| Piú viste - The Sun: just a star, like many others... |
Solar Flare.jpgLoops over the Sun69 visiteCaption originale:"How can gas float above the Sun? Twisted magnetic fields arching from the Solar Surface can trap ionized gas, suspending it in huge looping structures. These majestic plasma arches are seen as prominences above the Solar Limb. In September 1999, this dramatic and detailed image was recorded by the EIT experiment on board the space-based SOHO observatory in the light emitted by ionized Helium. It shows hot plasma escaping into space as a fiery prominence breaks free from magnetic confinement a hundred thousand kilometers above the Sun. These awesome events bear watching as they can affect communications and power systems over 100 MKM away on Planet Earth".
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The Sun-EitplumeG.jpgOur "restless" Sun... (9)69 visitenessun commento
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The_Sun_in_3D.jpg3-D Sun69 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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Sunspot-10982.jpgSunspot 1098269 visiteDa "NASA - Picture of the Day", del giorno 6 Febbraio 2008:"A new Solar Cycle has begun on our Sun. Over the past year, the Sun's Magnetic Field has reset and now a new 11 year period is beginning.
Pictured above in a specific color of light emitted by Hydrogen is Sunspot 10982, one of the first sunspots of the new Solar Cycle. The two dark lines visible just above and to either side of the bright sunspot are cool filaments held aloft by the Sun's Magnetic Field. Hot and cold regions are shown as regions of relative light and dark, respectively.
A Solar Cycle is caused by the changing Magnetic Field, and varies from Solar Maximum (when sunspots, coronal mass ejections and flare phenomena are most frequent), to Solar Minimum (meaning when such activity is relatively infrequent).
Solar Minima occurred in 1996 and 2007, while the last Solar Maximum occurred in 2001 (...)".MareKromium
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Solar_Eclipse~0.jpgA "Diamond Ring" among the clouds69 visiteDa "NASA - Picture of the Day" del giorno 8 Agosto 2009:"Cloudy skies over Wuhan, China hid the delicate Solar Corona during July's Total Eclipse of the Sun. Still, the Moon's silhouette was highlighted by these glistening diamonds as the Total Eclipse Phase ended. Caused by bright Sunlight streaming through dips and valleys in the irregular terrain along the Moon's edge, the effect is known as Baily's Beads, named after Francis Baily who called attention to the phenomenon in 1836.
The dramatic appearance of the beads at the beginning or end of a Total Solar Eclipse is also known as the Diamond Ring effect. In this remarkable image, a small, pinkish solar prominence can also be seen along the edge, below the diamonds".MareKromium
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ZZ-ZZ-Annular_seip_big.jpgThe "Annular Eclipse" of October, 3rd, 2005 (HR)68 visiteDa "NASA - Picture of the Day" del 5 Ottobre 2005:"On Monday, part of the Sun went missing. The missing piece was no cause for concern because the Moon was only momentarily in the way. The event was not a total eclipse of the Sun for any Earth-bound sky enthusiast but rather, at best, an annular eclipse, where the Moon blocked most of the Sun. Because of the relatively large distance to the Moon during this Earth-Moon-Sun alignment, the Moon did not have a large enough angular size to block the entire Sun. Those who witnessed the solar eclipse from a narrow path through Spain and Africa, however, were lucky enough to see the coveted Ring of Fire, a dark Moon completely surrounded by the brilliant light of the distant Sun. Pictured above is a Ring of Fire captured two days ago in unusually HR above Spain. The resulting image shows details of the granular solar surface as well as many prominences around the Sun".
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Solar Eclipse 2006.jpgFrom Space, from Earth...68 visiteDa "NASA - Picture of the Day" del 31 Marzo 2006:"Neither rain, nor snow, nor dark of night can keep the space-based SOlar Heliospheric Observatory (SOHO) from watching the Sun. In fact, from its vantage point 150 MKM sunward of planet Earth, SOHO's cameras can always monitor the Sun's Outer Atmosphere, or Corona.
But only during a total solar eclipse can earth-based observers see the lovely coronal streamers and structures - such as when the Moon briefly blocks the overwhelmingly bright solar surface.
In this composite view, SOHO's uninterrupted view of the Solar Corona above the Solar Photosphere (center) and Corona far beyond the Sun's disk, are shown in orange hues. The middle, donut-shaped region is the Corona as recorded by the Williams College Eclipse Expedition to Kastelorizo Island, Greece during the March 29th, 2006 total solar eclipse.
Merging ground and space-based views allows astronomers to trace features in the Corona that reach from just above the Sun's surface into the Solar Wind".
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The Sun-C3bulb_crop.jpgOur "restless" Sun... (5)68 visitenessun commento
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The_Sun-Coronal_Hole.jpgCoronal Hole68 visiteCaption NASA:"The dark expanse below the Equator of the Sun is a Coronal Hole, such as a Low Density Region extending above the surface, where the Solar Magnetic Field opens freely into interplanetary space.
Shown in false color, the picture was recorded on September 19th, 2007, in Extreme Ultraviolet Light by the EIT instrument onboard the space-based SOHO observatory. 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, atoms and electrons that flow outward along the open magnetic field lines.
The Solar Wind streaming from this coronal hole triggered colorful auroral displays on planet Earth begining late last week, enjoyed by spaceweather watchers at high latitudes".MareKromium
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Mercury and the Sun.jpgA "Superior Conjunction" Of Mercury67 visiteCaption originale NASA dal "NASA - Picture of the Day" dell'8-9-1999: "In astronomical parlance, an interior planet is at "Superior Conjunction" when it is located on the opposite side of the Sun from Earth. Mercury, the solar system's innermost planet, zips past this point in its orbit today. In fact, in this picture (taken on September 1999) from a solar coronagraph on board the the space-based SOHO observatory, shows Mercury positioned very close to the Sun as seen from a near Earth vantage point. The coronagraph uses an internal occulting disk to block the intense solar glare which otherwise hides this sight from ground-based observers. The shadow of the occulting disk is at the center with the Sun's size and position indicated by the white circle. Mercury is the bright dot with a horizontal line (a digital artifact), while faint dots scattered throughout the field are stars. Bright regions of the sun's outer atmosphere are also visible".
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The Solar Spectrum_noao.jpgThe Solar Spectrum and the "missing colors"...67 visiteDa "NASA - Picture of the Day" del 27 Febbraio 2005:"It is still not known why the Sun's light is missing some colors. Shown above are all the visible colors of the Sun, produced by passing the Sun's light through a prism-like device. The above spectrum was created at the McMath-Pierce Solar Observatory and shows, first off, that although our yellow-appearing Sun emits light of nearly every color, it does indeed appear brightest in yellow-green light. The dark patches in the above spectrum arise from gas at or above the Sun's surface absorbing sunlight emitted below. Since different types of gas absorb different colors of light, it is possible to determine what gasses compose the Sun. Helium, for example, was first discovered in 1870 on a solar spectrum and only later found here on Earth. Today, the majority of spectral absorption lines have been identified - but not all".
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ZZ-ZZ-HybridEclypse-Espenak_tse2005_1.jpgAn unusual "Hybrid Solar Eclipse" (1)67 visiteDa "NASA - Picture of the Day" del 6 Maggio 2005:"April's spectacular geocentric celestial event was a rare Hybrid Eclipse of the Sun - such as a total or an annular eclipse could be seen depending on the Observer's location.
For Fred Espenak, aboard a gently swaying ship within the middle of the Moon's shadow track about 2.200 Km west of the Galapagos, the eclipse was total, the lunar silhouette exactly covering the bright solar disk for a few brief moments.
His camera captured a picture of totality revealing the extensive Solar Corona and prominences rising above the Sun's edge".
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