Astronomy Picture of the Day – Teimareh Petroglyphs and Star Trails

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.

2012 July 12

Teimareh Petroglyphs and Star Trails  

Image Credit & Copyright: Babak Tafreshi (TWAN)

Explanation: Engraved in rock, these ancient petroglyphs are abundant in the Teimareh valley, located in the Zagros Mountains of central Iran. They likely tell a tale of hunters and animals found in the middle eastern valley 6,000 years ago or more, etched by artists in a prehistoric age. In the night sky above are star trails etched by the rotation of planet Earth during the long composite exposure made with a modern digital camera. On the left, the center of the star trail arcs is the North Celestial Pole (NCP), the extension of Earth’s axis into space, with Polaris, the North Star, leaving the bright, short, stubby trail closest to the NCP. But when these petroglyphs were carved, Polaris would have made a long arc through the night. Since the Earth’s rotation axis precesses like a wobbling top, 6,000 years ago the NCP was near the border of the constellations Draco and Ursa Major, some 30 degrees from its current location in planet Earth’s sky.

Astronomy Picture of the Day – A Morning Line of Stars and Planets

Astronomy Picture of the Day

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2012 July 11

 A Morning Line of Stars and Planets

 Image Credit & Copyright: Yuri Beletsky (Las Campanas ObservatoryCarnegie Institution for Science)

Explanation: Early morning dog walkers got a visual treat last week  as bright stars and planets appeared to line up. Pictured above, easily visible from left to right, were the  Pleiades open star cluster,  Jupiter,  Venus, and the  “Follower” star  Aldebaran, all seen before a starry background. The image was taken from the  Atacama desert in western  South America.  The glow of the rising Sun can be seen over the eastern horizon. Jupiter and Venus will  continue to dazzle pre-dawn strollers all over planet Earth  for the rest of the month,  although even now the  morning planets are seen projected away from the line connecting their distant stellar  sky mates.

Astronomy Picture of the Day – Volcano and Aurora in Iceland

Astronomy Picture of the Day

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Volcano and Aurora in Iceland  

Image Credit & Copyright: Sigurdur H. Stefnisson

 

 Explanation: Sometimes both heaven and Earth erupt.   In  Iceland in 1991, the  volcano Hekla erupted at the same time that  auroras were visible overhead.   Hekla, one of the most  famous volcanoes in the world, has  erupted at least 20 times over the   past millennium,  sometimes causing  great destruction.   The last eruption occurred only twelve years ago but caused only minor  damage.   The green auroral band occurred fortuitously about 100 kilometers above the erupting  lava.   Is Earth the Solar System’s only planet with both auroras and volcanos?

Astronomy Picture of the Day

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.

2012 June 9

Venus at the Edge

Image Credit: JAXANASA, Lockheed Martin  

Explanation: As its June 6 2012 transit begins Earth’s sister planet crosses the edge of the Sun in this stunning view from the Hinode spacecraft. The timing of limb crossings during the rare transits was used historically to triangulate the distance to Venus and determine a value for the Earth-Sun distance called the astronomical unit. Still, modern space-based views like this one show the event against an evocative backdrop of the turbulent solar surface with prominences lofted above the Sun’s edge by twisting magnetic fields. Remarkably, the thin ring of light seen surrounding the planet’s dark silhouette is sunlight refracted by Venus’ thick atmosphere.

Astronomy Picture of the Day for February 11

Astronomy Picture of the Day

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2012 January 17
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IC 2118: The Witch Head Nebula
Image Credit & Copyright: Gimmi Ratto & Davide Bardini (Collecting Photons) 

 

Explanation: Double, double toil and trouble; Fire burn, and cauldron bubble — maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula is associated with the bright star Rigel in the constellation Orion. More formally known as IC 2118, the Witch Head Nebula glows primarily by light reflected from bright star Rigel, located just below the lower edge of the above image. Fine dust in the nebula reflects the light. The blue color is caused not only by Rigel’s blue color but because the dust grains reflect blue light more efficiently than red. The same physical process causes Earth’s daytime sky to appear blue, although the scatterers in Earth’s atmosphere are molecules of nitrogen and oxygen. The nebula lies about 1000 light-years away.

Astronomy Picture of the Day for Thursday, Feb. 9th

Astronomy Picture of the Day

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Nobels for a Strange Universe
Image Credit: High-Z Supernova Search Team, HST, NASA

 

Explanation: Thirteen years ago results were first presented indicating that most of the energy in our universe is not in stars or galaxies but is tied to space itself. In the language of cosmologists, a large cosmological constant is directly implied by new distant supernova observations. Suggestions of a cosmological constant (lambda) were not new — they have existed since the advent of modern relativistic cosmology. Such claims were not usually popular with astronomers, though, because lambda is so unlike known universe components, because lambda’s value appeared limited by other observations, and because less-strange cosmologies without lambda had previously done well in explaining the data. What is noteworthy here is the seemingly direct and reliable method of the observations and the good reputations of the scientists conducting the investigations. Over the past thirteen years, independent teams of astronomers have continued to accumulate data that appears to confirm the existence of dark energy and the unsettling result of a presently accelerating universe. This year, the team leaders were awarded the Nobel Prize in Physics for their work. The above picture of a supernova that occurred in 1994 on the outskirts of a spiral galaxy was taken by one of these collaborations.

Astronomy Picture of the Day for February 8

Astronomy Picture of the Day

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2012 February 8
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Enceladus Backlit by Saturn
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA; Color Composite: Gordan Ugarkovic 

Explanation: This moon is shining by the light of its planet. Specifically, a large portion of Enceladus pictured above is illuminated primarily by sunlight first reflected from the planet Saturn. The result is that the normally snow-white moon appears in the gold color of Saturn’s cloud tops. As most of the illumination comes from the image left, a labyrinth of ridges throws notable shadows just to the right of the image center, while the kilometer-deep canyon Labtayt Sulci is visible just below. The bright thin crescent on the far right is the only part of Enceladus directly lit by the Sun. The above image was taken last year by the robotic Cassini spacecraft during a close pass by by the enigmatic moon. Inspection of the lower part of this digitally sharpened image reveals plumes of ice crystals thought to originate in a below-surface sea.

Astronomy Picture of the Day for Feb. 6th

Astronomy Picture of the Day

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2012 February 6
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Dust of the Orion Nebula
Image Credit & Copyright: Nicolás Villegas 

Explanation: What surrounds a hotbed of star formation? In the case of the Orion Nebula — dust. The entire Orion field, located about 1600 light years away, is inundated with intricate and picturesque filaments of dust. Opaque to visible light, dust is created in the outer atmosphere of massive cool stars and expelled by a strong outer wind of particles. The Trapezium and other forming star clusters are embedded in the nebula. The intricate filaments of dust surrounding M42 and M43 appear brown in the above image, while central glowing gas is highlighted in red. Over the next few million years much of Orion’s dust will be slowly destroyed by the very stars now being formed, or dispersed into the Galaxy.

Astronomy Picture of the Day for Feb. 4th

Astronomy Picture of the Day

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2012 February 4
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Comet Garradd and M92
Image Credit & Copyright: Rolando Ligustri (CARA Project, CAST) 

Explanation: Sweeping slowly through the constellation Hercules, Comet Garradd (C2009/P1) passed with about 0.5 degrees of globular star cluster M92 on February 3. Captured here in its latest Messier moment, the steady performer remains just below naked-eye visibility with a central coma comparable in brightness to the dense, well-known star cluster. The rich telescopic view from New Mexico’s, early morning skies, also features Garradd’s broad fan shaped dust tail and a much narrower ion tail that extends up and beyond the right edge of the frame. Pushed out by the pressure of sunlight, the dust tail tends to trail the comet along its orbit while the ion tail, blown by the solar wind, streams away from the comet in the direction opposite the Sun. Of course, M92 is over 25,000 light-years away. Comet Garradd is 12.5 light-minutes from planet Earth, arcing above the ecliptic plane.

Astronomy Picture of the Day for February 3rd

Astronomy Picture of the Day

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2012 February 3
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Inside the Eagle Nebula
Credit: Far-infrared: ESA/Herschel/PACS/SPIRE/Hill, Motte, HOBYS Key Programme Consortium;
X-ray: ESA/XMM-Newton/EPIC/XMM-Newton-SOC/Boulanger 

Explanation: In 1995, a now famous picture from the Hubble Space Telescope featured Pillars of Creation, star forming columns of cold gas and dust light-years long inside M16, the Eagle Nebula. This remarkable false-color composite image revisits the nearby stellar nursery with image data from the orbiting Herschel Space Observatory and XMM-Newton telescopes. Herschel’s far infrared detectors record the emission from the region’s cold dust directly, including the famous pillars and other structures near the center of the scene. Toward the other extreme of the electromagnetic spectrum, XMM-Newton’s X-ray vision reveals the massive, hot stars of the nebula’s embedded star cluster. Hidden from Hubble’s view at optical wavelengths, the massive stars have a profound effect, sculpting and transforming the natal gas and dust structures with their energetic winds and radiation. In fact, the massive stars are short lived and astronomers have found evidence in the image data pointing to the remnant of a supernova explosion with an apparent age of 6,000 years. If true, the expanding shock waves would have destroyed the visible structures, including the famous pillars. But because the Eagle Nebula is some 6,500 light-years distant, their destruction won’t be witnessed for hundreds of years.