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Comets-Comet_Lulin03-Richins.jpgThe Two Tails of Comet Lulin54 visiteCaption NASA:"Go outside tonight and see Comet Lulin. From a dark location, you should need only a good star map and admirable perseverance -- although wide-field binoculars might help. Yesterday, Comet Lulin passed its closest to Earth, so that the comet will remain near its brightest over the next few days. The comet is currently almost 180° around from the Sun and so visible nearly all night long, but will appear to move on the sky about 10 full moons a night. Pictured above, Comet Lulin was captured in spectacular form two nights ago from New Mexico, USA.
The central coma of the comet is appearing quite green, a color likely indicating glowing cyanogen and molecular carbon gasses. Bright stars and a distant spiral galaxy are clearly visible in the image background. The yellow dust tail, reflecting sunlight, is visible sprawling to the coma's left trailing behind the comet, while the textured bluish-glowing ion tail is visible to the coma's right, pointing away from the Sun. Over the past few weeks, from the current vantage point of Earth, these two tails appeared to point in opposite directions. Comet Lulin is expected to slowly fade over the next few weeks".MareKromium
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Comets-Comet_Lulin04-Lodriguss.jpgLulin and Saturn near Opposition57 visiteDa "NASA - Picture of the Day" del giorno 27 Febbraio 2009:"Tracking through the constellation Leo on February 23rd, bright planet Saturn and Comet Lulin were both near Opposition -- such as opposite to the Sun in Planet Earth's Sky.
They also passed within only 2° of each other creating a dramatic celestial photo-op. Comet Lulin was near its closest approach to planet Earth at the time, at a distance of some 61 MKM, but was orbiting in the opposite direction.
As a result it swept remarkably rapidly across the background of stars. This telephoto image captures both bright Saturn and greenish Lulin in the same field in a scene not too different from binocular views.
Don't recognize ringed Saturn? The rings are presently tilted nearly edge-on to our view and the brighter Planet is overexposed to record details of the fainter comet. At the upper right, Saturn is marked by multiple diffraction spikes created by the aperture blades in the telephoto lens".
MareKromium
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Comets-Comet_Lulin_05.jpgComet Lulin and distant Galaxies54 visiteCaption NASA, da "NASA - Picture of the Day" del giorno 7 Marzo 2009:"Now fading in our night sky, Comet Lulin has provided some lovely cosmic vistas. Moving rapidly against the background of stars, Lulin briefly posed with the likes of Saturn and Regulus (Alpha Leo).
But here it is seen against a field of distant galaxies. To reveal the faint background galaxies and trace the Comet's fading tail, the remarkable picture is a blended composite of telescopic exposures aligned with the both the stars and the speedy comet. The largest galaxies seen left of the comet's head or coma are cataloged as NGC 3016, NGC 3019, NGC 3020 and NGC 3024 and lie at a distance of 100 MLY or so.
When the exposures were made, on February 28, the Lulin was about 3,6 Light-Minutes from Earth".MareKromium
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Comets-Comet_Mach_Holz.jpgThe C/2004 Q2 Comet97 visiteScoperta solo pochi mesi fa, la Cometa C/2004 Q2 (Machholz) è già chiaramente visibile (a magn. 5 o superiore) nei Cieli del Sud. Ma nessuna paura, non occorrerà viaggiare per vederla: essa si sta rapidamente portando verso i nostri Cieli e, nel frattempo, continuerà ad aumentare il suo splendore (probabilmente sino alla prima metà di Gennaio 2005). La luminosità massima che C/2004 Q2 potrà raggiungere non ci è ancora nota; ciò che sappiamo, invece, è che essa resterà nei "nostri" Cieli per buona parte del 2005 e la potremo anche vedere in prossimità della Stella Polare nei primi giorni di Marzo. L'immagine che Vi proponiamo (da "NASA - Picture of the Day" del 13.12.2004) è stata ripresa ai primi di Dicembre e, come potete vedere, la cometa già ci mostra una consistente "chioma", un'abbondante coda di polveri e detriti (di colore bianco e verde) ed un'abbastanza intricata "coda ionica" (andante verso la Dx dell'Osservatore), che presenta delle increspature verso la fine.
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Comets-Comet_Machholtz.jpgComet Machholtz, from SST54 visitenessun commentoMareKromium
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Comets-Comet_Machholz-Pleiades.jpgComet Machholz and M 4572 visiteRipresa amatoriale (ma di grande effetto scenico) effettuata il giorno 9 Gennaio 2005 dalla Germania - Baviera (località Oberjoch) dal Sig. Stefan Seip. Perfetta la visione della chioma - color verde/acqua - della Cometa (le dimensioni stimate della chioma stessa si aggirano intorno ai 500.000 Km mentre il suo nucleo roccioso dovrebbe avere un diametro compreso fra i 5/7 Km) e molto suggestiva la combinazione (ma si tratta, come ovvio, di un semplice effetto prospettico) fra l'alone blu proprio di M 45 e la coda ionica (anch'essa vagamente bluastra) della Cometa Machholz. Da notarsi che le dimensioni ridotte (ma solo in apparenza) della coda di Machholz (la quale si estende per svariati milioni di Km - 8/10) dipendono anch'esse da un semplice effetto prospettico il quale sfavorisce la nostra osservazione.
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Comets-Comet_Machholz.jpgComet Machholz67 visiteDa "NASA - Picture of the Day" del 5 Gennaio 2005:"Good views of Comet Machholz are in store for northern hemisphere comet watchers in January. Now making its closest approach to planet Earth, the comet will pass near the lovely Pleiades star cluster on January 7th and the double star cluster in Perseus on January 27th as Machholz moves relatively quickly through the evening sky. Currently just visible to the unaided eye from dark locations, the comet should be an easy target in binoculars or a small telescope. In fact, this telephoto time exposure from January 1, shows Comet Machholz sporting two lovely tails in skies over Colorado, USA. Extending to the left, strands of the comet's ion or gas tail are readily affected by the solar breeze and point away from the Sun. Dust, which tends to trail along the comet's orbit, forms the tail jutting down and to the right".
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Comets-Comet_Pojmanski-2.jpgThe "Pojmanski" Comet57 visiteE' passata inosservata, lontana dalla nostra Terra, ed è 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 è 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)60 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 SWAN83 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 Comet54 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 SWAN55 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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