APOD: 2021 November 21 - Introducing Comet Leonard 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 21 Introducing Comet Leonard Image Credit & Copyright: Dan Bartlett Explanation: Here comes Comet Leonard.Comet C/2021 A1 (Leonard) was discovered as a faint smudge in January 2021 when it was out past Mars -- but its orbit will take the giant shedding ice-ball into the inner Solar System, passing near both Earth and Venus in December before it swoops around the Sun in early January 2022.Although comets are notoriously hard to predict, some estimations have Comet Leonard brightening to become visible to theunaided eye in December. Comet Leonard was captured just over a week ago already sporting a green-tinged coma and an extended dust tail.The featured picture was composed from 62 images taken through a moderate-sized telescope -- one set of exposures tracking the comet, while another set tracking the background stars.The exposures were taken from the dark skies above the Eastern Sierras (Mountains), near June Lake in California, USA. Soon after passing near the Earth in mid-December, the comet will shift from northern to southern skies....

APOD: 2021 November 20 - An Almost Total Lunar Eclipse 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 20 An Almost Total Lunar Eclipse Image Credit &Copyright:Robert Fedez Explanation: Predawn hours of November 19 found the Moonin partly cloudy skies over Cancun, Mexico.Captured in thistelephoto snapshot,the lunar disk is not quite entirely immersed in Earth's darkumbral shadowduring a long partial lunar eclipse.The partial eclipse was deep though, deep enough to showthe dimmed but reddened light in Earth's shadow.That's a sightoften anticipated byfans of total lunar eclipses.Wandering through the constellation Taurus,the eclipsedMoon's dimmer lightalso made it easier to spot the Pleiades star cluster.The stars of theSeven Sistersshare this frame at the upper right, with thealmost totally eclipsed Moon. Notable APOD Submissions (so far): Lunar Eclipse of 2021 November 19 Tomorrow's picture: New Bright Comet?<| 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 19 - NGC 281: Starless with Stars 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 19 NGC 281: Starless with Stars Image Credit &Copyright:Wido Oerlemans -X-ray: Chandra,Infrared: Spitzer Explanation: In visible light the stars have been removed from this narrow-band imageof NGC 281,a star forming region some 10,000 light-years away towardthe constellation Cassiopeia.Stars were digitally added back to the resultingstarless image though.But instead of using visible light image data, the stars were added withX-ray data(in purple) from the Chandra X-ray Observatory andinfrared data(in red) from the Spitzer Space Telescope.The mergedmultiwavelengthview reveals a multitude ofstars in the region's embedded star clusterIC 1590.The young stars are normally hidden in visible light images bythe natal cloud's gas and obscuring dust.Also known to backyard astro-imagers as thePacmanNebula for its overall appearance in visible light,NGC 281 is about 80 light-years across. 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 18 - Full Moonlight 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 18 Full Moonlight Image Credit &Copyright:Zhengjie Wu andJeff Dai(TWAN) Explanation: A photographer in silhouette stands in bright moonlight asthe Full Moon risesin this well-planned telephoto image.Of course, the Full Moon is normally the brightest lunar phase.But onNovember 18/19, the Full Moon's light will be dimmed during a deep partial lunar eclipseseen across much of planet Earth.At maximum eclipse only a few percent of the lunar disk's diameter shouldremain outside the Earth's dark umbral shadow when the Moon slidesclose to the shadow's southern edge.Near apogee, the farthest point in its orbit,the Moon's motion will be slow.That should make this secondlunar eclipse of 2021an exceptionally long partial lunar eclipse.For most ofNorth America the eclipse partial phaseswill be visible in predawn hours.Since eclipsestend to come in pairs, this lunar eclipse will be followed by asolar eclipse in two weeks on December 4. Tomorrow's picture: starless with stars<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights...

APOD: 2021 November 17 - NGC 3314: When Galaxies Overlap 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 17 NGC 3314: When Galaxies Overlap Image Credit: NASA, ESA, Hubble; Processing & Copyright: William Ostling (The Astronomy Enthusiast) Explanation: Why doesn't the nearby galaxy create a gravitational lensing effect on the background galaxy?It does, but since both galaxies are so nearby, the angular shift is much smaller than the angular sizes of the galaxies themselves. The featured Hubble image of NGC 3314 shows two large spiral galaxies which happen to line up exactly. The foreground spiral NGC 3314a appears nearly face-on with its pinwheel shape defined by young bright star clusters. Against the glow of the background galaxy NGC 3314b, though, dark swirling lanes of interstellar dust can also be seen tracing the nearer spiral's structure. Both galaxies appear on the edge of the Hydra Cluster of Galaxies, a cluster that is about 200 million light years away.Gravitational lens distortions are much easier to see when the lensing galaxy is smaller and further away.Then, the background galaxy may even be distorted into a ring...

APOD: 2021 November 16 - Geminids from Gemini 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 16 Geminids from Gemini Image Credit & Copyright: Wang Jin Explanation: Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is theconstellationof Gemini. That is why the major meteor shower in December is known as theGeminids -- because shower meteors all appear to come from aradiant toward Gemini.Three dimensionally, however,sand-sized debrisexpelled from the unusual asteroid 3200 Phaethonfollows a well-defined orbit about our Sun, and the part of the orbit that approaches Earth is superposed in front of the constellation of Gemini.Therefore, when Earth crosses this orbit, theradiant point of falling debris appears in Gemini.Featured here, a composite of many images taken during the 2020 Geminids meteor shower shows over 200 bright meteors thatstreakedthrough the sky during the night December 14. The best meteor shower in November, the Leonids, peaks tonight and tomorrow.Unfortunately, this year, dim meteors during the early-morning peak will be hard to see against a sky lit by a bright gibbous moon. Still, a few bright...

APOD: 2021 November 15 - Light Pillar over Volcanic Etna 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 15 Light Pillar over Volcanic Etna Image Credit & Copyright: Giancarlo Tinè Explanation: What happening above that volcano?Something very unusual -- a volcanic light pillar.More typically, light pillars are caused by sunlight and so appear as a bright column that extends upward above a rising or setting Sun.Alternatively, other light pillars -- some quite colorful -- have been recorded above street and house lights.This light pillar, though, was illuminated by the red light emitted by the glowing magma of an erupting volcano.The volcano is Italy's Mount Etna, and the featured image was captured with a single shot a few hours after sunset in mid-June.Freezing temperatures above the volcano's ash cloud created ice-crystals either in cirrus clouds high above the volcano -- or in condensed water vapor expelled by Mount Etna.These ice crystals -- mostly flat toward the ground but fluttering -- then reflected away light from the volcano's caldera. Explore Your Universe: Random APOD Generator Tomorrow's picture: meteor flow <| Archive| Submissions | Index|...

APOD: 2021 November 14 - How to Identify that Light in the Sky 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 14 How to Identify that Light in the Sky Illustration Credit & Copyright: HK (The League of Lost Causes) Explanation: What is that light in the sky?Perhaps one of humanity's more common questions, an answer may result from a few quick observations. For example -- is it moving or blinking?If so, and if you live near a city, the answer is typically an airplane, since planes are so numerous and so few stars and satellites are bright enough to be seen over the din of artificial city lights.If not, and if you live far from a city, that bright light is likely a planet such as Venus or Mars -- the former of which is constrained to appear near the horizon just before dawn or after dusk. Sometimes the low apparent motion of a distant airplane near the horizon makes it hard to tell from a bright planet, but even this can usually be discerned by the plane's motion over a...

APOD: 2021 November 13 - Rosetta s Comet in Gemini 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 13 Rosetta's Comet in Gemini Image Credit &Copyright:Rolando Ligustri(CARA Project,CAST) Explanation: Returning alongits 6.4 year orbit,periodic comet Churyumov-Gerasimenko (67P) is caught in thistelescopic frame from November 7.Sweeping past background stars in the constellation Geminithe comet's dusty tail stretches toward the upper right to Upsilon Geminorum.Also known as Pollux,Beta Geminorum, Gemini's brightest star,shines just off the upper left edge of the field-of-view.Churyumov-Gerasimenkoreached its 2021 perihelionor closest approach to the Sun on November 2.At perigee, its closest approach to planet Earth on November 12,this comet was about 0.42 astronomical units away,though it remains too faint to be seen by eye alone.The well-studied cometwas explored by robots from planet Earthduring its last trip through the inner solar system.It's now famous as the final resting place for the historicRosetta spacecraft and Philae lander. Tomorrow's picture: What that was.<| 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...

APOD: 2021 November 12 - M33: The Triangulum Galaxy 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 12 M33: The Triangulum Galaxy Image Credit &Copyright:Bernard Miller Explanation: The small, northern constellationTriangulumharbors this magnificent face-on spiral galaxy, M33.Its popular names include the Pinwheel Galaxy or justthe Triangulum Galaxy.M33 is over 50,000 light-years in diameter, third largest in theLocalGroup of galaxies after the Andromeda Galaxy (M31), and ourown Milky Way.About 3 million light-years from the Milky Way,M33 is itself thought to be a satellite of theAndromeda Galaxy andastronomersin these two galaxies would likely have spectacular views ofeach other's grand spiral star systems.As for the view from planet Earth,this sharp imageshows off M33's blue star clustersand pinkish star forming regions alongthe galaxy's loosely wound spiral arms.In fact, thecavernous NGC 604 is thebrightest star forming region, seen here at about the 4 o'clock positionfrom the galaxy center.Like M31, M33's population of well-measured variable starshave helped make this nearby spiral a cosmic yardstick forestablishingthe distancescale of the Universe. Tomorrow's picture: 67P<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU)...

APOD: 2021 November 11 - NGC 1333: Stellar Nursery in Perseus 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 11 NGC 1333: Stellar Nursery in Perseus Image Credit &Copyright:Michael Sherick Explanation: NGC 1333 is seen in visible light asa reflection nebula,dominated by bluish hues characteristic of starlight reflected byinterstellar dust.A mere 1,000 light-years distant toward the heroic constellationPerseus,it lies at the edge of a large,star-formingmolecular cloud.This telescopic close-up spans about two full moons on the sky or just over15 light-years at the estimated distance of NGC 1333.It shows details of the dusty regionalong with telltale hints of contrasty red emission fromHerbig-Haroobjects, jets and shocked glowing gasemanating from recently formed stars.In fact, NGC 1333 contains hundreds of stars less thana million years old, most stillhidden from optical telescopesby the pervasive stardust.The chaotic environment may be similar to one in which our own Sunformed over 4.5 billion years ago. 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...

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...