Author Topic: APOD (Astronomy Picture of the Day)  (Read 95489 times)

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


IC 5067 in the Pelican Nebula 
 Image Credit & Copyright:  César Blanco González

 Explanation:  The prominent ridge of emission featured in this dramatic skyscape is cataloged as IC 5067. Part of a larger emission nebula with a distinctive shape, popularly called The Pelican Nebula, the ridge spans about 10 light-years following the curve of the cosmic pelican's head and neck. This false color view also translates the pervasive glow of narrow emission lines from atoms in the nebula to a color palette made popular in Hubble Space Telescope images of star forming regions. Fantastic, dark shapes inhabiting the 1/2 degree wide field are clouds of cool gas and dust sculpted by the winds and radiation from hot, massive stars. Close-ups of some of the sculpted clouds show clear signs of newly forming stars. The Pelican Nebula, itself cataloged as IC 5070, is about 2,000 light-years away. To find it, look northeast of bright star Deneb in the high flying constellation Cygnus.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


A Spectrum of Nova Delphini 
 Image Credit & Copyright:  Jürg Alean

 Explanation:  When a new star appeared in the constellation Delphinus late last week, astronomers found its spectrum hinted at the apparition's true nature. Now known as Nova Delphini, its visible light spectrum near maximum brightness is centered in this image of the nearby star field captured with prism and telescope on the night of August 16/17 at the Sternwarte Bülach, Switzerland. Strong absorption lines due to hydrogen atoms are seen as the darkest bands in the nova's spectrum, but the strong absorption lines are bordered along their redward edge by bright bands of emission. That pattern is the spectral signature of material blasted from a catalysmic binary system known as a classical nova. Other stars in field are fainter, identified by their Hipparcus catalog numbers, brightness in magnitudes, and spectral types. By chance, the faint emission line from planetary nebula NGC 6905 was also included, indicated at the lower right.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Earth Waves at Saturn 
 Credit:  NASA, JPL-Caltech, Cassini Project, Denizens of Earth

 Explanation:  This friendly photo collage is constructed from more than 1,400 images shared by denizens of planet Earth as part of the Cassini Mission's July 19th Wave at Saturn event. The base picture of Earth corresponds to the view from the Saturn-orbiting Cassini spacecraft on that date as its own cameras recorded images including planet Earth as a pale blue dot in the background. Of course, Saturn was 9.65 Astronomical Units away at the time, so it took light from all the waving Earth dwellers just over 80 minutes to travel there. Want to smile? Download and zoom in to the full-resolution (28MB jpg file) collage image available here.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


The Colliding Spiral Galaxies of Arp 271 
 Credit & Copyright:  Gemini Observatory, GMOS-South, NSF

 Explanation:  What will become of these galaxies? Spiral galaxies NGC 5426 and NGC 5427 are passing dangerously close to each other, but each is likely to survive this collision. Typically when galaxies collide, a large galaxy eats a much smaller galaxy. In this case, however, the two galaxies are quite similar, each being a sprawling spiral with expansive arms and a compact core. As the galaxies advance over the next tens of millions of years, their component stars are unlikely to collide, although new stars will form in the bunching of gas caused by gravitational tides. Close inspection of the above image taken by the 8-meter Gemini-South Telescope in Chile shows a bridge of material momentarily connecting the two giants. Known collectively as Arp 271, the interacting pair spans about 130,000 light years and lies about 90 million light-years away toward the constellation of Virgo. Recent predictions hold that our Milky Way Galaxy will undergo a similar collision with the neighboring Andromeda Galaxy in a few billion years.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Bright Planetary Nebula NGC 7027 from Hubble 
 Image Credit:  Hubble Legacy Archive, ESA, NASA;  Processing:  Delio Tolivia Cadrecha

 Explanation:  It is one of the brightest planetary nebulae on the sky -- what should it be named? First discovered in 1878, nebula NGC 7027 can be seen toward the constellation of the Swan (Cygnus) with a standard backyard telescope. Partly because it appears there as only an indistinct spot, it is rarely referred to with a moniker. When imaged with the Earth-orbiting Hubble Space Telescope, however, great details are revealed. Studying Hubble images of NGC 7027 have led to the understanding that it is a planetary nebula that began expanding about 600 years ago, and that the cloud of gas and dust is unusually massive as it appears to contain about three times the mass of our Sun. Pictured above in assigned colors, the resolved, layered, and dust-laced features of NGC 7027 might remind sky enthusiasts of a familiar icon that could be the basis for an informal name. Please feel free to make suggestions -- some suggestions are being recorded, for example, in an online APOD discussion forum.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


A Retreating Thunderstorm at Sunset 
 Image Credit & Copyright:  Alan Dyer (The Amazing Sky)

 Explanation:  What type of cloud is that? This retreating cumulonimbus cloud, more commonly called a thundercloud, is somewhat unusual as it contains the unusual bumpiness of a mammatus cloud on the near end, while simultaneously producing falling rain on the far end. Taken in mid-June in southern Alberta, Canada, the cloud is moving to the east, into the distance, as the sun sets in the west, behind the camera. In the above image, graphic sunset colors cross the sky to give the already photogenic cloud striking orange and pink hues. A darkening blue sky covers the background. Further in the distance, a rising, waxing, gibbous moon is visible on the far right.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Strawberry Sun 
 Image Credit & Copyright:  Laurie Hatch

 Explanation:  This striking, otherworldy scene really is a view from planet Earth. The ochre sky and strawberry red sun were photographed on August 22nd near the small village of Strawberry, California, USA. Found along Highway 108, that location is about 30 miles north of the origin of California's large Rim Fire, still threatening areas in and around Yosemite National Park. The extensive smoke plumes from the wildfire are easily visible from space. But seen from within the plumes, the fine smoke particles suspended in the atmosphere dim the Sun, scattering blue light and strongly coloring the sky

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


A Sagittarius Triplet 
 Image Credit & Copyright:  Tony Hallas

 Explanation:  These three bright nebulae are often featured in telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the large nebula left of center, and colorful M20 on the right. The third, NGC 6559, is above M8, separated from the larger nebula by a dark dust lane. All three are stellar nurseries about five thousand light-years or so distant. The expansive M8, over a hundred light-years across, is also known as the Lagoon Nebula. M20's popular moniker is the Trifid. Glowing hydrogen gas creates the dominant red color of the emission nebulae, with contrasting blue hues, most striking in the Trifid, due to dust reflected starlight. The colorful skyscape recorded with telescope and digital camera also includes one of Messier's open star clusters, M21, just above the Trifid.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


NGC 5195: The Dot Under the Question Mark 
 Image Credit:  Hubble Legacy Archive, NASA, ESA -  Processing:  José Jiménez Priego

 Explanation:  Dwarf galaxy NGC 5195 is best known as the smaller companion of spiral M51, the Whirlpool galaxy. Seen together they seem to trace the curve and dot of a cosmic question mark, recorded in Lord Rosse's 19th century drawings as one of the original spiral nebulae. Dwarfed by enormous M51 (aka NGC 5194), NGC 5195 spans about 20,000 light-years. A close encounter with M51 has likely triggered star formation and enhanced that galaxy's prominent spiral arms. Processed from image data available in the Hubble Legacy Archive, this majestic close-up of NGC 5195 makes it clear that the dwarf galaxy now lies behind M51. A tidal bridge of dark dust clouds and young blue star clusters stretches from the outskirts of M51 on the right, appearing in silhouette against the dwarf galaxy's yellowish glow. The famous pair of interacting galaxies lie some 30 million light-years away, toward the handle of the Big Dipper, and the constellation of the Hunting Dogs.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Fire on Earth 
 Image Credit:  (AFS, BLM)

 Explanation:  Sometimes, regions of planet Earth light up with fire. Since fire is the rapid acquisition of oxygen, and since oxygen is a key indicator of life, fire on any planet would be an indicator of life on that planet. Most of the Earth's land has been scorched by fire at some time in the past. Although causing many a tragedy, for many places on Earth fire is considered part of a natural ecosystem cycle. Large forest fires on Earth are usually caused by lightning and can be visible from orbit. Above, in the year 2000, stunned elk avoid a fire sweeping through Montana's Bitterroot Valley by standing in a river.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Milky Way Over Spain's Bardenas Reales 
 Image Credit & Copyright:  Maria Rosa Vila

 Explanation:  What's that below the Milky Way? First, across the top of the above image, lies the faint band that is our planet's sideways view of the central disk of our home Milky Way Galaxy. The Milky Way band can be seen most clear nights from just about anywhere on Earth with a dark sky. What lies beneath is, by comparison, is a much less common sight. It is the striking peak of Castildetierra, a rock formation located in Bardenas Reales, a natural badlands in northeast Spain. Standing 50 meters tall, the rock spire includes clay and sandstone left over from thousands of years of erosion by wind and water. The astrophotographer waited months for the sky to appear just right -- and then took the 14 exposures that compose the above image in a single night.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


North America and the Pelican 
 Image Credit & Copyright:  Scott Rosen

 Explanation:  Here lie familiar shapes in unfamiliar locations. On the left is an emission nebula cataloged as NGC 7000, famous partly because it resembles our fair planet's continent of North America. The emission region to the right of the North America Nebula is IC 5070, also known for its suggestive outlines as the Pelican Nebula. Separated by a dark cloud of obscuring dust, the two bright nebulae are about 1,500 light-years away. At that distance, the 4 degree wide field of view spans 100 light-years. This spectacular cosmic portrait combines narrow band images to highlight bright ionization fronts with fine details of dark, dusty forms in silhouette. Emission from atomic hydrogen, sulfur, and oxygen is captured in the narrow band data. These nebulae can be seen with binoculars from a dark location. Look northeast of bright star Deneb in the constellation of Cygnus the Swan.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


IRAS 20324: Evaporating Protostar 
 Image Credit:  NASA, ESA, Hubble Heritage Team (STScI/AURA), and IPHAS

 Explanation:  Will this caterpillar-shaped interstellar cloud one day evolve into a butterfly-shaped nebula? No one is sure. What is sure is that IRAS 20324+4057, on the inside, is contracting to form a new star. On the outside, however, energetic winds are blowing and energetic light is eroding away much of the gas and dust that might have been used to form the star. Therefore, no one is sure what mass the resulting star will have, and, therefore, no one knows the fate of this star. Were the winds and light to whittle the protostar down near the mass of the Sun, the outer atmosphere of this new star may one day expand into a planetary nebula, possibly even one that looks like a butterfly. Alternatively, if the stellar cocoon retains enough mass, a massive star will form that will one day explode in a supernova. The eroding protostellar nebula IRAS 20324+4057 spans about one light year and lies about 4,500 light years away toward the constellation of the Swan (Cygnus). The above image of IRAS 20324+4057 was taken with the Hubble Space Telescope in 2006 but released last week. The battle between gravity and light will likely take over 100,000 years to play out, but clever observations and deductions may yet yield telling clues well before that.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


M1: The Incredible Expanding Crab 
 Image Credit & Copyright:  Adam Block, Mt. Lemmon SkyCenter, U. Arizona

 Explanation:  The Crab Nebula is cataloged as M1, the first on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, an expanding cloud of debris from the explosion of a massive star. The violent birth of the Crab was witnessed by astronomers in the year 1054. Roughly 10 light-years across today, the nebula is still expanding at a rate of over 1,000 kilometers per second. Want to watch the Crab Nebula expand? Check out this video (vimeo) animation comparing an image of M1 taken in 1999 at the European Southern Observatory, with this one, taken in 2012 at the Mt. Lemmon Sky Center. Background stars were used to register the two images. The Crab Nebula lies about 6,500 light-years away in the constellation Taurus.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


The Quiet Sagittarius A* 
 Credit: X-ray - NASA / CXC / Q. Daniel Wang (UMASS) et al., IR - NASA/STScI

 Explanation:  Hot gas is hard to swallow. At least that seems to be true for the supermassive black hole at the center of our Milky Way Galaxy. Known as source Sagittarius A*, the Milky Way's black hole is  centered in this infrared (red and yellow hues) and X-ray (blue) composite. Based on data from an extensive campaign of observations by the orbiting Chandra X-ray telescope, the diffuse emission surrounding the black hole is seen in the close-up inset, the inset field spanning about 1/2 light-year across the galactic center some 26,000 light-years away. Astronomers have found that the X-ray emission originates in hot gas drawn from the winds of massive young stars in the region. The Chandra data indicate that only about 1% or less of the gas within the black hole's gravitational influence ever reaches the event horizon, losing enough heat and angular momentum to fall into the black hole, while the rest of the gas escapes in an outflow. The result explains why the Milky Way's black hole is so quiet, much fainter than might be expected in energetic X-rays. It likely holds for most supermassive black holes in galaxies in the nearby Universe.

Offline cousin it

  • Sniper Assassin
  • *****
  • drunk, and disorderly
tl;dr- super massive black hole at the center of our galaxy sucking the shit out of neighboring gasses, and heating them up.

Way cool!

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Night in the Andes Ice Forest 
 Image Credit & Copyright:  Babak Tafreshi (TWAN)

 Explanation:  This forest of snow and ice penitentes reflects moonlight shinning across the Chajnantor plateau. The region lies in the Chilean Andes at an altitude of 5,000 meters, not far from one of planet Earth's major astronomical observatories, the Atacama Large Millimeter/submillimeter Array. Up to several meters high, the flattened, sharp-edged shapes, and orientation of the penitentes tend to minimize their shadows at local noon. In the dry, cold, thin atmosphere, sublimation driven by sunlight is important for their formation. A direct transition from a solid to a gaseous state, sublimation shapes other solar system terrains too, like icy surfaces of comets and the polar caps of Mars.  Above the dreamlike landscape stretches the southern night sky. Their own forms rooted in myth, look for the constellations Pegasus, Andromeda, and Perseus near the panorama's left edge. Bright and colorful stars of Orion the Hunter are near center, with the Large Magellanic Cloud and the South Celestial Pole on the far right.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality

Roll Cloud Over Wisconsin
Image Credit: Megan Hanrahan (Pierre cb), Wikipedia
Explanation: What kind of cloud is this? A type of arcus cloud called a roll cloud. These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud. When this happens uniformly along an extended front, a roll cloud may form. Roll clouds may actually have air circulating along the long horizontal axis of the cloud. A roll cloud is not thought to be able to morph into a tornado. Unlike a similar shelf cloud, a roll cloud is completely detached from their parent cumulonimbus cloud. Pictured above, a roll cloud extends far into the distance as a storm approached in 2007 in Racine, Wisconsin, USA.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Nearby Cepheid Variable RS Pup 
 Image Credit:  Hubble Legacy Archive, NASA, ESA -  Processing:  Stephen Byrne

 Explanation:  It is one of the most important stars in the sky. This is partly because, by coincidence, it is surrounded by a dazzling reflection nebula. Pulsating RS Puppis, the brightest star in the image center, is some ten times more massive than our Sun and on average 15,000 times more luminous. In fact, RS Pup is a Cepheid type variable star, a class of stars whose brightness is used to estimate distances to nearby galaxies as one of the first steps in establishing the cosmic distance scale. As RS Pup pulsates over a period of about 40 days, its regular changes in brightness are also seen along the nebula delayed in time, effectively a light echo. Using measurements of the time delay and angular size of the nebula, the known speed of light allows astronomers to geometrically determine the distance to RS Pup to be 6,500 light-years, with a remarkably small error of plus or minus 90 light-years. An impressive achievement for stellar astronomy, the echo-measured distance also more accurately establishes the true brightness of RS Pup, and by extension other Cepheid stars, improving the knowledge of distances to galaxies beyond the Milky Way. The above image was taken by the Hubble Space Telescope and digitally processed by a volunteer.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Extrasolar Super-Earth Gliese 1214b Might Hold Water 
 Illustration Credit & License:  ESO, L. Calçada

 Explanation:  Might this distant planet hold water? Actually, given how close Gliese 1214b is to its parent star, any water, if it exists, would surely be in the form of steam. In the above artist's illustration, the super-Earth Gliese 1214b is imagined passing in front of its parent star, creating a mini-eclipse that alerted humanity to its presence. Gliese 1214b, also designated GJ 1214b, has been designated a super-Earth because it is larger than the Earth but smaller a planet like Neptune. The entire Gliese 1214 planetary system is of the closest known systems to our Sun, located only 42 light years away. The parent star, Gliese 1214 is a slightly smaller and cooler version of our Sun. Recent observations from the Subaru telescope in Hawaii found very little scattering of blue light from the parent star by the planet. This appears most consistent with a planet that has a watery atmosphere -- although it is still possible that the super-Earth has clouds so thick that little of any color of light was scattered. Detecting water on exoplanets is important partly because most lifeforms on Earth need water to survive.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


LADEE Launch Streak 
 Image Credit &  Copyright: Jeff Berkes

 Explanation:  On September 6, a starry night and the Milky Way witnessed the launch of a Minotaur V rocket from NASA's Wallops Flight Facility on Wallops Island, Virginia. So did a large part of the eastern United States, as the spectacular night launch was easily visible even from light polluted urban areas. This 35 second exposure captures part of the rocket's initial launch streak and 2nd stage ignition flare along with a fiery reflection in calm waters. The stunning view faces south and west from a vantage point overlooking Sinepuxent Bay in Maryland about 20 miles north of the launch pad. Heading east over the Atlantic, the multi-stage rocket placed LADEE, the Lunar Atmosphere and Dust Environment Explorer, into a highly elliptical Earth orbit to begin its journey to the Moon.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Stars and Dust Across Corona Australis 
 Image Credit &  Copyright: Ignacio Diaz Bobillo

 Explanation:  Cosmic dust clouds sprawl across a rich field of stars in this sweeping telescopic vista near the northern boundary of Corona Australis, the Southern Crown. Less than 500 light-years away the dust clouds effectively block light from more distant background stars in the Milky Way. The entire frame spans about 2 degrees or over 15 light-years at the clouds' estimated distance. Near center is a group of lovely reflection nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. A characteristic blue color is produced as light from hot stars is reflected by the cosmic dust. The dust also obscures from view stars in the region still in the process of formation. Smaller yellowish nebula NGC 6729 surrounds young variable star R Coronae Australis. Below it are arcs and loops identified as Herbig Haro objects associated with energetic newborn stars. Magnificent globular star cluster NGC 6723 is at the right. Though NGC 6723 appears to be part of the group, its ancient stars actually lie nearly 30,000 light-years away, far beyond the young stars of the Corona Australis dust clouds.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


Crescent Moon Meets Evening Star 
 Image Credit &  Copyright: Luis Argerich, Agustin Llorens, Guido Medici, Gabriel Remotti

 Explanation:  On September 8, brilliant planet Venus appearing as the evening star stood near a slender, crescent Moon at sunset. The close celestial pairing or conjunction was a scene enjoyed by skygazers around the world. But from some locations in South America, the Moon actually passed in front of Venus in a lunar occultation. Captured near Las Cañas, Uruguay, this two frame mosaic telescopic view shows the Moon and Venus before and after the occultation. The silvery evening star appears at right just before it winked out behind the dark lunar limb, still in bright twilight skies. About an hour later Venus emerged (left) along the three day old Moon's sunlit edge.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


A Landing on Planet Earth 
 Image Credit:  NASA, Bill Ingalls

 Explanation:  With parachute deployed and retro-rockets blazing, this spacecraft landed on planet Earth on September 11 (UT) in a remote area near the town of Zhezkazgan, Kazakhstan. Seen in silhouette against the rockets' glare, the spacecraft is a Soyuz TMA-08M. Its crew, Expedition 36 Commander Pavel Vinogradov and Flight Engineer Alexander Misurkin of the Russian Federal Space Agency (Roscosmos), and Flight Engineer Chris Cassidy of NASA were returning after five and half months aboard the International Space Station. The Soyuz retro-rockets fire very quickly and for an extremely short duration near touchdown. Capturing the moment, the well-timed photograph was taken from a helicopter flying over the landing site.

Offline Velvet Revolver

  • Administrator
  • *****
  • Location: Reality


M2-9: Wings of a Butterfly Nebula 
 Credit:  Hubble Legacy Archive, NASA, ESA -  Processing:  Judy Schmidt

 Explanation:  Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and M2-9 pictured above, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes. The expended gas frequently forms an impressive display called a planetary nebula that fades gradually over thousand of years. M2-9, a butterfly planetary nebula 2100 light-years away shown in representative colors, has wings that tell a strange but incomplete tale. In the center, two stars orbit inside a gaseous disk 10 times the orbit of Pluto. The expelled envelope of the dying star breaks out from the disk creating the bipolar appearance. Much remains unknown about the physical processes that cause planetary nebulae.