The Sun: just a star, like many others...
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SunFlame-Soho.jpgSolar Prominence58 visiteCaption NASA originale:"What happened to the Sun? Nothing very unusual: the strange-looking solar appendage on the lower left is actually just a spectacular looking version of a common solar prominence. A solar prominence is a cloud of solar gas held above the Sun's surface by the Sun's magnetic field. Pictured above in 2002 October, NASA's Sun-orbiting SOHO spacecraft imaged an impressively large prominence hovering over the surface, informally dubbed a flame. Over 40 Earths could line up along the vast length of the fireless flame of hovering 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".
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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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Sun_Shock-Wave.gifThe "Moreton Wave"54 visiteCaption NASA originale:"Tsunamis this large don't happen on Earth. One week ago (Dec. 2006), a large solar flare from an Earth-sized sunspot produced a tsunami-type shock wave that was spectacular even for the Sun. Pictured above, the tsunami wave was captured moving out from active region AR 10930 by the Optical Solar Patrol Network (OSPAN) telescope in New Mexico, USA. The resulting shock wave, known technically as a Moreton Wave, compressed and heated up gasses including Hydrogen in the photosphere of the Sun, causing a momentarily brighter glow.
The above image was taken in a very specific red color emitted exclusively by hydrogen gas. The rampaging tsunami took out some active filaments on the Sun, although many re-established themselves later.
The solar tsunami spread at nearly 1 MKM per hour, and circled the entire Sun in a matter of minutes".MareKromium
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Sun_Spot.jpgA really beautiful and DEEP SunSpot85 visitenessun commentoMareKromium
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Sunflare.jpgA Sunflare from the Skylab73 visiteUn'immagine d'epoca: l'anno è il 1973 e dallo Skylab (allora conosciuto come "Il Laboratorio Spaziale") ci arriva l'immagine di una "fiaccola" o, se preferite, di un "Solar Flare".
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Sungrazer-2010-SOHO.jpgSungrazer54 visiteCaption NASA:"Intense and overwhelming, the direct glare of the Sun is blocked by the smooth occulting disk in this image from the Sun-staring SOHO Spacecraft. Taken on January 3rd, 2010, an extreme UltraViolet image of the Sun to scale, is superimposed at the center of the disk. Beyond the disk's outer boundary, is a Sungrazer Comet, one of the brightest yet seen by SOHO.
The comet was discovered by an Australian Amateur Astronomer, Alan Watson, while examining earlier images from another Sun-watching Spacecraft, STEREO-A. Based on their orbits, Sungrazers are believed to belong to the Kreutz family of comets, created by successive break ups from a single large Parent Comet that passed very near the Sun in the twelfth century.
Subjected to strong Tidal Forces and intense Solar Heat, this Sungrazer did not survive its close encounter".MareKromium
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Sunjet.jpgA Jet from the Sun60 visiteCaption NASA:"What powers the Solar Wind? Our Sun is known to emit a powerful wind of particles with gusts that can even affect astronauts and satellites orbiting Earth. The cause of the Solar Wind has been debated for decades but is thought to be rooted in Alfvén Waves generated by the ever changing Magnetic Field of the Sun.
Newly released images from the Japanese Hinode satellite appear to bolster this hypothesis, imaging an average of 240 daily plasma jets that are excellent candidates to fuel the outwardly moving Alfvén Waves.
The jets and waves are themselves ultimately created by magnetic reconnection events, rapid events where lines of constant magnetic field suddenly move extremely rapidly, dragging electrons and protons along with them.
On the image left, one such jet is visible in X-ray light. Bright spots show relatively energetic regions elsewhere on the Sun".MareKromium
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Sunrise from Space.jpgSunrise from space...81 visiteCaption NASA originale:"Sunrise seen from low Earth orbit by the shuttle astronauts can be very dramatic indeed. In this view, the Sun is just visible peaking over towering anvil-shaped storm clouds whose silhouetted tops mark the upper boundary of the troposphere, the lowest layer of planet Earth's atmosphere. Sunlight filtering through suspended dust causes this dense layer of air to appear red. In contrast, the blue stripe marks the stratosphere, the tenuous upper atmosphere, which preferentially scatters blue light".
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Sunspot-1002.jpgActive Region 100253 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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Sunspot-10982.jpgSunspot 1098253 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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Sunspot-reversed-0.jpgSunspot-905: a sign of an incoming new "Solar Cycle"? (1)53 visiteDa "NASA - Picture of the Day" del 30 Agosto 2006:"Why is sunspot-905 backwards? Perhaps it is a key marker for the beginning of a new Magnetic Cycle on our Sun.
Every 11 years, our Sun goes through a Magnetic Cycle, at the end of which its overall magnetic orientation is reversed. An 11-year Solar Cycle has been observed for hundreds of years by noting peaks and valleys in the average number of sunspots.
Just now, the Sun is near Solar Minimum, and likely to start a long progression toward the most active time, called Solar Maximum, in about 5,5 years".
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Sunspot-reversed-1.jpgSunspot-905: a sign of an incoming new "Solar Cycle"? (2)54 visiteDa "NASA - Picture of the Day" del 30 Agosto 2006:"An indicator that the Sun's magnetic field is reversing is the appearance of sunspots with the reverse magnetic polarity.
A few weeks ago, one small candidate "reverse sunspot" was sited but faded quickly. Now, however, a larger sunspot with negative polarity is being tracked. This sunspot, numbered 905, appears as the unusual white spot in the above magnetic image of the Sun taken with the SOHO spacecraft a few days ago. In the past few days, Sunspot-905 has actually begun to break apart and might also become the source of coronal mass ejections and explosive solar flares.
Solar astronomers predict that the coming Solar Maximum will be unusually active".
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