APOD: 2021 November 10 - Video of a Green Flash Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation w ritten by a professional astronomer. Video of a Green Flash Video Credit & Copyright: Paolo Lazzarotti Explanation: Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from theSun. The truth is thegreen flashdoes exist and its cause is well understood. Just as the settingSun disappears completely from view,a last glimmer appears startlinglygreen. The effect is typically visible only from locations with a low,distant horizon, and lasts just a few seconds.A green flash is also visible for a risingSun, but takes better timing to spot. A dramaticgreen flash was caught on video last month as the Sun set beyond the Ligurian Sea from Tuscany, Italy.The second sequence in the featured video shows the green flash in real time, while the first is sped up and the last is in slow motion.The Sun itself does not turnpartly green -- the effect is caused by layers of theEarth's atmosphere acting like a prism. Discovery +...

APOD: 2021 November 9 - All of These Space Images are Fake Except One Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation w ritten by a professional astronomer. 2021 November 9 All of These Space Images are Fake Except One Image Credit: M. J. Smith et al. (U. Hertfordshire) Explanation: Why would you want to fake a universe?For one reason -- to better understand our real universe.Many astronomical projects seeking to learn properties of our universe now start with a robotic telescope taking sequential images of the night sky.Next, sophisticated computer algorithms crunch these digital images to find stars and galaxies and measure their properties. To calibrate these algorithms, it is useful to test them on fake images from a fake universe to see if the algorithms can correctly deduce purposely imprinted properties.The featured mosaic of fake images was created to specifically mimic the images that have appeared on NASA's Astronomy Picture of the Day (APOD). Only one image of the 225 images is real -- can you find it?The accomplished deceptors have made available individual fake APOD images that can be displayed by accessing their ThisIsNotAnAPOD webpage or Twitter...

APOD: 2021 November 8 - A Filament Leaps from the Sun Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation w ritten by a professional astronomer. A Filament Leaps from the Sun Video Credit & Copyright: Stéphane Poirier Explanation: Why, sometimes, does part of the Sun's atmosphere leap into space?The reason lies in changing magnetic fields that thread through the Sun's surface. Regions of strong surface magnetism, known as active regions, are usually marked by dark sunspots. Active regions can channel charged gas along arching or sweeping magnetic fields -- gas that sometimes falls back, sometimes escapes, and sometimes not only escapes but impacts our Earth. The featured one-hour time-lapse video -- taken with a small telescope in France -- captured an eruptive filament that appeared to leap off the Sun late last month.The filament is huge: for comparison, the size of the Earth is shown on the upper left.Just after the filament lifted off, the Sun emitted a powerful X-class flare while the surface rumbled with a tremendous solar tsunami.A result was a cloud of charged particles that rushed into our Solar System but mostly missed our Earth -- this...

APOD: 2021 November 7 - The Cats Eye Nebula in Optical and X-ray Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation w ritten by a professional astronomer. 2021 November 7 The Cat's Eye Nebula in Optical and X-ray Image Credit: NASA, ESA, Hubble Legacy Archive;Chandra X-ray Obs.; Processing & Copyright: Rudy Pohl Explanation: To some it looks like a cat's eye.To others, perhaps like a giant cosmic conch shell. It is actually one of brightest and most highly detailed planetary nebula known, composed of gas expelled in the brief yet glorious phase near the end of life of a Sun-like star.This nebula's dying central star may have produced the outer circular concentric shellsby shrugging offouterlayers in a series of regular convulsions.The formation of the beautiful, complex-yet-symmetric inner structures, however, is not well understood.The featured image is a composite of a digitally sharpened Hubble Space Telescope image with X-ray light captured by the orbiting Chandra Observatory. The exquisite floating space statue spans over half a light-year across.Of course,gazing into this Cat's Eye,humanity may well be seeingthe fate of our sun, destined to enter its ownplanetary nebulaphase of evolution ... in about...

APOD: 2021 November 6 - The Galaxy Between Two Friends 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. 2021 November 6 The Galaxy Between Two Friends Image Credit &Copyright:Martin Lefranc Explanation: On an August night two friendsenjoyed this view aftera day's hike on the Plateau d'Emparis in the French Alps.At 2400 meters altitude the sky was clear.Light from a setting moon illuminates the foregroundcaptured in the simple vertical panorama of images.Along the plane of our Milky Way galaxystars of Cassiopeia and Perseus shine along the panorama's left edge.But seen as a faint cloud with a brighter core, theAndromeda galaxy,stands directly above the two friends in the night.The nearest large spiral galaxy, Andromeda is about2.5 million light-years beyond the stars of the Milky Way.Adding to the evening's sharedextragalacticperspective, the fainter fuzzy spot in the sky right between them isM33, also known as the Triangulum galaxy.Third largest in thelocal galaxy group, after Andromeda andMilky Way, the Triangulum galaxy is about 3 million light-years distant.On that night, the two friends stood about 3light-nanosecondsapart. Tomorrow's picture: cosmic spirograph<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss|...

APOD: 2021 November 5 - The Dark Seahorse in Cepheus 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. 2021 November 5 The Dark Seahorse in Cepheus Image Credit &Copyright:Valerio Avitabile Explanation: Light-years across, thissuggestive shape known as the Seahorse Nebulaappears in silhouette against a rich, luminous background of stars.Seen toward the royal northern constellation of Cepheus,the dusty, obscuring clouds are part of a Milky Waymolecular cloud some 1,200 light-years distant.It is also listed as Barnard 150 (B150), one of 182dark markings of the skycataloged in the early 20th centuryby astronomer E. E. Barnard.Packs of low mass stars are formingwithin,but their collapsing cores are only visible at longinfrared wavelengths.Still, the colorful stars of Cepheus add to thispretty, galacticskyscape. Tomorrow's picture: light-weekend<| 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& Michigan Tech. U.

APOD: 2021 November 4 - NGC 147 and NGC 185 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. 2021 November 4 NGC 147 and NGC 185 Image Credit &Copyright:Dan Bartlett Explanation: Dwarf galaxiesNGC 147(left) andNGC 185stand side by side in this sharp telescopic portrait.The two are not-often-imaged satellites of M31, thegreat spiral Andromeda Galaxy,some 2.5 million light-years away.Their separation on the sky, less than one degree across a prettyfield of view, translates to only about 35 thousand light-years at Andromeda'sdistance, but Andromeda itself is found well outside this frame.Brighter and more famous satellite galaxies of Andromeda,M32 and M110, areseen closer to the great spiral.NGC 147 and NGC 185have been identified as binary galaxies, forminga gravitationally stable binary system.But recently discovered faintdwarf galaxy Cassiopeia IIalso seems tobe part of their system, forming a gravitationally bound groupwithin Andromeda's intriguing population of smallsatellite galaxies. Tomorrow's picture: pixels in space<| 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& Michigan Tech. U.

The Horsehead and Flame Nebulas

APOD: 2021 November 2 - SN Requiem: A Supernova Seen Three Times So Far 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. 2021 November 2 SN Requiem: A Supernova Seen Three Times So Far Image Credit: NASA, ESA, Hubble; Data: S. A. Rodney (U. South Carolina) et al.;Image Processing: J. DePasquale (STScI) Explanation: We've seen this same supernova three times -- when will we see it a fourth? When a distant star explodes in a supernova, we're lucky if we see it even once.In the case of AT 2016jka ("SN Requiem"), because the exploding star happened to be lined up behind the center of a galaxy cluster (MACS J0138 in this case), a comparison of Hubble Space Telescope images demonstrate that we saw it three times.These three supernova images are highlighted in circles near the bottom of the left frame taken in 2016.On the right frame, taken in 2019, the circles are empty because all three images of the single supernova had faded.Computer modeling of the cluster lens, however, indicates that a fourth image of the same supernova should eventually appear in the upper circle...

APOD: 2021 November 1 - A Waterfall and the Milky Way 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. 2021 November 1 A Waterfall and the Milky Way Image Credit & Copyright: Xie Jie Explanation: The dream was to capture both the waterfall and the Milky Way together.Difficulties included finding a good camera location, artificially illuminating the waterfall and the surrounding valley effectively, capturing the entire scene with numerous foreground and background shots, worrying that fireflies would be too distracting, keeping the camera dry, and avoiding stepping on a poisonous snake. Behold the result -- captured after midnight in mid-July and digitally stitched into a wide-angle panorama.The waterfall is the picturesque Zhulian waterfall in the Luoxiao Mountains in eastern Hunan Province, China.The central band of our Milky Way Galaxy crosses the sky and shows numerous dark dust filaments and colorful nebulas.Bright stars dot the sky -- all residing in the nearby Milky Way -- including the Summer Triangle with bright Vega visible above the Milky Way's arch.After capturing all 78 component exposures for you to enjoy, the photographer and friends enjoyed the view themselves for...

APOD: 2021 October 31 - Dark Matter in a Simulated 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. 2021 October 31 Dark Matter in a Simulated Universe Illustration Credit & Copyright: Tom Abel & Ralf Kaehler (KIPAC, SLAC), AMNH Explanation: Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and why visible matter is distributed as it is both in the local universe and on the cosmic microwave background. The featured image from the American Museum of Natural History's Hayden Planetarium Space Show Dark Universe highlights one example of how pervasive dark matter might haunt our universe. In this frame from a detailed computer simulation, complex filaments of dark matter, shown in black, are strewn about the universe like spider webs, while the relatively rare clumps of familiar baryonic matter are colored orange.These simulations are good statistical matches to astronomical observations. In what is perhaps a scarier turn of events,...

APOD: 2021 October 30 - A Rorschach Aurora 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. 2021 October 30 A Rorschach Aurora Image Credit &Copyright:Göran Strand Explanation: If you see this as a monster's face, don't panic.It's only pareidolia,often experienced as the tendency to see faces inpatterns of light and shadow.In fact, the startling visual scene is actually a 180 degree panorama ofNorthern Lights,digitally mirrored like inkblots on a folded piece of paper.Frames used to construct it were captured ona September night from themiddle of a waterfall-crossing suspension bridgein Jamtland, Sweden.With geomagnetic storms triggered byrecent solar activity,auroral displays could be very active atplanet Earth's high latitudes in the coming days.But if you see a monster's face inyour own neighborhoodtomorrow night, it might just be Halloween. Tomorrow's picture: The Dark Matter of Halloween<| 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& Michigan Tech. U.

APOD: 2021 October 29 - Haunting the Cepheus Flare 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. 2021 October 29 Haunting the Cepheus Flare Image Credit &Copyright:Leo Shatz Explanation: Spooky shapesseem to haunt this dusty expanse,drifting through the night in the royal constellationCepheus.Of course, the shapes are cosmic dust clouds visiblein dimly reflected starlight.Far fromyour own neighborhood,they lurk above the plane of the Milky Way at the edge of theCepheus Flaremolecular cloud complex some 1,200 light-years away.Over 2 light-years across and brighter than most of the other ghostlyapparitions, vdB 141 or Sh2-136 is also known as theGhost Nebula,seen at the right of the starry field of view.Inside the nebula are the telltale signs of dense corescollapsing in the early stagesof star formation.With the eerie hue of dust reflecting bluish light from hot young stars ofNGC 7023, the Iris Nebulastands out against the dark just left of center.In the broad telescopic frame,these fertile interstellar dust fields stretchalmost seven full moons across the sky. Tomorrow's picture: of light and shadow<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU)...

APOD: 2021 October 28 - Mirach's Ghost 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. 2021 October 28 Mirach's Ghost Image Credit &Copyright:John Chumack Explanation: As far asghosts go, Mirach's Ghost isn't really thatscary.Mirach's Ghost is just a faint, fuzzy galaxy, well known to astronomers,that happens to be seen nearly along the line-of-sight toMirach,a bright star.Centered in this star field,Mirach is also called Beta Andromedae.About 200 light-years distant, Mirach is a redgiant star, cooler than the Sun butmuch larger and so intrinsically much brighter than ourparent star.In most telescopic views, glare anddiffractionspikes tend to hide things that lie near Mirach and make thefaint, fuzzy galaxylook like a ghostly internal reflection of the almostoverwhelming starlight.Still, appearing inthis sharp imagejust above and to the right of Mirach,Mirach's Ghost is cataloged asgalaxy NGC 404and is estimatedto be some 10 million light-years away. Tomorrow's picture: just the dust<| 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& Michigan Tech. U.

APOD: 2021 October 27 - NGC 6995: The Bat Nebula 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. 2021 October 27 NGC 6995: The Bat Nebula Image Credit & Copyright: Howard Trottier Explanation: Do you see the bat? It hauntsthis cosmic close-up of the eastern Veil Nebula. The Veil Nebula itself is alarge supernova remnant, the expanding debris cloud from the death explosion of a massive star.While the Veil is roughly circular in shape and covers nearly 3 degreeson the sky toward the constellation of the Swan (Cygnus), NGC 6995, known informally as the Bat Nebula, spans only 1/2 degree, about the apparent sizeof the Moon.That translates to 12 light-years at the Veil'sestimated distance, a reassuring 1,400 light-years from planet Earth.In the composite of image data recorded through narrow band filters, emission from hydrogen atoms in the remnant is shown in red with strong emission from oxygen atoms shown in hues of blue.Of course, in the western part of the Veil lies another seasonal apparition:the Witch's Broom Nebula. Explore Your Universe: Random APOD Generator Tomorrow's picture: Mirach's Ghost <| Archive| Submissions | Index| Search| Calendar|...

APOD: 2021 October 26 - Jupiter Rotates 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. Jupiter Rotates Video Credit & Copyright: JL Dauvergne; Music: Oro Aqua (Benoit Reeves) Explanation: Observe the graceful twirl of our Solar System's largest planet.Many interesting features ofJupiter's enigmatic atmosphere, including dark belts and light zones, can be followed in detail.A careful inspection will reveal that different cloud layers rotateat slightly different speeds.The famous Great Red Spot is not visible at first -- but soon rotates into view.Other smaller storm systems occasionally appear.As large as Jupiter is, it rotates in only 10 hours.Our small Earth, by comparison, takes 24 hours to complete aspin cycle.The featured high-resolution time-lapse video wascaptured over five nights earlier this month by amid-sized telescope on an apartment balcony in Paris, France. Sincehydrogen andhelium gas are colorless, and those elements compose most of Jupiter's expansiveatmosphere, what trace elements create the observedcolors of Jupiter's clouds remains a topic of research. Discovery + Outreach: Graduate student research position open for APOD Tomorrow's picture: veil the bat <| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors...

APOD: 2021 October 25 - Road to the Galactic Center 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. 2021 October 25 Road to the Galactic Center Image Credit & Copyright: Michael Abramyan Explanation: Does the road to our galaxy's center go through Monument Valley?It doesn't have to, but if your road does -- take a picture.In this case, the road is US Route 163 and iconic buttes on the Navajo National Reservation populate the horizon. The band of Milky Way Galaxy stretches down from the sky and appears to be a continuation of the road on Earth.Filaments of dust darken the Milky Way, in contrast to billions of bright stars and several colorful glowing gas clouds including the Lagoon and Trifid nebulas.The featured picture is a composite of images taken with the same camera and from the same location -- Forest Gump Point in Utah, USA.The foreground was taken just after sunset in early September during the blue hour, while the background is a mosaic of four exposures captured a few hours later. Discovery + Outreach: Graduate student research position open for APOD Tomorrow's picture:...

APOD: 2021 October 24 - Halloween and the Ghost Head Nebula 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. 2021 October 24 Halloween and the Ghost Head Nebula Image Credit: Mohammad Heydari-Malayeri (Observatoire de Paris) et al.,ESA,NASA Explanation: Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With amodern calendar however, even though Halloween occurs next week,the real cross-quarter day will occur the week after. Another cross-quarter day is Groundhog Day.Halloween's modern celebration retains historic roots in dressing to scare away the spirits of the dead. Perhaps a fitting tribute to this ancient holiday is this view of theGhostHead Nebula taken with theHubble Space Telescope. Similar to the icon of afictional ghost, NGC 2080 is actually a star forming region in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way Galaxy. The Ghost Head Nebula (NGC 2080) spans about 50 light-years and is shown in representative colors. Tomorrow's picture:...

APOD: 2021 October 23 - 3D 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. 2021 October 23 3D Bennu Image Credit: NASA, GSFC, U. Arizona -Stereo Image Copyright:PatrickVantuyne Explanation: Put on your red/blue glasses and float next to asteroid101955 Bennu.Shaped like a spinning toy topwith boulderslittering its rough surface,the tiny Solar System world is aboutone Empire State Building(less than 500 meters) across.Frames used to construct this 3D anaglyph were taken by PolyCam on theOSIRIS_REx spacecrafton December 3, 2018 from a distance of about 80 kilometers.With a sample from the asteroid'srocky surface on board,OSIRIS_REx departed Bennu's vicinity this May and isnow enroute to planet Earth.The robotic spacecraft is scheduled to return the sample to Earthin September 2023. Tomorrow's picture: a cross-quarter day<| 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& Michigan Tech. U.

APOD: 2021 October 22 - A Comet and a Crab 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. 2021 October 22 A Comet and a Crab Image Credit &Copyright:Jose Mtanous Explanation: This pretty field of view spans over 2 degreesor 4 full moons on the sky,filled with stars toward the constellation Taurus, the Bull.Above and right of center in the frame you can spot the faint fuzzy reddishappearance of Messier 1 (M1),also known as the Crab Nebula.M1 is the first object in 18th century comet hunterCharles Messier's famous catalog of things which aredefinitely not comets.Made from image data captured this October 11,there is a comet in the picture though.Below center and left lies the faint greenish coma and dustytail of periodic comet67P Churyumov-Gerasimenko,also known as Rosetta's comet.In the 21st century, it became thefinal resting place ofrobots from planet Earth.Rosetta's comet isnow returning to the inner solar system, sweepingtoward its next perihelion or closest approach to the Sun, on November 2.Too faint to be seenby eye alone, the comet's next perigee or closestapproach to Earth will be November 12. Tomorrow's picture: stereo saturday<| Archive| Submissions |...