebula [ http://decoy.phast.umass.edu/bergin/chap5/node1.html ] is quite large and massive as it contains roughly 1000 times the mass of our Sun [ http://antwrp.gsfc.nasa.gov/apod/ap960520.html ]. The bright central region is about 15 light years across lies about 5000 light years away toward the constellation [ http://www.astro.wisc.edu/~dolan/constellations/constellations.html ] of Sagittarius [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Sagittarius.html ]. The distinctive shape causes this region to have several other names, including the Omega Nebula, the Horseshoe Nebula, and the Lobster Nebula.
A Close-Up of the Lagoon Neb …
Title A Close-Up of the Lagoon Nebula
Explanation Ribbons of red-glowing gas [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ] and dark dust [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#dust ] surround massive young stars in this close-up of the Lagoon Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap960127.html ] taken by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap950810.html ]. The Lagoon Nebula [ http://seds.lpl.arizona.edu/billa/twn/n6523x.html ] is relatively close and bright - it appears larger than the Full Moon [ http://antwrp.gsfc.nasa.gov/apod/ap960730.html ] and is visible even without a telescope [ http://aci.mta.ca/TheUmbrella/Physics/Astronomy/Telescope.html ]. Light takes about 5000 years to reach here from there. The Lagoon Nebula [ http://seds.lpl.arizona.edu/messier/m/m008.html ] houses the open star cluster [ http://antwrp.gsfc.nasa.gov/apod/lib/open_clusters.html ] M [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#messier ]8. This photograph [ http://scivax.stsci.edu/~hamilton/nuggets/HST_NUGGETS.HTML ] is combination of exposures taken in the red, green and ultraviolet. The unusual bright central part of the Lagoon Nebula [ http://adsabs.harvard.edu/cgi-bin/nph-article_query?bibcode=1990ApJ%2E%2E%2E357%2E%2E502M&page=1&plate_select=NO&type=GIF ] (lower left in this image) is known as the Hourglass Nebula.
M57: The Ring Nebula
Title M57: The Ring Nebula
Explanation Except for the rings of Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap000212.html ], the Ring Nebula [ http://seds.lpl.arizona.edu/messier/m/m057.html ] (M57) is probably the most famous celestial band. This planetary nebula's [ http://www.astro.washington.edu/balick/WFPC2/ ] simple, graceful appearance is thought to be due to perspective -- our view from planet Earth [ http://antwrp.gsfc.nasa.gov/apod/earth.html ] looking straight into what is actually a barrel-shaped cloud [ http://antwrp.gsfc.nasa.gov/apod/ap020618.html ] of gas shrugged off by a dying central star. Astronomers of the Hubble Heritage Project [ http://heritage.stsci.edu/ ] produced this strikingly sharp image [ http://heritage.stsci.edu/public/jan6/ringbond.html ] from Hubble Space Telescope [ http://www.stsci.edu/hst/ ] observations using natural appearing colors to indicate the temperature of the stellar gas shroud. Hot blue gas near the energizing central star gives way to progressively cooler green and yellow gas at greater distances [ http://antwrp.gsfc.nasa.gov/apod/ap990922.html ] with the coolest red gas along the outer boundary. Dark, elongated structures [ http://antwrp.gsfc.nasa.gov/apod/ap970720.html ] can also be seen near the nebula's edge. The Ring Nebula [ http://www.seds.org/billa/twn/n6720x.html ] is about one light-year [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/ question19.html ] across and 2,000 light-years away in the northern constellation Lyra [ http://www.astro.wisc.edu/~dolan/constellations/ constellations/Lyra.html ].
Copyright: Anglo-Australian …
Title Copyright: Anglo-Australian Telescope Board [ http://www.aao.gov.au/images.html ] Explanation: The photogenic M [ http://antwrp.gsfc.nasa.gov/apod/ap960626.html ]16 shown above is composed of a young star cluster [ http://antwrp.gsfc.nasa.gov/apod/ap950620.html ] associated with a spectacular emission nebulae [ http://seds.lpl.arizona.edu/messier/m/m016.html ] lined with clouds of interstellar dust [ http://antwrp.gsfc.nasa.gov/apod/ap961119.html ]. The gorgeous spectacle lies toward the galactic center region [ http://antwrp.gsfc.nasa.gov/apod/ap960723.html ], some 7,000 light years distant in the constellation Serpens [ http://galileo.gmu.edu/constellation/SER.html ]. Most of the stars in the cluster [ http://seds.lpl.arizona.edu/messier/cluster.html ] can be seen offset just above and to the right of the photograph's center. This type of star cluster is called an "open" or "galactic" cluster and typically has a few hundred young bright members. The redness of the surrounding emission nebula [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#emis_neb ] gas is caused by electrons recombining with hydrogen [ http://antwrp.gsfc.nasa.gov/apod/ap961218.html ] nuclei, while the dark regions are dust lanes [ http://antwrp.gsfc.nasa.gov/apod/ap950828.html ] that absorb light from background sources. The dust absorbs so much light it allows astronomers to determine which stars are inside the nebula and which are in the foreground. Stars are forming [ http://www.stsci.edu/pubinfo/background-text/m16eggs.txt ] within the nebula, also known as the Eagle Nebula [ http://www.stsci.edu/pubinfo/PR/95/44.html ].
The E Nebula in Aquila
Title The E Nebula in Aquila
Explanation Several unusual strands of darkness [ http://antwrp.gsfc.nasa.gov/apod/ap020526.html ] are prominent toward the constellation of Aquila [ http://chandra.harvard.edu/photo/constellations/aquila.html ]. This particular dark nebula [ http://zebu.uoregon.edu/~js/glossary/dark_nebula.html ] is known as the E Nebula, for its evocative shape, or B142 and B143, for its position(s) on a list of such nebula compiled by Barnard [ http://astro.uchicago.edu/yerkes/virtualmuseum/Barnard.html ]. The E Nebula [ http://www.eastbayastro.org/articles/lore/aquila.htm ] spans roughly the angle of a full Moon [ http://antwrp.gsfc.nasa.gov/apod/ap030810.html ] and lies about 2000 light years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] distant. The nebula [ http://www.abmedia.com/astro/current/b142-b143-fs102.html ] can be seen with binoculars and is particularly visible during the summer months in Earth's northern hemisphere. Other names for dark nebula [ http://antwrp.gsfc.nasa.gov/apod/dark_nebulae.html ] include absorption nebula [ http://www.glyphweb.com/esky/concepts/absorptionnebula.html ], as they efficiently absorb visible light emitted behind them, and molecular clouds [ http://etacha.as.arizona.edu/~eem/ttau/gmc.html ], as they frequently attain temperatures low enough so that several different types of stable molecules [ http://www.chem.ox.ac.uk/mom/ ] can exist. The low temperatures of these interstellar clouds [ http://antwrp.gsfc.nasa.gov/apod/ap020210.html ] facilitate the formation of dense knots [ http://antwrp.gsfc.nasa.gov/apod/ap011125.html ] of gas that may then collapse into bright stars.
Inside the Eagle Nebula
Title Inside the Eagle Nebula
Explanation From afar, the whole thing looks like an Eagle [ http://www.pbs.org/wnet/nature/eagles/ ]. A closer look at the Eagle Nebula [ http://www.seds.org/messier/m/m016.html ], however, shows the bright region [ http://www.noao.edu/image_gallery/html/im0051.html ] is actually a window into the center of a larger dark shell of dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ]. Through this window, a brightly-lit workshop appears where a whole open cluster [ http://antwrp.gsfc.nasa.gov/apod/open_clusters.html ] of stars is being formed. In this cavity tall pillars [ http://antwrp.gsfc.nasa.gov/apod/ap011125.html ] and round globules [ http://antwrp.gsfc.nasa.gov/apod/ap030816.html ] of dark dust and cold molecular gas [ http://antwrp.gsfc.nasa.gov/apod/ap030202.html ] remain where stars are still forming. Already visible are several young bright blue stars [ http://antwrp.gsfc.nasa.gov/apod/ap021201.html ] whose light and winds are burning away and pushing back the remaining filaments [ http://antwrp.gsfc.nasa.gov/apod/ap010812.html ] and walls of gas and dust. The Eagle emission nebula [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ], tagged M16, lies about 6500 light years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] away, spans about 20 light-years, and is visible with binoculars [ http://antwrp.gsfc.nasa.gov/apod/ap030921.html http://www.birdwatching.com/optics/binoculars1.html#How Binoculars Work ] toward the constellation [ http://www.astro.wisc.edu/~dolan/constellations/extra/constellations.html ] of Serpens [ http://www.astronomical.org/constellations/ser.html ]. The above picture [ http://www.noao.edu/image_gallery/html/im0725.html ] combines three specific emitted colors and was taken with the 0.9-meter telescope [ http://www.noao.edu/0.9m/manual.html ] on Kitt Peak [ http://www.noao.edu/kpno/ ], Arizona [ http://www.az.gov/ ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ].
Shells in the Egg Nebula
Title Shells in the Egg Nebula
Explanation The Egg Nebula is taking a beating. Like a baby chick pecking its way out of an egg, the star in the center of the Egg Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap960129.html ] is casting away shells of gas and dust [ http://antwrp.gsfc.nasa.gov/apod/ap961119.html ] as it slowly transforms itself into a white dwarf star [ http://antwrp.gsfc.nasa.gov/apod/ap961203.html ]. The above picture [ http://oposite.stsci.edu/pubinfo/PR/97/11.html ] was taken by the newly installed Near Infrared Camera and Multi-Object Spectrometer [ http://www.stsci.edu/ftp/instrument_news/NICMOS/topnicmos.html ] (NICMOS) now on board the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ]. A thick torus of dust now surrounds the star through which the shell gas is escaping. Newly expelled gas shells escape in beams as can be seen in the original HST image [ http://antwrp.gsfc.nasa.gov/apod/ap960129.html ] and in the recently released image shown above [ http://oposite.stsci.edu/pubinfo/PR/97/11/background.html ]. This infrared image is coded in false color to highlight two different types of emission. The red light represents hot hydrogen gas heated by the collisions of expanding shells. The blue light represents light from the central star scattered by the dust [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#dust ] in the nebula. It takes light about 3000 years to reach us from the Egg Nebula [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1989MNRAS%2E238P%2E%2E37P&db_key=AST&nosetcookie=1 ], which is hundreds of times the size of our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap961214.html ].
Pelican Nebula Ionization Fr …
Title Pelican Nebula Ionization Front
Explanation What's happening to the Pelican Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap020829.html ]? The light from young energetic stars is slowly transforming the Pelican [ http://antwrp.gsfc.nasa.gov/apod/ap000703.html ]'s cold gas to hot gas, with the advancing boundary between the two known as an ionization [ http://csep10.phys.utk.edu/astr162/lect/light/ionization.html ] front. Most of these bright stars lie off the top of the image, but part of the bright ionization front crosses on the upper right. Particularly dense and intricate filaments [ http://antwrp.gsfc.nasa.gov/apod/ap030118.html ] of cold gas are visible along the front. Millions of years from now this nebula might no longer [ http://antwrp.gsfc.nasa.gov/apod/ap020825.html ] be known as the Pelican [ http://www.audubon.org/bird/BoA/F41_G4b.html ], as the balance and placement of stars and gas will leave something that appears completely different. The above image [ http://www.noao.edu/image_gallery/html/im0849.html ] was taken with the Mayall 4-meter telescope [ http://www.noao.edu/kpno/40th/4m.html ] at Kitt Peak National Observatory [ http://www.noao.edu/kpno/ ] in Arizona [ http://az.gov/webapp/portal/ ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ]. The large circular artifact below the image center is not real. The nebula, also known as IC 5070 [ http://www.noao.edu/outreach/press/pr03/pr0308.html ], spans about 30 light years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] and lies about 1800 light years [ http://chandra.harvard.edu/photo/cosmic_distance.html ] away toward the constellation [ http://www.adlerplanetarium.org/history/exhibits/constellations/timeline.html ] of Cygnus [ http://www.seds.org/Maps/Stars_en/Fig/cygnus.html ].
The Great Nebula in Orion
Title The Great Nebula in Orion
Explanation The Great Nebula in Orion [ http://www.seds.org/billa/twn/n1976x.html ] can be found just below and to the left of the easily identifiable belt of three stars [ http://www.adler.uchicago.edu/ISE/ORION4.HTM ] in the popular constellation Orion [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Orion.html ]. This fuzzy patch contains one of the closest stellar nurseries, lying at a distance of about 1500 light years. In the above picture, the red region on the left consists of nebulae designated M42 and M43 and contains the bright Trapezium [ http://seds.lpl.arizona.edu/messier/more/m042_more.html ] open cluster [ http://antwrp.gsfc.nasa.gov/apod/ap971118.html ]. The blue region on the right is a nebula primarily reflecting [ http://antwrp.gsfc.nasa.gov/apod/index/ReflectionNebulae.html ] the light from internal bright stars. Recent observations of the Orion Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap971201.html ] by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ] have located solar-system sized star-forming regions [ http://antwrp.gsfc.nasa.gov/apod/ap961017.html ].
NGC 1977: Blue Reflection Ne …
Title NGC 1977: Blue Reflection Nebula in Orion
Explanation The Orion Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap980127.html ] is visible to the unaided eye as a fuzzy patch near the famous belt of three stars [ http://antwrp.gsfc.nasa.gov/apod/ap951114.html ] in the constellation [ http://galileo.gmu.edu/constellation/constellation.html ] Orion [ http://antwrp.gsfc.nasa.gov/apod/ap970523.html ]. The above picture captures a part of the Orion Nebula [ http://seds.lpl.arizona.edu/billa/twn/n1976x.html ] that primarily reflects light from bright Orion stars. This reflection nebula [ http://antwrp.gsfc.nasa.gov/apod/index/ReflectionNebulae.html ] appears blue because the blue light from the neighboring stars scatters more efficiently from nebula gas than does red light. The dark lanes are composed of mostly interstellar dust [ http://antwrp.gsfc.nasa.gov/apod/ap980116.html ] - fine needle-shaped carbon grains.
The Rosette Nebula
Title The Rosette Nebula
Explanation Would the Rosette [ http://c.gp.cs.cmu.edu:5103/prog/webster?rosette ] Nebula by any other name " look " as sweet [ http://the-tech.mit.edu/Shakespeare/Tragedy/romeoandjuliet/ romeoandjuliet.all.html ]? The bland New General Catalog [ http://www.aspsky.org/html/resources/ngc.html ] designation of NGC 2237 [ http://seds.lpl.arizona.edu/billa/twn/n2237x.html ] doesn't appear to diminish the appearance of the this flowery emission nebula [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#emis_neb ]. Inside the nebula lies an open cluster [ http://antwrp.gsfc.nasa.gov/apod/ap960522.html ] of bright young stars designated NGC 2244. These stars recently formed from the nebular material and their stellar "wind" has cleared a hole in the nebula's center, insulated by a layer of dust [ http://antwrp.gsfc.nasa.gov/apod/ap980104.html ] and hot gas [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ]. Ultraviolet [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#uv ] light from the hot cluster stars causes the surrounding nebula to glow.
M57: The Ring Nebula
Title M57: The Ring Nebula
Explanation It looked like a ring on the sky. Hundreds of years ago astronomers noticed a nebula with a most unusual shape. Now known as M57 or NGC 6720, the gas cloud became popularly known as the Ring Nebula [ http://seds.lpl.arizona.edu/messier/m/m057.html ]. It is now know to be a planetary nebula [ http://zebu.uoregon.edu/~imamura/208/feb22/feb22.html ], a gas cloud emitted at the end of a Sun-like star's existence. As one of the brightest planetary nebula [ http://antwrp.gsfc.nasa.gov/cgi-bin/cossc/apod_search?planetary+nebula ] on the sky, the Ring Nebula [ http://www.ezaccess.net/sbb/M57.html ] can be seen with a small telescope in the constellation of Lyra [ http://galileo.gmu.edu/constellation/LYR.html ]. The Ring Nebula [ http://www.seds.org/billa/twn/n6720x.html ] lies about 4000 light years away, and is roughly 500 times the diameter of our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap961214.html ]. In this recent picture [ http://www.astro.psu.edu/users/rbc/NGC6720.html ] by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ], dust [ http://antwrp.gsfc.nasa.gov/apod/ap980104.html ] filaments and globules [ http://antwrp.gsfc.nasa.gov/apod/ap961229.html ] are visible far from the central star. This helps indicate that the Ring Nebula is not spherical, but cylindrical. Perhaps the Ring Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap950727.html ] would appear differently [ http://antwrp.gsfc.nasa.gov/apod/ap971223.html ] if viewed sideways [ http://antwrp.gsfc.nasa.gov/apod/ap980427.html ].
Comet Hale-Bopp and the Nort …
Title Comet Hale-Bopp and the North America Nebula
Explanation Comet Hale-Bopp [ http://www2.jpl.nasa.gov/comet/ ]'s 1997 encounter with the inner Solar System [ http://www.nineplanets.org/overview.html ] allowed many breath-taking pictures [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?hale+bopp ]. Above [ http://www.skylook.net/album/comet/habo/hab3i.htm ], Comet Hale-Bopp was photographed crossing the constellation of Cygnus, sporting spectacular yellow dust and blue ion tails [ http://www.ifa.hawaii.edu/faculty/jewitt/tail.html ]. Visible on the right in red is the North America Nebula [ http://www.seds.org/messier/xtra/ngc/n7000.html ], a bright emission nebula [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ] observable from a dark location with binoculars. The North America Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap000501.html ] is about 1500 light-years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] away, much farther than the comet, which was only about 8 light minutes away. Several bright blue stars from the open cluster [ http://seds.lpl.arizona.edu/messier/open.html ] M39 [ http://antwrp.gsfc.nasa.gov/apod/ap040331.html ] are visible just above the comet's blue ion tail [ http://pwg.gsfc.nasa.gov/istp/events/halebopp/disconnect/ ].
The Orion Nebula from Subaru
Title The Orion Nebula from Subaru
Explanation The Orion Nebula [ http://www.seds.org/billa/twn/n1976x.html ] (M42) shows a host of treasures when viewed in infrared [ http://www.ipac.caltech.edu/Outreach/Edu/discovery.html ] light. Some stars in the Trapezium [ http://antwrp.gsfc.nasa.gov/apod/ap971118.html ], an open cluster [ http://antwrp.gsfc.nasa.gov/apod/ap970128.html ] of stars at the center, are only visible in infrared light. The orange feature above center is called the Kleinman-Low Nebula [ http://www-astronomy.mps.ohio-state.edu/~ryden/ast162_3/notes14.html ], and appears greatly affected by newly forming central star IRc2. The blue emission in this representative color photograph is caused by hot gas ionized by the Trapezium [ http://seds.lpl.arizona.edu/messier/more/m042_more.html ] stars. This is one of the first photographs [ http://www.subaru.naoj.org/outreach/press_releases/990128/ ] ever taken through Japan's new Subaru Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap990201.html ].
M42: A Mosaic of Orion's Gre …
Title M42: A Mosaic of Orion's Great Nebula
Explanation The Great Nebula in Orion [ http://www.stsci.edu/pubinfo/gif/OrionMos.txt ], an immense, nearby starbirth region, is probably the most famous of all astronomical nebulae. Here, 15 pictures [ http://www.stsci.edu/pubinfo/PR/95/45.html ] from the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ] have been mosaicked to cover the inner 2.5 light years of the nebula and illustrate its diverse nature. In addition to housing a bright open cluster of stars known as the Trapezium [ http://www.cita.utoronto.ca/~johnston/orion.html ], the Orion Nebula contains many stellar nurseries [ http://antwrp.gsfc.nasa.gov/apod/ap970305.html ]. These nurseries contain hydrogen [ http://antwrp.gsfc.nasa.gov/apod/ap980828.html ] gas, hot young stars [ http://antwrp.gsfc.nasa.gov/apod/ap990507.html ], proplyds [ http://antwrp.gsfc.nasa.gov/apod/ap961017.html ], and stellar jets [ http://antwrp.gsfc.nasa.gov/apod/ap951012.html ] spewing material at high speeds. Most of the filamentary structures visible in this image are actually shock waves - fronts where fast moving material encounters slow moving gas. Shocks are particularly apparent near the bright stars in the lower left of the picture. The Orion Nebula [ http://seds.lpl.arizona.edu/messier/m/m042.html ] is about 1500 light years distant, located in the same spiral arm of our Galaxy [ http://adc.gsfc.nasa.gov/mw/ ] as the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ].
Starbirth in the Trifid Nebu …
Title Starbirth in the Trifid Nebula
Explanation Tremendous pillars of gas and dust are being boiled away in the Trifid Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap980331.html ]. In the center of the picturesque Trifid [ http://www.seds.org/messier/m/m020.html ] lies a young hot star, located above and to the right of this picture [ http://eagle.la.asu.edu/hester/trifid.html ]. As soon as it was born, the massive star scorched its surroundings with bright and energetic light. Nearby stars trying to form ended up starved for gas as it was swept away [ http://antwrp.gsfc.nasa.gov/apod/ap990502.html ] from them by the bright star's light and wind. Lower mass stars should continue to form in the Trifid Nebula [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1985ApJ...294..578L ], as over 1500 times the mass of our Sun [ http://antwrp.gsfc.nasa.gov/apod/ap980830.html ] still exists in uncondensed gas. Also known as M20 [ http://antwrp.gsfc.nasa.gov/apod/ap970828.html ], the Trifid Nebula [ http://www.seds.org/billa/twn/n6514x.html ] is about 9000 light years away and easily visible [ http://antwrp.gsfc.nasa.gov/apod/ap971111.html ] with a small telescope in the constellation of Sagittarius [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Sagittarius.html ].
LL Ori and the Orion Nebula
Title LL Ori and the Orion Nebula
Explanation This esthetic close-up [ http://hubblesite.org/newscenter/newsdesk/archive/releases/ 2006/01/image/i ] of cosmic clouds and stellar winds features LL Orionis [ http://antwrp.gsfc.nasa.gov/apod/ap031115.html ], interacting with the Orion Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap060119.html ] flow. Adrift in Orion's stellar nursery [ http://archive.ncsa.uiuc.edu/Cyberia/Bima/ StarForm.html ] and still in its formative years, variable star LL Orionis produces a wind more energetic than the wind [ http://www-spof.gsfc.nasa.gov/Education/ wsolwind.html ] from our own middle-aged Sun. As the fast stellar wind runs into slow moving gas a shock front is formed, analogous to the bow wave [ http://www.ma.hw.ac.uk/solitons/LocalHeroes/sr.html ] of a boat moving through water or a plane traveling at supersonic [ http://antwrp.gsfc.nasa.gov/apod/ap010221.html ] speed. The small, arcing, graceful structure just above and left of center is LL Ori's cosmic bow shock, measuring about half a light-year across. The slower gas is flowing away from the Orion Nebula's hot central star cluster, the Trapezium [ http://seds.lpl.arizona.edu/messier/more/ m042_more.html ], located off the upper left corner of the picture. In three dimensions [ http://vis.sdsc.edu/research/orion.html ], LL Ori's wrap-around shock front is shaped like a bowl that appears brightest when viewed along the "bottom" edge. The beautiful picture is part of a large mosaic [ http://hubblesite.org/newscenter/newsdesk/archive/releases/ 2006/01/ ] view of the complex [ http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query? 2000AJ....119.2919B&db_key=AST&nosetcookie=1 ] stellar nursery in Orion, filled with a myriad of fluid [ http://antwrp.gsfc.nasa.gov/apod/ap990228.html ] shapes [ http://antwrp.gsfc.nasa.gov/apod/ap010504.html ] associated with star formation [ http://antwrp.gsfc.nasa.gov/apod/ap991129.html ].
M8: The Lagoon Nebula
Title M8: The Lagoon Nebula
Explanation This beautiful cosmic cloud is a popular stop on telescopic tours of the constellation Sagittarius [ http://www.hawastsoc.org/deepsky/sgr/index.html ]. Eighteenth century cosmic tourist Charles Messier [ http://www.seds.org/messier/xtra/history/biograph.html ] cataloged the bright nebula as M8 [ http://www.seds.org/messier/m/m008.html ], while modern day astronomers recognize the Lagoon Nebula as an active stellar nursery about 5,000 light-years distant, in the direction of the center [ http://antwrp.gsfc.nasa.gov/apod/ap990911.html ] of our Milky Way Galaxy. Striking details can be traced through this remarkable picture, processed [ http://www.mistisoftware.com/astronomy/ Compare_m8_Med.htm ] to reveal the Lagoon's range of filaments of glowing hydrogen gas [ http://antwrp.gsfc.nasa.gov/apod/ap051223.html ] and dark dust clouds along with the brighter, turbulent hourglass [ http://hubblesite.org/newscenter/newsdesk/archive/ releases/1996/38/ ] region at the upper right. The view is a color composite of narrow and broad band images recorded under dark skies in northwestern Arizona [ http://www.mistisoftware.com/astronomy/Site.htm ]. At the Lagoon's estimated distance, the picture spans [ http://chandra.harvard.edu/photo/scale_distance.html ] about 30 light-years.
Inside the Eagle Nebula
Title Inside the Eagle Nebula
Explanation From afar, the whole thing looks like an Eagle [ http://www.pbs.org/wnet/nature/eagles/ ]. A closer look at the Eagle Nebula [ http://www.seds.org/messier/m/m016.html ], however, shows the bright region [ http://www.noao.edu/image_gallery/html/im0051.html ] is actually a window into the center of a larger dark shell of dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ]. Through this window, a brightly-lit workshop appears where a whole open cluster [ http://antwrp.gsfc.nasa.gov/apod/open_clusters.html ] of stars is being formed. In this cavity tall pillars [ http://antwrp.gsfc.nasa.gov/apod/ap050424.html ] and round globules [ http://antwrp.gsfc.nasa.gov/apod/ap030816.html ] of dark dust and cold molecular gas [ http://antwrp.gsfc.nasa.gov/apod/ap041219.html ] remain where stars are still forming. Already visible are several young bright blue stars [ http://antwrp.gsfc.nasa.gov/apod/ap031227.html ] whose light and winds are burning away and pushing back the remaining filaments [ http://antwrp.gsfc.nasa.gov/apod/ap010812.html ] and walls of gas and dust. The Eagle emission nebula [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ], tagged M16, lies about 6500 light years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] away, spans about 20 light-years, and is visible with binoculars [ http://antwrp.gsfc.nasa.gov/apod/ap060226.html http://www.birdwatching.com/optics/binoculars1.html#How Binoculars Work ] toward the constellation [ http://www.astro.wisc.edu/~dolan/constellations/extra/constellations.html ] of Serpens [ http://www.astronomical.org/portal/modules/wfsection/article.php?articleid=76 ]. The above picture [ http://www.noao.edu/image_gallery/html/im0725.html ] combines three specific emitted colors and was taken with the 0.9-meter telescope [ http://www.noao.edu/0.9m/manual.html ] on Kitt Peak [ http://www.noao.edu/kpno/ ], Arizona [ http://www.az.gov/ ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ].
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