| Piú votate - The Sun: just a star, like many others... |
Solar_Corona~0.jpgDeep Coronal Holes107 visiteCaption NASA:"This ominous, dark shape sprawling across the face of the Sun is a Coronal Hole -- a low density region extending above the Surface where the Solar Magnetic Field opens freely into interplanetary space.
Studied extensively from space since the 1960s in UltraViolet and X-Ray Light, Coronal Holes are known to be the source of the high-speed Solar Wind (such as atoms and electrons which flow outward along the open Magnetic Field lines). During periods of low activity, Coronal Holes typically cover regions just above the Sun's Poles.
But this extensive Coronal Hole dominated the Sun's Northern Hemisphere earlier this week, captured here in Extreme UV Light by cameras onboard the Solar Dynamics Observatory. The solar wind streaming from this Coronal Hole triggered auroral displays on Earth".MareKromium
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Solar_Eclipse-2010.jpgMillennium's Annular Solar Eclipse55 visiteDa "NASA - Picture of the Day" del giorno 22 Gennaio 2010:"The Moon's shadow raced across planet Earth on January 15, 2010.
Observers within the central shadow track were able to witness an Annular Solar Eclipse as the Moon's apparent size was too small to completely cover the Sun. A visually dramatic "Ring of Fire", the annular phase lasted up to 11' and 8", depending on location: the longest Annular Solar Eclipse for the next 1000 years.
This picture of the Moon's silhouette just before mid-eclipse was taken within the eclipse path from the city of Kanyakumari at the southern tip of India. The telescopic image was made through a filter that blocks most Visible Light, but still transmits light from Hydrogen Atoms.
As a result, detailed mottling, or granulation, caused by heat convection in the Sun's Atmosphere can be seen around the dark Lunar Disk".MareKromium
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Solar_Prominence.jpgSolar Prominence55 visiteCaption NASA, da "NASA - Picture of the Day" del giorno 15 Marzo 2009:"What's happened to our Sun? It was sporting a spectacular -- but not very unusual -- Solar Prominence.
A Solar Prominence is a cloud of solar gas held above the Sun's Surface by the Sun's Magnetic Field. In 2004, NASA's Sun-orbiting SOHO Spacecraft imaged an impressively large prominence hovering over the surface, pictured above.
The Earth would easily fit under the hovering curtain of hot gas.
A quiescent Prominence typically lasts about a month, and may erupt in a Coronal Mass Ejection (CME) expelling hot gas into the Solar System. Although somehow related to the Sun's changing Magnetic Field, the energy mechanism that creates and sustains a Solar Prominence is still a topic of research".MareKromium
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Solar_Eclipse-Tse2008_200_mo1_big.jpgAugust 2008 Total Solar Eclipse58 visiteCaption NASA:"For a moment on August 1st, the daytime sky grew dark along the path of a Total Solar Eclipse. While watching the geocentric celestial event from Mongolia, photographer Miloslav Druckmuller recorded multiple images with two separate cameras as the Moon blocked the bright solar disk and darkened the sky.
This final composition consists of 55 frames ranging in exposure time from 1/125 to 8 seconds. It spans nearly 12°, with the relative position of the Moon and Sun corresponding to mid-eclipse. On the left is bright planet Mercury, but many stars are also visible, including the Praesepe Star Cluster (also known as M44 or the Beehive Cluster) in Cancer, above and to the right of the silhouetted Moon. Remarkably, the nearly perfect conditions and wide range in individual exposures allow the composite picture to register the lunar surface and follow the delicate solar corona out to a distance of nearly 20 times the radius of the Sun. In fact, the composite presents a range in brightness beyond what the eye could see during the eclipse".MareKromium
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Sunspot-1002.jpgActive Region 100254 visiteCaption NASA:"Why has the Sun been so quiet recently? No one is sure. Our Sun has shown few active regions -- that house even fewer associated sunspots -- for over a year now, and such a period of relative calm is quite unusual.
What is well known is that our Sun is in a transitional period between solar cycles called a Solar Minimum, where solar activity has historically been reduced.
The stark lack of surface tumult is unusual even during a Solar Minimum, however, and activity this low has not been seen for many decades. A few days ago, however, a "Bona-Fide Active Region! -- complete with Sunspots --appeared and continues to rotate across the Sun's face. Visible above, this region, dubbed "Active Region 1002" (AR 1002), was imaged in ultraviolet light yesterday by the SOHO Spacecraft, which co-orbits the Sun near the Earth.
Besides the tranquility on the Sun's surface, recent data from the Ulysses Spacecraft, across the Solar System, indicate that the intensity of the Solar Wind blowing out from the Sun is at a 50 year low. Predictions hold, however, that our Sun will show more and more active regions containing more and more Sunspots and Flares until Solar Maximum occurs in about 4 years from now (such as in the year 2012)".MareKromium
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The_Sun_-_Eclipse.jpgAt the Sun's Edge54 visiteCaption NASA:"A train trip on the Trans-Siberian railway to Novosibirsk resulted in this stunning view along the edge of the Sun, recorded during the August 1st, 2008, total Solar Eclipse.
The picture is a composite of two images taken at special moments in the eclipse sequence, corresponding to the very beginning and the very end of the total eclipse phase.
Those times are known to eclipse chasers as 2nd and 3rd contact.
Bright beads around the Moon's dark silhouette are rays of sunlight shining through lunar valleys at the edge of the Lunar Disk.
But the composite view also captures Solar Prominences, such as "looping structures" of hot plasma suspended in magnetic fields, extending beyond the Sun's edge".MareKromium
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SunFlare-prom1743_eit_big.jpgA Twisted Solar Eruptive Prominence55 visiteCaption NASA:"Ten Earths could easily fit in the "claw" of this seemingly solar monster. The monster, though, visible on the lower left, is a huge Eruptive Prominence seen moving out from our Sun. The above dramatic image taken early in the year 2000 by the Sun-orbiting SOHO satellite. This large prominence, though, is significant not only for its size, but its shape. The twisted figure eight shape indicates that a complex magnetic field threads through the emerging solar particles. Differential rotation inside the Sun might help account for the surface explosion.
Although large prominences and energetic Coronal Mass Ejections (CMEs) are relatively rare, they are occurred more frequently near Solar Maximum, the time of peak sunspot and solar activity in the eleven-year Solar Cycle".MareKromium
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Solar-Cycle.jpgA "Full Solar Cycle", from SOHO (extreme UV Light)54 visiteCaption NASA:"Every 11 years, our Sun goes through a Solar Cycle.
A complete Solar Cycle has now been imaged by the Sun-orbiting SOHO Spacecraft, celebrating the 12th anniversary of its launch yesterday (December, 12th, 2007).
A Solar Cycle is caused by the changing Magnetic Field of the Sun, and varies from Solar Maximum, when Sunspot, Coronal Mass Ejection, and Flare phenomena are most frequent, to Solar Minimum, when such activity is relatively infrequent.
Solar Minimums occurred in 1996 and 2007, while the last Solar Maximum occurred in 2001.
Pictured above is a SOHO image of the Sun in extreme ultraviolet light for each year of the last Solar Cycle, with images picked to illustrate the relative activity of the Sun".MareKromium
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The_Sun-PIA09324.jpgCloser View of the Equatorial Region of the Sun (March 24, 2007)54 visitenessun commentoMareKromium
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The_Sun-PIA09332.jpgLeft Limb of North Pole of the Sun (March 20, 2007)54 visitenessun commentoMareKromium
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The_Sun_in_3D.jpg3-D Sun56 visiteCaption NASA:"What does the Sun look like in all three spatial dimensions? To find out, NASA launched two STEREO satellites to perceive three dimensions on the Sun much like two eyes allow humans to perceive three dimensions on the Earth.
Such a perspective is designed to allow new insight into the surface of the rapidly changing Sun, allowing humans to better understand and predict things like Coronal Mass Ejections and solar flares that affect the Earth as well as satellites and astronauts orbiting the Earth. Pictured above are two simultaneous images of the Sun taken by STEREO A and STEREO B, now digitally combined to give one of the first 3-D pictures of the Sun ever taken. To fully appreciate the image, one should view it with 3-D red-blue glasses. The teeming and bubbling solar surface can be seen sporting a prominent solar prominence near the top of the image".MareKromium
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Earth&Sun-000-sunearth_01G.jpgMagnetic Fields... (1)55 visitenessun commento
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