APOD: 2021 December 10 - Eclipse on a Polar Day 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 December 10 Eclipse on a Polar Day Image Credit &Copyright:Stephanie Ziyi Ye Explanation: During polar day,in Arctic and Antarctic summer, the Sun stays abovethe horizon for periods of 24 hours or more.Recorded on December 4, thisfisheye timelapse imagetracks the Sun in multiple frames as it completes a circle in the summer skyabove Union Glacier, Antarctica.Of course on that date,Union Glacier's sky did grow dark even though the Sun was above the horizon.Captured during the brief period of totality,an eclipsed Sunis at bottom center of the composite view.Near the edge of the total eclipse path across planet Earth,the Moon's shadowdarkens the sky above. 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 December 9 - A Total Eclipse of the Sun 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 December 9 A Total Eclipse of the Sun Image Credit &Copyright:Theo Boris, Christian A. Lockwood, David Zimmermann(JM Pasachoff Antarctic Expedition)Compositing: Zev Hoover and Ron Dantowitz (MARS Scientific) Explanation: Few were able to stand in theMoon's shadowand watch theDecember 4 total eclipseof the Sun.Determined bycelestial mechanics and not geographical boundaries, thenarrow path of totality trackedacross planet Earth's relatively inaccessible southernmost continent.Still, some enthusiastic and well-insulated eclipse chasers wererewarded with the dazzlingspectacle in Antarctica's cold but clear skies.Taken just before the brief totality began, this image from a ground-basedtelescope inside the edge of the shadow pathat Union Glaciercatches a glimmer of sunlight near the top of the silhouetted lunar disk.Look closely for the pinkish solar prominences arcing above the Sun'slimb.During totality, themagnificent solar corona,the Sun's outer atmosphere,made its much anticipated appearance, seen in the compositeview streaming far from the Sun's edge. 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:...

APOD: 2021 December 8 - Comet Hale Bopp Over Val Parola Pass 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 December 8 Comet Hale-Bopp Over Val Parola Pass Image Credit & Copyright: A. Dimai, (Col Druscie Obs.),AAC Explanation: Comet Hale-Bopp,the Great Comet of 1997, became much brighter than any surrounding stars.It was seen even over bright city lights.Away from city lights, however, it put on quite aspectacular show.Here Comet Hale-Bopp was photographed above Val Parola Pass in the Dolomitemountains surroundingCortinad'Ampezzo,Italy.Comet Hale-Bopp'sblue ion tail, consisting ofions from thecomet's nucleus,is pushed out by the solar wind.The whitedust tail is composed of larger particles ofdust from the nucleus driven bythe pressure of sunlight, that orbit behind thecomet.Comet Hale-Bopp (C/1995 O1) remained visible to the unaided eye for 18 months -- longer than any other comet in recorded history.The large comet is next expected to return around the year 4385. This month, Comet Leonard is brightening and may soon become visible to the unaided eye. Tomorrow's picture: open space <| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry...

APOD: 2021 December 7 - Ninety Gravitational Wave Spectrograms and Counting 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 December 7 Ninety Gravitational Wave Spectrograms and Counting Image Credit: NSF, LIGO, VIRGO, KAGRA, Georgia Tech, Vanderbilt U.; Graphic : Sudarshan Ghonge & Karan Jani Explanation: Every time two massive black holes collide, a loud chirping sound is broadcast out into the universe in gravitational waves.Humanity has only had the technology to hear these unusual chirps for the past seven years, but since then we have heard about 90 -- during the first three observing runs.Featured above are the spectrograms -- plots of gravitational-wave frequency versus time -- of these 90 as detected by the giant detectors of LIGO (in the USA), VIRGO (in Europe), and KAGRA (in Japan).The more energy received on Earth from a collision, the brighter it appears on the graphic.Among many science firsts, these gravitational-radiation chirps are giving humanity an unprecedented inventory of black holes and neutron stars, and a new way to measure the expansion rate of our universe.A fourth gravitational wave observing run with increased sensitivity is currently planned...

APOD: 2021 December 6 - Space Station Silhouette on the Moon 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 December 6 Space Station Silhouette on the Moon Image Credit & Copyright: Andrew McCarthy Explanation: What's that unusual spot on the Moon?It's the International Space Station.Using precise timing, the Earth-orbiting space platform was photographed in front of a partially lit gibbous Moon last month.The featured composite, taken from Payson, Arizona, USA last month,was intricately composed by combining, in part, many 1/2000-second images from a video of the ISS crossing the Moon.A close inspection of this unusually crisp ISS silhouette will reveal the outlines of numerous solar panels and trusses. The bright crater Tycho is visible on the upper left, as well as comparatively rough, light colored terrain known as highlands, and relatively smooth, dark colored areas known as maria. On-line tools can tell you when the International Space Station will be visible from your area. Tomorrow's picture: 90 black holes merging <| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific...

Yesterday there was a total solar eclipse visible only at the end of the Earth.

Iridescent by Moonlight

APOD: 2021 December 3 - Comet Leonard and the Whale 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 December 3 Comet Leonard and the Whale Galaxy Image Credit &Copyright:Gregg Ruppel Explanation: Sweeping throughnorthern predawn skies, on November 24Comet Leonard (C/2021 A1)was caught betweentwo galaxies in thiscomposite telescopic image.Sporting a greenish coma the comet's dusty tail seems to harpoon theheartof NGC 4631 (top) also known as the Whale Galaxy.Of courseNGC 4631 and NGC 4656(bottom, aka the Hockey Stick)are background galaxies some 25 million light-years away.On that date the comet was about 6 light-minutes from our fair planet.Its closest approach to Earth (and even closer approachto Venus)still to come,Comet Leonard willgrow brighter in December.Already a good objectfor binoculars and small telescopes,this comet will likely not return to the inner Solar System.Its perihelion, or closest approach to the Sun, will be on January 3, 2022. 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 December 2 - NGC 6822: Barnard's 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 December 2 NGC 6822: Barnard's Galaxy Image Credit &Copyright:Dietmar Hager,Eric Benson Explanation: Grand spiral galaxiesoften seem to get all the glory, flaunting theiryoung, bright, blue star clusters in beautiful, symmetric spiral arms.But small galaxies form stars too, like nearby NGC 6822, also known asBarnard'sGalaxy.Beyond the rich starfields in the constellation Sagittarius,NGC 6822 is a mere 1.5 million light-years away, a member of ourLocal Groupof galaxies.A dwarf irregular galaxy similar to theSmall Magellanic Cloud,NGC 6822 is about 7,000 light-years across.Brighter foreground stars in our Milky Way have a spiky appearance.Behind them,Barnard's Galaxy is seen to be filled with young blue stars and mottledwith the telltale pinkish hydrogen glowof star forming regions in this deepcolor composite image. Tomorrow's picture: Queequeg's 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 December 1 - A Blue Banded Blood Moon 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 December 1 A Blue-Banded Blood Moon Image Credit: Angel Yu Explanation: What causes a blue band to cross the Moon during a lunar eclipse?The blue band is real but usually quite hard to see.The featured HDR image of last week's lunar eclipse, however -- taken from Yancheng, China -- has been digitally processed to equalize the Moon's brightness and exaggerate the colors. The gray color of the bottom right is the Moon's natural color, directly illuminated by sunlight.The upper left part of the Moon is not directly lit by the Sun since it is being eclipsed -- it in the Earth's shadow.It is faintly lit, though, by sunlight that has passed deep through Earth's atmosphere.This part of the Moon is red -- and called a blood Moon -- for the same reason that Earth's sunsets are red: because air scatters away more blue light than red.The unusual blue band is different -- its color is created by sunlight that has passed high through Earth's atmosphere, where...

APOD: 2021 November 30 - In Motion: Uranus and Moons 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. In Motion: Uranus and Moons Video Credit: David Campbell (U. Hertfordshire), Bayfordbury Observatory Explanation: What's that moving across the sky?A planet just a bit too faint to see with the unaided eye: Uranus.The gas giant out past Saturn was tracked earlier this month near opposition -- when it was closest to Earth and at its brightest.The featured video captured by the Bayfordbury Observatory in Hertfordshire, UK is a four-hour time-lapse showing Uranus with its four largest moons in tow: Titania, Oberon, Umbriel and Ariel.Uranus' apparent motion past background stars is really dominated by Earth's own orbital motion around our Sun. The cross seen centered on Uranus is called a diffraction spike and is caused by light diffracting around the four arms that hold one of the telescope's mirrors in place. The rotation of the diffraction spikes is not caused by the rotation of Uranus but, essentially, by the rotation of the Earth.During the next few months Uranus itself will be visible with binoculars, but, as always, to...

APOD: 2021 November 29 - The Extraordinary Spiral in LL 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 November 29 The Extraordinary Spiral in LL Pegasi Image Credit: NASA, ESA, Hubble, HLA;Processing & Copyright: Jonathan Lodge Explanation: What created the strange spiral structure on the upper left? No one is sure, although it is likely related to a star in a binary star system entering the planetary nebula phase, when its outer atmosphere is ejected. The huge spiral spans about a third of a light year across and, winding four or five complete turns, has a regularity that is without precedent. Given the expansion rate of the spiral gas, a new layer must appear about every 800 years, a close match to the time it takes for the two stars to orbit each other.The star system that created it is most commonly known as LL Pegasi, but also AFGL 3068 and IRAS 23166+1655. The featured image was taken in near-infrared light by the Hubble Space Telescope.Why the spiral glows is itself a mystery, with a leading hypothesis being illumination by light reflected from...

APOD: 2021 November 28 - A High Cliff on Comet Churyumov Gerasimenko 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 28 A High Cliff on Comet Churyumov-Gerasimenko Image Credit & Licence: ESA, Rosetta spacecraft, NAVCAM; Additional Processing: Stuart Atkinson Explanation: This high cliff occurs not on a planet, not on a moon, but on a comet.It was discovered to be part of the dark nucleus of Comet Churyumov-Gerasimenko (CG) by Rosetta, a robotic spacecraft launched by ESA that rendezvoused with the Sun-orbiting comet in 2014. The ragged cliff, as featured here, was imaged by Rosetta in 2014.Although towering about one kilometer high, the low surface gravity of Comet CG would likely make it an accessible climb -- and even a jump from the cliff survivable. At the foot of the cliff is relatively smooth terrain dotted with boulders as large as 20 meters across.Data from Rosetta indicates that the ice in Comet CG has a significantly different deuterium fraction -- and hence likely a different origin -- than the water in Earth's oceans. Rosetta ended its mission with a controlled impact onto Comet...

APOD: 2021 November 27 - Messier 101 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 27 Messier 101 Image Credit: NASA,ESA,CFHT,NOAO;Acknowledgement -K.Kuntz (GSFC),F.Bresolin (U.Hawaii),J.Trauger (JPL),J.Mould (NOAO),Y.-H.Chu (U. Illinois) Explanation: Big, beautiful spiral galaxy M101 is one of the last entries inCharles Messier'sfamous catalog, but definitely notone of the least.About 170,000 light-years across, this galaxy is enormous, almosttwice the size of our own Milky Way.M101 was also one of the originalspiral nebulaeobserved by Lord Rosse's large 19th century telescope, theLeviathanof Parsontown.Assembled from 51 exposures recorded by theHubble Space Telescopein the 20th and 21stcenturies, with additional data from ground based telescopes,this mosaic spans about 40,000 light-years across the central regionof M101 in one of the highest definitionspiral galaxy portraits ever released from Hubble.The sharp image shows stunning featuresof the galaxy's face-on disk of stars and dust along withbackground galaxies, some visible right through M101 itself.Also known as thePinwheel Galaxy, M101lies within the boundaries of the northern constellationUrsa Major, about 25 million light-years away. Tomorrow's picture: Churyumov-Gerasimenko<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell...

APOD: 2021 November 26 - Great Refractor and 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 26 Great Refractor and Lunar Eclipse Image Credit &Copyright:Laurie Hatch Explanation: Rain clouds passedand the dome of the Lick Observatory's 36 inch Great Refractoropened on November 19.The historic telescopewas pointed toward a partially eclipsed Moon.Illuminated by dim red lighting to preserve an astronomer'snight vision,telescope controls, coordinate dials, andthe refractor's 57 foot long barrel werecaptured in this high dynamic range image.Visible beyond the foreshortened barrel and dome slit,growing brighter after itsalmost total eclipse phase,the lunar disk created a colorful corona through lingering clouds.From the open dome, the view of theclearing sky above includes the Pleiades star clusterabout 5 degrees fromMoon and Earth's shadow. Notable APOD Submissions: Lunar Eclipse of 2021 November 19 Tomorrow's picture: M101<| 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 25 - At the Shadow's Edge 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 25 At the Shadow's Edge Image Credit &Copyright:Jean-Francois Gout Explanation: Shaped like a cone tapering into space, the Earth's darkcentral shadow or umbrahas a circular cross-section.It's wider than the Moon at the distance ofthe Moon's orbit though.Butduring the lunar eclipseof November 18/19, part ofthe Moon remained just outside the umbral shadow.The successive picturesin this composite of 5 images from thatalmost total lunar eclipsewere taken over a period of about 1.5 hours.The series is aligned to trace part of the cross-section'scirculararc, with the central image at maximum eclipse.It shows a bright, thin sliver of the lunar disk still beyondthe shadow's curved edge.Of course, even within the shadow the Moon's surface is not completelydark, reflecting the reddish hues of filtered sunlight scatteredinto the shadow by Earth's atmosphere. Notable APOD Submissions: Lunar Eclipse of 2021 November 19 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...

APOD: 2021 November 24 - Pleiades: The Seven Sisters 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 November 24 Pleiades: The Seven Sisters Star Cluster Image Credit & Copyright: Damien Cannane Explanation: Have you ever seen the Pleiades star cluster?Even if you have, you probably have never seen it as large and clear as this.Perhaps the most famous star cluster on the sky, the bright stars of the Pleiadescan be seen without binoculars from even the depths of alight-polluted city. With a long exposure from a dark location, though, the dust cloud surrounding the Pleiades star cluster becomes very evident.The featured exposure, taken from Florida, USA,covers a sky area several times the size of the full moon. Also known as the Seven Sisters andM45,the Pleiades lies about 400 light years away toward the constellation of the Bull (Taurus). A common legend with a modern twist is that one of the brighter stars faded since the cluster was named, leaving only six of the sister stars visible to the unaided eye.The actual number of Pleiades stars visible, however, may be more or less...

APOD: 2021 November 23 - The Sun in X rays from NuSTAR 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 23 The Sun in X-rays from NuSTAR Image Credit: NASA,NuSTAR, SDO Explanation: Why are the regions above sunspots so hot?Sunspots themselves are a bit cooler than the surrounding solar surface because the magnetic fields that create them reduce convective heating. It is therefore unusual that regions overhead -- even much higher up in the Sun's corona -- can be hundreds of times hotter.To help find the cause, NASA directed the Earth-orbiting Nuclear Spectroscopic Telescope Array (NuSTAR) satellite to point its very sensitive X-ray telescope at the Sun.Featured here is the Sun in ultraviolet light, shown in a red hue as taken by the orbiting Solar Dynamics Observatory (SDO). Superimposed in false-colored green and blue is emission above sunspots detected by NuSTAR in different bands of high-energy X-rays, highlighting regions of extremely high temperature.Clues about the Sun's atmospheric heating mechanisms come from NuSTAR images like this and shed lighton solar nanoflares and microflares as brief bursts of energy that may drive the unusual heating....

APOD: 2021 November 22 - Lunar Eclipse over a Skyscraper 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 22 Lunar Eclipse over a Skyscraper Image Credit & Copyright: Yuri Beletsky(CarnegieLas Campanas Observatory,TWAN) Explanation: Why is the Moon on top of this building?Planning.It took the astrophotographer careful planning -- including figuring out exactly where to place the camera and exactly when to take the shot -- to create this striking superposition.The single image featured was taken in the early morning hours of November 19, near the peak of the partial lunar eclipse that was occurring as the Moon passed through the Earth's shadow. At this time, almost the entire Moon -- 99.1 percent of its area -- was in the darkest part of the Earth's shadow. The building is the Gran Torre Santiago building in Chile, the tallest building in South America. Although the entire eclipse lasted an impressive six hours, this image had to be taken within just a few seconds to get the alignment right -- the Earth's rotation soon moved the building out of alignment.The next Earth-Moon eclipse will be a...

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....