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Astronomy Picture of the Day (General/Chat)

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  • APOD: The Cone Nebula from Hubble

    03/15/2017 8:19:34 AM PDT · by Purdue77 · 4 replies
    Astronomy Picture of the Day ^ | 15 March 2017 | Hubble Legacy Archive, NASA, ESA
    Explanation: Stars are forming in the gigantic dust pillar called the Cone Nebula. Cones, pillars, and majestic flowing shapes abound in stellar nurseries where natal clouds of gas and dust are buffeted by energetic winds from newborn stars. The Cone Nebula, a well-known example, lies within the bright galactic star-forming region NGC 2264. The Cone was captured in unprecedented detail in this close-up composite of several observations from the Earth-orbiting Hubble Space Telescope. While the Cone Nebula, about 2,500 light-years away in Monoceros, is around 7 light-years long, the region pictured here surrounding the cone's blunted head is a mere...
  • Sand dunes but no beach; a Martian breeze

    03/13/2017 9:28:11 PM PDT · by Rabin · 17 replies
    oilpro ^ | 22 hours ago | Brian Ricketts
    Despite the obvious similarities between Martian and Terrestrial dunes, one in-depth analysis has led a couple of researchers (Gary Kocurek and Ryan Ewing, see below) to suggest that there are also important differences.
  • Stray Black Hole Turned Cosmic Gas Cloud into Speeding 'Bullet'

    02/12/2017 10:30:51 AM PST · by ETL · 89 replies
    Space.com ^ | February 8, 2017 | Samantha Mathewson, Space.com Contributor
    A stray black hole may be responsible for turning a gas cloud into a speeding cosmic bullet trillions of miles long. The wandering black hole was discovered lurking just outside a supernova remnant, a shell of expelled material left behind after a massive star explodes. Using the Atacama Submillimeter Telescope Experiment (ASTE) in Chile and the 45-meter (148 feet) Radio Telescope at Nobeyama Radio Observatory, astronomers found that the black hole had been previously hidden by a compact gas cloud emerging from the remnant. The cloud itself has now been named "the Bullet," because of its long, cone shape and...
  • Astronomy Picture of the Day -- Aurorae on Jupiter

    07/10/2016 10:19:57 PM PDT · by SunkenCiv · 16 replies
    NASA ^ | Monday, July 11, 2016 | (see photo credit)
    Explanation: Jupiter has aurorae. Like Earth, the magnetic field of the gas giant funnels charged particles released from the Sun onto the poles. As these particles strike the atmosphere, electrons are temporarily knocked away from existing gas molecules. Electric force attracts these electrons back. As the electrons recombine to remake neutral molecules, auroral light is emitted. In the featured recently released composite image by the Hubble Space Telescope taken in ultraviolet light, the aurorae appear as annular sheets around the pole. Unlike Earth's aurorae, Jupiter's aurorae include several bright streaks and dots. Jupiter's Great Red Spot is visible on the...
  • Astronomy Picture of the Day -- Moon Meets Jupiter

    07/10/2016 5:36:14 AM PDT · by SunkenCiv · 9 replies
    NASA ^ | Sunday, July 10, 2016 | (see photo credit)
    Explanation: What's that next to the Moon? Jupiter -- and its four largest moons. Skygazers around planet Earth enjoyed the close encounter of planets and Moon in 2012 July 15's predawn skies. And while many saw bright Jupiter next to the slender, waning crescent, Europeans also had the opportunity to watch the ruling gas giant pass behind the lunar disk, occulted by the Moon as it slid through the night. Clouds threaten in this telescopic view from Montecassiano, Italy, but the frame still captures Jupiter after it emerged from the occultation along with all four of its large Galilean moons....
  • Astronomy Picture of the Day -- Noctilucent Clouds Tour France

    07/09/2016 10:05:29 AM PDT · by SunkenCiv · 2 replies
    NASA ^ | Saturday, July 09, 2016 | (see photo credit)
    Explanation: Bright noctilucent or night shining clouds are not familiar sights from northern France. But these electric-blue waves coursed through skies over the small town of Wancourt in Pas-de-Calais on July 6, just before the dawn. From the edge of space, about 80 kilometers above Earth's surface, the icy clouds still reflect sunlight even though the Sun itself is below the horizon as seen from the ground. Usually spotted at high latitudes in summer months the diaphanous apparitions are also known as polar mesospheric clouds. The seasonal clouds are understood to form as water vapor driven into the cold upper...
  • Astronomy Picture of the Day -- The Swirling Core of the Crab Nebula

    07/07/2016 10:04:25 PM PDT · by SunkenCiv · 11 replies
    NASA ^ | Friday, July 08, 2016 | (see photo credit)
    Explanation: At the core of the Crab Nebula lies a city-sized, magnetized neutron star spinning 30 times a second. Known as the Crab Pulsar, it's actually the rightmost of two bright stars, just below a central swirl in this stunning Hubble snapshot of the nebula's core. Some three light-years across, the spectacular picture frames the glowing gas, cavities and swirling filaments bathed in an eerie blue light. The blue glow is visible radiation given off by electrons spiraling in a strong magnetic field at nearly the speed of light. Like a cosmic dynamo the pulsar powers the emission from the...
  • Astronomy Picture of the Day -- The Altiplano Night

    07/07/2016 7:14:08 AM PDT · by SunkenCiv · 7 replies
    NASA ^ | Thursday, July 07, 2016 | (see photo credit)
    Explanation: The Milky Way is massively bright on this cold, clear, altiplano night. At 4,500 meters its reflection in a river, a volcanic peak on the distant horizon, is captured in this stitched panorama under naturally dark skies of the northern Chilean highlands near San Pedro de Atacama. Along the Solar System's ecliptic plane, the band of Zodiacal light also stands out, extending above the Milky Way toward the upper left. In the scene from late April, brilliant Mars, Saturn, and Antares form a bright celestial triangle where ecliptic meets the center of the Milky Way. Left of the triangle,...
  • Astronomy Picture of the Day -- Arp 286: Trio in Virgo

    07/06/2016 6:12:48 AM PDT · by SunkenCiv · 4 replies
    NASA ^ | Wednesday, July 06, 2016 | (see photo credit)
    Explanation: A remarkable telescopic composition in yellow and blue, this scene features a trio of interacting galaxies almost 90 million light-years away, toward the constellation Virgo. On the right, two, spiky, foreground Milky Way stars echo the trio galaxy hues, a reminder that stars in our own galaxy are like those in the distant island universes. With sweeping spiral arms and obscuring dust lanes, NGC 5566 is enormous, about 150,000 light-years across. Just above it lies small, blue NGC 5569. Near center, the third galaxy, NGC 5560, is multicolored and apparently stretched and distorted by its interaction with NGC 5566....
  • Astronomy Picture of the Day -- The Colorful Clouds of Rho Ophiuchi

    07/05/2016 3:30:17 AM PDT · by SunkenCiv · 7 replies
    NASA ^ | Tuesday, July 05, 2016 | (see photo credit)
    Explanation: The many spectacular colors of the Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star Rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light. The Earth's daytime sky appears blue for the same reason. The red and yellow regions shine primarily because of emission from the nebula's atomic and molecular gas. Light from nearby blue stars - more energetic than the bright star Antares - knocks electrons away from the gas, which then shines when the...
  • Astronomy Picture of the Day -- IC 4628: The Prawn Nebula

    07/05/2016 3:26:33 AM PDT · by SunkenCiv · 1 replies
    NASA ^ | Monday, July 04, 2016 | (see photo credit)
    Explanation: 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, radiate 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 an area equivalent to four full moons on the sky. The nebula is also cataloged as Gum 56 for Australian astronomer Colin Stanley Gum, but seafood-loving astronomers might...
  • Astronomy Picture of the Day -- The Cat's Eye Nebula

    07/03/2016 9:56:07 AM PDT · by SunkenCiv · 6 replies
    NASA ^ | Sunday, July 03, 2016 | (see photo credit)
    Explanation: Three thousand light-years away, a dying star throws off shells of glowing gas. This image from the Hubble Space Telescope reveals the Cat's Eye Nebula to be one of the most complex planetary nebulae known. In fact, the features seen in the Cat's Eye are so complex that astronomers suspect the bright central object may actually be a binary star system. The term planetary nebula, used to describe this general class of objects, is misleading. Although these objects may appear round and planet-like in small telescopes, high resolution images reveal them to be stars surrounded by cocoons of gas...
  • Astronomy Picture of the Day -- Firefly Trails and the Summer Milky Way

    07/01/2016 10:17:21 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | Saturday, July 02, 2016 | (see photo credit)
    Explanation: A camera fixed low to a tripod on a northern summer's eve captured the series of images used in this serene, southern Ontario skyscape. The lakeside view frames our fair galaxy above calm water and the night's quintessential luminous apparitions. But the trails of light are neither satellite glint, nor meteor flash, nor auroral glow. In the wide-field composite constructed with four consecutive 15 second exposures, a pulsing firefly enters at the right, first wandering toward the camera, then left and back toward the lake, the central Milky Way rising in the background.
  • Astronomy Picture of the Day -- Juno Approaching Jupiter

    07/01/2016 11:33:14 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | Friday, July 01, 2016 | (see photo credit)
    Explanation: Approaching over the north pole after nearly a five-year journey, Juno enjoys a perspective on Jupiter not often seen, even by spacecraft from Earth that usually swing by closer to Jupiter's equator. Looking down toward the ruling gas giant from a distance of 10.9 million kilometers, the spacecraft's JunoCam captured this image with Jupiter's nightside and orbiting entourage of four large Galilean moons on June 21. JunoCam is intended to provide close-up views of the gas giant's cloudy zoned and belted atmosphere. On July 4 (July 5 UT) Juno is set to burn its main engine to slow down...
  • Astronomy Picture of the Day -- The New World Atlas of Artificial Sky Brightness

    06/29/2016 11:03:43 PM PDT · by SunkenCiv · 15 replies
    NASA ^ | Thursday, June 30, 2016 | (see photo credit)
    Explanation: How far are you from a naturally dark night sky? In increasing steps, this world map (medium | large) shows the effect of artificial night sky brightness on the visual appearance of the night sky. The brightness was modeled using high resolution satellite data and fit to thousands of night sky brightness measurements in recent work. Color-coded levels are compared to the natural sky brightness level for your location. For example, artificial sky brightness levels in yellow alter the natural appearance of the night sky. In red they hide the Milky Way in an artificial luminous fog. The results...
  • Astronomy Picture of the Day -- From Alpha to Omega in Crete

    06/29/2016 7:39:42 AM PDT · by SunkenCiv · 7 replies
    NASA ^ | Wednesday, June 29, 2016 | (see photo credit)
    Explanation: This beautiful telephoto composition spans light-years in a natural night skyscape from the island of Crete. Looking south, exposures both track the stars and record a fixed foreground in three merged panels that cover a 10x12 degree wide field of view. The May 15 waxing gibbous moonlight illuminates the church and mountainous terrain. A mere 18 thousand light-years away, huge globular star cluster Omega Centauri (NGC 5139) shining above gives a good visual impression of its appearance in binoculars on that starry night. Active galaxy Centaurus A (NGC 5128) is near the top of the frame, some 11 million...
  • Astronomy Picture of the Day -- Juno Mission Trailer

    06/28/2016 10:45:32 AM PDT · by SunkenCiv · 8 replies
    NASA ^ | Tuesday, June 28, 2016 | (see photo credit)
    Explanation: What will NASA's Juno spacecraft find when it reaches Jupiter next Monday? Very little, if Juno does not survive Jupiter Orbit Insertion, a complex series of operations in an unknown environment just above Jupiter's cloud tops. If successful, as explained in the featured video, Juno will swoop around Jupiter, passing closer than any previous spacecraft. The goal is to decelerate, enter into a highly elliptical orbit, and begin two years of science operations. Juno's science mission objectives include mapping Jupiter's deep structure, determining how much water is in Jupiter's atmosphere, and exploring Jupiter's powerful magnetic field and how it...
  • Astronomy Picture of the Day -- Anticrepuscular Rays over Colorado (II)

    06/28/2016 10:40:43 AM PDT · by SunkenCiv · 10 replies
    NASA ^ | Monday, June 27, 2016 | (see photo credit)
    Explanation: What's happening over the horizon? Although the scene may appear somehow supernatural, nothing more unusual is occurring than a setting Sun and some well placed clouds. Pictured above are anticrepuscular rays. To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds. Now although sunlight indeed travels along straight lines, the projections of these lines onto the spherical sky are great circles. Therefore, the crepuscular rays from a setting (or rising) sun will appear to re-converge on the other side of the sky. At the anti-solar point 180 degrees around...
  • Astronomy Picture of the Day -- Jupiter's Clouds from New Horizons

    06/26/2016 10:54:07 AM PDT · by SunkenCiv · 12 replies
    NASA ^ | Sunday, June 26, 2016 | (see photo credit)
    Explanation: The New Horizons spacecraft took some stunning images of Jupiter on its way out to Pluto. Famous for its Great Red Spot, Jupiter is also known for its regular, equatorial cloud bands, visible through even modest sized telescopes. The featured image, horizontally compressed, was taken in 2007 near Jupiter's terminator and shows the Jovian giant's wide diversity of cloud patterns. On the far left are clouds closest to Jupiter's South Pole. Here turbulent whirlpools and swirls are seen in a dark region, dubbed a belt, that rings the planet. Even light colored regions, called zones, show tremendous structure, complete...
  • Astronomy Picture of the Day -- Strawberry to Honey Moonrise [Popsicle stick]

    06/25/2016 4:43:25 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | Saturday, June 25, 2016 | (see photo credit)
    Explanation: Near the horizon the Full Moon often seems to loom large, swollen in appearance by the famous Moon illusion. But timelapse images demonstrate that the Moon's apparent size doesn't really change as it climbs toward the zenith. Its color does, though. Recording a frame every 10 seconds, this image shows how dramatic that color change can be. The composite follows a solstice Full Moon climbing above a rugged horizon over northwestern Indiana. A shrinking line-of-sight through planet Earth's dense and dusty atmosphere shifted the moonlight from strawberry red through honey-colored and paler yellowish hues. That change seems appropriate for...