Author Topic: APOD (Astronomy Picture of the Day)  (Read 87421 times)

Offline Sverre

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Quote from: Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

In my opinion, apod.nasa.gov is one of the best sites on the Internet. Some of you may be familiar with it already, but I thought these amazing pictures could lay the foundation for an interesting topic...

Michele and I will try to keep the topic updated every day, and if you want to discuss or comment on the pictures, that's of course perfectly fine :)

Here's today's entry:

2012 February 25 - Stephan's Quintet



Image Data: Hubble Legacy Archive, ESA, NASA; Processing: Al Kelly

Explanation: The first identified compact galaxy group, Stephan's Quintet is featured in this eye-catching image constructed with data drawn from the extensive Hubble Legacy Archive. About 300 million light-years away, only four of these five galaxies are actually locked in a cosmic dance of repeated close encounters. The odd man out is easy to spot, though. The interacting galaxies, NGC 7319, 7318A, 7318B, and 7317 have an overall yellowish cast. They also tend to have distorted loops and tails, grown under the influence of disruptive gravitational tides. But the predominantly bluish galaxy, NGC 7320, is closer, just 40 million light-years distant, and isn't part of the interacting group. Stephan's Quintet lies within the boundaries of the high flying constellation Pegasus. At the estimated distance of the quartet of interacting galaxies, this field of view spans about 500,000 light-years. However, moving just beyond this field, above and to the left, astronomers can identify another galaxy, NGC 7320C, that is also 300 million light-years distant. Of course, including it would bring the interacting quartet back up to quintet status.
« Last Edit: March 25, 2012, 02:16:23 PM by Sverre »

Offline Velvet Revolver

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Remember when you were young and would look for the stars to make shapes or still do?  I see a sitting cat.   :)

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Offline Trist805#2

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Remember when you were young and would look for the stars to make shapes or still do?  I see a sitting cat.   :)

haha I see it with the blue pointy ears, and you can kind of see it's face too.  I might have to start calling you "catwoman".  :lol:  Also the first part of your post made me think of Pink Floyd's Shine On...  "remember when youuuu were young...you shone like the sun!"
« Last Edit: February 25, 2012, 07:41:18 PM by Trist805#2 »

Offline Velvet Revolver

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Wouldn't be the first time I was called that.   :lol:

Now I want to listen to Pink Floyd.

Offline Velvet Revolver

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Preview of a Forthcoming Supernova
NASA's Hubble Telescope captured an image of Eta Carinae. This image consists of ultraviolet and visible light images from the High Resolution Channel of Hubble's Advanced Camera for Surveys. The field of view is approximately 30 arcseconds across.

The larger of the two stars in the Eta Carinae system is a huge and unstable star that is nearing the end of its life, and the event that the 19th century astronomers observed was a stellar near-death experience. Scientists call these outbursts supernova impostor events, because they appear similar to supernovae but stop just short of destroying their star.

Although 19th century astronomers did not have telescopes powerful enough to see the 1843 outburst in detail, its effects can be studied today. The huge clouds of matter thrown out a century and a half ago, known as the Homunculus Nebula, have been a regular target for Hubble since its launch in 1990. This image, taken with the Advanced Camera for Surveys High Resolution Channel, is the most detailed yet, and shows how the material from the star was not thrown out in a uniform manner, but forms a huge dumbbell shape.

Eta Carinae is one of the closest stars to Earth that is likely to explode in a supernova in the relatively near future (though in astronomical timescales the "near future" could still be a million years away). When it does, expect an impressive view from Earth, far brighter still than its last outburst: SN 2006gy, the brightest supernova ever observed, came from a star of the same type, though from a galaxy over 200 million light-years away.

Image Credit: ESA/NASA


I found this at the NASA site and included it...onto the real APOD
« Last Edit: February 26, 2012, 08:12:47 AM by Sverre »

Offline Velvet Revolver

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2012 February 26 - The Mysterious Rings of Supernova 1987A



Image Credit: ESA/Hubble, NASA

Explanation: What's causing those odd rings in supernova 1987A? Twenty five years ago, in 1987, the brightest supernova in recent history was seen in the Large Magellanic Clouds. At the center of the above picture is an object central to the remains of the violent stellar explosion. Surrounding the center are curious outer rings appearing as a flattened figure 8. Although large telescopes including the Hubble Space Telescope monitor the curious rings every few years, their origin remains a mystery. Pictured above is a Hubble image of the SN1987A remnant taken last year. Speculation into the cause of the rings includes beamed jets emanating from an otherwise hidden neutron star left over from the supernova, and the interaction of the wind from the progenitor star with gas released before the explosion.
« Last Edit: February 26, 2012, 08:09:23 AM by Sverre »

Offline Sverre

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2012 February 27 - Shocked by Supernova 1987A



mage Credit: Hubble Space Telescope, NASA, ESA;  Video compilation:  Mark McDonald

Explanation:  Twenty five years ago, the brightest supernova of modern times was sighted. Over time, astronomers have watched and waited for the expanding debris from this tremendous stellar explosion to crash into previously expelled material. A clear result of such a collision is demonstrated in the above time lapse video of images recorded by the Hubble Space Telescope between 1994 and 2009. The movie depicts the collision of an outward moving blast wave with the pre-existing, light-year wide ring. The collision occurred at speeds near 60 million kilometers per hour and shock-heats the ring material causing it to glow. Astronomers continue to study the collision as it illuminates the interesting past of SN 1987A, and provides clues to the origin of the mysterious rings.

Offline Sverre

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2012 February 28 - The Opposing Tails of Comet Garradd



Image Credit & Copyright: Robert Pölzl

Explanation: Why does Comet Garradd have two tails? Visible on the left, Comet Garradd's dust tail is composed of ice and dust bits that trial the comet in its orbit around the Sun. Visible on the right, Comet Garradd's ion tail, is composed of ionized gas blown directly out from the Sun by the solar wind. Most comets show two tails, although it is unusual for them to appear to point in nearly opposite directions. Comet Garradd is currently showing opposing tails because of the Earth's opportunistic intermediate viewing angle. Subtle hues in the above image captured last week show the dust tail as slightly yellow as its large grains reflecting sunlight achromatically, while the ion tail shines slightly blue as the carbon monoxide ions reflect blue sunlight more efficiently. In the center, surrounding the comet's nucleus, is the green-tinted coma, so colored as it is a mix of dust and gasses that include green-emitting cyanogen. Although now drifting out from the Sun, Comet Garradd will make its closest approach to the Earth next week.

Offline Sverre

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2012 February 29 - Moon and Planets Over Catalonia



Image Credit & Copyright: Juan Carlos Casado (TWAN)

Explanation:  Venus and Jupiter will appear unusually close in the sky over the next month. The planetary conjunction will be easily visible to the unaided eye because Venus will appear brighter than any background star, and Jupiter will be nearly as bright. To see the near-alignment, simply look to the west after sunset. At their closest, on March 15, the two planets will appear only about three degrees apart. The planets will not be significantly closer in space - Venus will just be passing nearly in front of Jupiter as seen from the Earth. In the above image composite taken late last week from Catalonia, Spain, a bright crescent moon appears to the right of Venus, while Jupiter appears near the top of the image. The distant sun-illuminated spheres were photographed behind a sculpture depicting the legendary battle between a warrior and a dragon. A gallery of conjunction images is visible on the Asterisk -- APOD's discussion board. Please feel free to contribute. The next Jupiter-Venus conjunction will occur in May 2013.

Offline Velvet Revolver

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Image Credit & Copyright: Sean Walker (SkyandTelescope.com, MASIL Astro-Imaging)
Explanation: Brilliant Venus now shines in western skies at twilight. Seen as the prominent evening star, the planet is a tantalizing celestial beacon even for casual skygazers. Venus can offer less than satisfying telescopic views though. The planet is shrouded in reflective clouds that appear bright but featureless at the eyepiece. Still, careful imaging with a series of color filters, as used in these composite images, can reveal subtle cloud patterns. Captured early last month from a backyard observatory in Manchester, New Hampshire, USA, the images are based on video camera frames. The data was recorded through near-ultraviolet, green, and near-infrared filters (left), and red, green, and blue filters while Venus stood high above the western horizon just before sunset. This season's evening apparition of Venus is the best one for northern hemisphere observers in 7 years. It will ultimately end with a solar transit of the planet, the last one to occur in your lifetime, on June 5/6.

Offline Sverre

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2012 March 02 - Jupiter Unplugged



Drawing Credit & Copyright: Frédéric Burgeot

Explanation: Five hand drawn sketches of Jupiter were used to create this beautifully detailed flat map of the ruling gas giant's turbulent cloud tops. Made with colored pencils at the eyepiece of a 16 inch diameter telescope, the original drawings are about 5 inches (12.5 cm) in diameter. The drawn planisphere map dimensions are 16x8 inches (40x20 cm). Observing on different dates in November and December of 2011, astronomical artist Fred Burgeot has relied on Jupiter's rotation to cover the planet's complete circumference. Digital animator Pascal Chauvet has also translated Burgeot's drawings into an intriguing video (vimeo), synthesizing a telescopic view of the rotating planet with a tilt and phase appropriate for the observing dates. The video includes the Galilean moons moving along their orbits, beginning with Ganymede and Io casting shadows as they glide in front of Jupiter, followed by Europa and Callisto passing behind the planet's banded disk.

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Another Tail for Comet Garradd
Image Credit & Copyright: Olivier Sedan (Sirene Observatory)
Explanation: Remarkable comet Garradd (C2009/P1) has come to be known for two distinctive tails. From the perspective of earthbound comet watchers the tails are visible on opposite sides of its greenish coma. Seen here in a telescopic view, the recognizable dust tail fans out to the right, trailing the comet nucleus in its orbit. Streaming away from the sunward direction, a familiar bluish ion tail sweeps to the left. But the comet also seems to have, at least temporarily, sprouted a second ion tail recorded in this image from February 24. Other comet imagers have recently captured changing structures in Garradd's ion tail created as the plasma is buffeted by the magnetic fields in the solar wind. Now moving more quickly through northern skies, on March 5th comet Garradd will reach its closest approach to planet Earth, about 10.5 light-minutes distant.


Offline Sverre

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2012 March 04 - Warped Spiral Galaxy ESO 510 13



Image Credit: Hubble Heritage Team (STScI/AURA), C. Conselice (U. Wisconsin/STScI) et al., NASA

Explanation: How did spiral galaxy ESO 510-13 get bent out of shape? The disks of many spirals are thin and flat, but not solid. Spiral disks are loose conglomerations of billions of stars and diffuse gas all gravitationally orbiting a galaxy center. A flat disk is thought to be created by sticky collisions of large gas clouds early in the galaxy's formation. Warped disks are not uncommon, though, and even our own Milky Way Galaxy is thought to have a small warp. The causes of spiral warps are still being investigated, but some warps are thought to result from interactions or even collisions between galaxies. ESO 510-13, pictured above digitally sharpened, is about 150 million light years away and about 100,000 light years across.

Offline Sverre

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2012 March 05 - Flying Over the Earth at Night



Video Credit: Gateway to Astronaut Photography, NASA
Compilation: Bitmeizer (YouTube)
Music: Freedom Fighters (Two Steps from Hell)

Explanation: Many wonders are visible when flying over the Earth at night. A compilation of such visual spectacles was captured recently from the International Space Station (ISS) and set to rousing music. Passing below are white clouds, orange city lights, lightning flashes in thunderstorms, and dark blue seas. On the horizon is the golden haze of Earth's thin atmosphere, frequently decorated by dancing auroras as the video progresses. The green parts of auroras typically remain below the space station, but the station flies right through the red and purple auroral peaks. Solar panels of the ISS are seen around the frame edges. The ominous wave of approaching brightness at the end of each sequence is just the dawn of the sunlit half of Earth, a dawn that occurs every 90 minutes.

Quiz: Can you identify any of the landscapes?
« Last Edit: March 07, 2012, 09:01:06 AM by Sverre »

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NGC 2170: Celestial Still Life
Image Credit & Copyright: Leonardo Julio & Carlos Milovic (Astronomia Pampeana)
Explanation: Is this a painting or a photograph? In this beautiful celestial still life composed with a cosmic brush, dusty nebula NGC 2170 shines near the image center. Reflecting the light of nearby hot stars, NGC 2170 is joined by other bluish reflection nebulae, a red emission region, many dark absorption nebulae, and a backdrop of colorful stars. Like the common household items still life painters often choose for their subjects, the clouds of gas, dust, and hot stars pictured above are also commonly found in this setting - a massive, star-forming molecular cloud in the constellation of the Unicorn (Monoceros). The giant molecular cloud, Mon R2, is impressively close, estimated to be only 2,400 light-years or so away. At that distance, this canvas would be over 60 light-years across.

Offline Trist805#2

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Sverre, I love looking at the stars with you.  It's so romantic!  :smitten:

Offline Sverre

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Is this a painting or a photograph?

Could have fooled me!

It's so romantic!

Definitely not what I was aiming for...

Offline Sverre

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2012 March 07 - Conjunction Over Reunion Island



Image Credit & Copyright: Luc Perrot

Explanation: You don't have to be on Reunion Island to see this week's planetary conjunction. Only if you want to see this picturesque seascape as well. To see the conjunction from just about anywhere in the world, look to the west after sunset. The first planet you may notice is Venus, the brightest object in the western sky. Above Venus, the second brightest object is Jupiter. The hardest planet to spot is Mercury, which is visible only briefly after sunset as a faint dot just above the horizon. Picturesque rocks leading out from Reunion Island to the Indian Ocean populate the foreground of the above picture. Taken last week, the distant planets Venus and Jupiter were joined by a bright crescent Moon, which has now moved away.

Offline Trist805#2

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I just had a Stargasm!  (that is actually a song from Mastodon's latest album)  been wanting to say that for a while lol

I actually have a little "sum-thin, sum-thin" for this thread later.  It is some home footage I took of a recent event in the sky.  I just have it on a DVD I made but I'm gonna try to get a good picture of it, once I can borrow an iphone.  :o
« Last Edit: March 07, 2012, 11:05:24 PM by Trist805#2 »

Offline Velvet Revolver

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The Seagull Nebula
Image Credit & Copyright: Harel Boren
Explanation: A broad expanse of glowing gas and dust presents a bird-like visage to astronomers from planet Earth, suggesting its popular moniker - The Seagull Nebula. This portrait of the cosmic bird covers a 1.6 degree wide swath across the plane of the Milky Way, near the direction of Sirius, alpha star of the constellation Canis Major. Of course, the region includes objects with other catalog designations: notably NGC 2327, a compact, dusty emission region with an embedded massive star that forms the bird's head (aka the Parrot Nebula, above center). IC 2177 forms the sweeping arc of the seagull's wings. Dominated by the reddish glow of atomic hydrogen, the complex of gas and dust clouds with bright young stars spans over 100 light-years at an estimated 3,800 light-year distance.


Tomorrow's picture: northern trifid

Offline Sverre

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2012 March 09 - NGC 1579: Trifid of the North



Image Credit & Copyright: Adam Block, Mt. Lemmon SkyCenter, University of Arizona

Explanation: Colorful NGC 1579 resembles the better known Trifid Nebula, but lies much farther north in planet Earth's sky, in the heroic constellation Perseus. About 2,100 light-years away and 3 light-years across, NGC 1579 is, like the Trifid, a study in contrasting blue and red colors, with dark dust lanes prominent in the nebula's central regions. In both, dust reflects starlight to produce beautiful blue reflection nebulae. But unlike the Trifid, in NGC 1579 the reddish glow is not emission from clouds of glowing hydrogen gas excited by ultraviolet light from a nearby hot star. Instead, the dust in NGC 1579 drastically diminishes, reddens, and scatters the light from an embedded, extremely young, massive star, itself a strong emitter of the characteristic red hydrogen alpha light.

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Offline Trist805#2

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My favorite constellation was always "The Little Dipper"  only found it twice in my life.  Both very personal!!!

Offline Captain Tophat

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My favorite constellation was always "The Little Dipper"  only found it twice in my life.  Both very personal!!!

Really? You oughta come out this direction; can see it every night that isn't cloudy. I can find some of the major constellations pretty much every night; Big and Little Dipper, Orion etc.

Sverre, on a semi-related note, do you check out Luc Perrot's photos often? He's one of my favourite photographers. His pictures are stunning. I don't have the online accounts to be able to post pictures anymore, but his website is here.