juliensimon/nasa-apod huggingface dataset:
NGC 6888: X-Rays in the Wind (2003-10-16)

NGC 6888, also known as the Crescent Nebula, is a cosmic bubble of interstellar gas about 25 light-years across. Created by winds from the bright, massive star seen near the center of this composite image, the shocked filaments of gas glowing at optical wavelengths are represented in green and yellowish hues. X-ray image data from a portion of the nebula viewed by the Chandra Observatory is overlaid in blue. Such isolated stellar wind bubbles are not usually seen to produce energetic x-rays, which require heating gas to a million degrees celsius. Still, NGC 6888 seems to have accomplished this as slow moving winds from the central star's initial transition to a red supergiant were overtaken and rammed by faster winds driven by the intense radiation from the star's exposed inner layers. Burning fuel at a prodigious rate and near the end of its stellar life, NGC 6888's central star should ultimately go out with a bang, creating a supernova explosion in 100,000 years or so. NGC 6888 is about 5,000 light-years close, toward the constellation Cygnus.
Astronomy Quilt of the Week (2003-10-17)

Tomorrow's picture: moon shot  < | Archive | Index | Search | Calendar | Glossary | Education | About APOD | >  Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA) NASA Web Site Statements, Warnings, and Disclaimers NASA Official: Jay Norris. Specific rights apply. A service of: LHEA at NASA / GSFC & Michigan Tech. U.

Image credit: Judy W. Ross, 
Point Roberts, WA
The Last Moon Shot (2003-10-18)

In 1865 Jules Verne predicted the invention of a space capsule that could carry people. In his science fiction story "From the Earth to the Moon", he outlined his vision of a cannon in Florida so powerful that it could shoot a "Projectile-Vehicle" carrying three adventurers to the Moon. Over 100 years later, NASA, guided by  Wernher Von Braun's vision, produced the Saturn V rocket. From a spaceport in Florida, this rocket turned Verne's fiction into fact, launching 9 Apollo Lunar missions and allowing 12 astronauts to walk on the Moon. Pictured is the last moon shot, Apollo 17, awaiting its December 1972 night launch. Spotlights play on the rocket and launch pad at dusk. Humans have not walked on on the lunar surface since.
An Unusual Globule in IC 1396 (2003-10-19)

Is there a monster in IC 1396?  Known to some as the Elephant's Trunk Nebula, parts of gas and dust clouds of this star formation region may appear to take on foreboding forms, some nearly human.  The only real monster here, however, is a bright young star too far from Earth to hurt us.  Energetic light from this star is eating away the dust of the dark cometary globule near the top of the above image.  Jets and winds of particles emitted from this star are also pushing away ambient gas and dust.  Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a much larger region on the sky than shown here, with an apparent width of more than 10 full moons.

Image credit: Jean-Charles Cuillandre
Neptune and Triton from Palomar (2003-10-20)

How's the weather on Neptune?  Tracking major weather patterns on the Solar System's outermost gas giant can help in the understanding of global weather patterns here on Earth.  Each summer for the past five years, Neptune has been imaged and major weather patterns studied.  The latest picture, taken on September 15, is shown above in false color.  Visible in pink near Neptune's lower right is a new storm dubbed Annabelle that is several times larger than her terrestrial sister Isabel, a concurrent storm system that occurred here on Earth.  Although Isabel lasted a few weeks, no one knows how long Annabelle will endure.  On the upper right is Neptune's largest moon Triton, an unusual moon that sports volcanoes that spew ice.

Image credit: D. Banfield, 
P. D. Nicholson, & 
B. J. Conrath 
(Cornell), 
Palomar Obs., 
JPL, 
NASA
The Belt of Venus over the Valley of the Moon (2003-10-21)

Although you've surely seen it, you might not have noticed it.  During a cloudless twilight, just before sunrise or after sunset, part of the atmosphere above the horizon appears slightly off-color, slightly pink.  Called the Belt of Venus, this off-color band between the dark eclipsed sky and the blue sky can be seen in nearly every direction including that opposite the Sun.  Straight above, blue sky is normal sunlight reflecting off the atmosphere.  In the Belt of Venus, however, the atmosphere reflects light from the setting (or rising) Sun which appears more red.  The Belt of Venus can be seen from any location with a clear horizon.  Pictured above, the Belt of Venus was photographed above morning fog in the Valley of the Moon, a famous wine-producing region in northern California, USA. The belt is frequently caught by accident in other photographs.

Image credit: Christine Churchill
The Heart and Soul Nebulas (2003-10-22)

Is the heart and soul of our Galaxy located in Cassiopeia?  Possibly not, but that is where two bright emission nebulas nicknamed Heart and Soul can be found.  The Heart Nebula, officially dubbed IC 1805 and visible above on the right, has a shape reminiscent of a classical heart symbol.  Both nebulas shine brightly in the red light of energized hydrogen.  Several young open clusters of stars populate the image and are visible above in blue, including the nebula centers.  Light takes about 6,000 years to reach us from these nebulas, which together span roughly 300 light years.  Studies of stars and clusters like those found in the Heart and Soul Nebulas have focussed on how massive stars form and how they affect their environment.

Image credit: Richard Powell, 
Digitized Sky Survey,
Palomar Observatory, 
STScI
Cygnus Nebulosities (2003-10-23)

Looking toward the constellation Cygnus, a stunning and complex region of nebulae strewn along the plane of our Milky Way galaxy is revealed in this unique wide-angle sky view. Recorded with a filter designed to transmit light emitted by hydrogen atoms, the image emphasizes cosmic gas clouds in a 34 by 23 degree field centered on the well known Northern Cross asterism. Bright, hot, supergiant star Deneb (the top of the cross) and popular celestial sights such as the North America and Pelican emission regions, the IC 1318 "butterfly", and the Crescent and Veil nebulae can be identified by placing your cursor over the image. Silhouetted by the glowing interstellar clouds and crowded star fields, the dark Northern Coal Sack is also visible, part of a series of obscuring dust clouds forming the Great Rift in the Milky Way. These Cygnus nebulosities are all located about 2,000 light-years away. Along with the Sun, they lie within the Orion spiral arm of our galaxy.

Image credit: Steve Mandel,
Galaxy Images
Mars Moons (2003-10-24)

This year's record close approach of Mars inspired many to enjoy telescopic views of the red planet. But while Mars was so bright it was hard to miss, spotting Mars' two diminutive moons was still a good test for observers with modest sized instruments. Mars' moons were discovered in August of 1877 by Asaph Hall at the US Naval Observatory using the large 26-inch Alvan Clark refractor. Recorded on this August 22nd, innermost moon Phobos and outermost moon Deimos are seen here against the planet's glare in a digital composite image. The picture consists of of a long exposure capturing the faint, city-sized moons and overexposing the planetary disk, combined with a well exposed image of the red planet, revealing dark markings on the surface and the white south polar cap. The images were taken by astronomer Johannes Schedler using an 11-inch Schmidt-Cassegrain telescope at his observatory in southeastern Austria. (Editor's note: For help finding Mars' moons, just put your cursor over the image.)

Image credit: Johannes Schedler
(Panther Observatory)
Islands in the Photosphere (2003-10-25)

Awash in a sea of plasma and anchored in magnetic fields, sunspots are planet-sized, dark islands in the solar photosphere, the bright surface of the Sun. Before the enlightened(!) age of cameras, solar observers created detailed drawings of sunspots as they changed and progressed across the visible solar disk. But contemporary observers also regularly use this time-honored method of monitoring sunspots. In this sketch from March 6th 2001, astronomer Gunther Groenez has faithfully recorded the intriguing shapes and shades of major visible sunspot groups and labeled them according to their NOAA active region number. Solar north is up and east to the right. Groenez' technical equipment includes H and 2H pencil leads for the sunspot umbra (dark) and penumbra (light) areas respectively. Want to draw sunspots too? Now's your chance as two large sunspot groups are presently making their way across the solar disk. Activity associated with these large sunspots may trigger aurora in the coming days.

Image credit: Gunther
Groenez
M16: Stars from Eagle's EGGs (2003-10-26)

Newborn stars are forming in the Eagle Nebula.  This image, taken with the Hubble Space Telescope in 1995, shows evaporating gaseous globules (EGGs) emerging from pillars of molecular hydrogen gas and dust.  The giant pillars are light years in length and are so dense that interior gas contracts gravitationally to form stars.  At each pillars' end, the intense radiation of bright young stars causes low density material to boil away, leaving stellar nurseries of dense  EGGs exposed.  The Eagle Nebula, associated with the open star cluster M16, lies about 7000 light years away.
Large Sunspot Groups 10484 and 10486 (2003-10-27)

Two unusually large sunspot groups are now crossing the face of the Sun.  Each group, roughly the size of Jupiter, is unusual not only for its size but because it is appearing over three years after solar maximum, the peak of solar surface activity.  Sunspot group 10484 appears near the image center, while sunspot group 10486 is just coming over the left limb of the Sun.  The active region associated with Sunspot 484 (the shorter nickname) has already jettisoned a large coronal mass ejection (CME) of particles out into the Solar System.  When striking Earth, radiation of this sort has the power to interrupt normal satellite operations while simultaneously providing beautiful auroras.  Rotating with the Sun, sunspots 484 and 486 will take about 30 days to make one complete circle, slowly evolving in size and shape during this time.  After using extreme care never to look directly at the Sun, the above image was created by holding a digital camera up to a small telescope.

Image credit: Juan Carlos Casado
The SDSS 3D Universe Map (2003-10-28)

The latest map of the cosmos again indicates that dark matter and dark energy dominate our universe.  The Sloan Digital Sky Survey (SDSS) is on its way to measuring the distances to over one million galaxies.  Galaxies first identified on 2D images, like the one shown above on the right, have their distances measured to create the 3D map.  The SDSS currently reports 3D information for over 200,000 galaxies, now rivaling the 3D galaxy-count of the Two-Degree Field sky map.  The latest SDSS map, shown above on the left, could only show the galaxy distribution it does if the universe was composed and evolved a certain way.  After trying to match many candidate universes to it, the Cinderella universe that best fits the above map has 5% atoms, 25% dark matter, and 70% dark energy.  Such a universe was previously postulated because its rapid recent expansion can explain why distant supernovas are so dim, and its early evolution can explain the spot distribution on the very distant cosmic microwave background.
A Powerful Solar Flare (2003-10-29)

Yesterday, our Sun produced one of the most powerful solar flares in recorded history.  Seen across the electromagnetic spectrum, the Sun briefly became over 100 times brighter in X-rays than normal.  Over the next few days, as energetic particles emitted from these regions strike the Earth, satellite communications might be affected and auroras might develop.  The flare and resulting CME, emitted from giant sunspot group 10486, was captured above as it happened by the by the LASCO instrument aboard the Sun-orbiting SOHO satellite. The disk of the Sun is covered to accentuate surrounding areas.  The time-lapse movie shows the tremendous explosion in frames separated in real time by about 30 minutes each.  The frames appear progressively noisier as protons from the flare begin to strike the detector.  The SOHO satellite has been put in a temporary safe mode to avoid damage from the solar particle storm.
Aurora in Colorado Skies (2003-10-30)

Vivid auroral displays were triggered by a cloud of high energy particles and magnetic fields from the Sun that collided with planet Earth's magnetosphere yesterday, October 29, at about 06:30 Universal Time. The collision was anticipated, following an intense solar flare and coronal mass ejection detected on October 28, and many anxious skywatchers were rewarded with an enjoyable light show. While aurorae don't normally haunt skies in the southern United States, they were reported from locations in Missouri, Texas, New Mexico, and California in the early morning hours. Near Yampa, Colorado astronomer Jimmy Westlake also spent early yesterday morning enjoying the stormy space weather. He was impressed by this colorful apparition of the northern lights -- produced by oxygen and nitrogen atoms excited by collisions with energetic particles from the magnetosphere and returning to lower energy states, at altitudes of 100 kilometers or more. Brighter stars shine through the extreme high-altitude glow which shows much lower clouds and the distant horizon in silhouette.

Image credit: Jimmy Westlake
(Colorado
Mountain College)
A Dark and Stormy Night (2003-10-31)

It was a dark and stormy night. But on August 29th the red planet Mars, near its closest approach to Earth in almost 60,000 years, shone brightly in the sky against a background of stars in the constellation Aquarius. In the foreground of this scary view, huge thunder clouds are lit by lightning strokes from within. Mars, of course, has nothing to do with storms on Earth, though both have the power to excite the imagination and wonder of Earthdwellers. And who knows what luminous sights you might see if you go out tonight? Have a safe and Happy Halloween!

Image credit: T. Credner &
S. Kohle, AlltheSky.com
Halo of the Cat's Eye (2003-11-01)

The Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its haunting symmetries are seen in the very central region of this stunning false-color picture, processed to reveal the enormous but extremely faint halo of gaseous material, over three light-years across, which surrounds the brighter, familiar planetary nebula. Made with data from the Nordic Optical Telescope in the Canary Islands, the composite picture shows emission from nitrogen atoms as red and oxygen atoms as green and blue shades. Planetary nebulae have long been appreciated as a final phase in the life of a sun-like star. Only much more recently however, have some planetaries been found to have halos like this one, likely formed of material shrugged off during earlier active episodes in the star's evolution. While the planetary nebula phase is thought to last for around 10,000 years, astronomers estimate the age of the outer filamentary portions of this halo to be 50,000 to 90,000 years.
A Giant Starspot on HD 12545 (2003-11-02)

What could cause a star to have such a large spot?  Our Sun itself frequently has sunspots, relatively cool dark magnetic depressions that move across its surface.  HD 12545, however, exhibits the largest starspots yet observed.  Doppler imaging - the use of slight changes in color caused by the rotation of the star - was used to create this false-color image.  The vertical bar on the right gives a temperature scale in kelvins. This giant, binary, RS CVn star, also known as XX Trianguli, is visible with binoculars in the constellation of Triangulum.  The starspot is thought to be caused by large magnetic fields that inhibit hot matter from flowing to the surface.

Image credit: K. Strassmeier 
(U. Wien), 
Coude Feed Telescope, 
AURA,
NOAO, 
NSF
Spiral Galaxy NGC 3982 Before Supernova (2003-11-03)

What do stars look like just before they explode?  To find out, astronomers are taking detailed images of nearby galaxies now, before any supernova is visible.  Hopefully, a star in one of the hundreds of high resolution galaxy images  will explode in the coming years.  If so, archival images like that taken above by the Hubble Space Telescope can be inspected to find what the star looked like originally.  This information is likely important for better understanding of how and why supernovas occur, as well as why some supernovas appear brighter than others.  Pictured above, beautiful spiral galaxy NGC 3982 displays numerous spiral arms filled with bright stars, blue star clusters, and dark dust lanes.  NGC 3982, which spans about 30,000 light years, lies about 60 million light years from Earth and can be seen with a small telescope toward the constellation of Ursa Major.
Aurora Over Edmonton (2003-11-04)

Northern and southern locales saw many a beautiful aurora over the last week, as particles from several large solar flares impacted the Earth.  Many reported unusually red auroras, although colors across the spectrum were also seen.  Power grids and orbiting satellites braced for the onslaught, but little lasting damage was reported.  Pictured above, the Clover Bar Power Plant was photographed from the banks of the North Saskatchewan River in Edmonton, Alberta, Canada.  A small pond in the foreground reflects predominantly green aurora light far in the distance.  Two days ago, again unexpectedly, another  large solar flare occurred from sunspot group 10486, the site of other recent major flares.  This unusually active solar region is now rotating to the far side of the Sun.

Image credit: Lance Taylor 
(Edmonton RASC)
The Lynx Arc (2003-11-05)

While chasing the spectrum of a mysterious arc in a cluster of galaxies within the obscure northerly constellation Lynx, astronomers have stumbled upon the most massive and distant star-forming region ever discovered. The notably red "Lynx arc" lies right of center in this color image of the galaxy cluster, a composite of Hubble Space Telescope and ground-based data. While the galaxy cluster lies about 5 billion light-years distant, spectroscopic studies show that the arc itself is actually a distorted image of an even more distant but enormous star-forming region. The image is formed as the closer galaxy cluster's gravity bends light like a magnifying lens, an effect explained by Einstein's theory of gravity. In fact, the monster star-forming region is nearly 12 billion light-years away and about a million times brighter than the more familiar stellar nursery, the Orion Nebula. Estimates are that the star-forming region seen as the Lynx arc contains about a million massive, hot stars, compared to the four stars which power the Orion Nebula's glow.  Stars within the Lynx arc are more than twice as hot as the Orion Nebula's central stars and were formed when the Universe was a mere 2 billion years old. Still, astronomers believe that the first stars were formed at even earlier times.
Flare Well AR 10486 (2003-11-06)

Almost out of view from our fair planet, rotating around the Sun's western edge, giant sunspot region AR 10486 lashed out with another intense solar flare followed by a large coronal mass ejection (CME) on Tuesday, November 4th at about 1950 Universal Time. The flare itself is seen here at the lower right in an extreme ultraviolet image from the sun-staring SOHO spacecraft's EIT camera. Saturating the EIT camera pixels and detectors on other satellites, this giant X-class flare was among the most powerful ever recorded since the 1970s, the third such historic blast from AR 10486 within the last two weeks. While energetic particle radiation from the flare did cause substantial radio interference, the associated CME is not expected to trigger extremely widespread aurorae as it glances off the magnetosphere, unlike the direct hits from last week's CMEs. Say farewell to the mighty AR 10486, for now. For the next two weeks, the sunspot region will be on the Sun's far side.
November's Lunar Eclipse (2003-11-07)

The Moon slides through the Earth's shadow this Saturday night / Sunday morning (November 8/9) giving skygazers in the Americas, Europe, Africa, and western Asia a chance to enjoy a total lunar eclipse. As lunar eclipses go, this will be a brief one though, with the total phase lasting only about 25 minutes. The orientation and relative size of the Earth's shadow and the Moon's trajectory are illustrated in this thoughtful animation showing the full Moon moving up from the lower right, entering the penumbra or outer portion of the shadow region, and then passing well below the center of the darker inner shadow region or umbra. The total eclipse phase begins at 1:06 Universal Time, November 9 (8:06pm EST Nov. 8) when the Moon is completely within the umbra. While the off-center passage guarantees a short total phase, it also makes it likely that this November's eclipsed Moon will be dramatically visible and colorful with a brighter rim along the southern edge.

Image credit: Larry Koehn
Eclipsed Moon in Infrared (2003-11-08)

The total lunar eclipse of September 1996 disappointed many observers in North America who were cursed with cloudy skies. However, the Midcourse Space Experiment (MSX) satellite had a spectacular view from Earth orbit and SPIRIT III, an on board infrared telescope, was used to repeatedly image the moon during the eclipse. Above is one of the images taken during the 70 minute totality, the Moon completely immersed in the Earth's shadow. Infrared light has wavelengths longer than visible light - humans can not see it but feel it as heat. The bright spots correspond to the warm areas on the lunar surface, dark areas are cooler. The brightest spot below and left of center is the crater Tycho, the dark region at the upper right is the Mare Crisium. The series of SPIRIT III images allow the determination of cooling rates for geologically different areas, exploring the physical properties of the Moon's surface.
Apollo 17 Lunarscape: A Magnificent Desolation (2003-11-09)

Buzz Aldrin, Apollo 11 Lunar Module pilot and the second human to walk on the Moon, described the lunar landscape as "a magnificent desolation". Dramatic pictures from the Apollo missions to the lunar surface testify to this apt turn of phrase. Near the Apollo 17 landing site, Family Mountain (center background) and the edge of South Massif (left) frame the lunarscape in this photo of astronaut Harrison Schmitt working alongside the lunar roving vehicle. Schmitt and fellow astronaut Eugene Cernan were the last to walk on this magnificent desolation.
An Intermediate Polar Binary System (2003-11-10)

How can two stars create such a strange and intricate structure?  Most stars are members of multiple-star systems.  Some stars are members of close binary systems where material from one star swirls around the other in an accretion disk.  Only a handful of stars, however, are members of an intermediate polar, a system featuring a white dwarf star with a magnetic field that significantly pushes out the inner accretion disk, only allowing material to fall down its magnetic poles.  Shown above is an artist's depiction of an intermediate polar system, also known as a DQ Hercules system.  The foreground white dwarf is so close to the normal star that it strips away its outer atmosphere.  As the white dwarf spins, the columns of infalling gas rotate with it.  The name intermediate polar derives from observations of emitted light polarized at a level intermediate to non-disk binary systems known as polars.  Intermediate polars are a type of cataclysmic variable star system.

Image credit: Mark Garlick 
(Space-art)