APOD: 2021 October 4 - NGC 4676: When Mice Collide 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 4 NGC 4676: When Mice Collide Image Credit: NASA, ESA, Hubble; Processing & Copyright: William Ostling (The Astronomy Enthusiast) Explanation: These two mighty galaxies are pulling each other apart. Known as the "Mice" because they have such long tails, each spiral galaxy has likely already passed through the other.The longtails are created by the relative difference between gravitational pulls on the near and far parts of each galaxy. Because the distances are so large, the cosmic interaction takes place in slow motion -- over hundreds of millions of years. NGC 4676 lies about 300 million light-years away toward the constellation of Bernice's Hair (Coma Berenices) and are likely membersof the Coma Cluster of Galaxies. The featured picture was taken with the Hubble Space Telescope's Advanced Camera for Surveys in 2002.These galactic mice will probably collide again and again over the next billion years so that, instead of continuing to pull each other apart, they coalesce to form a single galaxy. Follow APOD in English on:...
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APOD: 2021 October 3 - The Holographic Principle and a Teapot 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 3 The Holographic Principle and a Teapot Image Credit: Caltech Explanation: Sure, you can see the 2D rectangle of colors, but can you see deeper? Counting color patches in the featured image, you might estimate that the mostinformation that this 2D digital image can hold is about60 (horizontal) x 50(vertical) x 256 (possible colors) = 768,000 bits. However, the yet-unproven Holographic Principle states that, counter-intuitively, the information in a 2D panel can include all of the information in a 3D room that can be enclosed by the panel. The principle derives from the idea that thePlanck length, the length scale wherequantum mechanics begins to dominateclassical gravity, is one side of an areathat can hold only about one bit of information. The limit was first postulated by physicistGerard 't Hooft in 1993. It can arise from generalizations from seeminglydistant speculation that the information held by ablack hole is determined not by itsenclosed volume but by the surface area of itsevent horizon. The term "holographic" arises...
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APOD: 2021 October 2 - A Light and Dusty Night 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 2 A Light and Dusty Night Image Credit &Copyright:Rodrigo Guerra Explanation: Posing as a brilliant evening star,Venus lies near the western horizonin this southern hemisphere, early spring, night skyscape.To create the composite view exposures tracking the skyand fixed for the foreground were taken onSeptember 25 from Cascavel in southern Brazil.In view after sunset, Venus appears immersed in a cone of zodiacal light,sunlight scattered from dust along theSolar System's ecliptic plane.In fact from either hemisphere of planet Earth,zodiacal light is most visibleafter sunset near a spring equinox,(or before sunrise near an autumn equinox)when its luminous arc lies at steep angles to the horizon.Extending above the sunset on this night, the zodiacal lightreaches toward rich starfields and immense interstellar dust cloudsin the bulge of the central Milky Way.Follow along the Milky Way from the central bulge back toward the horizonand you'll spot the closest star system to the Sun,Alpha Centauri, a mere 4.37 light-years away. Tomorrow's picture: holographic tea time<| Archive| Submissions | Index| Search| Calendar| RSS|...
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APOD: 2021 October 1 - The Central Milky Way from Lagoon to Pipe 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 1 The Central Milky Way from Lagoon to Pipe Image Credit &Copyright:Gabriel Rodrigues Santos Explanation: Dark markings and colorful cloudsinhabit this stellar landscape.The deep and expansive view spans more than 30 full moons acrosscrowded star fields toward the center of our Milky Way Galaxy.Cataloged inthe early 20th century by astronomerE. E. Barnard,the obscuring interstellar dust clouds seen toward the rightinclude B59, B72, B77 and B78,part of the Ophiuchus molecular cloud complex a mere 450 light-years away.To the eye their combined shapesuggests a pipestem and bowl, and so the dark nebula's popular name isthe Pipe Nebula.Three bright nebulae gathered on the left arestellar nurseries some 5,000 light-years distant towardthe constellation Sagittarius.In the 18th century astronomerCharles Messier includedtwo of them in his catalog of bright clusters and nebulae; M8, thelargest of the triplet,and colorful M20 just above.The third prominent emission region includes NGC 6559 at the far left.Itself divided by obscuring dust lanes, M20 is also known asthe Trifid.M8's popular moniker isthe Lagoon Nebula....
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APOD: 2021 September 30 - The Hydrogen Clouds of M33 Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2021 September 30 The Hydrogen Clouds of M33 Image Credit &Copyright:Luca Fornaciari Explanation: Gorgeous spiral galaxy M33 seems to have more than its fair share ofglowing hydrogen gas.A prominent member of the local group of galaxies, M33 is alsoknown as the Triangulum Galaxy andlies a mere 3 million light-years away. Sprawling along loose spiral arms that wind toward the core,M33's giantHII regions aresome of the largest known stellar nurseries,sites of the formation of short-lived but very massive stars.Intense ultraviolet radiationfrom the luminous massive stars ionizesthe surrounding hydrogen gas andultimately produces the characteristic red glow.To highlight the HII regions in this telescopic image,broadband data used to produce a color viewof the galaxy were combined with narrowband data recorded through ahydrogen-alpha filter,transmitting the light of the strongesthydrogen emission line.Close-ups of cataloged HII regions appear in the sidebar insets.Use the individual reference number tofind their location within the Triangulum Galaxy.For example, giantHII region NGC604is identified in an inset on the right and appears at position number 15.That's about 4 o'clock...
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Have you ever seen a gigantic jet?
APOD: 2021 September 28 - Night of the Perseids 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. Night of the Perseids Video Credit & Copyright: Vikas Chander & Dorje Angchuk; Music: Tea Time via PremiumBeat Explanation: Have you ever experienced a meteor shower?To help capture the wonder, a video was taken during the peak of the recent Perseid meteor shower above the Indian Astronomical Observatory in Hanle, India, high up in the Himalayan mountains. Night descends as the video begins, with the central plane of our Milky Way Galaxy approaching from the left and Earth-orbiting satellites zipping by overhead.During the night, the flash of meteors that usually takes less than a second is artificially extended. The green glow of most meteors is typically caused by vaporizing nickel.As the video continues, Orion rises and meteors flare above the 2-meter Himalayan Chandra Telescope and the seven barrels of the High Energy Gamma Ray Telescope (Hagar).The 2 minute 30 second movie ends with the Sun rising, preceded by a false dawn of zodiacal light. Tomorrow's picture: jet lightning video <| Archive| Submissions | Index| Search| Calendar| RSS| Education|...
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APOD: 2021 September 27 - Unwrapped: Five Decade Old Lunar Selfie 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 September 27 Unwrapped: Five Decade Old Lunar Selfie Image Credit: NASA, Apollo 11, Neil Armstrong; Processing: Michael Ranger Explanation: Here is one of the most famous pictures from the Moon -- but digitally reversed.Apollo 11 landed on the moon in 1969 and soon thereafter many pictures were taken, including an iconic picture of Buzz Aldrin taken by Neil Armstrong.The original image captured not only the magnificent desolation of an unfamiliar world, but Armstrong himself reflected in Aldrin's curved visor. Enter modern digital technology.In the featured image, the spherical distortion from Aldrin's helmet has been reversed. The result is the famous picture -- but now featuring Armstrong himself from Aldrin's perspective.Even so, since Armstrong took the picture, the image is effectively a five-decade old lunar selfie. The original visor reflection is shown on the left, while Earth hangs in the lunar sky on the upper right.A foil-wrapped leg of the Eagle lander is prominently visible. Preparations to return humans to the Moon in the next few...
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APOD: 2021 September 26 - The Red Square 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 September 26 The Red Square Nebula Image Credit & Copyright: Peter Tuthill(Sydney U.)& James Lloyd (Cornell U.) Explanation: How did a round star create this square nebula?No one is quite sure.The round star, known as MWC 922 and possibly part of a multiple star system, appears at the center of the Red Square Nebula. The featured image combinesinfrared exposures from theHale Telescope onMt. Palomar inCalifornia, and theKeck-2 Telescope onMauna Kea inHawaii. A leading progenitor hypothesis for thesquare nebula is that the central star or stars somehow expelled cones of gas during a latedevelopmental stage.For MWC 922,these cones happen to incorporate nearlyright anglesand be visible from the sides. Supporting evidence for theconehypothesis includes radial spokes in the image that might run along thecone walls.Researchers speculate that the cones viewed fromanother angle would appear similar to the gigantic rings ofsupernova 1987A,possibly indicating that a star in MWC 922 might one day itself explode in a similarsupernova. Tomorrow's picture: Armstrong moon <| Archive| Submissions | Index| Search| Calendar| RSS| Education|...
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APOD: 2021 September 25 - The Bubble and the Star Cluster 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 September 25 The Bubble and the Star Cluster Image Credit &Copyright:Lorand Fenyes Explanation: To the eye,this cosmic compositionnicely balances theBubble Nebula at the right with open star cluster M52.The pair would be lopsided on other scales, though.Embedded in a complex ofinterstellar dustand gas and blown by the winds from a single, massiveO-type star,the Bubble Nebula, also known as NGC 7635, is amere 10 light-years wide. On the other hand,M52 is a rich opencluster of around a thousand stars.The cluster is about 25 light-years across.Seen toward the northern boundaryof Cassiopeia, distance estimatesfor the Bubble Nebula and associated cloud complex are around11,000 light-years, whilestar cluster M52lies nearly 5,000 light-years away.The wide telescopic field of view spans about 1.5 degrees on the skyor three times the apparent size of a full Moon. Tomorrow's picture: The Red Square Nebula<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA...
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Perseid Outburst at Westmeath Lookout
APOD: 2021 September 23 - Harvest Moon Trail 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 September 23 Harvest Moon Trail Image Credit &Copyright:Mike Cohea Explanation: Famed in festival, story, and song the best knownfull moon is the Harvest Moon.For northern hemisphere dwellers that's a traditional name of thefull moon nearest the September equinox.Seen from Saunderstown,Rhode Island, planet Earth, thisHarvest Moon left a broad streak of warm hues as it rose through a twilightsky over the Newport Bridge.On September 20 its trail was captured in a single 22 minute exposureusing a dense filter and a digital camera.Only two days later the September equinoxmarked a change of season and the beginning of autumn in the north.In fact, recognizing a season as the timebetween solstice and equinox,this Harvest Moon was thefourth full moon of the season,coming just before the astronomical end of northern summer. Tomorrow's picture: Perseid meteor outburst<| 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 September 22 - Equinox on a Spinning Earth 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. Equinox on a Spinning Earth Image Credit: Meteosat 9, NASA, earthobservatory, Robert Simmon Explanation: When does the line between night and day become vertical?Today.Today is an equinox on planet Earth, a time of year when day and night are most nearly equal.At an equinox, the Earth's terminator -- the dividing line between day and night -- becomes vertical and connects the north and south poles.The featured time-lapse video demonstrates this by displaying an entire year on planet Earth in twelve seconds.From geosynchronous orbit, the Meteosat 9 satellite recorded these infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical.As the Earth revolved around the Sun, the terminator was seen to tilt in a way that provides less daily sunlight to the northern hemisphere, causing winter in the north.As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in...
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APOD: 2021 September 21 - Sun Spot Hill 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 September 21 Sun Spot Hill Image Credit & Copyright: Jordi Coy Explanation: Is this giant orange ball about to roll down that tree-lined hill?No, because the giant orange ball is actually the Sun.Our Solar System's central star was captured rising beyond a hill on Earth twelve days ago complete with a delightfully detailed foreground. The Sun's disk showed five sunspots, quite a lot considering that during the solar minimum in solar activity of the past few years, most days showed no spots.A close look at the hill -- Sierra del Cid in Perter, Spain -- reveals not only silhouetted pine trees, but silhouetted people -- by coincidence three brothers of the photographer. The trees and brothers were about 3.5-kilometers away during the morning of the well-planned, single-exposure image.A dark filter muted the usually brilliant Sun and brought up great detail on the lower sunspots. Within a few minutes, the Sun rose far above the hill, while within a week, the sunspots rotated around the Sun, out of view.The...
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APOD: 2021 September 20 - Lynds Dark 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 September 20 Lynds Dark Nebula 1251 Image Credit &Copyright:Cristiano Gualco Explanation: Stars are forming in Lynds Dark Nebula(LDN)1251.About 1,000 light-years away and drifting above the plane of ourMilky Way galaxy, the dusty molecular cloudis part of a complex of dark nebulae mapped toward theCepheus flare region.Across the spectrum,astronomical explorations of the obscuringinterstellar clouds reveal energetic shocks and outflowsassociated with newborn stars,including the telltale reddish glow from scatteredHerbig-Haroobjects hiding in the image.Distant background galaxies also lurk on the scene,almost buried behind the dusty expanse.This alluring viewspans over two full moons on the sky, or 17 light-years at theestimated distance of LDN 1251. Tomorrow's picture: sun spot hill<| 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.