Free Republic 3rd Quarter Fundraising Target: $85,000 Receipts & Pledges to-date: $26,270
30%  
Woo hoo!! And the first 30% is in!! Thank you all very much!!

Astronomy Picture of the Day (General/Chat)

Brevity: Headers | « Text »
  • Astronomy Picture of the Day -- Rho Ophiuchi Wide Field

    07/27/2014 6:48:52 AM PDT · by SunkenCiv · 4 replies
    NASA ^ | July 27, 2014 | (see photo credit)
    Explanation: The clouds surrounding the star system Rho Ophiuchi compose one of the closest star forming regions. Rho Ophiuchi itself is a binary star system visible in the light-colored region on the image right. The star system, located only 400 light years away, is distinguished by its colorful surroundings, which include a red emission nebula and numerous light and dark brown dust lanes. Near the upper right of the Rho Ophiuchi molecular cloud system is the yellow star Antares, while a distant but coincidently-superposed globular cluster of stars, M4, is visible between Antares and the red emission nebula. Near the...
  • Astronomy Picture of the Day -- NGC 253: Dusty Island Universe

    07/27/2014 6:47:45 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | July 26, 2014 | (see photo credit)
    Explanation: Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest. Some call it the Silver Dollar Galaxy for its appearance in small telescopes, or just the Sculptor Galaxy for its location within the boundaries of the southern constellation Sculptor. First swept up in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies. In addition to its spiral...
  • Astronomy Picture of the Day -- Cosmic Crab Nebula

    07/26/2014 8:29:05 AM PDT · by SunkenCiv · 7 replies
    NASA ^ | July 25, 2014 | (see photo credit)
    Explanation: The Crab Pulsar, a city-sized, magnetized neutron star spinning 30 times a second, lies at the center of this tantalizing wide-field image of the Crab Nebula. A spectacular picture of one of our Milky Way's supernova remnants, it combines optical survey data with X-ray data from the orbiting Chandra Observatory. The composite was created as part of a celebration of Chandra's 15 year long exploration of the high energy cosmos. Like a cosmic dynamo the pulsar powers the X-ray and optical emission from the nebula, accelerating charged particles to extreme energies to produce the jets and rings glowing in...
  • Astronomy Picture of the Day -- ALMA Milky Way

    07/24/2014 2:59:38 PM PDT · by SunkenCiv · 4 replies
    NASA ^ | July 24, 2014 | (see photo credit)
    Explanation: This alluring all-skyscape was taken 5,100 meters above sea level, from the Chajnantor Plateau in the Chilean Andes. Viewed through the site's rarefied atmosphere at about 50% sea level pressure, the gorgeous Milky Way stretches through the scene. Its cosmic rifts of dust, stars, and nebulae are joined by Venus, a brilliant morning star immersed in a strong band of predawn Zodiacal light. Still not completely dark even at this high altitude, the night sky's greenish cast is due to airglow emission from oxygen atoms. Around the horizon the dish antenna units of the Atacama Large Millimeter/submillimeter Array, ALMA,...
  • Astronomy Picture of the Day -- IC 4603: Reflection Nebula in Ophiuchius

    07/24/2014 2:57:38 PM PDT · by SunkenCiv · 4 replies
    NASA ^ | July 23, 2014 | (see photo credit)
    Explanation: Why does this starfield photograph resemble an impressionistic painting? The effect is created not by digital trickery but by large amounts of interstellar dust. Dust, minute globs rich in carbon and similar in size to cigarette smoke, frequently starts in the outer atmospheres of large, cool, evolved stars. The dust is dispersed as the star dies and grows as things stick to it in the interstellar medium. Dense dust clouds are opaque to visible light and can completely hide background stars. For less dense clouds, the capacity of dust to preferentially reflect blue starlight becomes important, effectively blooming the...
  • Astronomy Picture of the Day -- Cave with Aurora Skylight

    07/22/2014 4:05:06 PM PDT · by SunkenCiv · 11 replies
    NASA ^ | July 22, 2014 | (see photo credit)
    Explanation: Yes, but have you ever seen aurora from a cave? To capture this fascinating juxtaposition between below and above, astrophotographer Bjargmundsson spent much of a night alone in the kilometer-long Raufarhólshellir lava cave in Iceland during late March. There, he took separate images of three parts of the cave using a strobe for illumination. He also took a deep image of the sky to capture faint aurora, and digitally combined the four images later. The 4600-year old lava tube has several skylights under which stone rubble and snow have accumulated. Oh -- the person standing on each mound --...
  • Astronomy Picture of the Day -- Spacecraft Rosetta Shows Comet has Two Components

    07/21/2014 8:58:06 AM PDT · by SunkenCiv · 6 replies
    NASA ^ | July 21, 2014 | (see photo credit)
    Explanation: Why does this comet's nucleus have two components? The surprising discovery that Comet 67P/Churyumov–Gerasimenko has a double nucleus came late last week as ESA's robotic interplanetary spacecraft Rosetta continued its approach toward the ancient comet's core. Speculative ideas on how the double core was created include, currently, that Comet Churyumov–Gerasimenko is actually the result of the merger of two comets, that the comet is a loose pile of rubble pulled apart by tidal forces, that ice evaporation on the comet has been asymmetric, or that the comet has undergone some sort of explosive event. Pictured above, the comet's unusual...
  • Astronomy Picture of the Day -- A Solar Filament Erupts

    07/21/2014 8:53:26 AM PDT · by SunkenCiv · 7 replies
    NASA ^ | July 20, 2014 | (see photo credit)
    Explanation: What's happened to our Sun? Nothing very unusual -- it just threw a filament. Toward the middle of 2012, a long standing solar filament suddenly erupted into space producing an energetic Coronal Mass Ejection (CME). The filament had been held up for days by the Sun's ever changing magnetic field and the timing of the eruption was unexpected. Watched closely by the Sun-orbiting Solar Dynamics Observatory, the resulting explosion shot electrons and ions into the Solar System, some of which arrived at Earth three days later and impacted Earth's magnetosphere, causing visible aurorae. Loops of plasma surrounding an active...
  • Astronomy Picture of the Day -- Alicante Beach Moonrise

    07/19/2014 4:44:12 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | July 19, 2014 | (see photo credit)
    Explanation: In this beach and skyscape from Alicante, Spain, July's Full Moon shines in the dark blue twilight, its reflection coloring the Mediterranean waters. Near the horizon, the moonlight is reddened by its long path through the atmosphere, but this Full Moon was also near perigee, the closest point to Earth along the Moon's elliptical orbit. That made it a Supermoon, a mighty 14% larger and 30% brighter than a Full Moon at apogee, the Moon's farthest orbital swing. Of course, most warm summer nights are a good time to enjoy a family meal oceanside, but what fish do you...
  • Astronomy Picture of the Day -- Ou4: A Giant Squid Nebula

    07/19/2014 4:41:59 AM PDT · by SunkenCiv · 5 replies
    NASA ^ | July 18, 2014 | (see photo credit)
    Explanation: A mysterious, squid-like apparition, this nebula is very faint, but also very large in planet Earth's sky. In the mosaic image, composed with narrowband data from the 2.5 meter Isaac Newton Telescope, it spans some 2.5 full moons toward the constellation Cepheus. Recently discovered by French astro-imager Nicolas Outters, the remarkable nebula's bipolar shape and emission are consistent with it being a planetary nebula, the gaseous shroud of a dying sun-like star, but its actual distance and origin are unknown. A new investigation suggests Ou4 really lies within the emission region SH2-129 some 2,300 light-years away. Consistent with that...
  • Astronomy Picture of the Day -- 3D Homunculus Nebula

    07/19/2014 4:36:33 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | July 17, 2014 | (see photo credit)
    Explanation: If you're looking for something to print with that new 3D printer, try out a copy of the Homunculus Nebula. The dusty, bipolar cosmic cloud is around 1 light-year across but is slightly scaled down for printing to about 1/4 light-nanosecond or 80 millimeters. The full scale Homunculus surrounds Eta Carinae, famously unstable massive stars in a binary system embedded in the extensive Carina Nebula about 7,500 light-years distant. Between 1838 and 1845, Eta Carinae underwent the Great Eruption becoming the second brightest star in planet Earth's night sky and ejecting the Homunculus Nebula. The new 3D model of...
  • Astronomy Picture of the Day -- The Moon Eclipses Saturn

    07/16/2014 2:18:00 PM PDT · by SunkenCiv · 12 replies
    NASA ^ | July 16, 2014 | (see photo credit)
    Explanation: What happened to half of Saturn? Nothing other than Earth's Moon getting in the way. As pictured above on the far right, Saturn is partly eclipsed by a dark edge of a Moon itself only partly illuminated by the Sun. This year the orbits of the Moon and Saturn have led to an unusually high number of alignments of the ringed giant behind Earth's largest satellite. Technically termed an occultation, the above image captured one such photogenic juxtaposition from Buenos Aires, Argentina that occurred early last week. Visible to the unaided eye but best viewed with binoculars, there are...
  • Astronomy Picture of the Day -- A Blue Bridge of Stars between Cluster Galaxies

    07/15/2014 2:02:13 PM PDT · by SunkenCiv · 14 replies
    NASA ^ | July 15, 2014 | (see photo credit)
    Explanation: Why is there a blue bridge of stars across the center of this galaxy cluster? First and foremost the cluster, designated SDSS J1531+3414, contains many large yellow elliptical galaxies. The cluster's center, as pictured above by the Hubble Space Telescope, is surrounded by many unusual, thin, and curving blue filaments that are actually galaxies far in the distance whose images have become magnified and elongated by the gravitational lens effect of the massive cluster. More unusual, however, is a squiggly blue filament near the two large elliptical galaxies at the cluster center. Close inspection of the filament indicates that...
  • Astronomy Picture of the Day -- Auroras over Northern Canada

    07/14/2014 4:45:11 PM PDT · by SunkenCiv · 8 replies
    NASA ^ | July 14, 2014 | (see photo credit)
    Explanation: Gusting solar winds and blasts of charged particles from the Sun resulted in several rewarding nights last December for those anticipating auroras. The above image captured dramatic auroras stretching across a sky near the town of Yellowknife in northern Canada. The auroras were so bright that they not only inspired awe, but were easily visible on an image exposure of only 1.3 seconds. A video taken concurrently shows the dancing sky lights evolving in real time as tourists, many there just to see auroras, respond with cheers. The conical dwellings on the image right are teepees, while far in...
  • Astronomy Picture of the Day -- Planetary Nebula NGC 2818 from Hubble

    07/13/2014 6:09:41 AM PDT · by SunkenCiv · 7 replies
    NASA ^ | July 13, 2014 | (see photo credit)
    Explanation: NGC 2818 is a beautiful planetary nebula, the gaseous shroud of a dying sun-like star. It could well offer a glimpse of the future that awaits our own Sun after spending another 5 billion years or so steadily using up hydrogen at its core, and then finally helium, as fuel for nuclear fusion. Curiously, NGC 2818 seems to lie within an open star cluster, NGC 2818A, that is some 10,000 light-years distant toward the southern constellation Pyxis (the Compass). At the distance of the star cluster, the nebula would be about 4 light-years across. But accurate velocity measurements show...
  • Astronomy Picture of the Day -- SN 1006 Supernova Remnant

    07/12/2014 4:20:54 AM PDT · by SunkenCiv · 6 replies
    NASA ^ | July 12, 2014 | (see photo credit)
    Explanation: A new star, likely the brightest supernova in recorded human history, lit up planet Earth's sky in the year 1006 AD. The expanding debris cloud from the stellar explosion, found in the southerly constellation of Lupus, still puts on a cosmic light show across the electromagnetic spectrum. In fact, this composite view includes X-ray data in blue from the Chandra Observatory, optical data in yellowish hues, and radio image data in red. Now known as the SN 1006 supernova remnant, the debris cloud appears to be about 60 light-years across and is understood to represent the remains of a...
  • Astronomy Picture of the Day -- Spotty Sunrise over Brisbane

    07/10/2014 9:26:58 PM PDT · by SunkenCiv · 4 replies
    NASA ^ | July 11, 2014 | (see photo credit)
    Explanation: In this composite cityscape, dawn's first colors backdrop the lights along Brisbane's skyline at the southeastern corner of Queensland, Australia, planet Earth. Using a solar filter, additional exposures made every 3.5 minutes follow the winter sunrise on July 8 as planet-sized sunspots cross the visible solar disk. The sunspots mark solar active regions with convoluted magnetic fields. Even as the maximum in the solar activity cycle begins to fade, the active regions produce intense solar flares and eruptions launching coronal mass ejections (CMEs), enormous clouds of energetic particles, into our fair solar system.
  • Astronomy Picture of the Day -- M51: X-Rays from the Whirlpool

    07/10/2014 8:36:47 PM PDT · by SunkenCiv · 8 replies
    NASA ^ | June 10, 2014 | (see photo credit)
    Explanation: What if we X-rayed an entire spiral galaxy? This was done (again) recently by NASA's Chandra X-ray Observatory for the nearby interacting galaxies known as the Whirlpool (M51). Hundreds of glittering x-ray stars are present in the above Chandra image of the spiral and its neighbor. The image is a conglomerate of X-ray light from Chandra and visible light from the Hubble Space Telescope. The number of luminous x-ray sources, likely neutron star and black hole binary systems within the confines of M51, is unusually high for normal spiral or elliptical galaxies and suggests this cosmic whirlpool has experienced...
  • Astronomy Picture of the Day -- How to Identify that Light in the Sky

    07/10/2014 8:33:02 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | June 09, 2014 | (see photo credit)
    Explanation: What is that light in the sky? Perhaps one of humanity's more common questions, an answer may result from a few quick observations. For example -- is it moving or blinking? If so, and if you live near a city, the answer is typically an airplane, since planes are so numerous and so few stars and satellites are bright enough to be seen over the din of artificial city lights. If not, and if you live far from a city, that bright light is likely a planet such as Venus or Mars -- the former of which is constrained...
  • Astronomy Picture of the Day -- Open Cluster NGC 290: A Stellar Jewel Box

    07/10/2014 8:29:52 PM PDT · by SunkenCiv · 2 replies
    NASA ^ | June 08, 2014 | (see photo credit)
    Explanation: Jewels don't shine this bright -- only stars do. Like gems in a jewel box, though, the stars of open cluster NGC 290 glitter in a beautiful display of brightness and color. The photogenic cluster, pictured above, was captured recently by the orbiting Hubble Space Telescope. Open clusters of stars are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters of stars. NGC 290 lies about 200,000 light-years distant in a neighboring galaxy called the Small Cloud of Magellan (SMC). The open cluster contains hundreds of stars and spans about 65...
  • Astronomy Picture of the Day -- M16 and the Eagle Nebula

    07/10/2014 8:26:31 PM PDT · by SunkenCiv · 8 replies
    NASA ^ | June 07, 2014 | (see photo credit)
    Explanation: A star cluster around 2 million years young, M16 is surrounded by natal clouds of dust and glowing gas also known as The Eagle Nebula. This beautifully detailed image of the region includes cosmic sculptures made famous in Hubble Space Telescope close-ups of the starforming complex. Described as elephant trunks or Pillars of Creation, dense, dusty columns rising near the center are light-years in length but are gravitationally contracting to form stars. Energetic radiation from the cluster stars erodes material near the tips, eventually exposing the embedded new stars. Extending from the left edge of the frame is another...
  • Astronomy Picture of the Day -- Manhattanhenge: A New York City Sunset

    07/05/2014 10:42:01 PM PDT · by SunkenCiv · 21 replies
    NASA ^ | July 06, 2014 | (see photo credit)
    Explanation: This coming Saturday, if it is clear, well placed New Yorkers can go outside at sunset and watch their city act like a modern version of Stonehenge. Manhattan's streets will flood dramatically with sunlight just as the Sun sets precisely at each street's western end. Usually, the tall buildings that line the gridded streets of New York City's tallest borough will hide the setting Sun. This effect makes Manhattan a type of modern Stonehenge, although only aligned to about 30 degrees east of north. Were Manhattan's road grid perfectly aligned to east and west, today's effect would occur on...
  • Astronomy Picture of the Day -- M106 Across the Spectrum

    07/04/2014 9:25:25 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | July 05, 2014 | (see photo credit)
    Explanation: The spiral arms of bright, active galaxy M106 sprawl through this remarkable multiwavelength portrait, composed of image data from radio to X-rays, across the electromagnetic spectrum. Also known as NGC 4258, M106 can be found toward the northern constellation Canes Venatici. The well-measured distance to M106 is 23.5 million light-years, making this cosmic scene about 60,000 light-years across. Typical in grand spiral galaxies, dark dust lanes, youthful star clusters, and star forming regions trace spiral arms that converge on a bright nucleus. But this composite highlights two anomalous arms in radio (purple) and X-ray (blue) that seem to arise...
  • Astronomy Picture of the Day -- OCO-2 Night Launch

    07/04/2014 2:59:44 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | July 04, 2014 | (see photo credit)
    Explanation: In this alluring time exposure, star trails arc across the night sky above foggy Monterey Bay and the lights of Santa Cruz, California in the United States of America. Since the exposure began around 2:56am PDT on July 2 it also records the trail of a Delta II rocket lofting NASA's OCO-2 spacecraft into orbit. Seen from a vantage point 200 miles north of the Vandenberg Air Force Base launch site, the trail represents the first five minutes of the rocket's flight along a trajectory south and west over the Pacific to join the A-Train in polar orbit around...
  • Astronomy Picture of the Day -- Along the Cygnus Wall

    07/03/2014 3:59:35 AM PDT · by SunkenCiv · 5 replies
    NASA ^ | July 03, 2014 | (see photo credit)
    Explanation: The prominent ridge of emission featured in this vivid skyscape is known as the Cygnus Wall. Part of a larger emission nebula with a distinctive shape popularly called The North America Nebula, the ridge spans about 10 light-years along an outline that suggests the western coast of Mexico. Constructed from narrowband image data, the cosmic close-up maps emission from sulfur, hydrogen, and oxygen atoms to red, green, and blue colors. The result highlights the bright ionization front with fine details of dark, dusty forms in silhouette. Sculpted by energetic radiation from the region's young, hot, massive stars, the dark...
  • Astronomy Picture of the Day -- NGC 4651: The Umbrella Galaxy

    07/03/2014 3:55:36 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | July 02, 2014 | (see photo credit)
    Explanation: Image : : Explanation: Spiral galaxy NGC 4651 is a mere 62 million light-years distant, toward the well-groomed northern constellation Coma Berenices. About the size of our Milky Way, this island universe is seen to have a faint umbrella-shaped structure that seems to extend (left) some 100 thousand light-years beyond the bright galactic disk. The giant cosmic umbrella is now known to be composed of tidal star streams - extensive trails of stars gravitationally stripped from a smaller satellite galaxy. The small galaxy was eventually torn apart in repeated encounters as it swept back and forth on eccentric orbits...
  • Astronomy Picture of the Day -- Wolf-Rayet Star 124: Stellar Wind Machine

    07/01/2014 4:25:05 AM PDT · by SunkenCiv · 5 replies
    NASA ^ | July 01, 2014 | (see photo credit)
    Explanation: Some stars explode in slow motion. Rare, massive Wolf-Rayet stars are so tumultuous and hot that they slowly disintegrating right before our telescopes. Glowing gas globs each typically over 30 times more massive than the Earth are being expelled by violent stellar winds. Wolf-Rayet star WR 124, visible near the above image center spanning six light years across, is thus creating the surrounding nebula known as M1-67. Details of why this star has been slowly blowing itself apart over the past 20,000 years remains a topic of research. WR 124 lies 15,000 light-years away towards the constellation of Sagitta....
  • Astronomy Picture of the Day -- Peculiar Elliptical Galaxy Centaurus A

    07/01/2014 4:21:04 AM PDT · by SunkenCiv · 5 replies
    NASA ^ | June 30, 2014 | (see photo credit)
    Explanation: What's happened to the center of this galaxy? Unusual and dramatic dust lanes run across the center of elliptical galaxy Centaurus A. These dust lanes are so thick they almost completely obscure the galaxy's center in visible light. This is particularly unusual as Cen A's red stars and round shape are characteristic of a giant elliptical galaxy, a galaxy type usually low in dark dust. Cen A, also known as NGC 5128, is also unusual compared to an average elliptical galaxy because it contains a higher proportion of young blue stars and is a very strong source of radio...
  • Astronomy Picture of the Day -- Galaxy Cove Vista Revisited

    06/29/2014 3:09:02 PM PDT · by SunkenCiv · 7 replies
    NASA ^ | June 29, 2014 | (see photo credit)
    Explanation: To see a vista like this takes patience, hiking, and a camera. Patience was needed in searching out just the right place and waiting for just the right time. A short hike was needed to reach this rugged perch above a secluded cove in Julia Pfeiffer Burns State Park in California, USA. And a camera was needed for the long exposure required to bring out the faint light from stars and nebulae in the background Milky Way galaxy. Moonlight illuminated the hidden beach and inlet behind nearby trees in the above composite image taken last month. Usually obscured McWay...
  • Astronomy Picture of the Day -- Orion Arising

    06/28/2014 5:40:14 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | June 28, 2014 | (see photo credit)
    Explanation: Orion's belt runs just along the horizon, seen through Earth's atmosphere and rising in this starry snapshot from low Earth orbit on board the International Space Station. The belt stars, Alnitak, Alnilam, and Mintaka run right to left and Orion's sword, home to the great Orion Nebula, hangs above his belt, an orientation unfamiliar to denizens of the planet's northern hemisphere. That puts bright star Rigel, at the foot of Orion, still higher above Orion's belt. Of course the brightest celestial beacon in the frame is Sirius, alpha star of the constellation Canis Major. The station's Destiny Laboratory module...
  • Astronomy Picture of the Day -- Martian Anniversary Selfie

    06/28/2014 5:37:37 AM PDT · by SunkenCiv · 9 replies
    NASA ^ | June 27, 2014 | (see photo credit)
    Explanation: June 24th marked the first full Martian year of the Curiosity Rover's exploration of the surface of the Red Planet. That's 687 Earth days or 669 sols since its landing on August 5, 2012. To celebrate, consider this self-portrait of the car-sized robot posing next to a rocky outcrop dubbed Windjana, its recent drilling and sampling site. The mosaicked selfie was constructed with frames taken this April and May using the rover's Mars Hand Lens Imager (MAHLI), intended for close-up work and mounted at the end of the rover's robotic arm. The MAHLI frames used exclude sections that show...
  • Astronomy Picture of the Day -- Conjunction by the Sea

    06/25/2014 9:47:52 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | June 26, 2014 | (see photo credit)
    Explanation: Early morning risers were treated to a beautiful conjunction of Venus and waning Crescent Moon on June 24, captured in this seaside photo near Belmar, New Jersey, USA, planet Earth. The serene celestial pairing is seen above the Atlantic Ocean horizon as the eastern sky grows brighter with dawn's early light. Wispy, scattered clouds appear in silhouette. But the exposure also reveals the night side of the lunar orb in the arms of the sunlit crescent. That shadowed part of the Moon, with hints of the smooth, dark lunar seas or maria, is illuminated by Earthshine, sunlight reflected from...
  • Astronomy Picture of the Day -- The Hercules Cluster of Galaxies

    06/25/2014 9:43:55 PM PDT · by SunkenCiv · 2 replies
    NASA ^ | June 25, 2014 | (see photo credit)
    Explanation: These are galaxies of the Hercules Cluster, an archipelago of island universes a mere 500 million light-years away. Also known as Abell 2151, this cluster is loaded with gas and dust rich, star-forming spiral galaxies but has relatively few elliptical galaxies, which lack gas and dust and the associated newborn stars. The colors in this remarkably deep composite image clearly show the star forming galaxies with a blue tint and galaxies with older stellar populations with a yellowish cast. The sharp picture spans about 3/4 degree across the cluster center, corresponding to over 6 million light-years at the cluster's...
  • Astronomy Picture of the Day -- The Iris Nebula in a Field of Dust

    06/24/2014 3:29:01 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | June 24, 2014 | (see photo credit)
    Explanation: What flowers in this field of dark star dust? The Iris Nebula. The striking blue color of the Iris Nebula is created by light from the bright star SAO 19158 reflecting off of a dense patch of normally dark dust. Not only is the star itself mostly blue, but blue light from the star is preferentially reflected by the dust -- the same affect that makes Earth's sky blue. The brown tint of the pervasive dust comes partly from photoluminescence -- dust converting ultraviolet radiation to red light. Cataloged as NGC 7023, the Iris Nebula is studied frequently because...
  • Astronomy Picture of the Day -- Four Lasers over Mauna Kea

    06/24/2014 3:28:57 AM PDT · by SunkenCiv · 4 replies
    NASA ^ | June 23, 2014 | (see photo credit)
    Explanation: Are lasers from giant telescopes being used to attack the Galactic center? No. Lasers shot from telescopes are now commonly used to help increase the accuracy of astronomical observations. In some sky locations, Earth atmosphere-induced fluctuations in starlight can indicate how the air mass over a telescope is changing, but many times no bright star exists in the direction where atmospheric information is needed. In these cases, astronomers create an artificial star where they need it -- with a laser. Subsequent observations of the artificial laser guide star can reveal information so detailed about the blurring effects of the...
  • Astronomy Picture of the Day -- Persistent Saturnian Auroras

    06/22/2014 10:19:18 AM PDT · by SunkenCiv · 7 replies
    NASA ^ | June 22, 2014 | (see photo credit)
    Explanation: Are Saturn's auroras like Earth's? To help answer this question, the Hubble Space Telescope and the Cassini spacecraft monitored Saturn's South Pole simultaneously as Cassini closed in on the gas giant in January 2004. Hubble snapped images in ultraviolet light, while Cassini recorded radio emissions and monitored the solar wind. Like on Earth, Saturn's auroras make total or partial rings around magnetic poles. Unlike on Earth, however, Saturn's auroras persist for days, as opposed to only minutes on Earth. Although surely created by charged particles entering the atmosphere, Saturn's auroras also appear to be more closely modulated by the...
  • Astronomy Picture of the Day -- Lisbon Honey Moon

    06/21/2014 1:46:10 PM PDT · by SunkenCiv · 4 replies
    NASA ^ | June 21, 2014 | (see photo credit)
    Explanation: The Sun set on Friday the 13th as a full Honey Moon rose, captured in this well-planned time-lapse sequence. Lisbon, Portugal's Christ the King monument is in the foreground, about 6 kilometers distant from camera and telephoto lens. During the days surrounding today's solstice (June 21, 10:51 UT) the Sun follows its highest arc through northern hemisphere skies as it travels along the ecliptic plane. At night the ecliptic plane is low, and the Full Moon's path close to the ecliptic was also low, the rising Moon separating more slowly from the distant horizon. Northern moon watchers were likely...
  • Astronomy Picture of the Day -- Rio at Night

    06/21/2014 1:39:12 PM PDT · by SunkenCiv · 2 replies
    NASA ^ | June 20, 2014 | (see photo credit)
    Explanation: In this night skyscape setting stars trail above the western horizon over Rio de Janeiro, Brazil, a venue for the 2014 World Cup. Gentle arcs from the bright, colorful stars of Orion are near the center of the frame, while the starfield itself straddles planet Earth's celestial equator during the long exposure. Of course, trails from more local lights seem to create the strident paths through the scene. Air traffic smears an intense glow over an airport at the far right, while helicopters fly above the city and boats cruise near the coast. Striping the waterfront are tantalizing reflections...
  • Astronomy Picture of the Day -- Over the Top

    06/19/2014 2:46:13 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | June 19, 2014 | (see photo credit)
    Explanation: The central bulge of our Milky Way Galaxy rises above a sea of clouds in this ethereal scene. An echo of the Milky Way's dark dust lanes, the volcanic peak in foreground silhouette is on France's Réunion Island in the southern Indian Ocean. Taken in February, the photograph was voted the winner of the 2014 International Earth and Sky Photo Contest's Beauty of the Night Sky Category. This and other winning and notable images from the contest were selected from over a thousand entries from 55 countries around planet Earth. Also featured in the contest compilation video (vimeo), the...
  • Astronomy Picture of the Day -- NGC 6334: The Cat's Paw Nebula

    06/18/2014 7:07:21 PM PDT · by SunkenCiv · 12 replies
    NASA ^ | June 18, 2014 | (see photo credit)
    Explanation: Nebulas are perhaps as famous for being identified with familiar shapes as perhaps cats are for getting into trouble. Still, no known cat could have created the vast Cat's Paw Nebula visible in Scorpius. At 5,500 light years distant, Cat's Paw is an emission nebula with a red color that originates from an abundance of ionized hydrogen atoms. Alternatively known as the Bear Claw Nebula or NGC 6334, stars nearly ten times the mass of our Sun have been born there in only the past few million years. Pictured above is a deep field image of the Cat's Paw...
  • Astronomy Picture of the Day -- V838 Light Echo: The Movie

    06/17/2014 3:07:20 PM PDT · by SunkenCiv · 8 replies
    NASA ^ | June 17, 2014 | (see photo credit)
    Explanation: What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon suddenly became one of the brightest stars in the entire Milky Way Galaxy. Then, just a few months later, it faded. A stellar flash like this has never been seen before -- supernovas and novas expel a tremendous amount of matter out into space. Although the V838 Mon flash appeared to expel some material into space, what is seen in the above eight-frame movie, interpolated for smoothness, is actually an outwardly moving light echo of the flash. The actual time-span of the above movie is from...
  • Astronomy Picture of the Day -- APOD Heatmap

    06/16/2014 2:39:31 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | June 16, 2014 | (see photo credit)
    Explanation: The first APOD appeared 19 years ago today. To help celebrate, APOD brings you today an all-sky heatmap of (nearly) 19 years of APOD entries. The brighter a region appears on the above heatmap, the more APODs that occur in that region. Clicking anywhere on the map will bring up a link to all APODs, if any, that appear nearby. We at APOD again thank our readers, NASA, astrophotographers, volunteers who translate APOD daily into over 20 languages, volunteers who run APOD's over 20 mirror sites, volunteers who answer questions and administer APOD's main discussion board, and volunteers who...
  • Astronomy Picture of the Day -- CMB Dipole: Speeding Through the Universe

    06/15/2014 3:20:44 AM PDT · by SunkenCiv · 13 replies
    NASA ^ | June 15, 2014 | (see photo credit)
    Explanation: Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of Galaxies. The Local Group falls toward the Virgo Cluster of Galaxies. But these speeds are less than the speed that all of these objects together move relative to the cosmic microwave background radiation (CMBR). In the above all-sky map from the COBE satellite, radiation in the Earth's direction of motion appears blueshifted and hence hotter, while radiation on the opposite side of the sky is redshifted and...
  • Astronomy Picture of the Day -- New York to London Milky Way

    06/14/2014 5:23:26 AM PDT · by SunkenCiv · 12 replies
    NASA ^ | June 14, 2014 | (see photo credit)
    Explanation: Bright stars of Sagittarius and the center of our Milky Way Galaxy lie just off the wing of a Boeing 747 in this astronomical travel photo. The stratospheric scene was captured earlier this month during a flight from New York to London, 11,0000 meters above the Atlantic Ocean. Of course the sky was clear and dark at that altitude, ideal conditions for astronomical imaging. But there were challenges to overcome while looking out a passenger window of the aircraft moving at nearly 1,000 kilometers per hour (600 mph). Over 90 exposures of 30 seconds or less were attempted with...
  • Astronomy Picture of the Day -- A Strawberry Moon

    06/13/2014 3:54:00 AM PDT · by SunkenCiv · 6 replies
    NASA ^ | June 13, 2014 | (see photo credit)
    Explanation: June's Full Moon (full phase on June 13, 0411 UT) is traditionally known as the Strawberry Moon or Rose Moon. Of course those names might also describe the appearance of this Full Moon, rising last month over the small Swedish village of Marieby. The Moon looks large in the image because the scene was captured with a long focal length lens from a place about 8 kilometers from the foreground houses. But just by eye a Full Moon rising, even on Friday the 13th, will appear to loom impossibly large near the horizon. That effect has long been recognized...
  • Astronomy Picture of the Day -- The Tarantula Zone

    06/12/2014 4:06:01 PM PDT · by SunkenCiv · 2 replies
    NASA ^ | June 12, 2014 | (see photo credit)
    Explanation: The Tarantula Nebula is more than 1,000 light-years in diameter, a giant star forming region within our neighboring galaxy the Large Magellanic Cloud (LMC). That cosmic arachnid lies toward the upper left in this deep and colorful telescopic view made through broad-band and narrow-band filters. The image spans nearly 2 degrees (4 full moons) on the sky and covers a part of the LMC over 8,000 light-years across. Within the Tarantula (NGC 2070), intense radiation, stellar winds and supernova shocks from the central young cluster of massive stars, cataloged as R136, energize the nebular glow and shape the spidery...
  • Astronomy Picture of the Day -- Three Galaxies over New Zealand

    06/12/2014 4:03:25 PM PDT · by SunkenCiv · 3 replies
    NASA ^ | June 11, 2014 | (see photo credit)
    Explanation: No, radio dishes cannot broadcast galaxies. Although they can detect them, the above image features a photogenic superposition during a dark night in New Zealand about two weeks ago. As pictured above, the central part of our Milky Way Galaxy is seen rising to the east on the image left and arching high overhead. Beneath the Galactic arc and just above the horizon are the two brightest satellite galaxies of our Milky Way, with the Small Magellanic Cloud to the left and the Large Magellanic Cloud on the right. The radio dish is the Warkworth Satellite Station located just...
  • Astronomy Picture of the Day -- M51: X-Rays from the Whirlpool

    06/10/2014 1:56:23 PM PDT · by SunkenCiv · 16 replies
    NASA ^ | June 10, 2014 | (see photo credit)
    Explanation: What if we X-rayed an entire spiral galaxy? This was done (again) recently by NASA's Chandra X-ray Observatory for the nearby interacting galaxies known as the Whirlpool (M51). Hundreds of glittering x-ray stars are present in the above Chandra image of the spiral and its neighbor. The image is a conglomerate of X-ray light from Chandra and visible light from the Hubble Space Telescope. The number of luminous x-ray sources, likely neutron star and black hole binary systems within the confines of M51, is unusually high for normal spiral or elliptical galaxies and suggests this cosmic whirlpool has experienced...
  • Astronomy Picture of the Day -- How to Identify that Light in the Sky

    06/10/2014 1:54:16 PM PDT · by SunkenCiv · 16 replies
    NASA ^ | June 09, 2014 | (see photo credit)
    Explanation: What is that light in the sky? Perhaps one of humanity's more common questions, an answer may result from a few quick observations. For example -- is it moving or blinking? If so, and if you live near a city, the answer is typically an airplane, since planes are so numerous and so few stars and satellites are bright enough to be seen over the din of artificial city lights. If not, and if you live far from a city, that bright light is likely a planet such as Venus or Mars -- the former of which is constrained...
  • Astronomy Picture of the Day -- Open Cluster NGC 290: A Stellar Jewel Box

    06/08/2014 6:51:38 AM PDT · by SunkenCiv · 4 replies
    NASA ^ | June 08, 2014 | (see photo credit)
    Explanation: Jewels don't shine this bright -- only stars do. Like gems in a jewel box, though, the stars of open cluster NGC 290 glitter in a beautiful display of brightness and color. The photogenic cluster, pictured above, was captured recently by the orbiting Hubble Space Telescope. Open clusters of stars are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters of stars. NGC 290 lies about 200,000 light-years distant in a neighboring galaxy called the Small Cloud of Magellan (SMC). The open cluster contains hundreds of stars and spans about 65...