APOD: 2021 October 11 - Juno Flyby of Ganymede and Jupiter 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. Juno Flyby of Ganymede and Jupiter Video Credit: Images: NASA,JPL-Caltech,SWRI,MSSS; Animation: Koji Kuramura, Gerald Eichstädt, Mike Stetson; Music: Vangelis Explanation: What would it be like to fly over the largest moon in the Solar System?In June, the robotic Juno spacecraft flew past Jupiter's huge moon Ganymede and took images that have been digitally constructed into a detailed flyby.As the featured video begins, Juno swoops over the two-toned surface of the 2,000-km wide moon, revealing an icy alien landscape filled with grooves and craters.The grooves are likely caused by shifting surface plates, while the craters are caused by violent impacts.Continuing on in its orbit, Juno then performed its 34th close pass over Jupiter's clouds.The digitally-constructed video shows numerous swirling clouds in the north, colorful planet-circling zones and bands across the middle -- featuring several white-oval clouds from the String of Pearls, and finally more swirling clouds in the south. Next September, Juno is scheduled to make a close pass over another of Jupiter's large moons: Europa. Tomorrow's picture: fireball...
APOD: 2021 October 10 - Full Moon Silhouettes 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. Full Moon Silhouettes Video Credit & Copyright: Mark Gee; Music: Tenderness (Dan Phillipson) Explanation: Have you ever watched the Moon rise?The slow rise of a nearly full moon over a clear horizon can be an impressive sight.One impressive moonrise was imaged in early 2013 over Mount VictoriaLookout in Wellington, New Zealand.With detailed planning, an industrious astrophotographer placed a camera about two kilometers away and pointed it across the lookout to where the Moon would surely soon be making its nightly debut.The featured single shot sequence is unedited and shown in real time -- it is not a time lapse.People on Mount Victoria Lookout can be seen in silhouette themselves admiring the dawn of Earth's largest satellite.Seeing a moonrise yourself is not difficult: it happens every day, although only half the time at night.Each day the Moon rises about fifty minutes later than the previous day, with a full moon always rising at sunset. This Saturday, October 16, is International Observe the Moon Night, where you observe a first-quarter Moon...
APOD: 2021 October 9 - 50 Light years to 51 Pegasi 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 9 50 Light-years to 51 Pegasi Image Credit &Copyright:Josselin Desmars Explanation: It's only 50 light-yearsto 51 Pegasi.That star's position is indicated in this snapshot fromAugust, taken on a hazy night with mostly brighter stars visible abovethe dome at Observatoire de Haute-Provence in France.Twenty-six years ago,in October of 1995, astronomersMichel Mayor and Didier Quelozannounced a profound discovery made at the observatory.Using a precise spectrograph they had detected a planet orbiting 51 Peg,the first known exoplanet orbiting a sun-like star.Mayor and Queloz had used the spectrograph to measure changes in thestar's radial velocity,a regular wobble caused by the gravitationaltug of the orbiting planet.Designated 51 Pegasi b,the planet was determined tohave a mass at least half of Jupiter's massand an orbital period of 4.2 days,making it much closer to its parent star than Mercury is to the Sun.Their discovery was quickly confirmed and Mayor and Quelozwere ultimately awarded theNobel Prize in physicsin 2019.Now recognized as the prototype for the class of exoplanetsfondly known ashot Jupiters,51 Pegasi b...
APOD: 2021 October 8 - The Double Cluster 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 October 8 The Double Cluster in Perseus Image Credit &Copyright:Jack Groves Explanation: This pretty starfield spans about three full moons (1.5 degrees)across the heroic northern constellation ofPerseus.It holds the famouspair of open star clusters,h and Chi Persei.Also cataloged asNGC 869 (top) and NGC 884,both clusters are about 7,000 light-years away andcontain stars much younger and hotter than the Sun. Separated by only a few hundred light-years, the clusters areboth 13 million years youngbased onthe ages oftheir individualstars,evidence that they were likely a product of the samestar-forming region.Always a rewardingsight in binoculars,the Double Cluster iseven visible to the unaided eye fromdark locations.But a shroud of guitar strings was used to producediffraction spikeson the colorful stars imaged in this vibrant telescopic view. Global Moon Party: Including APOD's Best Moon Images: Saturday, October 9 Tomorrow's picture: 50 light-years to planet Dimidium<| 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...
APOD: 2021 October 7 - NGC 6559: East of the Lagoon 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 7 NGC 6559: East of the Lagoon Image Credit &Copyright:Roberto Sartori Explanation: Slide your telescope just east of the Lagoon Nebula to find thisalluring field of viewin the rich starfields of the constellationSagittarius toward the central Milky Way.Of course the Lagoon nebula is also known as M8, the eighth objectlisted inCharles Messier'sfamous catalog of bright nebulae and star clusters.Close on the skybut slightly fainter than M8,this complex of nebulae was left out of Messier's list though.It contains obscuring dust, striking red emissionand blue reflection nebulae of star-forming regionNGC 6559 at right.Like M8, NGC 6559 is located about 5,000 light-years awayalong the edge of a large molecular cloud.At that distance,this telescopic frame nearly 3 full moons widewould span about 130 light-years. Global Moon Party: NASA's Night Sky Network: Saturday, October 9 Tomorrow's picture: when stars play guitars<| 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...
APOD: 2021 October 6 - M43: Streams of Orion 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 6 M43: Streams of Orion Image Credit & Copyright: Jari Saukkonen Explanation: Where do the dark streams of dust in the Orion Nebula originate?This part of the Orion Molecular Cloud Complex, M43, is the often imaged but rarely mentioned neighbor of the more famous M42.M42, seen in part to the upper right, includes many bright stars from the Trapezium star cluster.M43 is itself a star forming region that displays intricately-laced streams of dark dust -- although it is really composed mostly of glowing hydrogen gas.The entire Orion field is located about 1600 light years away. Opaque to visible light, the picturesque dark dust is created in the outer atmosphere of massive cool stars and expelled by strong outer winds of protons and electrons. Tomorrow's picture: open 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.
APOD: 2021 October 5 - Sunrise at the South Pole 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 5 Sunrise at the South Pole Image Credit & Copyright: Martin Wolf (U. Wisconsin), IceCube Neutrino Obs.,NSF; ht: Alice Allen Explanation: Sunrise at the South Pole is different.Usually a welcome sight, it follows months of darkness -- and begins months of sunshine.At Earth's poles, it can take weeks for the Sun to rise, in contrast with hours at any mid-latitude location. Sunrise at a pole is caused by the tilt of the Earth as it orbits the Sun, not by the rotation of the Earth. Although at a pole, an airless Earth would first see first Sun at an equinox, the lensing effect of the Earth's atmosphere and the size of the solar disk causes the top of the Sun to appear about two-weeks early. Pictured two weeks ago, the Sun peeks above the horizon of a vast frozen landscape at Earth's South Pole. The true South Pole is just a few meters to the left of the communications tower.This polar sunrise capture was particularly...
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:...
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...
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|...
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....
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...
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|...
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...