| Piú votate - Asteroids and Comets |
Man-Made_Nebula.gifMan-Made Nebula, such as: a warning sign of the Kessler Syndrome (GIF Movie)79 visiteCaption NASA:"What's that cloud drifting in space? It's not an astronomical nebula because...those appear to stay put.
Atmospheric clouds don't look like this.
The answer to last week's sky mystery turned out to be orbiting and expanding debris from the upper stage of a failed Russian rocket that exploded unexpectedly. The cloud became visible to unaided southern hemisphere observers, and its cause was initially unknown. The above time lapse movie shows the cloud drifting as seen from Australia. Streaks in and near the cloud are likely large pieces of debris. The debris cloud is more than an astronomical curiosity -- particles from this cloud and others could become projectiles damaging existing satellites. As the cloud disperses, many particles will fall to Earth, but many more may help make low Earth orbit an increasingly hostile environment".MareKromium
(7 voti)
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McNaught-09.jpgThe "Tail" of McNaught, at Sunset...63 visiteCaption NASA originale:"What's happening over the horizon? Many a sky enthusiast who thought they had seen it all had never seen anything like this. To the surprise of many Northern Hemisphere observers, the tail of Comet McNaught remained visible even after the comet's head set ahead of the Sun. What's more, visible were bright but extremely rare filamentary striae from the comet's expansive dust tail. The cause of dust tail striae are not known for sure, but are possibly related to fragmentation of comet's nucleus. The last comet to show prominent striae was Comet Hale-Bopp in 1997.
Pictured above, the tail of Comet McNaught was caught just after Sunset last Friday above the Carnic Alps of Northern Italy".
(7 voti)
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McNaught-07.jpgComet McNaught (8)57 visiteCaption NASA:"Comets grow bright when they're close to the Sun, basking in the intense solar radiation. Of course, they're also usually impossible to see against the overwhelming scattered Sunlight. But surprising Comet McNaught - whose January 12, 2007, closest approach to the Sun (perihelion passage) was well inside the orbit of Mercury - gave an enjoyable performance in bright blue daytime skies. In fact, comet expert David Levy captured this remarkable inset (upper left) telescopic view of McNaught within an hour of perihelion, with the comet in broad daylight only about 7° away from the Sun's position.
Stefan Seip's wider daytime view of the comet and fluffy clouds was recorded approximately a day later. Seip used a polarizing filter and a telescope/camera set up near Stuttgart, Germany.
No longer visible in broad daylight, Comet McNaught is now touring twilight Southern Skies".
(7 voti)
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McNaught-00.jpgComet McNaught (1)56 visiteCaption NASA:"Early morning risers with a clear and unobstructed eastern horizon can enjoy the sight of Comet McNaught (C/2006 P1) in dawn skies over the next few days. Discovered in August by R. H. McNaught (Siding Spring Survey) the comet has grown bright enough to see with the unaided eye but will soon be lost in the glare of the Sun. Still, by January 11 sun-staring spacecraft SOHO should be able to offer web-based views as the comet heads toward a perihelion passage inside the orbit of Mercury. This image captures the new naked-eye comet at about 2nd magnitude in twilight skies near sunset on January 3rd. After rounding the Sun and emerging from the solar glare later this month, Comet McNaught could be even brighter".
(7 voti)
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Comets-Comet_SWAN-1.jpgThe SWAN Comet57 visiteComet SWAN, which unexpectedly flared up to naked-eye brightness, has been showing detail in its ion tail that might be described as ghostly. The ion tail is made of ionized gas, energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind itself is quite structured and sculpted by the Sun's complex and ever changing magnetic field. Following the wind, structure in Comet SWAN's tail can be seen to move outward from the Sun even alter its wavy appearance over time.
The blue color of the ion tail is dominated by recombining Carbon Monoxide atoms. The color of the coma surrounding the head of the comet is tinged green by slight amounts of the molecule cyanogen. This week (6-13 Nov. 2006) may be the best remaining chance for Northern Hemisphere observers to see the fading interplanetary snowball. SWAN has now past both the Earth and the Sun and will fade as it moves away from the Earth and heads out into the vast space between the stars.
(7 voti)
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![Comets-Halley-Giotto-86hc145[1].jpg](albums/userpics/10008/small_Comets-Halley-Giotto-86hc145%5B1%5D.jpg "Nome del file=Comets-Halley-Giotto-86hc145[1].jpg
Dimensione del file=634KiB
Dimensioni=1756x1788
Aggiunta il=Set 17, 2006")
Comets-Halley-Giotto-86hc145[1].jpgThe "Halley Comet", from Giotto56 visitenessun commento
(7 voti)
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Asteroids-Asteroid_2002JF56-PIA09230-00.jpgUnknown Asteroid56 visiteUn'immagine non particolarmente suggestiva, ma comunque importante, molto importante: ci arriva dalla Sonda New Horizons che sta calibrando le proprie fotocamere, in attesa (una LUNGA attesa...) di giungere nello Spazio di Plutone e quindi nella Fascia di Kuiper, tra il 2015 ed il 2020...
(7 voti)
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Itokawa-3.jpgItokawa and Hayabusa's shadow59 visiteDi asteroidi dalla forma bizzarra ne abbiamo visti davvero molti, ma mai così curiosi quanto Itokawa. Questa immagine, che peraltro possiede una definizione davvero ottima, ci mostra l'ombra della Sonda Hayabusa che si staglia, perfettamente definita, sul versante di Itokawa illuminato dal Sole.
Ed ora, qualche informazione su Hayabusa direttamente dall'Agenzia Spaziale Giapponese:"HAYABUSA's return trip from Earth to Itokawa is 2 billion kilometres long. Needless to say, such a long journey requires a large amount of fuel. HAYABUSA is the first long-distance interplanetary probe to use an ion engine as its main propulsion device.
Traditionally, propulsion occurs when gas is emitted at high speed. Until now, the main form of propulsion has consisted of super-heated gases created by burning fuel with an oxidant. An ion engine, in contrast, gets thrust from ionized gas accelerated by electricity. Therefore, it can accelerate much faster than by traditional propulsion, and only requires a tenth of the fuel.".
(7 voti)
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Itokawa-2.jpgItokawa in natural colors59 visiteThis is the composite color image of Itokawa taken at September 12, 2005. This image composed of three images with different filters as red, green and blue. The irregular shape of this body is clearly seen and Hayabusa science observations started.
Hayabusa will approach Itokawa at a distance of 0,3 BKM from Earth. At this distance, even light takes about 17' to travel, so if Hayabusa needed an emergency instruction from Earth, it would not reach the probe in time. Therefore, Hayabusa is designed to pilot itself: to use the on-board camera and laser to read the asteroid's geography and judge when to approach it and where to land.
The exploration of small Solar System Bodies will contribute to improve our understanding of the Earth itself and it will also ead us to a more comprehensive interpretation of the constituents and potential resources that these celestial objects may have.
(7 voti)
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Itokawa.jpgHayabusa's "shadow"!58 visiteWhat's that unusual looking spot on asteroid Itokawa? It's the shadow of the robot spacecraft Hayabusa that took the image. Japan's Hayabusa Mission arrived at the asteroid in early September and has been imaging and maneuvering around the floating space mountain ever since. The above picture was taken earlier this month (November 2005).
Asteroid Itokawa spans about 300 mt.
One scientific goal of the Hayabusa mission is to determine out how much ice, rock and trace elements reside on the asteroid's surface, which should give indications about how asteroids and planets formed in the early Solar System. A can-sized robot MINERVA that was scheduled to hop around the asteroid's surface has not, so far, functioned as hoped. Later this month, Hayabusa is scheduled to descend to asteroid Itokawa and collect surface samples in a return capsule. In December, Hayabusa will fire its rockets toward Earth and drop the return capsule down to Earth's Australian outback in 2007 June.
(7 voti)
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Tempel1-Z-I-HST.jpgThe impact sequence from HST67 visiteDa "NASA - Picture of the Day", del giorno 18 Luglio 2005:"It was a human-made event visible across the Solar System. At the direction of terrestrial scientists, a refrigerator-sized probe from the Deep Impact mission struck Comet Tempel-1 on July 4 at over 35.000 Km per hour.
The unexpectedly bright explosion was not nuclear but rather originated from a large plume that reflected back sunlight. Pictured above is how the event looked to the Earth-orbiting HST. A large cloud of bright material is seen emanating from the comet's nucleus and then dispersing. The area encompassing the comet became over two times brighter in the hours after the impact. Astronomers will continue to study the images and data returned by Deep Impact to better determine the nature of Comet Tempel-1 and discern clues about the formation dynamics of the early Solar System".
Nota: leggendo questa poche righe non serve uno Scienziato per capire che, al momento, l'unico scopo chiaro dell'esperimento era quello di fare propaganda...
(7 voti)
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Tempel1-Z-HST-1-061405.jpgDeep Impact from HST60 visiteLa NASA - anzi: l'attuale Amministrazione USA - dunque, ce l'ha fatta: per festeggiare il 4 di Luglio, dato che la siccità domina in quasi tutti gli Stati Uniti ed i "fireworks" sono stati vietati, i fuochi artificiali si è pensato bene di andare a farli nello Spazio. Abbiamo letto i commenti della Dott.ssa M. Hack su questo evento e, sebbene le sue motivazioni sul fatto che sia stata una cattiva idea sono diverse dalle nostre, per stavolta ci troviamo in sostanziale sintonia con quanto espresso da questo 'Monumento Vivente' della divulgazione scientifica in Italia. Però il punto nodale di tutta le questione è, a nostro parere, un altro: quando la Francia, in passato, ha utilizzato Mururoa come poligono nucleare, il Mondo si è indignato, ma l'esperimento è stato eseguito lo stesso. Ora sembra che qualcuno abbia deciso di inziare a fare esperimenti 'sparando addosso' a corpi celesti ed il fatto che non sia stata usata (ancora...) una testata nucleare, secondo noi, non rende il fatto meno grave.
(7 voti)
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