| Piú votate - The Universe Inside |
VENUS_MERCURY.jpgMercury and Venus from Earth109 visiteGli elementi sino ad ora individuati in questa "esosfera" sono H, He, O2, Na, K e Ca.
I primi 2 elementi giungono, molto probabilmente, dalla corrente di gas ionizzati proveniente dal Sole (ci che comunemente chiamiamo "Vento Solare"), mentre gli altri 4 potrebbero scaturire direttamente dalle rocce esistenti sulla (o al di sotto della) superficie di Mercurio.
Come? Abbiamo tre ipotesi al riguardo (e tutte ugualmente plausibili):
1) potrebbe trattarsi di una lenta "evaporazione" (!) delle rocce superficiali causata dalla (e, per lunghi periodi di tempo, costante) temperatura elevatissima;
2) fenomeni di "outgassing" simili a quelli che - si dice - accadano anche sulla nostra Luna (si tratta di sacche di gas, imprigionate da ere ed ere al di sotto della superficie del Pianeta, che si liberano improvvisamente - a seguito di eventi sismici o di impatti veri e propri - e fuoriescono, ora incendiandosi e generando delle "flares" - fiammate o fiaccole -, ora disperdendosi nell'ambiente circostante); 
(20 voti)
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UnknownOrigin.jpgUnknown Origin (by Dr Marco Faccin)84 visite"...We are not, what we are;
And we are not, what we seem to be.
We are not, what we do;
And we are not, what we feel and fight for.
We are not, what we say;
And we are not, what we think.
We are not, what we are;
And we are not, what we pretend to be..."
Paolo C. Fienga - "Repetita Iuvant"MareKromium
(19 voti)
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SOL442-2N165615279EFFA978P1997R0M1-2.jpgDreaming a New Day...87 visite"...Il Sole che tramonta per alcuni, per altri il Sole che sorge..."
(anonimo)MareKromium
(19 voti)
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Polar Flash.jpgPolar "Flash"85 visitenessun commento
(19 voti)
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Aurora Borealis~0.jpgAurora Borealis over North Dakota89 visiteDa "NASA - Picture of the Day" del 20 Novembre 2005:"This aurora was a bit of a surprise. For starters, on this Friday morning in August 2002, no intense auroral activity was expected at all. Possibly more surprising, however, the aurora appeared to show an usual structure of green rays from some locations. In the above image, captured from North Dakota, USA, a picket fence of green rays stretches toward the horizon. Mirroring the green rays is a red band, somewhat rare in its own right. Lights from the cities of Bismarck and Mandan are visible near the horizon. Large sunspot groups indicate that activity from an active Sun is relatively likely, possibly causing other streams of energetic particles to cascade onto the Earth and so causing more auroras".
(19 voti)
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Moon River.jpgThe Moon over St. Lawrence River134 visiteDa "NASA - Picture of the Day" del 9 Settembre 2005:"Shortly after sunset on September 6th, sky gazers around the world were treated to a lovely crescent Moon in western skies - joined by bright planets Venus and Jupiter.
In this colorful telephoto view from near Quebec City, Canada, the Moon is nestled just above the wide St. Lawrence River. Lights on the horizon are along the river's southern shore. Also known as the evening star, Venus is at the upper left and Jupiter at the upper right, while another prominent celestial beacon, Spica, can be seen shining through the twilight below Venus.
Spica, actually a very close pair of hot blue stars some 260 LY away, is the brightest star in the constellation Virgo".
(19 voti)
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ZZ-ZZ-ZZ-ZZ-ZZ-LunarGreenFlash_laveder_f.jpgA "green flash" over the Moon141 visiteDa "NASA - Picture of the Day" del 26 Agosto 2005:"July's Full Moon looks strangely darkened and distorted in this remarkable telescopic view. The image is one of a series recorded when the Moon was very near the horizon. The long sight-line through a turbulent atmosphere gives rise to the tantalizing optical effects, including the thin "mirage" shape that seems to float just above the Moon's upper edge. Also seen (more easily in the inset), along the Moon's upper edge is a noticeable green rim. Substantial atmospheric refraction produces this prism-like effect -- related to the more commonly witnessed green flash of the setting Sun. Careful inspection of the full image reveals a corresponding red rim along the lower edge, another intriguing signature of atmospheric refraction".
(19 voti)
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Moonrise.jpgThe "Moon Illusion"...From Cape Sounion223 visiteDa "NASA - Picture of the Day" del 23 Giugno 2005:"The Moon was full this month on June 22nd, only a day after the northern hemisphere's summer solstice. Since this solstice marked the northernmost point of the Sun's annual motion through planet Earth's sky, the full Moon rising near the ecliptic plane opposite the Sun was at its farthest south for the year. Only a month earlier, on May 23rd, astronomer Anthony Ayiomamitis recorded this picture of another southerly full Moon rising above Cape Sounion, Greece. The twenty-four hundred year old Temple of Poseidon lies in the foreground, also visible to sailors on the Aegean Sea. In this well-planned, single exposure, a long telephoto lens makes the Moon loom large, but even without optical aid casual skygazers often find the full Moon looking astonishingly large when seen near the horizon.
That powerful visual effect is known as the Moon Illusion".
(19 voti)
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BlackSun in Antarctica.jpgBlack Sun in Antarctica (November 2003)152 visitenessun commento
(19 voti)
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Afterlight.jpgAfterlight (by Dr Gianluigi Barca)146 visitenessun commentoMareKromium
(18 voti)
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Time_to_Change.jpgTime to Change (by Dr Gianluigi Barca)114 visitenessun commentoMareKromium
(18 voti)
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Eternity_in_the_Rainbow.jpgEternity in a Rainbow (by Dr Gianluigi Barca)152 visitenessun commentoMareKromium
(18 voti)
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