Explosions from White Dwarf Star RS Oph

APOD: 2021 August 22 - Explosions from White Dwarf Star RS Oph 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 22 Explosions from White Dwarf Star RS Oph Illustration Credit & Copyright: David A. Hardy & PPARC Explanation: Spectacular explosions keep occurring in the binary star system named RS Ophiuchi. Every 20 years or so, the red giant star dumps enough hydrogen gas onto its companion white dwarf star to set off a brilliant thermonuclear explosion on the white dwarf's surface. At about 5,000 light years distant, the resulting nova explosions cause the RS Oph system to brighten up by a huge factor and become visible to the unaided eye. The red giant star is depicted on the right of the above drawing, while the white dwarf is at the center of the bright accretion disk on the left. As the stars orbit each other, a stream of gas moves from the giant star to the white dwarf. Astronomers speculate that at some time in the next 100,000 years, enough matter will have accumulated on the white dwarf to push it over the...

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Triple Transit and Mutual Events

APOD: 2021 August 21 - Triple Transit and Mutual Events 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 21 Triple Transit and Mutual Events Image Credit &Copyright:Christopher Go Explanation: These three panels feature the Solar System's rulinggas giant Jupiteron August 15 as seen from Cebu City, Phillipines, planet Earth.On that date thewell-timed telescopic viewsdetail some remarkable performances,transits and mutual events, by Jupiter's Galilean moons.In the top panel,Iois just disappearing into Jupiter's shadow atthe far right, but the three other large Jovian moons appear against theplanet's banded disk.BrighterEuropaand darkerGanymedeare at the far left, also castingtheir two shadows on the gas giant's cloud tops.Callistois below and right near the planet's edge, the three moons ina triple transit across the face of Jupiter.Moving to the middle panel, shadowsof Europa and Ganymede are still visible near centerbut Ganymede has occulted or passed in front of Europa.The bottom panel captures a rare view of Jovian moons in eclipsewhile transiting Jupiter, Ganymede's shadow falling on Europa itself.From planet Earth's perspective, similar mutual events,when Galilean moons occult and eclipse each other,can be seen every six years or so whenJupiter is...

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Three Perseid Nights

APOD: 2021 August 20 - Three Perseid Nights 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 20 Three Perseid Nights Image Credit &Copyright:Balint Lengyel Explanation: Frames from a camerathat spent three moonless nights under the starscreate this composite night skyscape.They were recorded during August 11-13while planet Earth was sweepingthrough the dusty trailof comet Swift-Tuttle.One long exposure, untracked for the foreground, and the manystar tracking captures of Perseid shower meteorswere taken from the village of Magyaregres, Hungary.Each aligned against the background stars,the meteor trailsall point back to the annual shower's radiant in the constellation Perseusheroically standing above this rural horizon.Of course the comet dust particles are traveling along trajectoriesparallel to each other.The radiant effect is due only to perspective, as the parallel tracksappear toconvergein the distance against the starry sky. Notable APOD Image Submissions: Perseid Meteor Shower 2021 Tomorrow's picture: mutual events<| 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.

Bright Meteor, Starry Sky

APOD: 2021 August 19 - Bright Meteor, Starry Sky 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 19 Bright Meteor, Starry Sky Image Credit &Copyright:Miguel Claro(TWAN,Dark Sky Alqueva) Explanation: Plowing throughEarth's atmosphere at 60 kilometers per second,this bright perseid meteor streaks along a starry Milky Way.Captured in dark Portugal skies on August 12, it movesright to left through the frame.Its colorful trail starts near Deneb (alpha Cygni)and ends near Altair (alpha Aquilae),stars of the northernsummer triangle.In fact this perseid meteorvery briefly outshines both,two of the brightest stars in planet Earth's night.The trail's initial greenish glow is typical of the brightperseid shower meteors.The grains of cosmic sand,swept updust from periodic comet Swift-Tuttle,are moving fast enough to excitethe characteristic green emission of atomic oxygenat altitudes of 100 kilometersor so before vaporizing in an incandescent flash. Notable APOD Image Submissions: Perseid Meteor Shower 2021 Tomorrow's picture: Three Dark Nights<| 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.

Rings Around the Ring Nebula

APOD: 2021 August 18 - Rings Around the Ring 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 August 18 Rings Around the Ring Nebula Image Credit: Hubble, Large Binocular Telescope,Subaru Telescope; Composition & Copyright: Robert Gendler Explanation: The Ring Nebula (M57), is more complicated than it appears through a small telescope. The easily visible central ring is about one light-year across,but this remarkably deep exposure -a collaborative effort combining data from three different large telescopes -exploresthe looping filaments of glowing gas extending much farther from the nebula's central star.This composite image includes red light emitted by hydrogen as well asvisible and infrared light.The Ring Nebula is an elongated planetary nebula, a type of nebula created when a Sun-like star evolves to throw off its outer atmosphere to become a white dwarf star. The Ring Nebula is about 2,500 light-years away toward the musicalconstellationLyra. Amateur Astronomers: Please take the Night Sky Network's Survey Tomorrow's picture: pixels in space dust <| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights...

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M57: The Ring Nebula from Hubble

APOD: 2021 August 17 - M57: The Ring Nebula from Hubble 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 17 M57: The Ring Nebula from Hubble Image Credit: NASA, ESA, Hubble Legacy Archive; Processing: Judy Schmidt Explanation: Except for the ringsof Saturn, the RingNebula (M57) is probably the most famous celestial circle.Its classic appearance isunderstood to be due to our own perspective, though.The recent mapping of theexpanding nebula's3-D structure, based in part onthis clear Hubble image,indicates thatthe nebula is a relatively dense, donut-like ring wrappedaround the middle of a (American) football-shaped cloud of glowing gas.The view from planet Earth looks down the long axis of the football,face-on to the ring.Of course, in this well-studied example of aplanetary nebula, the glowing materialdoes not come from planets.Instead, the gaseous shroud represents outer layers expelledfrom the dying,oncesun-like star, now a tiny pinprick of lightseen at the nebula's center.Intense ultraviolet light from the hot central starionizes atoms in the gas.The Ring Nebula is about one light-yearacross and 2,500 light-years away. Share the Sky: NASA Open API for APOD Tomorrow's picture: rings upon Ring <| Archive| Submissions |...

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Perseid Meteor, Red Sprites, and Nova RS Oph

APOD: 2021 August 16 - Perseid Meteor, Red Sprites, and Nova RS Oph 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 16 Perseid Meteor, Red Sprites, and Nova RS Ophiuchus Image Credit & Copyright: Daniel Korona Explanation: This was an unusual sky.It wasn't unusual because of the central band the Milky Way Galaxy, visible along the image left. Most dark skies show part of the Milky Way.It wasn't unusual because of the bright meteor visible on the upper right.Many images taken during last week's Perseid Meteor Shower show meteors, although this Perseid was particularly bright.This sky wasn't unusual because of the red sprites, visible on the lower right.Although this type of lightning has only been noted in the past few decades, images of sprites are becoming more common.This sky wasn't unusual because of the nova, visible just above the image center.Novas bright enough to be seen with the unaided eye occur every few years, with pictured Nova RS Ophiuchus discovered about a week ago. What was most unusual, though, was to capture all these things together, in a single night, on a single...

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Perseid Rain

APOD: 2021 August 15 - Perseid Rain 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 15 Perseid Rain Image Credit & Copyright: Luo Hongyang Explanation: Comet dust rained down on planet Earth last week, streakingthrough dark skies in the annual Perseid meteor shower.The featured picture is a composite of many images taken from the same locationover the peak night of the Perseids.The umbrella was not needed as a shield from meteors, since they almost entirely evaporate high in the Earth's atmosphere.Many of the component images featured individual Perseids, while one image featured the foreground nearJiuquan City, Gansu Province, China.The stellar background includes the central band of our Milky Way Galaxy, appearing nearly vertical, as well as the planets Jupiter and Saturn on the left.Although the comet dust particles are traveling parallel to each other, the resulting shower meteors clearly seem to radiate from a single point on the sky -- the radiant in the eponymous constellation Perseus.The image captured so long an angular field that the curvature of the sky is visible in the trajectory of the Perseids. Notable APOD Image Submissions: Perseid...

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Island Universe, Cosmic Sand

APOD: 2021 August 14 - Island Universe, Cosmic Sand 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 14 Island Universe, Cosmic Sand Image Credit &Copyright: Marzena Rogozinska Explanation: Stars in our own Milky Way Galaxy are scattered through thiseye-catching field of view.From the early hours after midnight on August 13,the 30 second exposure of the night sky over Busko-Zdroj, Polandrecords thecolorful and bright trail of aPerseid meteor.Seen near the peak of theannual Perseid meteor shower itflashes from lower left to upper right.The hurtling grain of cosmic sand, a piece of dust fromperiodic comet Swift-Tuttle,vaporized as it passed through planet Earth's atmosphereat almost 60 kilometers per second.Just above and right of center, well beyond the stars ofthe Milky Way, lies the island universeknown as M31 or the Andromeda Galaxy.The Andromeda Galaxyis the most distant object easily visible to the naked-eye,about 2.5 million light-years away.The visible meteor trail begins only about100 kilometersabove Earth's surface, though.It points back to the meteor shower radiantin the constellation Perseus off the lower left edge of the frame.Follow this bright perseid meteor trail below and left tothe stars of NGC...

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A Perfect Spiral

APOD: 2021 August 13 - A Perfect Spiral 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 13 A Perfect Spiral Image Credit: NASA, ESA, Hubble, HLA; Processing: Mehmet Hakan Ozsarac Explanation: If not perfect then thisspiralgalaxy is at least one of the most photogenic.An island universe of about 100 billion stars,32 million light-years away toward the constellation Pisces,M74 presentsa gorgeous face-on view.Classified asan Sc galaxy,the grand design of M74's graceful spiralarms are traced by bright bluestar clusters and dark cosmic dustlanes.This sharp compositewas constructed from image data recorded by the Hubble Space Telescope'sAdvanced Camera for Surveys.Spanning about 30,000 light-years across theface of M74, it includes exposures recording emission fromhydrogen atoms, highlighting the reddish glow of thegalaxy's large star-forming regions.With a lower surface brightness than most galaxies in theMessier catalog,M74 is sometimes known as thePhantom Galaxy. Notable APOD Image Submissions: Perseid Meteor Shower 2021 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.

A Beautiful Trifid

APOD: 2021 August 12 - A Beautiful Trifid 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 12 A Beautiful Trifid Image Credit &Copyright: Mike Selby Explanation: The beautiful Trifid Nebulais a cosmicstudy in contrasts.Also known as M20, it lies about5,000light-years away toward the nebula richconstellation Sagittarius.A star forming region in the plane of our galaxy,the Trifid does illustrate three different types ofastronomical nebulae;red emission nebulae dominated bylight from hydrogen atoms,blue reflection nebulae producedby dust reflecting starlight, anddark nebulae wheredense dust clouds appear in silhouette.But the red emission region roughly separated into threeparts by obscuring dust lanes is what lends the Trifid itspopular name.Pillars and jets sculpted by newborn stars, below and left ofthe emission nebula's center, appear in famous Hubble Space Telescopeclose-upimages of the region.The Trifid Nebula is about 40 light-years across.Just too faint to be seen by the unaided eye, it almost covers thearea of a full moon in planet Earth's sky. Tomorrow's picture: a perfect spiral<| 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...

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Mammatus Clouds over Saskatchewan

APOD: 2021 August 11 - Mammatus Clouds over Saskatchewan 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 11 Mammatus Clouds over Saskatchewan Image Credit & Copyright: Michael F Johnston Explanation: When do cloud bottoms appear like bubbles?Normally, cloud bottoms are flat.This is because moist warm airthat rises and cools will condense into water droplets at a specific temperature, which usually corresponds to a very specific height. As waterdroplets grow, an opaque cloud forms. Under some conditions, however, cloud pockets can develop that contain large droplets of water or ice that fall into clear air as they evaporate. Such pockets may occur in turbulent air near a thunderstorm. Resulting mammatus clouds can appear especially dramatic if sunlit from the side. The mammatus clouds pictured here, lasting only a few minutes, were photographed over Regina,Saskatchewan, Canada,just after a storm in 2012. Meteor Shower Tonight: Peak of the Perseids Tomorrow's picture: a beautiful trifid <| 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...

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Fire in Space

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...

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Perseus and the Lost Meteors

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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A Perseid Below

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|...

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