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Comets-Comet_Pojmanski-2.jpgThe "Pojmanski" Comet71 visiteE' passata inosservata, lontana dalla nostra Terra, ed stata ben lungi dall'essere spettacolare come lo fu, qualche anno fa, la meravigliosa Hale-Bopp.
Certo, la cometina Pojmanski non aveva - forse - i numeri giusti per entrare nell'Albo delle (cosiddette) Grandi Comete, ma certo che i media (TUTTI!) se ne sono guardati bene dal pubblicizzarla. E la NASA? Leggerete Voi stessi le scarne note prodotte al riguardo nel "NASA - Picture of the Day" del giorno 6 Marzo 2006. Noi, nel nostro piccolo, dato che ci meravigliamo per niente, siamo andati in cerca di fotografie di questa cometa ed abbiamo "scoperto" una straordinaria somiglianza fra C/2006 A1 (la Pojmanski Comet appunto) e la C/2004 Q2 (meglio nota come Machholz Comet). Uguale tipologia - o classe visuale - di appartenenza (nucleo sferico e chioma filiforme) e, soprattutto, uguale colore (ergo uguale - o comunque molto simile - composizione chimica). Deduzione logica: si tratta di "Sister-Comets". Domanda: ci sono altre "sorelle" in arrivo?!?
Have you ever seen a comet? Comets bright enough to be visible to the unaided eye appear only every few years. Right now, however, a new comet has brightened unexpectedly and is visible as a faint streak to the unaided northern observer in the eastern morning sky just before sunrise. Binoculars may help. Comet Pojmanski, officially designated C/2006 A1 and discovered only in January, now sports a turquoise tail several times longer than the full moon. Comet Pojmanski's ion tail is due to gas particles expelled by the comet being pushed away from the Sun by the solar wind, the same wind that ionizes gas in the tail causing its blue tint. Pictured above as it appeared only last week, Comet Pojmanski has now begun to fade as its orbit around the Sun takes it further from the Earth.
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Comets-Comet_Pojmanski-4.jpgThe "Pojmanski" Comet (HR)74 visiteComet Pojmanski flew by planet Earth last weekend (March 4/5, 2006) on a surprise trip through the Inner Solar System. (...)
Pojmanski ultimately showed off a long tail, but also presented some lovely green-blue hues as gas molecules in its tenuous coma and tail fluoresced in the sunlight. Astronomers Adam Block and Jay GaBany recorded this colorful HR view on March 3rd, 2006, in the darkness just before twilight. The picture spans about two full moons on the sky. Comet Pojmanski (C/2006 A1) is outward bound and fading now, still visible in binoculars for northern hemisphere observers.
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Comets-Comet_SWAN-0.jpgComet SWAN107 visiteDa "NASA - Picture of the Day", del 19 Ottobre 2006:" This cosmic portrait recorded October 9th features the lovely blue-green coma of Comet SWAN posing with spiral galaxy NGC 5005 in the northern constellation Canes Venatici. At the time the comet (center) was in the close foreground, a mere 9 LM (Light-Minutes) from planet Earth, with the galaxy a more substantial 60 million LY (Light-Years) distant. Not actually related to a bird, Comet SWAN (C/2006 M4) was so named as it was first spotted in image data from the SWAN (Solar Wind ANisotropies) camera aboard the Sun-staring SOHO spacecraft. Having rounded the Sun, this comet is headed for interstellar space, but first it will make its closest approach to Earth on October 24. With binoculars, northern hemisphere observers can now spot the comet above the northwestern horizon, near the handle of the Big Dipper in the early evening sky".
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Comets-Comet_SWAN-1.jpgThe SWAN Comet65 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.
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Comets-Comet_SWAN-2.jpgComet SWAN66 visiteCaption NASA originale:"Near its closest approach to planet Earth, comet SWAN (C/2006 M4) brightened unexpectedly earlier this week, becoming visible to naked-eye observers under dark night skies. Telescopic observers also noticed dramatic changes in the comet's colorful coma and tail, seen in this view recorded on October 25th, 2006.
To make the picture, images totaling eight minutes in exposure time were stacked and centered on the comet as it moved relatively quickly against the background star field. The picture covers about 1 of the sky.
Northern Hemisphere observers should still find the comet an easy binocular target in the early evening, even though moonlight will increase the overall sky brightness in the next few days.
Look toward the North-Western horizon and the Constellation Hercules".
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Comets-Comet_SWAN-3.jpgComet "SWAN"68 visiteDa "NASA - Picture of the Day" del 4 Ottobre 2006:"A newly discovered comet has brightened enough to be visible this week with binoculars. The picturesque comet is already becoming a favored target for northern sky imagers. Pictured above just last week, Comet SWAN showed a bright blue-green coma and an impressive tail. Comet C/2006 M4 (SWAN) was discovered in June in public images from the Solar Wind Anisotropies (SWAN) instrument of NASA and ESA's Sun-orbiting SOHO spacecraft. Comet SWAN, near magnitude six, will be visible with binoculars in the North-Eastern sky not far from the Big Dipper over the next few days before dawn. The comet is expected to reach its peak brightness this week. Passing its closest to the Sun two days ago, Comet SWAN and will be at its closest to the Earth toward the end of this month. Comet SWAN's unusual orbit appears to be hyperbolic, meaning that it will likely go off into interstellar space, never to return".
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Comets-Comet_Siding_Spring-PIA12836.jpgComet Siding Spring81 visiteCaption NASA:"Is it a bird, or a plane? It's comet Siding Spring streaking across the sky, as seen by NASA's Wide-field Infrared Survey Explorer, or WISE.
The comet, also known as C/2007 Q3, was discovered in 2007 by observers in Australia. The snowball-like mass of ice and dust spent billions of years orbiting in the deep freeze of the Oort Cloud, a spherical cloud of comets surrounding our Solar System. At some point, it got knocked out of this orbit and onto a course that brings it closer to the Sun. Sunlight has warmed the Comet, causing it to shed ices and dust in a long tail that trails behind it.
On October 7, 2009, comet Siding Spring passed as close as 1,2 Astronomical Units from Earth and 2,25 Astronomical Units from the Sun (an Astronomical Unit - AU - is the distance between the Sun and Earth). Now, the comet is leaving the warmer, more hospitable neighborhood of the Solar System and heading back out to chillier parts. In this view, longer wavelengths of InfraRed Light are red and shorter wavelengths are blue.
The comet appears red because it is more than ten times colder than the surrounding stars. Colder objects give off more of their light at longer wavelengths.
An ice cube, for example, pours out a larger fraction of its light at longer InfraRed wavelengths than a cup of hot tea emits".MareKromium
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Comets-Comet_Tuttle_and_M33.jpgComet 8-P/Tuttle and M-3369 visiteCaption NASA:"This gorgeous galaxy and comet portrait was recorded on December 30th, 2007, in the skies over Hoogeveen (NL). The combined series of 60-by-60" exposures finds the lovely green coma of Comet 8P/Tuttle near its predicted conjunction with the Triangulum Galaxy.
Aligning each exposure with the stars shows the comet as a streak, slowly moving against the background stars and galaxy. An alternative composition with exposures centered on the comet, shows the background stars and galaxy as streaks.
The alluring celestial scene would also have been a rewarding one for the influential 18th Century comet hunter Charles Messier. While Messier scanned French skies for comets, he carefully cataloged positions of things which were fuzzy and comet-like in appearance but did not move against the background stars and so were definitely not comets. The Triangulum Galaxy, also known as M-33, is the 33rd object in his famous not-a-comet catalog.
The modern understanding holds that the Triangulum Galaxy is a large spiral galaxy some 3 MLY distant. Comet 8P/Tuttle, just bright enough to be visible to the unaided eye in dark, Northern Skies, is about 40 MKM (such as 2 LM - Light Minutes) away".MareKromium
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Comets-Garrad-PIA12985.jpgComet Garradd77 visiteThis image from the WISE mission was taken on January 2nd, 2010, during the check-out phase, before the start of the WISE survey. It is a mosaic of 3 individual WISE frames spanning an area on the sky about 7 times the size of the full Moon in portions of the constellations Bootes and Canes Venatici.
In the lower right portion of the image there is a streak of orange light. This is most likely a human-made satellite, orbiting Earth at a higher altitude than the WISE telescope, which is at 523 km above the surface. WISE sees many of these as it scans the sky.
Just above the satellite in the image is Comet C/2008 Q3 (Garradd). Comets are balls of dust and ice left over from the formation of the Solar System. As a comet approaches the Sun it is heated and releases gas and dust from its surface that is blown back by the solar wind into a long, spectacular tail. This comet was discovered in August 2008 by Gordon Garradd of the Siding Spring Observatory in Australia. This comet probably comes from the Oort Cloud, a vast collection of remnants from the formation of the Solar System thought to surround it. At the time the comet was observed by WISE, in the constellation Bootes, it was a distance of 419 million kilometers (2.789 Astronomical Units, AU) from Earth. But we are just catching it while it is near the Sun. The orbit calculated for Comet C/2008 Q3 (Garradd) is inclined to the plane of the Solar System by nearly 140 degrees and takes it very far from the Sun (trillions of kilometers). It made its closest approach to the Sun in June of 2009 at a distance of 1.8 AU (270 million km), just outside the orbit of Mars. If it comes back near the Sun at all, it won't be for hundreds of thousands of years.
In the upper left of the image is the impressive globular cluster Messier 3 (M3). M3 was discovered in the constellation Canes Venatici by famous French Astronomer, Charles Messier in 1764, and first seen to be made of stars around 1784 by the British astronomer who discovered infrared light, William Herschel. Globular clusters are huge globs of stars (hence the name) that are found orbiting in the outer reaches of most galaxies. They are thought to form around the same time that a galaxy forms. The Milky Way has over 200 known globular clusters. M3 is one of the largest and brightest globular clusters around the Milky Way. It is just barely visible to the naked eye from a dark location. M3 is made of about half a million stars, thought to be about 8 billion years old. It is about 150 light-years across (1 light-year is equal to 9.46 trillion km) and located some 34,000 light-years from Earth.
WISE sees invisible infrared light, and the colors here are mapped to 3 of the 4 wavelength bands observed by WISE. Blue represents light with a wavelength of 3.4 microns, cyan maps to 4.6 microns and red is lightat 12 microns (a micron is 1 millionth of a meter, and visible light runs from 0.4-0.7 microns). The light from relatively hot objects, like stars in M3, is seen in blue and cyan. Red color represents cooler things, like dust from the comet and its tail. When this image was taken the WISE team was still calibrating the rate of the scan mirror with the motion of the WISE telescope. The rate was not yet perfected and careful examination of this image reveals some stars that are a little smeared and not exactly aligned in the blue/cyan with the red.
MareKromium
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Comets-Hale-Bopp-00.jpgHale-Bopp - HST (1)87 visiteDue immagini della famosissima Cometa Hale Bopp che, qualche anno fa, ci tenne tutti con il naso "all'ins" per qualche tempo.
Queste immagini (HST) nascondono un'Anomalia che hanno evidenziato (a quanto ne sappiamo) solo pochi Ricercatori: alla Sn del nucleo di Hale-Bopp - per di chi guarda il secondo dei due frames - si vede qualcosa (una sorta di "nuvoletta") che gli Scienziati si sono ben guardati dal tentare di interpretare (forse per paura di fare figuracce e/o di dire sciocchezze...). Di che cosa si tratta? Un frammento della Cometa? Un difetto dell'immagine? O forse, come dicono i Ricercatori pi smaliziati, una "Nave Spaziale" che seguiva la cometa - ed ora perdonateci il gioco di parole - "accodandosi" ad essa?!?...
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Comets-Hale-Bopp-01.jpgHale-Bopp - HST (2)67 visiteIn questi 8 frames HST l'Anomalia di cui parlavamo per il quadro precedente si vede ancora solo nelle prime due immagini (26 Settembre e 23 Ottobre). Noi diciamo con chiarezza che si tratta di qualcosa di reale e di inspiegabile; magari non sar una Nave Spaziale aliena che si accodata ad Hale-Bopp ma certo che qualcosa era vicino alla cometa e 1) la seguiva oppure 2) faceva parte di essa.
Le Fonti Ufficiali non hanno detto MAI nulla, ma queste immagini parlano - chiaramente - da sole.
Che cosa, dunque, seguiva e/o accompagnava Hale-Bopp?!?...
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Comets-Hale_Bopp-02.jpgThe "Dust" and "Ion" Tails of Hale-Bopp100 visiteLo splendore e la magnificenza della Cometa Hale-Bopp, durante il suo passaggio del 1997. Nell'immagine, vediamo le due code di Hale-Bopp: la coda ionica (blu intenso), composta da molecole di gas ionizzati - il monossido di carbonio che, quando viene 'eccitato', risplende di luce azzurra - la quale si crea dall'interazione fra le particelle contenute nel Vento Solare ed i gas presenti in prossimit del nucleo della cometa. La coda ionica, in quanto spinta dal Vento Solare, si muove come una sorta di banderuola e si dirige sempre in posizione diametralmente opposta rispetto al Sole (la sorgente del "Vento"). Anche la coda di polveri (grigio-celeste) segue le leggi della coda ionica, ma essa si orienta in maniera meno netta rispetto al Sole. Questa seconda coda formata da particelle di roccia e polveri - le cui dimensioni variano dal micron al metro ed oltre - staccatisi dal nucleo della cometa durante - ed a causa - della sua "Corsa verso il Sole".
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