Space
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The Matter of the Bullet Cluster
What's the matter with the Bullet Cluster? This massive cluster of galaxies (1E 0657-558) creates gravitational lens distortions of background galaxies in a way that has been interpreted as strong evidence for the leading theory: that dark matter exists within. Different recent analyses, though, indicate that a less popular alternative -- modifying gravity-- could explain cluster dynamics without dark matter, and provide a more likely progenitor scenario as well.
Currently, the two scientific hypotheses are competing to explain the observations: it's invisible matter versus amended gravity. The duel is dramatic as a clear Bullet-proof example of dark matter would shatter the simplicity of modified gravity theories. For the near future, the battle over the Bullet cluster is likely to continue as new observations, computer simulations, and analyses are completed.
The featured image is a Hubble/Chandra/Magellan composite with red depicting the X-rays emitted by hot gas, and blue depicting the suggested separated dark matter distribution.
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A Rainbow Geminid Meteor
Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured is a Geminid captured by camera during last week's meteor shower that was not only impressively bright, but colorful. The radiant grit cast off by asteroid 3200 Phaethon blazed a path across Earth's atmosphere longer than 60 times the angular diameter of the Moon.
Colors in meteors usually originate from ionized elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green. Red, however, typically originates from energized nitrogen and oxygen in the Earth's atmosphere. This bright meteoric fireball was gone in a flash -- less than a second -- but it left a wind-blown ionization trail that remained visible for several minutes, the start of which can be seen here.2 -
Red Nebula, Green Comet, Blue Stars
This festively colored skyscape was captured in the early morning hours of December 17, following Comet Wirtanen's closest approach to planet Earth. The comet was just visible to the eye. The lovely green color of its fluorescing cometary atmosphere or coma is brought out here only by adding digital exposures registered on the comet's position below the Pleiades star cluster.
The exposures also bring out blue starlight reflected by the dust clouds surrounding the young Pleiades stars. Gaze (toward the left) across dusty dark nebulae along the edge of the Perseus molecular cloud and you'll travel to emission nebula NGC 1499, also known as the California nebula. Too faint for the eye, the cosmic cloud's pronounced reddish glow is from electrons recombining with ionized hydrogen atoms.
Around December 23rd, Comet Wirtanen should be easy to find with binoculars when it sweeps close to bright star Capella in the northern winter constellation Auriga, the Charioteer.1 -
Extraordinary Solar Halos
Welcome to the December Solstice, the first day of winter in planet Earth's northern hemisphere and summer in the south. To celebrate, consider this extraordinary display of beautiful solar ice halos! More common than rainbows, simple ice halos can be easy to spot, especially if you can shade your eyes from direct sunlight. Still it's extremely rare to see anything close to the complex of halos present in this astounding scene.
Captured at lunchtime on a cold December 14 near Utendal, Sweden the image includes the relatively ordinary 22 degree halo, sundogs (parhelia) and sun pillars. The extensive array of rarer halos has been identified along with previously unknown features. All the patterns are generated as sunlight (or moonlight) is reflected and refracted in flat six-sided water ice crystals in Earth's atmosphere. In this case, likely local contributors to the atmospheric ice crystals are snow making machines operating at at nearby ski center.1 -
A Piercing Celestial Eye Stares Back at Hubble
This dramatic image from the NASA/ESA Hubble Space Telescope shows the planetary nebula NGC 3918.1 -
The Great Carina Nebula
A jewel of the southern sky, the Great Carina Nebula, also known as NGC 3372, spans over 300 light-years, one of our galaxy's largest star forming regions. Like the smaller, more northerly Great Orion Nebula, the Carina Nebula is easily visible to the unaided eye, though at a distance of 7,500 light-years it is some 5 times farther away. This gorgeous telescopic close-up reveals remarkable details of the region's central glowing filaments of interstellar gas and obscuring cosmic dust clouds.
The field of view is over 50 light-years across. The Carina Nebula is home to young, extremely massive stars, including the stars of open cluster Trumpler 14 (above and left of center) and the still enigmatic variable Eta Carinae, a star with well over 100 times the mass of the Sun.
Eta Carinae is the brightest star, centered here just below the dusty Keyhole Nebula (NGC 3324). While Eta Carinae itself maybe on the verge of a supernova explosion, X-ray images indicate that the Great Carina Nebula has been a veritable supernova factory.1 -
NGC 1365: Majestic Island Universe
Barred spiral galaxy NGC 1365 is truly a majestic island universe some 200,000 light-years across. Located a mere 60 million light-years away toward the chemical constellation Fornax, NGC 1365 is a dominant member of the well-studied Fornax galaxy cluster.
This impressively sharp color image shows intense star forming regions at the ends of the bar and along the spiral arms, and details of dust lanes cutting across the galaxy's bright core. At the core lies a supermassive black hole. Astronomers think NGC 1365's prominent bar plays a crucial role in the galaxy's evolution, drawing gas and dust into a star-forming maelstrom and ultimately feeding material into the central black hole.
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"ORANGE SOIL" LUNAR DUST
These tiny, glassy orange spherules originate from a fire-fountain volcano that erupted over 3.8 billion years ago on the moon. Apollo 17 astronauts discovered this "orange soil" on the rim of Shorty Crater in the Taurus Littrow Valley. Magnified 340 times
HADLEY RILLE LUNAR DUST
The Apollo 15 lunar landing site was close to a deep canyon, known as Hadley Rille, which is thought to be a collapsed lava tube. On their way up to Spur Crater on the flank of Mount Hadley Delta in the lunar Apennine Mountain range, astronauts Dave Scott and Jim Irwin spotted several clod-like boulders that contained green material that sparkled in the sunlight. By the time the bag in which they had been placed was opened back on Earth, the boulders had broken into several pieces. Some tiny glass spheres and other fragments were also found in the bottom of the bag. Chemical analysis reveals that the glass is a mixture of silicon, iron, magnesium, and calcium oxide, with only trace amounts of titanium and sodium. It is thought that these spheres, like that in the previous photograph, originated from a fire-fountain volcano that erupted over 3.3 billion years ago. Magnified 105 times
LUNAR DUST FROM THE SEA OF TRANQUILITY
Whether you are walking along a beach, climbing the dunes of a scorched desert, or making a "giant leap for mankind," you are treading on millions of years of geological history. This beautiful gem-like particle found in a sample of lunar dust collected from the Sea of Tranquility, may have started out as a large pyroxene crystal, but along the way it has undergone several fractures, and its internal structure has been modified. The dark vertical lines indicate where one section of the crystal has been sheared with respect to another when a micrometer traveling at a speed close to fifty thousand miles per hour smashed into the lunar surface. Magnified 520 times2 -
The Witch Head Nebula
Double, double toil and trouble; Fire burn, and cauldron bubble .... maybe Macbeth should have consulted the Witch Head Nebula. A frighteningly shaped reflection nebula, this cosmic crone is about 800 light-years away though. Its malevolent visage seems to glare toward nearby bright star Rigel in Orion, just off the right edge of this frame.
More formally known as IC 2118, the interstellar cloud of dust and gas is nearly 70 light-years across, its dust grains reflecting Rigel's starlight. In this composite portrait, the nebula's color is caused not only by the star's intense bluish light but because the dust grains scatter blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers in planet Earth's atmosphere are molecules of nitrogen and oxygen.
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The Orion Nebula in Infrared from WISE
The Great Nebula in Orion is an intriguing place. Visible to the unaided eye, it appears as a small fuzzy patch in the constellation of Orion. But this image, an illusory-color four-panel mosaic taken in different bands of infrared light with the Earth orbiting WISE observatory, shows the Orion Nebula to be a bustling neighborhood of recently formed stars, hot gas, and dark dust.
The power behind much of the Orion Nebula (M42) is the stars of the Trapezium star cluster, seen near the center of the featured image. The orange glow surrounding the bright stars pictured here is their own starlight reflected by intricate dust filaments that cover much of the region. The current Orion Nebula cloud complex, which includes the Horsehead Nebula, will slowly disperse over the next 100,000 years.2 -
The small, icy world known as Ultima Thule has finally been revealed.
A new picture returned from Nasa's New Horizons spacecraft shows it to be two objects joined together - to give a look like a "snowman".
The US probe's images acquired as it approached Ultima hinted at the possibility of a double body, but the first detailed picture from Tuesday's (1-1-2019) close flyby confirms it.
New Horizons encountered Ultima 6.5 billion km from Earth.
The event set a record for the most distant ever exploration of a Solar System object.
The previous mark was also set by New Horizons when it flew past the dwarf planet Pluto in 2015.3 -
The Sombrero Galaxy in Infrared
This floating ring is the size of a galaxy. In fact, it is a galaxy -- or at least part of one: the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies. The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light.
The featured image, digitally sharpened, shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light. The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away.
M104 can be seen with a small telescope in the direction of the constellation Virgo.2 -
Ultima Thule Rotation
Ultima Thule is the most distant world explored by a spacecraft from Earth. In the dim light 6.5 billion kilometers from the Sun, the New Horizons spacecraft captured these two frames 38 minutes apart as it sped toward the Kuiper belt world on January 1 at 51,000 kilometers per hour.
A contact binary, the two lobes of Ultima Thule rotate together once every 15 hours or so. Shown as a blinking gif, the rotation between the frames produces a tantalizing 3D perspective of the most primitive world ever seen. Dubbed separately by the science team Ultima and Thule, the larger lobe Ultima, is about 19 kilometers in diameter. Smaller Thule is 14 kilometers across.2 -
NGC 1365: Majestic Island Universe
Barred spiral galaxy NGC 1365 is truly a majestic island universe some 200,000 light-years across. Located a mere 60 million light-years away toward the chemical constellation Fornax, NGC 1365 is a dominant member of the well-studied Fornax galaxy cluster. This impressively sharp color image shows intense star forming regions at the ends of the bar and along the spiral arms, and details of dust lanes cutting across the galaxy's bright core.
At the core lies a supermassive black hole. Astronomers think NGC 1365's prominent bar plays a crucial role in the galaxy's evolution, drawing gas and dust into a star-forming maelstrom and ultimately feeding material into the central black hole.
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Stars, Meteors, and a Comet in Taurus
This was an unusual night to look in the direction of the Bull. The constellation Taurus is always well known for hosting two bright star clusters -- the Pleaides, visible on the right, and the comparatively diffuse Hyades, visible on the left. This night last month, however, was atypically the peak of the Geminid meteor shower, and so several meteors were caught shooting through the constellation with parallel trails.
More unusually still, Comet Wirtanen was drifting through the constellation, here appearing near the image bottom surrounded by a greenish coma. The comet was near its brightest as it sped past the Earth. The orange star on the upper left is Aldebaran, considered to be the eye of the Bull. Aldebaran is the brightest star in Taurus and the 15th brightest star in the sky.
The featured image is a combination of nearly 800 exposures taken from the Spanish village Albanyà.2 -
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NGC 4676: When Mice Collide
These two mighty galaxies are pulling each other apart. Known as "The Mice" because they have such long tails, each spiral galaxy has likely already passed through the other. They will probably collide again and again until they coalesce. The long tails are created by the relative difference between gravitational pulls on the near and far parts of each galaxy. Because the distances are so large, the cosmic interaction takes place in slow motion -- over hundreds of millions of years.
NGC 4676 lies about 300 million light-years away toward the constellation of Bernice's Hair (Coma Berenices) and are likely members of the Coma Cluster of Galaxies. The above picture was taken with the Hubble Space Telescope's Advanced Camera for Surveys which is more sensitive and images a larger field than previous Hubble cameras. The camera is scheduled to be serviced during the coming flight of Space Shuttle.
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Quadrantids
Named for a forgotten constellation, the Quadrantid Meteor Shower is an annual event for planet Earth's northern hemisphere skygazers It usually peaks briefly in the cold, early morning hours of January 4. The shower's radiant on the sky lies within the old, astronomically obsolete constellation Quadrans Muralis. That position is situated near the boundaries of the modern constellations Hercules, Bootes, and Draco.
About 30 Quadrantid meteors can be counted in this skyscape composed of digital frames recorded in dark and moonless skies between 2:30am and local dawn. The shower's radiant is rising just to the right of the Canary Island of Tenerife's Teide volcano, and just below the familiar stars of the Big Dipper on the northern sky. A likely source of the dust stream that produces Quadrantid meteors was identified in 2003 as an asteroid. Look carefully and you can also spot a small, telltale greenish coma above the volcanic peak and near the top of the frame. That's the 2018 Christmas visitor to planet Earth's skies, Comet Wirtanen.
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Vela Supernova Remnant Mosaic
The plane of our Milky Way Galaxy runs through this complex and beautiful skyscape. Seen toward colorful stars near the northwestern edge of the constellation Vela (the Sails), the 16 degree wide, 200 frame mosaic is centered on the glowing filaments of the Vela Supernova Remnant, the expanding debris cloud from the death explosion of a massive star. Light from the supernova explosion that created the Vela remnant reached Earth about 11,000 years ago.
In addition to the shocked filaments of glowing gas, the cosmic catastrophe also left behind an incredibly dense, rotating stellar core, the Vela Pulsar. Some 800 light-years distant, the Vela remnant is likely embedded in a larger and older supernova remnant, the Gum Nebula. Objects identified in this broad mosaic include emission and reflection nebulae, star clusters, and the remarkable Pencil Nebula.1 -
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NGC 346 in the Small Magellanic Cloud
A satellite galaxy of the Milky Way, the Small Magellanic Cloud (SMC) is a wonder of the southern sky, a mere 210,000 light-years distant in the constellation Tucana. Found among the SMC's clusters and nebulae NGC 346 is a star forming region about 200 light-years across, pictured above by the Hubble Space Telescope. Exploring NGC 346, astronomers have identified a population of embryonic stars strung along the dark, intersecting dust lanes visible here on the right.
Still collapsing within their natal clouds, the stellar infants' light is reddened by the intervening dust. A small, irregular galaxy, the SMC itself represents a type of galaxy more common in the early Universe. But these small galaxies are thought to be a building blocks for the larger galaxies present today. Within the SMC, stellar nurseries like NGC 346 are also thought to be similar to those found in the early Universe.
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JustReadTheInstructions wrote: »Watch the SpaceX launch live for 10 Iridium NEXT satellites at 10:31 EST
https://youtu.be/VshdafZvwrg
ETA: Falcon 9's first stage will attempt to land on my favorite droneship - "Just Read The Instructions"
Thank you.
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JustReadTheInstructions wrote: »Watch the SpaceX launch live for 10 Iridium NEXT satellites at 10:31 ESThttps://youtu.be/VshdafZvwrg
ETA: Falcon 9's first stage will attempt to land on my favorite droneship - "Just Read The Instructions"
25 mins to go. Setting my alarm. 1 -
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And... I just missed it.0
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Yay, my people.0
This discussion has been closed.
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