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Comets-Comet_Ikeya_Zhang_2.jpgComet Ikeya-Zhang (from Colorado)71 visiteThis lovely early evening view of the comet in Rocky Mountain skies looks northwest over ridges and low clouds. The time exposure was recorded on March 31st from an 8.000 foot elevation near Yampa, Colorado, USA. Sporting a sweeping yellowish dust tail and blue ion tail eight to ten degrees long, Ikeya-Zhang is nestled near the horizon in the northern constellation of Andromeda. To the comet's left is the bright star Mirach or Beta Andromedae while the stretched celestial fuzzball to the comet's right is M 31 or the Andromeda galaxy, the nearest bright spiral galaxy to our own Milky Way. As the days pass, Comet Ikeya-Zhang's apparent motion through the sky is towards the right in this image. Tonight, comet-watchers blessed with clear skies should find Ikeya-Zhang posing perfectly for binoculars and cameras just above M 31, less than two degrees from the center of the bright galaxy.
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Comets-Comet_Ikeya_Zhang_3.jpgComet Ikeya-Zhang - the "ion tail"93 visiteThis composite color image from March 3rd, 2002, captured with a wide-field telescope, shows this active comet's bright, condensed coma and a delightful array of subtle structures in its developing tail. The bluish tail stretches for 5 degrees or so against a background of stars in the constellation Pisces. Cataloged as comet C/2002 C1, improved orbit determinations now make it seem very likely that Comet Ikeya-Zhang has been around here before. Refined calculations indicate this comet's last trip through the inner Solar System was 344 years ago, in 1661, when it was recorded as a bright comet.
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Comets-Comet_Ikeya_Zhang_4.jpgComet Ikeya-Zhang - the "ion tail"88 visiteAs Comet Ikeya-Zhang approached the Sun, it developed a complex blue "ion tail". The "ion tail" is composed of ions that boiled off the nucleus and were pushed away from the Sun by the out-flowing fast-moving particles of the solar wind. Complexity in the tail is created by comet nucleus rotation, variability in the comet surface evaporation rate and variability of the Sun's magnetic field and solar wind.
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Comets-Comet_Lulin-00.jpgComet Lulin is approaching...67 visiteDa "NASA - Picture of the Day", del giorno 2 Febbraio 2009:"How bright will Comet Lulin become? No one knows for sure. Although it is notoriously difficult to accurately predict the brightness of newly discovered comets, Comet Lulin could well become visible to the unaided eye later this month (such as February 2009).
As Comet Lulin moves into the Northern Sky in mid February to rise around midnight, it should at least be spotted by comet watchers with binoculars and a good sky chart. Tracking observations indicate that the comet officially designated C/2007 N3 (Lulin) has now swung by the Sun and is approaching Earth on a trajectory that will bring it within half the Earth-Sun distance in late February.
Comet Lulin's orbit indicates that this is likely the comet's first trip into the Inner Solar System. The comet was discovered by Quanzhi Ye of Sun Yat-sen University, on images obtained by Chi-Sheng Lin at the Lu-Lin Observatory of National Central University.
In this picture, taken from Italy last Friday, are Comet Lulin's coma and tails, one tail pointing away from the Sun, and an anti-tail - dust that trails the comet in its orbit and may appear to point toward the Sun".MareKromium
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Comets-Comet_Lulin-01.jpgStill Comet Lulin66 visiteDa "NASA - Picture of the Day" del giorno 7 Febbraio 2009:"Sweeping through the Inner Solar System, Comet Lulin is easily visible in both Northern and Southern Hemispheres with binoculars or a small telescope. Recent changes in Lulin's lovely greenish Coma and Tails are featured in this two panel comparison of images taken on January 31st (top) and February 4th, 2009.
Taken from dark New Mexico Skies, the images span over 2°. In both views the comet sports an apparent Anti-Tail at the left - the comet's Dust Tail appearing almost edge on from an earth-based perspective as it trails behind in Lulin's orbit.
Extending to the right of the coma, away from the Sun, is the beautiful Ion Tail. Remarkably, as captured in the bottom panel, Comet Lulin's Ion Tail became disconnected on February 4, likely buffeted and torn away by magnetic fields in the Solar Wind.
In 2007 NASA satellites recorded a similar disconnection event for Comet Encke. Don't worry, though: comet tails can grow back".MareKromium
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Comets-Comet_Lulin03-Richins.jpgThe Two Tails of Comet Lulin64 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. MareKromium
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Comets-Comet_Lulin04-Lodriguss.jpgLulin and Saturn near Opposition67 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 Galaxies81 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 Comet110 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 SST63 visitenessun commentoMareKromium
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Comets-Comet_Machholz-Pleiades.jpgComet Machholz and M 4582 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 Machholz82 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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