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APOD: 2021 August 10 - Fire in Space 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 August 10 Fire in Space Image Credit: NASA Explanation: What does fire look like in space?In the gravity on Earth, heated air rises and expands, causing flames to be teardrop shaped.In the microgravity of the air-filled International Space Station (ISS), however, flames are spheres.Fire is the rapid acquisition of oxygen, and space flames meet new oxygen molecules when they float by randomly from all directions -- creating the enveloping sphere. In the featured image taken in the ISS's Combustion Integration Rack, a spherical flame envelopes clusters of hot glowing soot. Without oxygen, say in the vacuum of empty space, a fire would go out immediately. The many chemical reactions involved with fire are complex, and testing them in microgravity is helping humanity not only to better understand fire -- but how to put out fire, too. Tomorrow's picture: bubble cloud row <| 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...

Cats aren't indecisive - they know darn well what they want. They just won't let *you* know. Unless they want wet food. Then they'll let you know. Space cats are no different.

APOD: 2021 August 9 - Perseus and the Lost Meteors 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 August 9 Perseus and the Lost Meteors Image Credit & Copyright: Tomas Slovinsky (Slovakia) & Petr Horalek (Czech Republic;Institute of Physics in Opava) Explanation: What's the best way to watch a meteor shower? This question might come up later this week when the annual Perseid Meteor Shower peaks.One thing that is helpful is a dark sky, as demonstrated in the featured composite image of last year's Perseids. Many more faint meteors are visible on the left image, taken through a very dark sky in Slovakia, than on the right image, taken through a moderately dark sky in the Czech Republic. The band of the Milky Way Galaxy bridges the two coordinated images, while the meteor shower radiant in the constellation of Perseus is clearly visible on the left.In sum, many faint meteors are lost through a bright sky.Light pollution is shrinking areas across our Earth with dark skies, although inexpensive ways to combat this might be implemented. Notable Perseids Submissions to APOD: 2018, 2019, 2020 Tomorrow's...

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APOD: 2021 August 8 - A Perseid Below 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 August 8 A Perseid Below Image Credit: NASAISS Expedition 28 Crew,Ron Garan Explanation: Earthlings typically watch meteor showers by looking up.But thisremarkable view, captured on August 13, 2011 by astronaut Ron Garan, caught a Perseid meteor by looking down.From Garan'sperspective onboard theInternational Space Stationorbiting at an altitude of about 380 kilometers,the Perseid meteors streak below,swept up dustleft from comet Swift-Tuttle heated to incandescence.The glowing comet dustgrains are traveling atabout 60 kilometers per second throughthe denser atmosphere around 100 kilometers above Earth's surface.In this case, the foreshortened meteor flash is right of frame center,below the curving limb of the Earth and a layer of greenishairglow, just below bright starArcturus.Want to look up at a meteor shower? You're in luck, as the 2021 Perseids meteor shower peaks this week.This year, even relatively faint meteors should be visible through clear skies from a dark location as the bright Moon will mostly absent. Notable Perseids Submissions to APOD: 2018, 2019, 2020 Tomorrow's picture: perseids from perseus <| Archive| Submissions | Index| Search|...

APOD: 2021 August 7 - Jezero Crater: Raised Ridges in 3D 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 August 7 Jezero Crater: Raised Ridges in 3D Image Credit:NASA,JPL-Caltech,Ingenuity Explanation: Get out your red-blue glasses andhover over the surface of Mars.Taken on July 24, the 3D color view is from the MarsIngenuity Helicopter's 10thflight above the Red Planet.Two images from Ingenuity's color camera,both captured at an altitude of 12 meters (40 feet), but a few meters apartto provide a stereo perspective, were used to construct the color anaglyph.Ingenuity's stereo images were made at the request of the MarsPerseverancerover science team.The team is considering a visitto these raised ridges on the floor of Jezero Crater during Perseverance'sfirst science campaign. Tomorrow's picture: meteor below<| 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 August 6 - Stars and Dust Across Corona Australis 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 August 6 Stars and Dust Across Corona Australis Image Credit &Copyright:Vikas Chander Explanation: Cosmic dust clouds cross a rich field of stars inthis telescopic vista near the northern boundary ofCorona Australis, the Southern Crown.Less than 500 light-years away the dust cloudseffectively block light frommore distant background stars in theMilky Way.Top to bottom the frame spans about 2 degrees or over 15 light-years atthe clouds' estimated distance.At top right is a groupof lovely reflection nebulae cataloged asNGC 6726, 6727, 6729,and IC 4812.A characteristic blue color is produced as lightfrom hot stars is reflected bythe cosmic dust.The dust also obscures from view starsin the regionstill in the process of formation.Just above the bluish reflection nebulae a smaller NGC 6729 surroundsyoung variable starR Coronae Australis.To its right are telltale reddish arcs and loops identified asHerbig Haro objectsassociated with energetic newborn stars.Magnificent globular star cluster NGC 6723is at bottom left in the frame.Though NGC 6723 appearsto be partof the group,its ancient stars actually lie nearly 30,000 light-years away,far beyond...

APOD: 2021 August 5 - Tycho and Clavius 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 August 5 Tycho and Clavius Image Credit &Copyright:Eduardo Schaberger Poupeau Explanation: South is upin this detailed telescopic view across the Moon's ruggedsouthern highlands.Captured on July 20, the lunar landscape features the Moon's young and old,the large craters Tycho and Clavius.About 100 million years young,Tycho isthe sharp-walled 85 kilometerdiameter crater near center, its 2 kilometer tall central peakin bright sunlight anddark shadow.Debris ejected during the impact that created Tycho still make it thestandout lunar crater when theMoon is near full, producinga highly visible radiating system of light streaks,bright rays that extend across much of the lunar near side.In fact, some of the material collected at the Apollo 17 landing site,about 2,000 kilometers away, likely originatedfrom the Tycho impact. One of the oldest and largest craters on the Moon's near side,225 kilometer diameterClavius is due south(above) of Tycho.Clavius crater'sown ray system resulting from its original impact eventwould have faded long ago.The old crater's worn walls and smooth floor are now overlayed bysmaller craters from impacts that occurred after Clavius wasformed.Observations...

APOD: 2021 August 4 - EHT Resolves Central Jet from Black Hole in Cen A 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 August 4 EHT Resolves Central Jet from Black Hole in Cen A Image Credit: Radboud University; CSIRO/ATNF/I.Feain et al., R.Morganti et al., N.Junkes et al.; ESO/WFI; MPIfR/ESO/APEX/A. Weiss et al.; NASA/CXC/CfA/R. Kraft et al.; TANAMI/C. Mueller et al.; EHT/M. Janssen et al. Explanation: How do supermassive black holes create powerful jets?To help find out, the Event Horizon Telescope (EHT) imaged the center of the nearby active galaxy Centaurus A. The cascade of featured inset images shows Cen A from it largest, taking up more sky than many moons, to its now finest, taking up only as much sky as an golf ball on the moon.The new image shows what may look like two jets -- but is actually two sides of a single jet. This newly discovered jet-edge brightening does not solve the jet-creation mystery, but does imply that the particle outflow is confined by a strong pressure -- possibly involving a magnetic field. The EHT is a coordination of radio...

APOD: 2021 August 3 - A Perseid Meteor 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 August 3 A Perseid Fireball and the Milky Way Image Credit & Copyright: Dandan Huang Explanation: It was bright and green and flashed as it moved quickly along the Milky Way.It left a trail that took 30 minutes to dissipate. Given the day, August 12, and the direction, away from Perseus, it was likely a small bit from the nucleus of Comet Swift-Tuttle plowing through the Earth's atmosphere -- and therefore part of the annual Perseids meteor shower. The astrophotographer captured the fireball as it shot across the sky in 2018 above a valley in Yichang, Hubei, China.The meteor's streak, also caught on video, ended near the direction of Mars on the lower left.Next week, the 2021 Perseids meteor shower will peak again. This year the Moon will set shortly after the Sun, leaving a night sky ideal for seeing lots of Perseids from dark and clear locations across planet Earth. Follow APOD in English on: Facebook, Instagram, or Twitter Tomorrow's picture: Event Horizon...

APOD: 2021 August 2 - The Hubble Ultra Deep Field in Light and Sound 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 August 2 The Hubble Ultra Deep Field in Light and Sound Image Credit: NASA, ESA, Hubble; Sonification: G. Salvesen (UCSB); Data: M. Rafelski et al. Explanation: Have you heard about the Hubble Ultra-Deep Field? Either way, you've likely not heard about it like this -- please run your cursor over the featured image and listen! The Hubble Ultra-Deep Field (HUDF) was created in 2003-2004 with the Hubble Space Telescope staring for a long time toward near-empty space so that distant, faint galaxies would become visible. One of the most famous images in astronomy, the HUDF is featured here in a vibrant way -- with sonified distances.Pointing to a galaxy will play a note that indicates its approximate redshift.Because redshifts shift light toward the red end of the spectrum of light, they are depicted here by a shift of tone toward the low end of the spectrum of sound. The further the galaxy, the greater its cosmological redshift (even if it appears blue),...

APOD: 2021 August 1 - Pluto in Enhanced Color 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 August 1 Pluto in Enhanced Color Image Credit: NASA,Johns Hopkins Univ./APL,Southwest Research Inst. Explanation: Pluto is more colorful than we can see.Color data and high-resolution images of our Solar System's most famous dwarf planet, taken by the robotic New Horizons spacecraft during its flyby in 2015 July, have been digitally combined to give an enhanced-color view of this ancient world sporting an unexpectedly young surface.The featured enhanced color image is not only esthetically pretty but scientifically useful, making surface regions of differing chemical composition visually distinct.For example, the light-colored heart-shaped Tombaugh Regio on the lower right is clearly shown here to be divisible into two regions that are geologically different, with the leftmost lobe Sputnik Planitia also appearing unusually smooth.After Pluto, New Horizons continued on, shooting past asteroid Arrokoth in 2019 and has enough speed to escape our Solar System completely. Pluto-Related Images with Brief Explanations: APOD Pluto Search Tomorrow's picture: deep galaxy sounds <| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| >...

APOD: 2021 July 31 - Remembering NEOWISE 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 July 31 Remembering NEOWISE Image Credit &Copyright:Petr Horalek /Institute of Physics in Opava Explanation: It was just last July.If you could see the stars ofthe Big Dipper, you could findComet NEOWISE in your evening sky.After sunsetdenizens of the north could look for the naked-eye cometbelow the bowl of that famous celestial kitchen utensiland above the northwestern horizon.The comet looked like a fuzzy 'star' with a tail, though probably not so long a tail as in thismemorable skyviewrecorded from the Czech Republic on July 23th, 2020, near the comet'sclosest approach to planet Earth.Photographs ofC/2020 F3(NEOWISE) often did show the comet's broad dust tail and fainter butseparate bluish ion tail extendingfarther than the eye could follow.Skygazers around the world weredelightedto witness Comet NEOWISE,surprise visitor from the outer Solar System. Notable Comet NEOWISE Images 2020: July 3130, 29,28,27,26,25,24 Tomorrow's picture: better than Pluto<| 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...

APOD: 2021 July 30 - Mimas in Saturnlight 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 July 30 Mimas in Saturnlight Image Credit: Cassini Imaging Team, SSI, JPL, ESA,NASA Explanation: Peering from the shadows, theSaturn-facing hemisphere of Mimas lies in near darkness alongside adramatic sunlit crescent.The mosaic was captured near the Cassinispacecraft's finalclose approach on January 30, 2017.Cassini's camera was pointed in anearly sunward direction only 45,000 kilometers from Mimas.The result is one of the highest resolution views of the icy, crater-pocked,400kilometer diameter moon.An enhanced version better reveals the Saturn-facing hemisphere ofthe synchronously rotating moon lit by sunlight reflected fromSaturn itself.To see it, slide your cursor over the image (orfollow this link).Other Cassini images of Mimas include the small moon's large and ominousHerschel Crater. Tomorrow's picture: remember when <| 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 July 29 - The Tulip and Cygnus X 1 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 July 29 The Tulip and Cygnus X-1 Image Credit &Copyright:Carlos Uriarte Explanation: This tall telescopic field of viewlooks out along the plane of our Milky Way Galaxytoward the nebula rich constellationCygnusthe Swan.Popularly called the Tulip Nebula,the brightest glowing cloud of interstellar gas and dustabove center is also found in the1959 catalogby astronomer Stewart Sharplessas Sh2-101.Nearly 70 light-years across the complex and beautiful Tulip Nebulablossoms about 8,000 light-years away, shown in aHubble palette image that maps the glow of thenebula's sulfur, hydrogen, and oxygen ions intored, green, and blue colors.Ultraviolet radiation from young energetic starsat the edge of the CygnusOB3 association, includingO star HDE 227018,ionizes the atomsand powers the emission from the Tulip Nebula.Also in the field of view is microquasarCygnus X-1,one of the strongest X-ray sources in planet Earth's sky.Driven by powerful jets from a black hole accretion disk,its fainter bluish curved shock front isonly just visible though, directlyabove the cosmic Tulip's petals near the top of the frame. Tomorrow's picture: Saturnshine<| Archive| Submissions |...

APOD: 2021 July 28 - Ring Galaxy AM 0644 741 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 July 28 Ring Galaxy AM 0644-741 Image Credit: NASA, ESA, Hubble, HLA; Processing: Jonathan Lodge Explanation: The rim of the large blue galaxy at the rightis an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars. AM 0644-741is known as a ring galaxy and was caused by an immense galaxy collision. When galaxies collide, they pass through each other and their individual stars rarely come into contact. The large galaxy's ring-like shape is the result of the gravitational disruption caused by a small intruder galaxy passing through it.When this happens, interstellar gas and dust become compressed, causing a wave of star formation to move out from the impact point like a ripple across the surface of a pond. Other galaxies in the field of view are background galaxies, notinteracting with AM 0644-741.Foreground spiky stars are within our own Milky Way.But the smaller intruder galaxy is caughtabove and right, near the top of the frame taken by the Hubble Space...

APOD: 2021 July 27 - Flemings Triangular Wisp 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 July 27 Fleming's Triangular Wisp Image Credit & Copyright: Anthony Saab Explanation: Chaotic in appearance,these tangled filaments of shocked, glowing gas are spread acrossplanet Earth's sky toward the constellation of Cygnus as part of theVeil Nebula.The Veil Nebula itself is a largesupernova remnant, an expandingcloud born of the death explosion of a massive star.Light from the original supernova explosion likely reachedEarth over 5,000 years ago.The glowing filaments are really more like long ripples in a sheet seenalmost edge on, remarkably well separated intothe glow of ionized hydrogen atoms shown in blue and oxygen in red hues.Also known as the Cygnus Loop and cataloged as NGC 6979, theVeil Nebula now spans about 6 times the diameter of the full Moon.The length of the wisp corresponds to about 30 light years, given its estimated distance of 2,400 light years. Often identified as Pickering's Trianglefor a director of Harvard College Observatory, it is also named for its discoverer,astronomer Williamina Fleming, asFleming'sTriangular Wisp. Tomorrow's picture: ring of fire galaxy <| Archive| Submissions...

APOD: 2021 July 26 - CG4: A Ruptured Cometary Globule 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 July 26 CG4: A Ruptured Cometary Globule Image Credit & Copyright: Nicolas Rolland & Martin Pugh Explanation: Can a gas cloud grab a galaxy? It's not even close. The "claw" of this odd looking "creature" in the featured photo is a gas cloud known as a cometary globule. This globule, however, has ruptured. Cometary globules are typically characterized by dusty heads andelongated tails. These features cause cometary globules to have visual similarities to comets, but in reality they are very much different. Globules are frequently the birthplaces of stars, and many show very young stars in their heads.The reason for the rupture in the head of this object is not yet known.The galaxy to the left of the globule is huge, very far in the distance, and only placed near CG4 by chance superposition. Tomorrow's picture: wisp of star death <| 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...

APOD: 2021 July 25 - Crescent Neptune and Triton 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 July 25 Crescent Neptune and Triton Image Credit: NASA,Voyager 2 Explanation: Gliding silently through the outerSolar System, theVoyager 2 spacecraft camera capturedNeptune andTriton together in crescent phase. The elegant picture of theice-giant planet and itscloudy moon was taken from behind just afterclosest approach in 1989. It could not have been taken fromEarth becauseNeptune never shows a crescent phase to sunward Earth.Theunusual vantage point also robsNeptune of its familiar blue hue,as sunlight seen from here is scattered forward,and so is reddened like thesetting Sun. Neptune is smaller but more massive thanUranus, has severaldark rings, and emits more light than it receives from the Sun. Tomorrow's picture: galaxy grabber <| 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.