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  #211  
Παλιά 28-08-07, 07:59
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Τελευταία φορά Online: 12-11-16 11:12
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Could Hydrogen Peroxide Life Survive on Mars?
Credit: Viking Project, NASA

Explanation: Is there life on Mars? Although no unambiguous evidence for indigenous life on Mars has ever been found, a more speculative question -- could some life forms survive on Mars -- has taken on a new twist. Two planetary scientists recently speculated that were extremophile microbes to involve a mixture of hydrogen peroxide (H2O2) and water (H2O), these microbes might well be able survive the thin, cold, dry atmosphere on Mars. Life that involves hydrogen peroxide does exist here on Earth, they note, and such life would be better able to absorb water on Mars. They also claim that such life would be consistent with the ambiguous results coming out from the life-detecting experiments aboard the old Viking Landers. Although such speculation is not definitive, debating possibilities for life on Mars has again proven to be fun and a magnet for media attention. Pictured above, the Viking Lander 2 captured an unusual image of the Martian surface in 1979 sporting a thin layer of seasonal water ice.

Tomorrow's picture: lightning jets

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  #212  
Παλιά 28-08-07, 09:07
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Τελευταία φορά Online: 22-05-11 01:20
Φύλο: Γυναίκα
Η διαθεσή μου τώρα:
Αν αλλάξεις λίγο το χρώμα προς το μαύρο θα μπορούσε να είναι και ο Ταΰγετος
Και ψάχνουν να βρουν ίχνη ζωής
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  #213  
Παλιά 29-08-07, 07:33
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Τελευταία φορά Online: 12-11-16 11:12
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Gigantic Jets Over Oklahoma
Credit: Richard Smedley

Explanation: Have you ever seen a gigantic jet? They are extremely rare but tremendously powerful. Gigantic jets are a newly discovered type of lightning discharge between some thunderstorms and the Earth's ionosphere high above them. Pictured above is one such jet caught by accident by a meteor camera in Oklahoma, USA. The gigantic jet, at the lower left, traversed perhaps 70 kilometers in just under one second. Clicking on the image will bring up a movie in many browsers, also visible here. Gigantic jets are much different from regular cloud-to-cloud and cloud-to-ground lightning. The bottoms of gigantic jets appear similar in appearance to another type cloud-to-ionosphere strike called blue jets, while the tops appear similar to upper-atmosphere red sprites. Although the mechanism and trigger that causes gigantic jets is a topic of research, it is clear that the jets reduce charge imbalance between different parts of Earth's atmosphere. A good way to look for gigantic jets is to watch a powerful but distant thunderstorm from a clear location.

Tomorrow's picture: open space

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  #214  
Παλιά 30-08-07, 08:07
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Τελευταία φορά Online: 12-11-16 11:12
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Dark Lunar Eclipse
Credit & Copyright: Martin Pugh

Explanation: The Moon passed close to the center of Earth's shadow on August 28th. Seen best by skywatchers in western North America, and the Pacific region, the resulting total lunar eclipse was a dark one, lasting about 90 minutes. In this telescopic image taken near mid totality from Yass, NSW Australia, the 85 kilometer wide ray crater Tycho lies near the top right of the shadowed lunar surface. Of course, even during a total lunar eclipse,the Moon is not completely dark. Instead the Moon remains visible during totality, reflecting reddened light filtering into the Earth's shadow. The light comes from all the sunsets and sunrises, as seen from the lunar perspective, around the edges of a silhouetted Earth.

Tomorrow's picture: snake eyes

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  #215  
Παλιά 31-08-07, 08:47
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Stars Forming in Serpens
Credit & Copyright: ESO, HAWK-1 Instrument Team

Explanation: Stars are forming in a dense molecular cloud a mere 1,000 light-years away in the constellation Serpens Cauda (The Serpent's Tail). At that estimated distance, this sharp, near-infrared close-up of the active Serpens star-forming region spans about 2 arcminutes or just over half a light-year. Though such near-infrared observations can be made by mountain-top telescopes with specialized detectors, near-infrared light has too long a wavelength to be visible to the eye. This view was recorded with a sensitive camera, HAWK-I (High Acuity, Wide field K-band Imaging), just commissioned at the Paranal Observatory in Chile. Intended to illustrate HAWK-I's impressive capabilities, the tantalizing image highlights reddish young stars and protostars, likely up to a few million years old, emerging from the nebular gas and dust.

Tomorrow's picture: lakeside moon

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  #216  
Παλιά 01-09-07, 09:11
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Τελευταία φορά Online: 12-11-16 11:12
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Kalamalka Lake Eclipse
Credit & Copyright: Yuichi Takasaka

Explanation: Recorded on August 28th, this serene total lunar eclipse sequence looks southwest down Kalamalka Lake toward the lights of Coldstream, British Columbia. An exposure every 4 minutes captured the Moon's position and eclipse phase, until the Moon set behind the town lights and a hill on the horizon. In fact, the sequence effectively measures the 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.

Tomorrow's picture: moon phase

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  #217  
Παλιά 02-09-07, 09:37
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Τελευταία φορά Online: 12-11-16 11:12
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http://antwrp.gsfc.nasa.gov/apod/image/0709/lunation_ajc_big.jpg
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Lunation
Credit & Copyright: António Cidadão

Explanation: Our Moon's appearance changes nightly. This time-lapse sequence shows what our Moon looks like during a lunation, a complete lunar cycle. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The Moon always keeps the same face toward the Earth. The Moon's apparent size changes slightly, though, and a slight wobble called a libration is discernable as it progresses along its elliptical orbit. During the cycle, sunlight reflects from the Moon at different angles, and so illuminates different features differently. A full lunation takes about 29.5 days, just under a month (moon-th). Click on the picture to view the animated gif file.

Tomorrow's picture: star clouds

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  #218  
Παλιά 03-09-07, 07:24
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Τελευταία φορά Online: 12-11-16 11:12
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The Colorful Clouds of Rho Ophiuchi
Credit: Adam Block, KPNO Visitor Program, NOAO, AURA, NSF

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 electrons recombine with the gas. The dark regions are caused by dust grains - born in young stellar atmospheres - which effectively block light emitted behind them. The Rho Ophiuchi star clouds, well in front of the globular cluster M4 visible above on far lower left, are even more colorful than humans can see - the clouds emits light in every wavelength band from the radio to the gamma-ray.

Tomorrow's picture: martian crater

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  #219  
Παλιά 04-09-07, 07:53
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A Path Into Victoria Crater on Mars
Credit: Mars Exploration Rover Mission, Cornell, JPL, NASA; Acknowledgement: Eduardo Tesheiner

Explanation: What's inside Victoria Crater? Now that the dust has settled from the regional Martian dust storms that immobilized the rolling Martian rovers, the task ahead has become clear. Opportunity arrived at Victoria Crater last month and was poised to enter when the dust storms flared up unexpectedly. The above image was taken last week by the Opportunity rover perched at a possibly traversable slope into the 750-meter impact feature. Victoria Crater is the largest crater that either Martian rover has come across during their explorations. The crater walls might hold clues about the Martian surface before the tremendous impact that created Victoria Crater.

Tomorrow's picture: open space

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  #220  
Παλιά 05-09-07, 08:01
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Τελευταία φορά Online: 12-11-16 11:12
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Aurigids from 47,000 Feet
Credit: Jeremie Vaubaillon, Caltech, NASA

Explanation: On September 1, Aurigid meteors filled the sky, in keeping with inovative predictions of an outburst from this historically tentative meteor shower. Astronomers flying at 47,000 feet on a dedicated mission to observer the outburst collected image data for this composite photo of the Aurigids' bright and colorful streaks. The source of the shower is understood to be Comet Kiess, a comet that would have last swung through the inner solar system around 2,000 years ago. Influenced by gravity, dust from the tail of the comet has been drifting toward the Earth's orbit ever since. Predicted to pass through a clump of dust this year creating the 2007 outburst, Earth has also passed through dust clumps from this comet in 1935, 1986, and 1994. Of course, the shower's radiant point is in the eponymous constellation Auriga, the Charioteer.

Tomorrow's picture: time travel

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  #221  
Παλιά 05-09-07, 22:26
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Τελευταία φορά Online: 24-12-09 02:01
Φύλο: Γυναίκα
Η διαθεσή μου τώρα:
απλα τελεια! να μου τις δωσεις και εμενα!!!
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  #222  
Παλιά 06-09-07, 08:57
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Τελευταία φορά Online: 12-11-16 11:12
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Time Tunnel
Credit & Copyright: Johannes Schedler (Panther Observatory)
Additional Image Data: Ken Crawford (Rancho Del Sol Observatory)

Explanation: Spiky stars are nearby, but fuzzy galaxies are strewn far across the Universe in this cosmic view. Spanning about 1/2 degree on the sky, the pretty picture is the result of astronomer Johannes Schedler's project to look back in time, toward a quasar 12.7 billion light-years away. The quasar is just visible in the full resolution image at the position marked by short vertical lines (center). The intrinsically bright nucleus of a young, active galaxy powered by a supermassive black hole, the quasar was recently identified as one of the most distant objects known. Since light travels at a finite speed, the galaxies receding into the distance are seen as they were in the increasingly remote past. The quasar appears as it did about 12.7 billion years ago, when the Universe was just 7 percent of its present age. Of course, the expansion of the Universe has redshifted the light. Schedler added image data extending to the near-infrared, acquired by collaborator Ken Crawford, to detect the distant quasar, with a measured redshift of 6.04.

Tomorrow's picture: closer to now

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  #223  
Παλιά 07-09-07, 07:31
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South Pole Lunar Eclipse
Credit & Copyright: Robert Schwarz (South Pole Station)

Explanation: The Moon was up continuously for 14 days in August -- when viewed from the South Pole. But during the total lunar eclipse on August 28, it circled only about 10 degrees above the horizon. For Robert Scharwz, the resulting long line-of-sight through the atmosphere that blurred his images was a minor problem when he recorded this four hour long lunar eclipse sequence. A more severe problem was the outdoor air temperature of -68 C (-90 F). The extreme cold required him to make the series of exposures through a slit in a window from inside a heated room. Though the heat produced convection and further blurring, it was the only way to keep the camera at a reasonable operating temperature for an extended period of time. Still, he was rewarded with this impressive record of August's lunar eclipse from a unique perspective on planet Earth.

Tomorrow's picture: light-weekend

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  #224  
Παλιά 08-09-07, 07:50
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Τελευταία φορά Online: 12-11-16 11:12
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Ισως η πιο συγκινητική ενέργεια του ανθρώπου, για επικοινωνία με εξωγήινους πολιτισμούς.

Κρατείστε την φωτογραφία αυτή, ήδη ταξιδεύει εκτός του Πλανητικού μας συστήματος, όπως το μπουκάλι ενός ναυαγού.

Oi Voyagers, ήταν μια απλουστάτη κατασκευή, η οποία όμως στηρίχτηκε στην εφυία πολλών ανθρώπων και δουλεύοντας με τις βαρύτητες στο πλανητικό μας σύστημα, κινήθηκαν χωρίς καμιά ενέργεια και πρόσφεραν στον άνθρωπο, τεράστιες γνώσεις για του πλανήτες μας.

The Voyagers' Message in a Bottle
Credit: Voyager Project, JPL, NASA

Explanation: Launched thirty years ago, NASA's Voyager 1 and 2 spacecraft are now respectively 15 billion and 12.5 billion kilometers from the Sun, equivalent to about 14 and 11.5 light-hours distant. Still functioning, the Voyagers are being tracked and commanded through the Deep Space Network. Having traveled beyond the outer planets, they are only the third and fourth spacecraft from planet Earth to escape toward interstellar space, following in the footsteps of Pioneer 10 and 11. A 12-inch gold plated copper disk (a phonograph record) containing recorded sounds and images representing human cultures and life on Earth, is affixed to each Voyager - a message in a bottle cast into the cosmic sea. The recorded material was selected by a committee chaired by astronomer Carl Sagan. Simple diagrams on the cover symbolically represent the spacecraft's origin and give instructions for playing the disk. The exotic construction of the disks should provide them with a long lifetime as they coast through interstellar space.

Tomorrow's picture: survivor moon

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  #225  
Παλιά 09-09-07, 07:54
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Τελευταία φορά Online: 12-11-16 11:12
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The Great Basin on Saturn's Tethys
Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: Some moons wouldn't survive the collision. Tethys, one of Saturn's larger moons at about 1000 kilometers in diameter, survived the collision, but sports today the expansive impact crater Odysseus. Sometimes called the Great Basin, Odysseus occurs on the leading hemisphere of Tethys and shows its great age by the relative amount of smaller craters that occur inside its towering walls. Another large crater, Melanthius, is visible near the moon's terminator. The density of Tethys is similar to water-ice. The above digitally enhanced image was captured in July by the robot Cassini spacecraft in orbit around Saturn as it swooped past the giant ice ball.

Tomorrow's picture: building galaxies

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