| Piú viste - The Sun: just a star, like many others... |
A-The Sun-Solar flare from Soho.jpgPowerful solar flare from Soho57 visiteCaption originale NASA: "Seen through the electromagnetic spectrum, the Sun briefly becomes over than 100 times brighter (in the X-rays wavelength) than normal. This is a so-called "Solar Flare" and, when it happens, energetic particles which are emitted from the Sun strike the Earth causing malfunctions in satellite communications or, in some specific areas, a very unusual (and yet very impressive) phoenomenon known as "Aurora Borealis".
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Sun & Comet.jpgA comet approaching the Sun (from SOHO)57 visiteCaption NASA originale:"These 3 frames from SOHO's coronograph were taken two hours apart from each other on April 29, 2000. They show a "sungrazer" (SOHO comet discovery number 111) with a long, bright tail headed toward its fiery encounter.
The Sun itself is hidden behind the coronograph's occulting disk at each frame's upper right".
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ZZ-ZZ-HybridEclypse-Espenak_tse2005_1.jpgAn unusual "Hybrid Solar Eclipse" (1)57 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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Sun-Saturn-IMG001612-br500.jpgSaturn's "superior conjunction"57 visiteIn this SOHO image taken July 21, 2005, the Sun is represented by the white circle in the center. Saturn is the bright object to the left of the Sun. Interestingly, the streak accompanying Saturn is not the rings but a distortion caused by Saturn's brightness. Saturn is approaching "superior conjunction," that is, it will be almost directly behind the Sun from Earth - thus the Cassini spacecraft, in orbit around Saturn, will not be able to send or receive transmissions normally. Regular science data collection has been temporarily suspended.
As Cassini passes closest by the limb of the Sun on July 24 PDT, all the communications will be impossible because of the Sun's radio noise. The spacecraft will regain full communication with Earth on July 27, once again returning Saturn science data. In the meantime, controllers are sending approximately 100 commands per day to test communication status. Cassini radio scientists are taking advantage of this opportunity to study the Sun's corona from its effects on the radio signals that reach Earth.
SOHO (Solar and Heliospheric Observatory Satellite) orbits the Sun parked in one of the five gravitational-neutral spots, called Lagrange Points. This specific spot, called L1, stays in the same place relative to the Sun and the Earth, offering a continuously uninterrupted view of the Sun.
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Solar Flare.jpgLoops over the Sun57 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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Solar_Eclipse~0.jpgA "Diamond Ring" among the clouds57 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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The Sun in Hydrogen-Alpha light (2).jpgThe Sun in Hydrogen-Alpha light56 visiteCaption NASA originale:"The above image, taken in a single color of light called Hydrogen Alpha, records a great amount of detail of the simmering surface of our parent star. The gradual darkening towards the Sun's edge, called limb darkening, is caused by increased absorption of relatively cool solar gas. Further over the edge, a giant prominence is visible, while a different prominence can be seen in silhouette as the dark streak near the image center. Two active areas of the Sun are marked by bright plages. The above amateur photograph of the Sun was taken just through a small telescope and a standard digital camera".
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Sun - Coronal holes.jpgCoronal "Holes"56 visiteCaption NASA originale:"The ominous, dark shapes haunting the left side of the Sun are coronal holes - low density regions 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, 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. These coronal holes, however, have just moved into view near the Sun's equator, and particles escaping them have already caused notable aurora here on Earth. Coronal holes like this one may last for a few solar rotations before the magnetic fields shift and change configurations. Shown in false-color, this picture of the Sun on March 9, 2003, was made in extreme ultraviolet light by the EIT instrument on board the space-based SOHO observatory".
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The Solar Spectrum_noao.jpgThe Solar Spectrum and the "missing colors"...56 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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The Sun from SOHO.jpgAnagliph of the Sun56 visitenessun commento
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Sunspot-reversed-1.jpgSunspot-905: a sign of an incoming new "Solar Cycle"? (2)56 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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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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