juliensimon/nasa-apod huggingface dataset:
NGC 1566: The Spanish Dancer Spiral Galaxy (2019-07-02)

If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe containing billions of stars and situated about 40 million light-years away toward the constellation of the Dolphinfish (Dorado), NGC 1566 presents a gorgeous face-on view. Classified as a grand design spiral, NGC 1566's shows two prominent and graceful spiral arms that are traced by bright blue star clusters and dark cosmic dust lanes. Numerous Hubble Space Telescope images of NGC 1566 have been taken to study star formation, supernovas, and the spiral's unusually active center. Some of these images, stored online in the Hubble Legacy Archive, were freely downloaded, combined, and digitally processed by an industrious amateur to create the featured image. NGC 1566's flaring center makes the spiral one of the closest and brightest Seyfert galaxies, likely housing a central supermassive black hole wreaking havoc on surrounding stars and gas.   Today: Total solar eclipse visible in parts of South America
Robotic Dragonfly Selected to Fly Across Titan (2019-07-03)

If you could fly across Titan, what would you see? To find out and to better explore this exotic moon of Saturn, NASA recently green-lighted Dragonfly, a mission to Titan with plans to deploy a helicopter-like drone. Saturn's moon Titan is one of the largest moons in the Solar System and the only moon known to have a thick atmosphere and changing hydrocarbon lakes. After development, building, testing, and launch, Dragonfly is currently scheduled to reach Titan in 2034. The featured animated video envisions Dragonfly arriving at Titan, beginning its airborne exploration, landing to establishing a radio link back to Earth, and then continuing on to another trans-Titanian flight. It is hoped that Dragonfly will not only help humanity better understanding Titan's weather, chemistry, and changing landscape, but also bolster humanity's understanding of how life first developed on our young Earth.   Astrophysicists: Browse 1,900+ codes in the Astrophysics Source Code Library
In the Shadow of the Moon (2019-07-04)

On July 2 denizens of planet Earth could stand in the Moon's dark umbral shadow during South America's 2019 total solar eclipse. It first touched down in the Southern Pacific Ocean, east of New Zealand. Racing toward the east along a narrow track, the shadow of the Moon made landfall along the Chilean coast with the Sun low on the western horizon. Captured in the foreground here are long shadows still cast by direct sunlight though, in the final moments before totality began. While diffraction spikes are from the camera lens aperture, the almost totally eclipsed Sun briefly shone like a beautiful diamond ring in the clear, darkened sky.

Image credit: Yuri Beletsky
La Silla Eclipse Sequence (2019-07-05)

The road to the high mountaintop La Silla Observatory in the Chilean Atacama Desert also led in to the path of July 2nd's total solar eclipse. Recorded at regular intervals before and after the total eclipse phase, the frames in this composite sequence include the moment the Moon's dark shadow fell across some of planet Earth's advanced large telescopes. The dreamlike view looks west toward the setting Sun and the approaching Moon shadow. In fact La Silla was a little north of the shadow track's center line, so the region's stunning, clear skies are slightly brighter to the north (right) in the scene.

Image credit: Petr
Horálek
8 Minute and 30 Second Eclipse (2019-07-06)

The total phase of the July 2nd solar eclipse lasted about 4 minutes and 30 seconds at the point of maximum eclipse. On the surface of planet Earth, that was about 600 nautical miles north of Easter Island in the Southern Pacific Ocean. But from 41,000 feet above, on a charter flight intercepting the Moon's shadow, the Moon could be seen to completely block the Sun for about 8 minutes and 30 seconds. With a tailwind at the mid-eclipse intercept point, the plane was traveling around 488 nautical miles per hour chasing along the Moon's shadow track. From above the clouds this wide-field image of the totally eclipsed Sun and shimmering solar corona over the wing records the spectacular view from a window seat on the sunward side of the aircraft.

Image credit: Bob Minor
Crescent Saturn (2019-07-07)

Saturn never shows a crescent phase -- from Earth.  But when viewed from beyond, the majestic giant planet can show an unfamiliar diminutive sliver. This image of crescent Saturn in natural color was taken by the robotic Cassini spacecraft in 2007. The featured image captures Saturn's majestic rings from the side of the ring plane opposite the Sun -- the unilluminated side -- another vista not visible from Earth. Pictured are many of Saturn's photogenic wonders, including the subtle colors of cloud bands, the complex shadows of the rings on the planet, and the shadow of the planet on the rings. A careful eye will find the moons Mimas (2 o'clock) and Janus (4 o'clock), but the real challenge is to find Pandora (8 o'clock).  Saturn is now nearly opposite from the Sun in the Earth's sky and so can be seen in the evening starting just after sunset for the rest of the night.
The Galactic Center in Radio from MeerKAT (2019-07-08)

What's happening at the center of our galaxy? It's hard to tell with optical telescopes since visible light is blocked by intervening interstellar dust. In other bands of light, though, such as radio, the galactic center can be imaged and shows itself to be quite an interesting and active place.  The featured picture shows the inaugural image of the MeerKAT array of 64 radio dishes just completed in South Africa. Spanning four times the angular size of the Moon (2 degrees), the image is impressively vast, deep, and detailed.  Many known sources are shown in clear detail, including many with a prefix of Sgr, since the Galactic Center is in the direction of the constellation Sagittarius.  In our Galaxy's Center lies Sgr A, found here just to the right of the image center, which houses the Milky Way's central supermassive black hole.  Other sources in the image are not as well understood, including the Arc, just to the left of  Sgr A, and numerous filamentary threads. Goals for MeerKAT include searching for radio emission from neutral hydrogen emitted in a much younger universe and brief but distant radio flashes.
Birds During a Total Solar Eclipse (2019-07-09)

What do birds do during a total solar eclipse? Darkness descends more quickly in a total eclipse than during sunset, but returns just as quickly -- and perhaps unexpectedly  to the avians -- just a few minutes later. Stories about the unusual behavior of birds during eclipses have been told for centuries, but bird reactions were recorded and studied systematically by citizen scientists participating in an eBird project during the total solar eclipse that crossed the USA in 2017 August.  Although some unusual behaviors were observed, many observers noted birds acting like it was dusk and either landing or flying low to the ground.  Radar confirmed a significant decrease in high-flying birds and insects during and just after totality.  Conversely, several sightings of normally nocturnal birds were reported.  Pictured, a flock of birds in La Serena, Chile flew through the air together during the total solar eclipse that crossed South America last week. The photographer captured the scene in frames from an eclipse video.  The next total solar eclipse in 2020 December will also cross South America, while in 2024 April a total solar eclipse will cross North America from Mexico through New England, USA.   Gallery 2019: Notable total eclipse images submitted to APOD

Image credit: Leonardo Caldas
4000 Exoplanets (2019-07-10)

Over 4000 planets are now known to exist outside our Solar System. Known as exoplanets, this milestone was passed last month, as recorded by NASA's Exoplanet Archive. The featured video highlights these exoplanets in sound and light, starting chronologically from the first confirmed detection in 1992.  The entire night sky is first shown compressed with the central band of our Milky Way Galaxy making a giant U.  Exoplanets detected by slight jiggles in their parents-star's colors (radial velocity) appear in pink, while those detected by slight dips in their parent star's brightness (transit) are shown in purple. Further, those exoplanets imaged directly appear in orange, while those detected by gravitationally magnifying the light of a background star (microlensing) are shown in green.  The faster a planet orbits its parent star, the higher the accompanying tone played. The retired Kepler satellite has discovered about half of these first 4000 exoplanets in just one region of the sky, while the new TESS mission is on track to find even more, all over the sky, orbiting the brightest nearby stars.  Finding exoplanets not only helps humanity to better understand the potential prevalence of life elsewhere in the universe, but also how our Earth and Solar System were formed.   Follow APOD on Instagram in: English, Indonesian, or Persian
The Ghost of Jupiter's Halo (2019-07-11)

Close-up images of NGC 3242 show the cast off shroud of a dying, sun-like star fancifully known as The Ghost of Jupiter nebula. But this deep and wide telescopic view also finds the seldom seen outer halo of the beautiful planetary nebula at the upper left, toward Milky Way stars and background galaxies in the serpentine constellation Hydra. Intense and otherwise invisible ultraviolet radiation from the nebula's central white dwarf star powers its illusive glow in visible light. In fact, planets of NGC 3242's evolved white dwarf star may have contributed to the nebula's symmetric features and shape. Activity beginning in the star's red giant phase, long before it produced a planetary nebula, is likely the cause of the fainter more extensive halo. About a light-year across NGC 3242 is some 4,500 light-years away. The tenuous clouds of glowing material at the right could well be interstellar gas, by chance close enough to the NGC 3242's white dwarf to be energized by its ultraviolet radiation.

Image credit: CHART32 Team
Magellanic Galaxy NGC 55 (2019-07-12)

Irregular galaxy NGC 55 is thought to be similar to the Large Magellanic Cloud (LMC). But while the LMC is about 180,000 light-years away and a well-known satellite of our own Milky Way Galaxy, NGC 55 is more like 6 million light-years distant, a member of the Sculptor Galaxy Group. Classified as an irregular galaxy, in deep exposures the LMC itself resembles a barred disk galaxy. Spanning about 50,000 light-years, NGC 55 is seen nearly edge-on though, presenting a flattened, narrow profile in contrast with our face-on view of the LMC. Just as large star forming regions create emission nebulae in the LMC, NGC 55 is also seen to be producing new stars. This highly detailed galaxy portrait highlights a bright core crossed with dust clouds, telltale pinkish star forming regions, and young blue star clusters in NGC 55.

Image credit: Eric Benson
The Eagle Rises (2019-07-13)

Get out your red/blue glasses and check out this stereo view from lunar orbit. The 3D anaglyph was created from two photographs (AS11-44-6633, AS11-44-6634) taken by astronaut Michael Collins during the 1969 Apollo 11 mission. It features the lunar module ascent stage, dubbed The Eagle, rising to meet the command module in lunar orbit on July 21. Aboard the ascent stage are Neil Armstrong and Buzz Aldrin, the first to walk on the Moon. The smooth, dark area on the lunar surface is Mare Smythii located just below the equator on the extreme eastern edge of the Moon's near side.  Poised beyond the lunar horizon is our fair planet Earth.

Image credit: ALSJ
Eagle Aurora over Norway (2019-07-14)

What's that in the sky? An aurora. A large coronal mass ejection occurred on our Sun five days before this 2012 image was taken, throwing a cloud of fast moving electrons, protons, and ions toward the Earth. Although most of this cloud passed above the Earth, some of it impacted our Earth's magnetosphere and resulted in spectacular auroras being seen at high northern latitudes. Featured here is a particularly photogenic auroral corona captured above Grotfjord, Norway. To some, this shimmering green glow of recombining atmospheric oxygen might appear as a large eagle, but feel free to share what it looks like to you.  Although the Sun is near Solar Minimum, streams of the solar wind continue to impact the Earth and create impressive auroras visible even last week.

Image credit: Bj�rn J�rgensen
The Space Station Crosses a Spotless Sun (2019-07-15)

That's no sunspot. It's the International Space Station (ISS) caught passing in front of the Sun. Sunspots, individually, have a dark central umbra, a lighter surrounding penumbra, and no solar panels.  By contrast, the ISS is a complex and multi-spired mechanism, one of the largest and most sophisticated machines ever created by humanity.  Also, sunspots occur on the Sun, whereas the ISS orbits the Earth.  Transiting the Sun is not very unusual for the ISS, which orbits the Earth about every 90 minutes, but getting one's timing and equipment just right for a great image is rare.  Strangely, besides that fake spot, in this recent two-image composite, the Sun  lacked any real sunspots.  The featured picture combines two images -- one capturing the space station transiting the Sun -- and another taken consecutively capturing details of the Sun's surface.  Sunspots have been rare on the Sun since the dawn of the current Solar Minimum, a period of low solar activity. For reasons not yet fully understood, the number of sunspots occurring during both the previous and current solar minima have been unusually low.

Image credit: Rainee Colacurcio
Apollo 11 Launches Humans to the Moon (2019-07-16)

verybody saw the Moon. Nobody had ever been there.  Humans across planet Earth watched in awe 50 years ago today as a powerful Saturn V rocket attempted to launch humans -- to the Moon. Some in space flight guessed that the machinery was so complex, that so many things had to go right for it to work, that Apollo 11 would end up being another useful dress rehearsal for a later successful Moon-landing mission.  But to the Moon they went. The featured video starts by showing astronauts Aldrin, Armstrong, and Collins making their way to the waiting rocket. As the large and mighty Saturn V launched, crowds watched from Cape Canaveral in Florida, USA and on television around the world.  The events that unfolded over the next few days, including a dramatic moon walk 50 years ago this Saturday, will forever be remembered as a milestone in human history and an unrivaled demonstration of human ingenuity.  This week, many places around the world are planning celebrations of the 50th anniversary of the first humans landing on the Moon.    NASA Remembers: Apollo 50th: Next Giant Leap
Apollo 11: Descent to the Moon (2019-07-17)

It had never been done before. But with the words "You're Go for landing", 50 years ago this Saturday, Apollo 11 astronauts Aldrin and Armstrong were cleared to make the first try. The next few minutes would contain more than a bit of drama, as an unexpected boulder field and an unacceptably sloping crater loomed below.  With fuel dwindling, Armstrong coolly rocketed the lander above the lunar surface as he looked for a clear and flat place to land.  With only seconds of fuel remaining, and with the help of Aldrin and mission control calling out data, Armstrong finally found a safe spot -- and put the Eagle down.  Many people on Earth listening to the live audio felt great relief on hearing "The Eagle has landed", and great pride knowing that for the first time ever, human beings were on the Moon. Combined in the featured descent video are two audio feeds, a video feed similar to what the astronauts saw, captions of the dialog, and data including the tilt of the Eagle lander. The video concludes with the panorama of the lunar landscape visible outside the Eagle. A few hours later, hundreds of millions of people across planet Earth, drawn together as a single species, watched fellow humans walk on the Moon.   NASA Remembers: Apollo 50th: Next Giant Leap
Shadowed Moon and Mountain (2019-07-18)

On July 16 the Moon celebrated the 50th anniversary of the launch of Apollo 11 with a lunar eclipse visible from much of planet Earth. In this view part of the lunar disk is immersed in Earth's dark, reddened umbral shadow. Near the maximum eclipse phase, it just touches down along a mountain ridge. The rugged Tyrolean nightscape was recorded after moonrise south of Innsbruck, Austria with a dramatically lit communication tower along the ridgeline. Of course eclipses rarely travel alone. This partial lunar eclipse was at the Full Moon following July 2nd's New Moon and total eclipse of the Sun.
Tranquility Base Panorama (2019-07-19)

On July 20, 1969 the Apollo 11 lunar module Eagle safely touched down on the Moon. It landed near the southwestern corner of the Moon's Mare Tranquillitatis at a landing site dubbed Tranquility Base. This panoramic view of Tranquility Base was constructed from the historic photos taken from the lunar surface. On the far left astronaut Neil Armstrong casts a long shadow with Sun is at his back and the Eagle resting about 60 meters away ( AS11-40-5961). He stands near the rim of 30 meter-diameter Little West crater seen here to the right ( AS11-40-5954). Also visible in the foreground is the top of the camera intended for taking stereo close-ups of the lunar surface.
Apollo 11 Landing Panorama (2019-07-20)

Have you seen a panorama from another world lately? Assembled from high-resolution scans of the original film frames, this one sweeps across the magnificent desolation of the Apollo 11 landing site on the Moon's Sea of Tranquility. The images were taken by Neil Armstrong looking out his window of the Eagle Lunar Module fifty years ago, shortly after the July 20, 1969 landing. The frame at the far left (AS11-37-5449) is the first picture taken by a person on another world. Toward the south, thruster nozzles can be seen in the foreground on the left, while at the right, the shadow of the Eagle is visible to the west. For scale, the large, shallow crater on the right has a diameter of about 12 meters. Frames taken from the Lunar Module windows about an hour and a half after landing, before walking on the lunar surface, were intended to initially document the landing site in case an early departure was necessary.
Moonquakes Surprisingly Common (2019-07-21)

Why are there so many moonquakes?   Analyses of seismometers left on the moon by the Apollo moon landings reveals a surprising number of moonquakes occurring within 100 kilometers of the surface.   In fact, 62 moonquakes were detected in data recorded between 1972 and 1977.   Many of these moonquakes are not only strong enough to move furniture in a lunar apartment, but the stiff rock of the moon continues to vibrate for many minutes, significantly longer than the softer rock earthquakes on Earth.   The cause of the moonquakes remains unknown, but a leading hypothesis is the collapse of underground faults. Regardless of the source, future moon dwellings need to be built to withstand the frequent shakings.   Pictured here 50 years ago today, Apollo 11 astronaut Buzz Aldrin stands beside a recently deployed lunar seismometer, looking back toward the lunar landing module.
HDR: Earth's Circular Shadow on the Moon (2019-07-22)

What could create such a large circular shadow on the Moon? The Earth. Last week's full Moon -- the Buck Moon -- was so full that it fell almost exactly in a line with the Sun and the Earth.  When that happens the Earth casts its shadow onto the Moon. The circularity of the Earth's shadow on the Moon was commented on by Aristotle and so has been noticed since at least the 4th century BC.  What's new is humanity's ability to record this shadow with such high dynamic range (HDR).  The featured HDR composite of last week's partial lunar eclipse combines 15 images and include an exposure as short as 1/400th of a second -- so as not to overexpose the brightest part -- and an exposure that lasted five seconds -- to bring up the dimmest part. This dimmest part -- inside Earth's umbra -- is not completely dark because some light is refracted through the Earth's atmosphere onto the Moon.  A total lunar eclipse will occur next in 2021 May.   Partial Lunar Eclipse in 2019 July: Some memorable images submitted to APOD

Image credit: Cristian Fattinnanzi
M82: Galaxy with a Supergalactic Wind (2019-07-23)

Why is the Cigar Galaxy billowing red smoke?  M82, as this starburst galaxy is also known, was stirred up by a recent pass near large spiral galaxy M81.  This doesn't fully explain the source of the red-glowing outwardly expanding gas and dust, however.  Evidence indicates that this gas and dust is being driven out by the combined emerging particle winds of many stars, together creating a galactic superwind.  The dust particles are thought to originate in M82's interstellar medium and are actually similar in size to particles in cigar smoke.  The featured photographic mosaic highlights a specific color of red light strongly emitted by ionized hydrogen gas, showing detailed filaments of this gas and dust.  The filaments extend for over 10,000 light years. The 12-million light-year distant Cigar Galaxy is the brightest galaxy in the sky in infrared light, and can be seen in visible light with a small telescope towards the constellation of the Great Bear (Ursa Major).   APOD in other languages: Arabic, Catalan, Chinese (Beijing), Chinese (Taiwan), Croatian, Czech, Dutch, Farsi, French, French, German, Hebrew, Indonesian, Japanese, Korean, Montenegrin, Polish, Russian, Serbian, Slovenian,  Spanish and Ukrainian
Zodiacal Road (2019-07-24)

What's that strange light down the road? Dust orbiting the Sun. At certain times of the year, a band of sun-reflecting dust from the inner Solar System appears prominently just after sunset -- or just before sunrise -- and is called zodiacal light.  Although the origin of this dust is still being researched, a leading hypothesis holds that zodiacal dust originates mostly from faint Jupiter-family comets and slowly spirals into the Sun. Recent analysis of dust emitted by Comet 67P, visited by ESA's robotic Rosetta spacecraft, bolster this hypothesis.  Pictured when climbing a road up to Teide National Park in the Canary Islands of Spain, a bright triangle of zodiacal light appeared in the distance soon after sunset. Captured on June 21, the scene includes bright Regulus, alpha star of Leo, standing above center toward the left. The Beehive Star Cluster (M44) can be spotted below center, closer to the horizon and also immersed in the zodiacal glow.

Image credit: Ruslan Merzlyakov  
(RMS Photography)
Cygnus Skyscape (2019-07-25)

In brush strokes of interstellar dust and glowing hydrogen gas, this beautiful skyscape is painted across the plane of our Milky Way Galaxy near the northern end of the Great Rift and the constellation Cygnus the Swan. Composed with three different telescopes and about 90 hours of image data the widefield mosaic spans an impressive 24 degrees across the sky. Alpha star of Cygnus, bright, hot, supergiant Deneb lies near top center. Crowded with stars and luminous gas clouds Cygnus is also home to the dark, obscuring Northern Coal Sack Nebula, extending from Deneb toward the center of the view. The reddish glow of star forming regions NGC 7000, the North America Nebula and IC 5070, the Pelican Nebula, are just left of Deneb. The Veil Nebula is a standout below and left of center. A supernova remnant, the Veil is some 1,400 light years away, but many other nebulae and star clusters are identifiable throughout the cosmic scene. Of course, Deneb itself is also known to northern hemisphere skygazers for its place in two asterisms -- marking the top of the Northern Cross and a vertex of the Summer Triangle.

Image credit: Alistair Symon