jueves, 24 de abril de 2014

Today's Astronomy Picture

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.



Lyrids in Southern Skies
Image Credit & Copyright: Yuri Beletsky (Las Campanas Observatory, Carnegie Institution)

Explanation: Earth's annual Lyrid meteor shower peaked before dawn on April 22nd, as our fair planet plowed through dust from the tail of long-period comet Thatcher. Even in the dry and dark Atacama desert along Chile's Pacific coast, light from a last quarter Moon made the night sky bright, washing out fainter meteor streaks. But brighter Lyrid meteors still put on a show. Captured in this composited earth-and-sky view recorded during early morning hours, the meteors stream away from the shower's radiant near Vega, alpha star of the constellation Lyra. The radiant effect is due to perspective as the parallel meteor tracks appear to converge in the distance. Rich starfields and dust clouds of our own Milky Way galaxy stretch across the background.

Tomorrow's picture: pixels in space


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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martes, 22 de abril de 2014

Today's Astronomy Picture

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.



The El Gordo Massive Galaxy Cluster
Image Credit: NASA, ESA, J. Jee (UC Davis) et al.

Explanation: It is bigger than a bread box. In fact, it is much bigger than all bread boxes put together. Galaxy cluster ACT-CL J0102-4915 is one of the largest and most massive objects known. Dubbed "El Gordo", the seven billion light years (z = 0.87) distant galaxy cluster spans about seven million light years and holds the mass of a million billion Suns. The above image of El Gordo is a composite of a visible light image from the Hubble Space Telescope, an X-ray image from the Chandra Observatory showing the hot gas in pink, and a computer generated map showing the most probable distribution of dark matter in blue, computed from gravitational lens distortions of background galaxies. Almost all of the bright spots are galaxies. The blue dark matter distribution indicates that the cluster is in the middle stages of a collision between two large galaxy clusters. A careful inspection of the image will reveal a nearly vertical galaxy that appears unusually long. That galaxy is actually far in the background and has its image stretched by the gravitational lens action of the massive cluster.

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Tomorrow's picture: open space


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.


This is an automated email (pulled from http://antwrp.gsfc.nasa.gov/apod/astropix.html). If you notice any problems, just send me a note gtracy@cs.wisc.edu. If you'd like to remove yourself from the list, please go here.

domingo, 20 de abril de 2014

Today's Astronomy Picture

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.



Ash and Lightning above an Icelandic Volcano
Image Credit & Copyright: Sigurður Stefnisson

Explanation: Why did a picturesque 2010 volcanic eruption in Iceland create so much ash? Although the large ash plume was not unparalleled in its abundance, its location was particularly noticeable because it drifted across such well-populated areas. The Eyjafjallajökull volcano in southern Iceland began erupting on 2010 March 20, with a second eruption starting under the center of a small glacier on 2010 April 14. Neither eruption was unusually powerful. The second eruption, however, melted a large amount of glacial ice which then cooled and fragmented lava into gritty glass particles that were carried up with the rising volcanic plume. Pictured above during the second eruption, lightning bolts illuminate ash pouring out of the Eyjafjallajökull volcano.

Tomorrow's picture: massive galaxy


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.


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viernes, 18 de abril de 2014

Today's Astronomy Picture

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.



Red Moon, Green Beam
Image Credit & Copyright: Dan Long (Apache Point Observatory) - Courtesy: Tom Murphy (UC San Diego)

Explanation: This is not a scene from a sci-fi special effects movie. The green beam of light and red lunar disk are real enough, captured in the early morning hours of April 15. Of course, the reddened lunar disk is easy to explain as the image was taken during this week's total lunar eclipse. Immersed in shadow, the eclipsed Moon reflects the dimmed reddened light of all the sunsets and sunrises filtering around the edges of planet Earth, seen in silhouette from a lunar perspective. But the green beam of light really is a laser. Shot from the 3.5-meter telescope at Apache Point Observatory in southern New Mexico, the beam's path is revealed as Earth's atmosphere scatters some of the intense laser light. The laser's target is the Apollo 15 retroreflector, left on the Moon by the astronauts in 1971. By determining the light travel time delay of the returning laser pulse, the experimental team from UC San Diego is able to measure the Earth-Moon distance to millimeter precision and provide a test of General Relativity, Einstein's theory of gravity. Conducting the lunar laser ranging experiment during a total eclipse uses the Earth like a cosmic light switch. With direct sunlight blocked, the reflector's performance is improved over performance when illuminated by sunlight during a normal Full Moon, an effect fondly known as The Full Moon Curse.

Tomorrow's picture: in the zone


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.


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jueves, 17 de abril de 2014

Today's Astronomy Picture

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.



Waterton Lake Eclipse
Image Credit & Copyright: Yuichi Takasaka / TWAN / www.blue-moon.ca

Explanation: Recorded on April 15th, this total lunar eclipse sequence looks south down icy Waterton Lake from the Waterton Lakes National Park in Alberta, Canada, planet Earth. The most distant horizon includes peaks in Glacier National Park, USA. An exposure every 10 minutes captured the Moon's position and eclipse phase, as it arced, left to right, above the rugged skyline and Waterton town lights. In fact, the sequence effectively measures the roughly 80 minute duration of the total phase of the eclipse. Around 270 BC, the Greek astronomer Aristarchus also measured the duration of lunar eclipses - though probably without the benefit of digital clocks and cameras. Still, using geometry, he devised a simple and impressively accurate way to calculate the Moon's distance, in terms of the radius of planet Earth, from the eclipse duration. This modern eclipse sequence also tracks the successive positions of Mars, above and right of the Moon, bright star Spica next to the reddened lunar disk, and Saturn to the left and below.

Tomorrow's picture: moon beam


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.


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martes, 15 de abril de 2014

Today's Astronomy Picture

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.



Mammatus Clouds over Nebraska
Image Credit & Copyright: Jorn Olsen Photography

Explanation: When do cloud bottoms appear like bubbles? Normally, cloud bottoms are flat. This is because moist warm air that rises and cools will condense into water droplets at a specific temperature, which usually corresponds to a very specific height As water droplets grow, an opaque cloud forms. Under some conditions, however, cloud pockets can develop that contain large droplets of water or ice that fall into clear air as they evaporate. Such pockets may occur in turbulent air near a thunderstorm Resulting mammatus clouds can appear especially dramatic if sunlit from the side. The mammatus clouds pictured above were photographed over Hastings, Nebraska during 2004 June.

Tomorrow's picture: open space


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.


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domingo, 13 de abril de 2014

Today's Astronomy Picture

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.



Saturn in Blue and Gold
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: Why is Saturn partly blue? The above picture of Saturn approximates what a human would see if hovering close to the giant ringed world. The above picture was taken in 2006 March by the robot Cassini spacecraft now orbiting Saturn. Here Saturn's majestic rings appear directly only as a thin vertical line. The rings show their complex structure in the dark shadows they create on the image left. Saturn's fountain moon Enceladus, only about 500 kilometers across, is seen as the bump in the plane of the rings. The northern hemisphere of Saturn can appear partly blue for the same reason that Earth's skies can appear blue -- molecules in the cloudless portions of both planet's atmospheres are better at scattering blue light than red. When looking deep into Saturn's clouds, however, the natural gold hue of Saturn's clouds becomes dominant. It is not known why southern Saturn does not show the same blue hue -- one hypothesis holds that clouds are higher there. It is also not known why Saturn's clouds are colored gold.

Tomorrow's picture: modern cyclops


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.


This is an automated email (pulled from http://antwrp.gsfc.nasa.gov/apod/astropix.html). If you notice any problems, just send me a note gtracy@cs.wisc.edu. If you'd like to remove yourself from the list, please go here.