juliensimon/nasa-apod huggingface dataset:
Apollo 11: Armstrong's Lunar Selfie (2023-07-22)

A photograph of Buzz Aldrin standing on the Moon taken by Neil Armstrong, was digitally reversed to create this lunar selfie. Captured in July 1969 following the Apollo 11 moon landing, Armstrong's original photograph recorded not only the magnificent desolation of an unfamiliar world, but Armstrong himself reflected in Aldrin's curved visor.  In the unwrapped image, the spherical distortion of the reflection in Aldrin's helmet has been reversed.  The transformed view features Armstrong himself from Aldrin's perspective. Since Armstrong took the original picture, today the image represents a fifty-four year old lunar selfie.  Aldrin's visor reflection in the original image appears here on the left. Bright (but distorted) planet Earth hangs in the lunar sky above Armstrong's figure, toward the upper right. A foil-wrapped leg of the Eagle lander and Aldrin's long shadow stretching across the lunar surface are prominently visible.  In 2024 NASA's Artemis II mission will return humans to the Moon.
The Antikythera Mechanism (2023-07-23)

It does what?  No one knew that 2,000 years ago, the technology existed to build such a device.  The Antikythera mechanism, pictured, is now widely regarded as the first computer. Found at the bottom of the sea aboard a decaying Greek ship, its complexity prompted decades of study, and even today some of its functions likely remain unknown.  X-ray images of the device, however, have confirmed that a main function of its numerous clock-like wheels and gears is to create a portable, hand-cranked, Earth-centered, orrery of the sky, predicting future star and planet locations as well as lunar and solar eclipses.  The corroded core of the Antikythera mechanism's largest gear is featured, spanning about 13 centimeters, while the entire mechanism was 33 centimeters high, making it similar in size to a large book. Recently, modern computer modeling of missing components is allowing for the creation of a more complete replica of this surprising ancient machine.
Chemicals Glow as a Meteor Disintegrates (2023-07-24)

Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured here is a fireball, a disintegrating meteor that was not only one of the brightest the photographer has ever seen, but colorful. The meteor was captured by chance in mid-July with a camera set up on Hochkar Mountain in Austria to photograph the central band of our Milky Way galaxy. The radiant grit, likely cast off by a comet or asteroid long ago, had the misfortune to enter Earth's atmosphere.  Colors in meteors usually originate from ionized chemical elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green. Red, however, typically originates from energized nitrogen and oxygen in the Earth's atmosphere.  This bright meteoric fireball was gone in a flash -- less than a second -- but it left a wind-blown ionization trail that remained visible for almost a minute.

Image credit: Michael Kleinburger
The Eagle Nebula with X-ray Hot Stars (2023-07-25)

What do the famous Eagle Nebula star pillars look like in X-ray light? To find out, NASA's orbiting Chandra X-ray Observatory peered in and through these interstellar mountains of star formation. It was found that in M16 the dust pillars themselves do not emit many X-rays, but a lot of small-but-bright X-ray sources became evident. These sources are shown as bright dots on the featured image which is a composite of exposures from Chandra (X-rays), XMM (X-rays), JWST (infrared), Spitzer (infrared), Hubble (visible), and the VLT (visible).  What stars produce these X-rays remains a topic of research, but some are hypothesized to be hot, recently-formed, low-mass stars, while others are thought to be hot, older, high-mass stars.  These X-ray hot stars are scattered around the frame -- the previously identified Evaporating Gaseous Globules (EGGS) seen in visible light are not currently hot enough to emit X-rays.
IC 4628: The Prawn Nebula (2023-07-26)

South of Antares, in the tail of the nebula-rich constellation Scorpius, lies emission nebula IC 4628. Nearby hot, massive stars, millions of years young, irradiate the nebula with invisible ultraviolet light, stripping electrons from atoms. The electrons eventually recombine with the atoms to produce the visible nebular glow, dominated by the red emission of hydrogen. At an estimated distance of 6,000 light-years, the region shown is about 250 light-years across, spanning over three full moons on the sky. The nebula is also cataloged as Gum 56 for Australian astronomer Colin Stanley Gum, but seafood-loving deep sky-enthusiasts might know this cosmic cloud as the Prawn Nebula. The graceful color image is a new astronomical composition taken over several nights in April from Rio Hurtado, Chile.

Image credit: Daniel Stern
Galaxies in the River (2023-07-27)

Large galaxies grow by eating small ones. Even our own galaxy engages in a sort of galactic cannibalism, absorbing small galaxies that are too close and are captured by the Milky Way's gravity. In fact, the practice is common in the universe and illustrated by this striking pair of interacting galaxies from the banks of the southern constellation Eridanus, The River. Located over 50 million light years away, the large, distorted spiral NGC 1532 is seen locked in a gravitational struggle with dwarf galaxy NGC 1531, a struggle the smaller galaxy will eventually lose. Seen nearly edge-on, spiral NGC 1532 spans about 100,000 light-years. The merging galaxies are captured in this sharp image from the Dark Energy Camera mounted on the National Science Foundation’s Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile. The NGC 1532/1531 pair is thought to be similar to the well-studied system of face-on spiral and small companion known as M51.
Young Stars, Stellar Jets (2023-07-28)

High-speed outflows of molecular gas from a pair of actively forming young stars shine in infrared light, revealing themselves in this NIRcam image from the James Webb Space Telescope. Cataloged as HH (Herbig-Haro) 46/47, the young stars are lodged within a dark nebula that is largely opaque when viewed in visible light.  The pair lie at the center of the prominent reddish diffraction spikes in the NIRcam image.  Their energetic stellar jets extend for nearly a light-year, burrowing into the dark interstellar material. A tantalizing object to explore with Webb's infrared capabilities, this young star system is relatively nearby, located only some 1,140 light-years distant in the nautical constellation Vela.
Apollo 11: Catching Some Sun (2023-07-29)

Bright sunlight glints as long dark shadows mark this image of the surface of the Moon. It was taken fifty-four years ago, July 20, 1969, by Apollo 11 astronaut Neil Armstrong, the first to walk on the lunar surface. Pictured is the mission's lunar module, the Eagle, and spacesuited lunar module pilot Buzz Aldrin. Aldrin is unfurling a long sheet of foil also known as the Solar Wind Composition Experiment. Exposed facing the Sun, the foil trapped particles streaming outward in the solar wind, catching a sample of material from the Sun itself. Along with moon rocks and lunar soil samples, the solar wind collector was returned for analysis in earthbound laboratories.
Spiral Aurora over Icelandic Divide (2023-07-30)

Admire the beauty but fear the beast. The beauty is the aurora overhead, here taking the form of a great green spiral, seen between picturesque clouds with the bright Moon to the side and stars in the background.  The beast is the wave of charged particles that creates the aurora but might, one day, impair civilization.  In 1859, following notable auroras seen all across the globe, a pulse of charged particles from a coronal mass ejection (CME) associated with a solar flare impacted Earth's magnetosphere so forcefully that it created the Carrington Event. This assault from the Sun compressed the Earth's magnetic field so violently that it created high currents and sparks along telegraph wires, shocking many telegraph operators.  Were a Carrington-class event to impact the Earth today, speculation holds that damage might occur to global power grids and electronics on a scale never yet experienced.  The featured aurora was imaged in 2016 over Thingvallavatn Lake in Iceland, a lake that partly fills a fault that divides Earth's large Eurasian and North American tectonic plates.   Almost Hyperspace: Random APOD Generator

Image credit: Juan Carlos Casado
Phobos over Mars (2023-07-31)

Why is Phobos so dark?  Phobos, the largest and innermost of the two Martian moons, is the darkest moon in the entire Solar System.  Its unusual orbit and color indicate that it may be a captured asteroid composed of a mixture of ice and dark rock.  The featured assigned-color picture of Phobos near the edge of Mars was captured in late 2021 by ESA's robot spacecraft Mars Express, currently orbiting Mars.  Phobos is a heavily cratered and barren moon, with its largest crater located on the far side.  From images like this, Phobos has been determined to be covered by perhaps a meter of loose dust.  Phobos orbits so close to Mars that from some places it would appear to rise and set twice a day, while from other places it would not be visible at all.  Phobos' orbit around Mars is continually decaying -- it will likely break up with pieces crashing to the Martian surface in about 50 million years.   Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)
Monster Solar Prominence (2023-08-01)

The monsters that live on the Sun are not like us. They are larger than the Earth and made of gas hotter than in any teapot. They have no eyes, but at times, many tentacles. They float.  Usually, they slowly change shape and just fade back onto the Sun over about a month. Sometimes, though, they suddenly explode and unleash energetic particles into the Solar System that can attack the Earth.  Pictured is a huge solar prominence imaged almost two weeks ago in the light of hydrogen. Captured by a small telescope in Gilbert, Arizona, USA, the monsteresque plume of gas was held aloft by the ever-present but ever-changing magnetic field near the surface of the Sun. Our active Sun continues to show an unusually high number of prominences, filaments, sunspots, and large active regions as solar maximum approaches in 2025.

Image credit: Mike
Wenz
M82: Galaxy with a Supergalactic Wind (2023-08-02)

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 world languages: Arabic, Bulgarian, Catalan, Chinese (Beijing), Chinese (Taiwan), Croatian, Czech, Dutch, French, German, Hebrew, Indonesian, Japanese, Montenegrin, Polish, Russian, Serbian, Slovenian,  Spanish, Taiwanese, Turkish, and  Ukrainian
The Falcon and the Redstone (2023-08-03)

In a photo from the early hours of July 29 (UTC), a Redstone rocket and Mercury capsule are on display at Cape Canaveral Launch Complex 5. Beyond the Redstone, the 8 minute long exposure has captured the arcing launch streak of a SpaceX Falcon Heavy rocket. The Falcon's heavy communications satellite payload, at a record setting 9 metric tons, is bound for geosynchronous orbit some 22,000 miles above planet Earth. The historic launch of a Redstone rocket carried astronaut Alan Shepard on a suborbital spaceflight in May 1961 to an altitude of about 116 miles. Near the top of the frame, this Falcon rocket's two reusable side boosters separate and execute brief entry burns. They returned to land side by side at Canaveral's Landing Zone 1 and 2 in the distance.

Image credit: Launch Complex 5
Moonrays of August (2023-08-04)

A Full Moon rose as the Sun set on August 1. Near perigee, the closest point in its almost moonthly orbit, the brighter than average lunar disk illuminated night skies around planet Earth as the second supermoon of 2023. Seen here above Ragusa, Sicily, cloud banks cast diverging shadows through the supermoonlit skies, creating dramatic lunar crepuscular rays. The next Full Moon in 2023 will also shine on an August night. Rising as the Sun sets on August 30/31, this second Full Moon in a month is known as a Blue Moon. Blue moons occur only once every 2 or 3 years because lunar phases take almost a calendar month (29.5 days) to go through a complete cycle. But August's Blue Moon will also be near perigee, the third supermoon in 2023.

Image credit: Gianni Tumino
NGC 1360: The Robin's Egg Nebula (2023-08-05)

This pretty nebula lies some 1,500 light-years away, its shape and color in this telescopic view reminiscent of a robin's egg. The cosmic cloud spans about 3 light-years, nestled securely within the boundaries of the southern constellation Fornax. Recognized as a planetary nebula, egg-shaped NGC 1360 doesn't represent a beginning though. Instead it corresponds to a brief and final phase in the evolution of an aging star. In fact, visible at the center of the nebula, the central star of NGC 1360 is known to be a binary star system likely consisting of two evolved white dwarf stars, less massive but much hotter than the Sun.  Their intense and otherwise invisible ultraviolet radiation has stripped away electrons from the atoms in their mutually surrounding gaseous shroud. The predominant blue-green hue of NGC 1360 seen here is the strong emission produced as electrons recombine with doubly ionized oxygen atoms.

Image credit: Dong Liang
SN 1006: A Supernova Ribbon from Hubble (2023-08-06)

What created this unusual space ribbon?  The answer: one of the most violent explosions ever witnessed by ancient humans. Back in the year 1006 AD, light reached Earth from a stellar explosion in the constellation of the Wolf (Lupus), creating a "guest star" in the sky that appeared brighter than Venus and lasted for over two years. The supernova, now cataloged at SN 1006, occurred about 7,000 light years away and has left a large remnant that continues to expand and fade today.  Pictured here is a small part of that expanding supernova remnant dominated by a thin and outwardly moving shock front that heats and ionizes surrounding ambient gas. The supernova remnant SN 1006 now has a diameter of nearly 60 light years.
The Pelican Nebula in Gas, Dust, and Stars (2023-08-07)

The Pelican Nebula is slowly being transformed.  IC 5070 (the official designation) is divided from the larger North America Nebula by a molecular cloud filled with dark dust.  The Pelican, however, receives much study because it is a particularly active mix of star formation and evolving gas clouds.  The featured picture was produced in three specific colors -- light emitted by sulfur, hydrogen, and oxygen --  that can help us to better understand these interactions.  The light from young energetic stars is slowly transforming the cold gas to hot gas, with the advancing boundary between the two, known as an ionization front, visible in bright orange on the right. Particularly dense tentacles of cold gas remain.  Millions of years from now, the Pelican nebula, bounded by dark nebula LDN 935, might no longer be known as the Pelican, as the balance and placement of stars and gas will surely leave something that appears completely different.

Image credit: Abe Jones
Moon Meets Jupiter (2023-08-08)

What's that below the Moon? Jupiter -- and its largest moons.  Many skygazers across planet Earth enjoyed the close conjunction of Earth's Moon passing nearly in front of Jupiter in mid-June. The featured image is a single exposure of the event taken from Morón de la Frontera, Spain. The sunlit lunar crescent on the left is overexposed, while the Moon's night side, on the right, is only faintly illuminated by Earthshine. Lined up diagonally below the Moon, left to right, are Jupiter's bright Galilean satellites: Callisto, Ganymede, Io (hard to see as it is very near to Jupiter), and Europa.  In fact, Callisto, Ganymede, and Io are larger than Earth's Moon, while Europa is only slightly smaller. NASA's robotic spacecraft Juno is currently orbiting Jupiter and made a close pass near Io only a week ago.  If you look up in the night sky tonight, you will again see two of the brightest objects angularly close together -- because tonight is another Moon-Jupiter conjunction.

Image credit: Jordi L. Coy
Meteor Shower: Perseids from Perseus (2023-08-09)

This is a good week to see meteors.  Comet dust will rain down on planet Earth, streaking through dark skies during peak nights of the annual Perseid Meteor Shower.  The featured composite image was taken during the 2018 Perseids from the Poloniny Dark Sky Park in Slovakia.  The dome of the observatory in the foreground is on the grounds of Kolonica Observatory. Although the comet dust particles travel parallel to each other, the resulting shower meteors clearly seem to radiate from a single point on the sky in the eponymous constellation Perseus.  The radiant effect is due to perspective, as the parallel tracks appear to converge at a distance, like train tracks.  The Perseid Meteor Shower is expected to reach its highest peak on Saturday after midnight.  Since a crescent Moon will rise only very late that night, cloudless skies will be darker than usual, making a high number of faint meteors potentially visible this year.

Image credit: Petr Horálek /
Institute of Physics in Opava
Five Meters over Mars (2023-08-10)

On mission sol 872 (Earth date August 3) Ingenuity snapped this sharp image on its 54th flight above the surface of the Red Planet. During the flight the Mars Helicopter hovered about 5 meters, or just over 16 feet, above the Jezero crater floor. Tips of Ingenuity's landing legs peek over the left and right edges in the camera's field of view. Tracks visible near the upper right corner lead to the Perseverance Mars Rover, seen looking on from a distance at the top right edge of the frame. Planned as a brief "pop-up" flight, Ingenuity's 54th flight lasted less than 25 seconds. It followed Ingenuity's 53rd flight made on July 22 that resulted in an unscheduled landing.
Messier 51 in 255 Hours (2023-08-11)

An intriguing pair of interacting galaxies, M51 is the 51st entry in Charles Messier's famous catalog. Perhaps the original spiral nebula, the large galaxy with whirlpool-like spiral structure seen nearly face-on is also cataloged as NGC 5194. Its spiral arms and dust lanes sweep in front of a companion galaxy (right), NGC 5195. Some 31 million light-years distant, within the boundaries of the well-trained constellation Canes Venatici, M51 looks faint and fuzzy to the eye in direct telescopic views. But this remarkably deep image shows off stunning details of the galaxy pair's striking colors and extensive tidal debris. A collaboration of astro-imagers using telescopes on planet Earth combined over 10 days of exposure time to create this definitive galaxy portrait of M51. The image includes 118 hours of narrowband data that also reveals a vast glowing cloud of reddish ionized hydrogen gas discovered in the M51 system.  Weekend Watch: Perseid Meteor Shower

Image credit: The Deep Sky Collective
Ghirigori - Star Scribbles (2023-08-12)

It's fun to scribble on the canvas of the sky. You can use a creative photographic technique to cause the light of point-like stars to dance across a digital image by tapping lightly on the telescope while making an exposure. The result will be a squiggly line traced by the star (or two squiggles traced by binary stars) that can reveal the star's color. Colorful lines, dubbed Ghirigori, made from stars found in the northern sky constellations Bootes, Corona Borealis, Ophiucus, and Coma Berenices, are captured in this artistic mosaic. The 25 stars creating the varied and colorful squiggles are identified around the border. Of course, temperature determines the color of a star. While whitish stars tend to be close to the Sun's temperature, stars with bluer hues are hotter, and yellow and red colors are cooler than the Sun.  Weekend Watch: Perseid Meteor Shower

Image credit: Paolo Palma
The Sombrero Galaxy in Infrared (2023-08-13)

This floating ring is the size of a galaxy.  In fact, it is a galaxy -- or at least part of one: the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies.  The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light.  The featured image, digitally sharpened, shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in visible light. The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away.  M104 can be seen with a small telescope in the direction of the constellation Virgo.
The Ring Nebula from Webb and Hubble (2023-08-14)

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 remarkable combined exposure by the James Webb Space Telescope and the Hubble Space Telescope explores this popular nebula with  deep exposures in visible and infrared light. Strings of gas, like eyelashes around a cosmic eye, become evident around the Ring in this digitally enhanced featured image in assigned colors. These long filaments may be caused by shadowing of knots of dense gas in the ring from energetic light emitted within. The Ring Nebula is an elongated planetary nebula, a type of gas cloud created when a Sun-like star evolves to throw off its outer atmosphere to become a white dwarf star.  The central oval in the Ring Nebula lies about 2,500 light-years away toward the musical constellation Lyra.
A Triply Glowing Night Sky over Iceland (2023-08-15)

The Sun is not the quiet place it seems.  It expels an unsteady stream of energetic electrons and protons known as the solar wind.  These charged particles deform the Earth's magnetosphere, change paths, and collide with atoms in Earth's atmosphere, causing the generation of light in auroras like that visible in green in the image left.  Earth itself is also geologically active and covered with volcanoes. For example, Fagradalsfjall volcano in Iceland, seen emitting hot gas in orange near the image center. Iceland is one of the most geologically active places on Earth. On the far right is the Svartsengi geothermal power plant which creates the famous human-made Blue Lagoon, shown emitting white gas plumes. The featured composition therefore highlights three different sky phenomena, including both natural and human-made phenomena.

Image credit: Wioleta Gorecka;
Text: Natalia Lewandowska 
(SUNY Oswego)