| Piú votate - The Sun: just a star, like many others... |
BlueSun.jpgBlue Sun81 visiteDa "NASA - Picture of the Day" del giorno 4 Novembre 2009:"Our Sun may look like all soft and fluffy, but it is not. Our Sun is an extremely large ball of bubbling hot gas, mostly Hydrogen gas. The above picture of our Sun was taken last month in a specific red color of light emitted by Hydrogen gas called "Hydrogen-alpha" and then color inverted to appear blue.
In this light, details of the Sun's Chromosphere are particularly visible, highlighting numerous thin tubes of magnetically-confined hot gas known as spicules rising from the Sun like bristles from a shag carpet.
Our Sun glows because it is hot, but it is not on fire. Fire is the rapid acquisition of Oxygen, and there is very little Oxygen on the Sun. The energy source of our Sun is the nuclear fusion of Hydrogen into Helium deep within its core. No Sunspots or large active regions were visible on the Sun this day, although some Solar Prominences are visible around the edges".MareKromium
(6 voti)
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Solar_Prominence-304erupt_crop.jpgSolar Eruption!76 visiteCaption NASA:"On September 29, 2008, this magnificent eruptive Solar Prominence lifted away from the Sun's Surface, unfurling into space over the course of several hours.
Suspended in twisted Magnetic Fields, the hot plasma structure is many times the size of planet Earth and was captured in this view by the Sun-watching STEREO (Ahead) Spacecraft.
The image was recorded in extreme ultraviolet light emitted by ionized Helium, an element originally identified in the Solar Spectrum. Seen against the brilliant Solar Surface in visible light, such prominences appear as dark filaments because they are relatively cool. But they are bright themselves when viewed against the blackness of space, arcing above the Sun's edge".MareKromium
(6 voti)
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Solar_Corona.jpgIt's a "Corona", but it is not a "Beer", it's a "Crown", but is not a "Cola"...76 visiteDa "NASA - Picture of the Day", del giorno 8 Agosto 2008:"During a Total Solar Eclipse, the Sun's extensive Outer Atmosphere, or Corona, is an inspirational sight. The subtle shades and shimmering features of the Corona that engage the eye span a brightness range of over 10000 to 1, making them notoriously difficult to capture in a single picture. But this composite of 28 digital images - ranging in exposure time from 1/1000th to 2" - comes close to revealing the Crown of the Sun in all its glory.
The telescopic views were recorded near Kochenevo, Russia during the August 1 total Solar Eclipse and also show Solar Prominences extending just beyond the edge of the eclipsed Sun. Remarkably, features on the dark near side of the New Moon can also be made out, illuminated by sunlight reflected from a Full Earth".MareKromium
(6 voti)
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The_Sun_-_Eclipse.jpgAt the Sun's Edge74 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
(6 voti)
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The_Sun-PIA09322.jpgClose-up View of an Active Region of the Sun (March 23, 2007)81 visitenessun commentoMareKromium
(6 voti)
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The_Sun-PIA09332.jpgLeft Limb of North Pole of the Sun (March 20, 2007)78 visitenessun commentoMareKromium
(6 voti)
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The_Sun-PIA09330.jpgThe South Pole of the Sun79 visiteSTEREO, a two-year mission, launched October 2006, will provide a unique and revolutionary view of the Sun-Earth System. The two nearly identical observatories -- one ahead of Earth in its orbit, the other trailing behind -- will trace the flow of energy and matter from the Sun to Earth. They will reveal the 3D structure of coronal mass ejections; violent eruptions of matter from the sun that can disrupt satellites and power grids, and help us understand why they happen. STEREO will become a key addition to the fleet of space weather detection satellites by providing more accurate alerts for the arrival time of Earth-directed solar ejections with its unique side-viewing perspective. MareKromium
(6 voti)
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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
(6 voti)
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Green-Sun.jpgGreen flash from Italy70 visiteCaption originale, da "NASA - Picture of the Day" del 29 Gennaio 2007:"How could the Sun turn green? Difficult to observe, the momentary green flash above the rising or setting Sun has been documented as a phenomenon caused by the atmospheric bending or refraction of sunlight.
Like a weak prism, the Earth's atmosphere breaks white sunlight into colors, bending red colors slightly and green and blue colors through increasingly larger angles.
When the sky is (VERY) clear, a green flash just above the Sun's edge can sometimes be seen for a second or so, when the sun is close to a distant horizon. Still, from a site atop Mt. Autore (altitude 1.850 mt) in Italy, astrophotographer Danilo Pivato captured this dramatic green flash movie. The time between frames varies from over one minute in the beginning to about one second as the flash becomes visible".
(6 voti)
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The Sun-EIT99promcloseG.jpgOur "restless" Sun...and Us!73 visitenessun commento
(6 voti)
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The Sun-CropplumeG.jpgOur "restless" Sun... (6)88 visitenessun commento
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Solar Prominence.jpgSolar "Blow"...76 visiteDa "NASA - Picture of the Day" del 7 Agosto 2006:"Our Sun is still very active. In the year 2000, our Sun went though Solar Maximum, the time in its 11-year cycle where the most sunspots and explosive activities occur. Sunspots, the Solar Cycle, and Solar Prominences are all caused by the Sun's changing magnetic field.
Pictured above is a solar prominence that erupted in 2002, July, throwing electrons and ions out into the Solar System.
The above image was taken in the ultraviolet light emitted by a specific type of Ionized Helium, a common element on the Sun. Particularly hot areas appear in white, while relatively cool areas appear in red. Our Sun should gradually quiet down until Solar Minimum occurs, and the Sun is most quiet. No one can precisely predict when Solar Minimum will occur, although some signs indicate that it has started already".
(6 voti)
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