Η διαστημική φωτογραφία της ημέρας - Αρχείο

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Thor's Helmet from CFHT

Credits & Copyright : Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT

Πηγή : ASTRONOMY PHOTO OF THE DAY (APOD)

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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.

A Tail of Two Hemispheres

Credit & Copyright: S. Deiries (ESO), M. Fulle (INAF)

Πηγή : Astronomy Picture of the Day

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Flame Nebula Close-Up
Credit & Copyright: Robert Gendler, Jan-Erik Ovaldsen

Explanation: Of course, the Flame Nebula is not on fire. Also known as NGC 2024, the nebula's suggestive reddish color is due to the glow of hydrogen atoms at the edge of the giant Orion molecular cloud complex some 1,500 light-years away. The hydrogen atoms have been ionized, or stripped of their electrons, and glow as the atoms and electrons recombine. But what ionizes the hydrogen atoms? In this close-up view, a dark lane of absorbing interstellar dust stands out in silhouette against the hydrogen glow and actually hides the true source of the Flame Nebula's energy from optical telescopes. Behind the dark lane lies a cluster of hot, young stars, seen at infrared wavelengths through the obscuring dust. A young, massive star in that cluster is the likely source of energetic ultraviolet radiation that ionizes the hydrogen gas in the Flame Nebula.

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Alborz Mountains in Moonlight
Credit & Copyright: Babak Tafreshi

Explanation: On January 25th, light from a first quarter Moon illuminated this dreamlike landscape looking across the rugged, snow-covered peaks of the Alborz Mountain Range in northern Iran. The stunning sky is filled with stars, including the yellow-tinged Betelgeuse at the shoulder of Orion. Sirius, alpha star of Canis Major and the brightest star in planet Earth's night, stands above and left of picture center. The erie glow along the Haraz valley in the foreground is light from cars traveling a highway leading from Tehran to the Caspian Sea.

Πηγή : Astronomy Picture of the Day

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Shadow of a Martian Robot

Credit : Mars Exploration Rover Mission, JPL, NASA

Explanation: What if you saw your shadow on Mars and it wasn't human? Then you might be the Opportunity rover currently exploring Mars. Opportunity and sister robot Spirit have been probing the red planet since early 2004, finding evidence of ancient water, and sending breathtaking images across the inner Solar System. Pictured above, Opportunity looks opposite the Sun into Endurance Crater and sees its own shadow. Two wheels are visible on the lower left and right, while the floor and walls of the unusual crater are visible in the background. Opportunity and Spirit have now spent over three years exploring the red world, find new clues into the wet ancient past of our Solar System's second most habitable planet.

Πηγή : Astronomy Picture of the Day

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Ο κομήτης McNaught μεταξύ καταιγίδας και πυροτεχνημάτων

Credit & Copyright: Antti Kemppainen

Explanation: Sometimes the sky itself is the best show in town. On January 26, people from Perth, Australia gathered on a local beach to watch a sky light up with delights near and far. Nearby, fireworks exploded as part of Australia Day celebrations. On the far right, lightning from a thunderstorm flashed in the distance. Near the image center, though, seen through clouds, was the most unusual sight of all: Comet The photogenic comet was so bright that it even remained visible though the din of Earthly flashes. Comet McNaught continues to move out from the Sun and dim, but should remain visible in southern skies with binoculars through the end of this month. The above image is actually a three photograph panorama digitally processed to reduce red reflections from the exploding firework.

Πηγή : Astronomy Picture of the Day

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Sun Storm: A Coronal Mass Ejection

Credit: SOHO Consortium, ESA, NASA

Explanation: What's happening to our Sun? Another Coronal Mass Ejection (CME)! The Sun-orbiting SOHO spacecraft has imaged many erupting filaments lifting off the active solar surface and blasting enormous bubbles of magnetic plasma into space. Direct light from the sun is blocked in the inner part of the above image, taken in 2002, and replaced by a simultaneous image of the Sun in ultraviolet light. The field of view extends over two million kilometers from the solar surface. While hints of these explosive events, called coronal mass ejections or CMEs, were discovered by spacecraft in the early 70s, this dramatic image is part of a detailed record of this CME's development from the presently operating SOHO spacecraft. Near the minimum of the solar activity cycle CMEs occur about once a week, but near solar maximum rates of two or more per day are typical. Strong CMEs may profoundly influence space weather. Those directed toward our planet can have serious effects.

Πηγή : Astronomy Picture of the Day

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Liquid Lakes on Saturn's Titan

Credit: Cassini Radar Mapper, ESA, NASA

Explanation: Why would some regions on Titan reflect very little radar? The leading explanation is that these regions are lakes, possibly composed of liquid methane. The above image is a false-color synthetic radar map of a northern region of Titan taken during a flyby of the cloudy moon by the robotic Cassini spacecraft last July. On this map, which spans about 150 kilometers across, dark regions reflect relatively little of the broadcast radar signal. Images like this show Titan to be only the second body in the Solar System to possess liquids on the surface. Future observations from Cassini during Titan flybys will further test the methane lake hypothesis, as comparative wind affects on the regions are studied.

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Galaxies Away

Credit: NASA, ESA, Hubble Heritage Team (STScI / AURA)
Acknowledgment: J. Blakeslee (http://www.physics.wsu.edu/)

Explanation: This stunning group of galaxies is far, far away - about 450 million light-years from planet Earth - cataloged as galaxy cluster Abell S0740. Dominated by the cluster's large central elliptical galaxy (ESO 325-G004), this sharp Hubble view takes in a remarkable assortment of galaxy shapes and sizes with only a few spiky foreground stars scattered through the field. The giant elliptical galaxy spans over 100,000 light years and contains about 100 billion stars, comparable in size to our own spiral Milky Way. The Hubble data reveal a wealth of detail in even these distant galaxies, including magnificent arms and dust lanes, star clusters, ring structures, and gravitational lensing arcs.



Πηγή : Astronomy Picture of the Day

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Ptolemaeus, Alphonsus and Arzachel

Credit & Copyright: Alan Friedman

Explanation: These three ancient, large impact craters lie on the north eastern shores of Mare Nubium, the lunar Sea of Clouds. Along the top of the stark mosaic (left to right) are the namesakes of Ptolemaeus, Alphonsus and Arzachel. The picture offers a remarkably detailed view of the well-studied region with shadows emphasizing the large crater central peaks and slumping walls. Careful examination also reveals the 110 kilometer long Straight Wall, a fault 200-300 meters high, and the intriguing Davy crater chain. Overall, the striking moonscape is similar to the final images recorded by the Ranger 9 spacecraft, before it crashed into the 108 kilometer wide crater Alphonsus in March of 1965.

Πηγή : Astronomy Picture of the Day

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Io: The Prometheus Plume

Credit: Galileo Project, JPL, NASA

Explanation: What's happening on Jupiter's moon Io? Two sulfurous eruptions are visible on Jupiter's volcanic moon Io in this color composite image from the robotic Galileo spacecraft that orbited Jupiter from 1995 to 2003. At the image top, over Io's limb, a bluish plume rises about 140 kilometers above the surface of a volcanic caldera known as Pillan Patera. In the image middle, near the night/day shadow line, the ring shaped Prometheus plume is seen rising about 75 kilometers above Io while casting a shadow below the volcanic vent. Named for the Greek god who gave mortals fire, the Prometheus plume is visible in every image ever made of the region dating back to the Voyager flybys of 1979 - presenting the possibility that this plume has been continuously active for at least 18 years. The above digitally sharpened image was originally recorded in 1997 on June 28 from a distance of about 600,000 kilometers.

Πηγή : Astronomy Picture of the Day

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Το πέρασμα του κομήτη McNaught πάνω από την Νέα Ζηλανδία

Credit & Copyright: Minoru Yoneto

Explanation: Comet McNaught is perhaps the most photogenic comet of our time. After making quite a show in the northern hemisphere in mid January, the comet moved south and developed a long and unusual dust tail that dazzled southern hemisphere observers starting in late January. Comet McNaught was imaged two weeks ago between Mount Remarkable and Cecil Peak in this spectacular image taken from Queenstown, South Island, New Zealand. The bright comet dominates the right part of the above image, while the central band of our Milky Way Galaxy dominates the left. Careful inspection of the image will reveal a meteor streak just to the left of the comet. Comet McNaught continues to move out from the Sun and dim, but should remain visible in southern skies with binoculars through the end of this month.

Πηγή : Astronomy Picture of the Day

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Vela Supernova Remnant in Visible Light

Credit: Digitized Sky Survey, ESA/ESO/NASA FITS Liberator
Color Composite: Davide De Martin (Skyfactory)

Explanation: The explosion is over but the consequences continue. About eleven thousand years ago a star in the constellation of Vela could be seen to explode, creating a strange point of light briefly visible to humans living near the beginning of recorded history. The outer layers of the star crashed into the interstellar medium, driving a shock wave that is still visible today. A roughly spherical, expanding shock wave is visible in X-rays. The above image captures much of that filamentary and gigantic shock in visible light, spanning almost 100 light years and appearing twenty times the diameter of the full moon. As gas flies away from the detonated star, it decays and reacts with the interstellar medium, producing light in many different colors and energy bands. Remaining at the center of the Vela Supernova Remnant is a pulsar, a star as dense as nuclear matter that completely rotates more than ten times in a single second.

Astronomy Picture of the Day

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The Rosette Nebula

Credit & Copyright: Robert Gendler

Explanation: Would the Rosette Nebula by any other name look as sweet? The bland New General Catalog designation of NGC 2237 doesn't appear to diminish the appearance of the this flowery emission nebula. Inside the nebula lies an open cluster of bright young stars designated NGC 2244. These stars formed about four million years ago from the nebular material and their stellar winds are clearing a hole in the nebula's center, insulated by a layer of dust and hot gas. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow. The Rosette Nebula spans about 100 light-years across, lies about 5000 light-years away, and can be seen with a small telescope towards the constellation of Monoceros.

Πηγή : Astronomy Picture of the Day

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Αυτή η σελίδα είναι για την κόρη μου! Είναι fan.