Galaxies and a Comet

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 20 Galaxies and a Comet Image Credit &Copyright:Dan Bartlett Explanation: Galaxies abound in this sharptelescopic image recorded onOctober 12 in dark skies over June Lake, California.The celestial scene spans nearly 2 degrees within the boundariesof the well-trained northern constellation Canes Venatici.Prominent at the upper left 23.5 million light-years distantis big, beautiful spiral galaxy NGC 4258,known to some as Messier 106.Eye-catching edge-on spiral NGC 4217 is above and right of centerabout 60 million light-years away.Just passing through the pretty field of view is cometC/2023 H2 Lemmon,discovered last April in image data from theMount Lemmon Survey.Here the comet sports more of a lime green coma though, alongwith a faint, narrow ion tail stretchingtoward the top of the frame.Thisvisitor to the inner Solar Systemis presently less than 7 light-minutes away and still difficult to spotwith binoculars, but it's growing brighter.Comet C/2023 H2 Lemmonwill reachperihelion, its closest point to the Sun, on October 29 andperigee, its closest to our fair planet, on November 10as it transitions from morning to evening northern skies. Tomorrow's picture:...

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A Sunrise at Sunset Point

This timelapse series captured on October 14 is set against

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Hydrogen Clouds of M33

APOD: 2023 October 13 - Hydrogen Clouds of M33 Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 13 Hydrogen Clouds of M33 Image Credit &Copyright:Reinhold Wittich Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share ofglowing hydrogen gas.A prominent member of the local group of galaxies, M33 is alsoknown as the Triangulum Galaxy andlies a mere 3 million light-years away. The galaxy's central 30,000 light-years or so are shown in thissharp galaxy portrait.The portrait features M33'sreddish ionized hydrogen clouds orHII regions.Sprawling along loose spiral arms that wind toward the core,M33's giant HII regionsare some of the largest known stellar nurseries,sites of the formation of short-lived but very massive stars.Intense ultraviolet radiation from the luminous, massive stars ionizesthe surrounding hydrogen gas and ultimately produces thecharacteristic red glow.In this image, broadband data were combinedwith narrowband data recorded through a hydrogen-alpha filter.That filter transmits the light of the strongest visible hydrogenemission line. Tomorrow's picture: ring around the Sun<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific...

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Circular Sun Halo

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 14 Circular Sun Halo Image Credit &Copyright:Vincenzo Mirabella Explanation: Want to see a ring around the Sun?It's easy to doin daytime skies around the world.Created by randomly oriented ice crystals in thin high cirrus clouds,circular 22 degree halos are visible much more often than rainbows.This one wascaptured by smart phonephotographyon May 29, 2021 near Rome, Italy.Carefullyblocking the Sun,for example with a finger tip,is usually all that it takes to reveal the common bright halo ring.The halo's characteristic angular radius is about equalto the span of your hand, thumb to little finger,at the end of your outstretched arm. Want to see aring of fire eclipse?That's harder.The spectacular annular phase oftoday's (October 14) solar eclipse,known as a ring of fire,is briefly visible only when standing alongthe Moon's narrow shadow track that passes over limited parts ofNorth, Central, and South America.The solar eclipse is partial though, when seenfrom broader regions throughout the Americas. Tomorrow's picture: Sun Day<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert...

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Mu Cephei

APOD: 2023 October 12 - Mu Cephei Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 12 Mu Cephei Image Credit &Copyright:David Cruz Explanation: Mu Cepheiis a very large star.An M-class supergiant some 1500 times the size of the Sun, it is one ofthe largest stars visible to the unaided eye,and even one of the largest in the entire Galaxy.If it replaced the Sun inour fair Solar System,Mu Cephei would easily engulf Mars and Jupiter.Historically known asHerschel's Garnet Star,Mu Cephei is extremely red.Approximately 2800 light-years distant, the supergiant isseen near the edge of reddish emission nebulaIC 1396 towardthe royal northern constellation Cepheus inthis telescopic view.Much cooler and hence redder than the Sun,this supergiant's light is further reddened by absorption andscattering due to intervening dust within the Milky Way.A well-studied variable starunderstood to be in a late phaseof stellar evolution, Mu Cephei is a massive star too,destinedto ultimately explode as a core-collapsesupernova. APOD editor to speak: in Houghton, Michigan tonight, Thursday, October 12, at 6 pm Tomorrow's picture: pixels in space<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors &...

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Hydrogen Clouds of M33

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 13 Hydrogen Clouds of M33 Image Credit &Copyright:Reinhold Wittich Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share ofglowing hydrogen gas.A prominent member of the local group of galaxies, M33 is alsoknown as the Triangulum Galaxy andlies a mere 3 million light-years away. The galaxy's central 30,000 light-years or so are shown in thissharp galaxy portrait.The portrait features M33'sreddish ionized hydrogen clouds orHII regions.Sprawling along loose spiral arms that wind toward the core,M33's giant HII regionsare some of the largest known stellar nurseries,sites of the formation of short-lived but very massive stars.Intense ultraviolet radiation from the luminous, massive stars ionizesthe surrounding hydrogen gas and ultimately produces thecharacteristic red glow.In this image, broadband data were combinedwith narrowband data recorded through a hydrogen-alpha filter.That filter transmits the light of the strongest visible hydrogenemission line. Tomorrow's picture: ring around the Sun<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy...

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Mu Cephei

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 12 Mu Cephei Image Credit &Copyright:David Cruz Explanation: Mu Cepheiis a very large star.An M-class supergiant some 1500 times the size of the Sun, it is one ofthe largest stars visible to the unaided eye,and even one of the largest in the entire Galaxy.If it replaced the Sun inour fair Solar System,Mu Cephei would easily engulf Mars and Jupiter.Historically known asHerschel's Garnet Star,Mu Cephei is extremely red.Approximately 2800 light-years distant, the supergiant isseen near the edge of reddish emission nebulaIC 1396 towardthe royal northern constellation Cepheus inthis telescopic view.Much cooler and hence redder than the Sun,this supergiant's light is further reddened by absorption andscattering due to intervening dust within the Milky Way.A well-studied variable starunderstood to be in a late phaseof stellar evolution, Mu Cephei is a massive star too,destinedto ultimately explode as a core-collapsesupernova. APOD editor to speak: in Houghton, Michigan tonight, Thursday, October 12, at 6 pm Tomorrow's picture: pixels in space<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert...

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Edwin Hubble Discovers the Universe

APOD: 2023 October 6 - Edwin Hubble Discovers the Universe Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 6 Edwin Hubble Discovers the Universe Image Credit & Copyright: CourtesyCarnegie Institution for Science Explanation: How big is our universe?This question, among others, was debated by two leading astronomers in 1920 in what has sincebecome known as astronomy'sGreat Debate. Many astronomers then believed that our Milky Way Galaxy was the entire universe. Many others, though, believed that our galaxy was just one of many. In the Great Debate, each argument was detailed, but no consensus was reached. The answer came over three years later with the detected variation of single spot in the Andromeda Nebula, as shown on the original glass discovery plate digitally reproduced here.When EdwinHubble compared images, he noticed that thisspot varied, and on October 6, 1923wrote "VAR!" on the plate. The best explanation, Hubble knew, was that this spot was the image of a variable star that was very far away.So M31 was really the Andromeda Galaxy -- a galaxy possibly similar to our own. Annotated 100 years ago, the featured image...

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The Once and Future Stars of Andromeda

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 7 The Once and Future Stars of Andromeda Image Credit: NASA, NSF, NOAJ, Hubble, Subaru,Mayall, DSS, Spitzer; Processing & Copyright: Robert Gendler & Russell Croman Explanation: This picture of Andromeda shows not only where stars are now, but where stars will be.The big, beautiful Andromeda Galaxy,M31, is a spiral galaxya mere 2.5 million light-yearsaway. Image data from space-based and ground-based observatories have been combined here to produce this intriguing compositeview of Andromeda at wavelengths bothinside and outside normally visible light.The visible lightshows where M31's stars are now, highlighted inwhite and blue hues and imaged by the Hubble, Subaru, and Mayall telescopes. The infrared lightshows where M31's future stars will soon form,highlighted in orange hues and imaged by NASA's Spitzer Space Telescope. The infrared light tracks enormous lanes of dust, warmed by stars, sweeping along Andromeda's spiral arms. This dust is a tracer of the galaxy's vastinterstellar gas, raw material for future star formation. Of course, the new stars will likely form over the next hundred million years or so.That's well...

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Ring of Fire over Monument Valley

APOD: 2023 October 5 - Ring of Fire over Monument Valley Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 05 Ring of Fire over Monument Valley Image Credit &Copyright:Tunc Tezel(TWAN) Explanation: Tracking along a narrow path, the shadow of anew moonwill race across North, Central, and South America,on October 14.When viewed from the shadow path the apparent size of thelunar disk will not quite completely cover the Sun though.Instead, the moon in silhouette will appear duringthe minutes of totality surrounded by a fiery ring,an annular solar eclipse more dramatically known as aring of fire eclipse.This striking time lapse sequence from May of 2012illustrates the stages of a ring of fire eclipse.From before eclipse start until sunset, they are seen over the iconicbuttes of planet Earth'sMonument Valley.Remarkably, the October 14 ring of fire eclipse will alsobe visible over Monument Valley, beginning aftersunrise in the eastern sky. Tomorrow's picture: 100th anniversary <| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA...

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Edwin Hubble Discovers the Universe

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 6 Edwin Hubble Discovers the Universe Image Credit & Copyright: CourtesyCarnegie Institution for Science Explanation: How big is our universe?This question, among others, was debated by two leading astronomers in 1920 in what has sincebecome known as astronomy'sGreat Debate. Many astronomers then believed that our Milky Way Galaxy was the entire universe. Many others, though, believed that our galaxy was just one of many. In the Great Debate, each argument was detailed, but no consensus was reached. The answer came over three years later with the detected variation of single spot in the Andromeda Nebula, as shown on the original glass discovery plate digitally reproduced here.When EdwinHubble compared images, he noticed that thisspot varied, and on October 6, 1923wrote "VAR!" on the plate. The best explanation, Hubble knew, was that this spot was the image of a variable star that was very far away.So M31 was really the Andromeda Galaxy -- a galaxy possibly similar to our own. Annotated 100 years ago, the featured image may not be pretty, but...

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Ring of Fire over Monument Valley

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 05 Ring of Fire over Monument Valley Image Credit &Copyright:Tunc Tezel(TWAN) Explanation: Tracking along a narrow path, the shadow of anew moonwill race across North, Central, and South America,on October 14.When viewed from the shadow path the apparent size of thelunar disk will not quite completely cover the Sun though.Instead, the moon in silhouette will appear duringthe minutes of totality surrounded by a fiery ring,an annular solar eclipse more dramatically known as aring of fire eclipse.This striking time lapse sequence from May of 2012illustrates the stages of a ring of fire eclipse.From before eclipse start until sunset, they are seen over the iconicbuttes of planet Earth'sMonument Valley.Remarkably, the October 14 ring of fire eclipse will alsobe visible over Monument Valley, beginning aftersunrise in the eastern sky. Tomorrow's picture: 100th anniversary <| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA /GSFC,NASA ScienceActivation& Michigan Tech. U.

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Back from Bennu

APOD: 2023 September 29 - Back from Bennu Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 September 29 Back from Bennu Image Credit: NASA/Keegan Barber Explanation: Back from asteroid 101955 Bennu,a 110-pound, 31-inch wide sample return capsulerests in adesert on planet Earthin this photo, taken at theDepartment of Defense Utah Test and Training Range near Salt Lake Citylast Sunday, September 24.Dropped off by the OSIRIS-Rex spacecraft, the capsule lookscharred from the extreme temperatures experienced during itsblistering descent through Earth's dense atmosphere.OSIRIS-Rex began its home-ward journey from Bennu in May of 2021.Delivered to NASA’s Johnson Space Center in Houston on September 25,the capsule's canister is expected to contain an uncontaminatedsample of about a half pound (250 grams) ofBennu's loosely packed regolith.Working in a new laboratory designed for the OSIRIS-REx mission,scientists and engineers will complete thecanister disassembly process,and plan to unveil the sample ofthe near-Earth asteroidin a broadcast event on October 11. Tomorrow's picture: shine on<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA...

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A Harvest Moon over Tuscany

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 September 30 A Harvest Moon over Tuscany Image Credit &Copyright: Antonio Tartarini Explanation: For northern hemisphere dwellers, September's Full Moon wasthe Harvest Moon.Reflecting warm hues at sunset, it risesbehind cypress trees huddled on a hill top in Tuscany, Italyin this telephoto view from September 28. Famed in festival, story, and song,Harvest Moon is just the traditional name of the full moon nearest theautumnalequinox. According to lore the name is a fitting one.Despite the diminishing daylight hours as thegrowing seasondrew to a close, farmers could harvest crops by the light of a full moonshining onfrom dusk to dawn.This Harvest Moon was also known to some as a supermoon,a term becoming a traditional name for afullmoon near perigee.It was the fourth and final supermoonfor 2023. Note: Non-NASA APOD mirror sites will be updated if the US goverment shuts down. Tomorrow's picture: new moon near apogee<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and...

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Back from Bennu

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 September 29 Back from Bennu Image Credit: NASA/Keegan Barber Explanation: Back from asteroid 101955 Bennu,a 110-pound, 31-inch wide sample return capsulerests in adesert on planet Earthin this photo, taken at theDepartment of Defense Utah Test and Training Range near Salt Lake Citylast Sunday, September 24.Dropped off by the OSIRIS-Rex spacecraft, the capsule lookscharred from the extreme temperatures experienced during itsblistering descent through Earth's dense atmosphere.OSIRIS-Rex began its home-ward journey from Bennu in May of 2021.Delivered to NASA’s Johnson Space Center in Houston on September 25,the capsule's canister is expected to contain an uncontaminatedsample of about a half pound (250 grams) ofBennu's loosely packed regolith.Working in a new laboratory designed for the OSIRIS-REx mission,scientists and engineers will complete thecanister disassembly process,and plan to unveil the sample ofthe near-Earth asteroidin a broadcast event on October 11. Tomorrow's picture: shine on<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA...

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The Deep Lagoon

APOD: 2023 September 28 - The Deep Lagoon Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 September 28 The Deep Lagoon Image Credit &Copyright:Josep Drudis,Christian Sasse Explanation: Ridges of glowing interstellar gas and dark dust cloudsinhabit theturbulent, cosmic depthsof the Lagoon Nebula.Also known as M8, The bright star forming region is about5,000 light-years distant.It makes for a popular stop ontelescopic tours ofthe constellation Sagittarius toward the centerof our Milky Way Galaxy.Dominated by the telltale red emission of ionized hydrogen atomsrecombining with stripped electrons, thisdeep telescopic viewof the Lagoon's central reaches is about 40 light-years across.The bright hourglass shape near the centerof the frame is gas ionized and sculpted by energetic radiationand extreme stellar winds from amassive young star. Tomorrow's picture: just back from Bennu<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA /GSFC,NASA ScienceActivation& Michigan Tech. U.

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The Deep Lagoon

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 September 28 The Deep Lagoon Image Credit &Copyright:Josep Drudis,Christian Sasse Explanation: Ridges of glowing interstellar gas and dark dust cloudsinhabit theturbulent, cosmic depthsof the Lagoon Nebula.Also known as M8, The bright star forming region is about5,000 light-years distant.It makes for a popular stop ontelescopic tours ofthe constellation Sagittarius toward the centerof our Milky Way Galaxy.Dominated by the telltale red emission of ionized hydrogen atomsrecombining with stripped electrons, thisdeep telescopic viewof the Lagoon's central reaches is about 40 light-years across.The bright hourglass shape near the centerof the frame is gas ionized and sculpted by energetic radiationand extreme stellar winds from amassive young star. Tomorrow's picture: just back from Bennu<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA /GSFC,NASA ScienceActivation& Michigan Tech. U.

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Today's Bit of Wisdom

Never Trust a Naked Bus Driver

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Afternoon Analemma

Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 September 23 Afternoon Analemma Image Credit &Copyright:Ian Griffin(Otago Museum) Explanation: An analemma is that figure-8 curveyou get when you mark the positionof the Sun at the same time each day for one year.To make this one, a 4x5 pinholecamera was set up looking north insouthern New Zealand skies.The shutter was briefly opened each clear day in the afternoon at 4pmlocal time exposing the samephotosensitized glass platefor the year spanning September 23, 2022 to September 19, 2023.On two days, the winter and summer solstices,the shutter was opened again 15 minutes after the mainexposure and remained open until sunset to create the sun trails atthe bottom and top of the curve.The equinox dates correspond to positions in the middle of thecurve, not the crossover point.Of course,the curve itself is inverted compared to an analemma tracedfrom the northern hemisphere.And while fall begins todayat the Autumnal Equinox for the northern hemisphere,it's the Spring Equinox in the south. Tomorrow's picture: sunrise solar eclipse<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors...

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Cosmos in Reflection

APOD: 2023 September 22 - Cosmos in Reflection Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 September 22 Cosmos in Reflection Image Credit &Copyright:Jeff Dai(TWAN) Explanation: During the day,over 12,000 large mirrors reflectsunlight at the 100-megawatt, molten-salt, solar thermal power plant at thewestern edge of the Gobi desert nearDunhuang, Gansu Province, China.Individual mirror panels turn to track the sun like sunflowers.They conspire to act as a single super mirror reflectingthe sunlight toward a fixed position,the power station's central tower.During the nightthe mirrors stand motionless though.They reflect the light of the countless distant stars,clusters and nebulae of the Milky Wayand beyond.Thissci-finight skyscape was created with a camera fixedto a tripod near the edge of the giant mirror matrix onSeptember 15.The camera's combined sequence of digital exposures capturesconcentric arcs of celestialstar trails through the nightwith star trails insurreal mirrored reflection. Tomorrow's picture: analog analemma's afternoon<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA /GSFC,NASA ScienceActivation& Michigan Tech. U.

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