Cometa 17P/Holmes brilha nos céus

Vince

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O até aqui discreto cometa 17P/Holmes, descoberto em 1892 por Edwin Holmes, surpreendeu na 4ªfeira a comunidade astronómica ao aumentar subitamente de brilho em mais de um milhão de vezes, passando de magnitude 17 para 2.8 em poucas horas. É agora observável mesmo a olho nu na constelação Perseu, assemelhando-se a uma pequena e brilhante estrela amarela.

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Incredible comet eruption: from under 17th to 3rd magnitude in hours!
A most amazing eruption is occuring on comet 17P/Holmes which was at 17 mag. at best but on October 24 suddenly began to brighten like crazy: Now (afternoon UTC) it has already reached 3rd magnitude and is easily visible to the naked eye, as reports from Japan indicate: "Perseus does not look 'Perseus' familiar to us due to the bright stellar object now." The comet looks like a bright, yellow star, and only magnification reveals a fuzzy coma around the dusty core. Holmes was discovered in 1892 thanks to a similar outburst, and hope is that the further development will be similar now: the coma should expand over time but stay bright for a week or more. "Following the initial stages of the [1892] outburst, the comet's total magnitude faded only very slowly and it remained visible to the unaided eye for about 3 weeks," advises comet guru John Bortle: "During this interval the coma expanded dramatically (as might be expected), reaching 20'-30' in size before its outer regions began to drop below the sky background." Moreover, there was a second outburst "of almost equal amplitude to the first one, about 75 days following its 1892 November brightening. Thus, I would urge everyone to watch very carefully for a possible repeat of this secondary event about the turn of the year."
http://www.astro.uni-bonn.de/~dfischer/mirror/306.html
 

Vince

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Aparentemente foi um "outburst" idêntico que permitiu a sua descoberta em 1892, diminuindo depois gradualmente de intensidade ao longo de 3 semanas, para ocorrer um novo passado 75 dias.

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(c) Mick Benedetti, Mackay, Queensland, Australia

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(c) Jack Dembicky, Sunspot, New Mexico, USA

STRANGE COMET: Astronomers around the world agree, Comet 17P/Holmes is one of the strangest things ever to explode in the night sky. It's a comet, yet it looks like a planet with a golden core and a green atmosphere:

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Chris Shur of Payson, Arizona, took this picture last night using his 12.5-inch telescope and a Canon XTi digital camera. "The comet was yellow and green, very bright in the viewfinder," he says.

Yesterday, Comet Holmes shocked sky watchers with a spectacular eruption, brightening almost a million-fold from 17th to 2.5th magnitude in a matter of hours. The comet is now visible to the naked eye--even from light polluted cities--high in the northern sky after sunset: finder chart.

The golden hue of Holmes' core is probably the color of sunlight scattered by comet dust, while the green fringe likely signifies an atmosphere rich in diatomic carbon and cyanogen (substances found in many green comets). There are reports that the fuzzball is expanding and taking on a lopsided shape--the first signs of a tail? Amateur astronomers are encouraged to monitor developments. After sunset, point your backyard telescope at the extra "star" in the thigh of Perseus.

Mais fotos e informação em: Space Weather
 

Minho

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Hoje é uma boa oportunidade para vermos... o vento ajuda a limpar as poeiras em suspensão. Além disso, a sua órbita aparente circumpolar permite que seja visível toda a noite..
 

Minho

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Continua o brilho do Cometa. É muito fácil vê-lo a olho nu... a magnitude tem-se mantido estável desde o outburst entre 2 e 3.

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Basta localizar a Cassiopeia e seguir na direcção do horizonte.


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Minho

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O Cometa Holmes continua em expansão. Neste preciso momento (01h13) é muito fácil localiza-lo pois está exactamente sobre o nosso Zénite...

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Rog

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Norte Madeira (500m)
O tempo por aqui na Madeira vai favorável para as observações com ceu pouco nublado, e ontem e no dia anterior tive oportunidade e observar o cometa. Com uns binoculos salta logo à vista aquele que parece um pequeno borrão no céu. Esta foi a foto possível do cometa que tirei ontem à noite:

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Minho

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Não o consigo ver :( .Mas tambem há muitas luzes no local onde moro...

Com luz não é muito fácil ver...
Quanto mais escuro melhor porque o cometa pode ser facilmente confundido com uma estrela, só com bastante escuridão é que se nota que a luz do cometa não é igual à das estrelas mas antes uma luz difusa...
 

Vince

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O Sol deixou de ser o maior objecto do nosso sistema solar

Dêm as boas vindas ao nosso novo astro Rei, de nome Holmes. Embora seja um reinado temporário :)

GIANT COMET

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"Formerly, the sun was the largest object in the Solar System," says University of Hawaii astronomer David Jewett. "Now, Comet 17P/Holmes holds that distinction." On Nov. 9th, a team of Hawaii astronomers led by Rachel Stevenson measured the diameter of the comet's expanding debris cloud: 1.4 million kilometers, slightly larger than the sun itself.

his composite image prepared by Jewett shows a Nov. 9th photo of the comet beside the sun and Saturn for scale. To photograph the comet, Stevenson et al used the 3.6 meter Canada-France-Hawaii Telescope atop Mauna Kea, "one of the few professional instruments still capable of capturing the whole comet in one image," notes Jewett.

Comet Holmes exploded on Oct. 23th and it has been expanding ever since. How big will it get? See for yourself. The comet is visible to the naked eye as a fuzzball in the constellation Perseus. With only a backyard telescope you can see the comet's debris cloud in crisp detail and watch it expand from night to night. Nov. 19th is a good night to look: The comet will glide by the star Mirfak (alpha Persei) and appear to swallow it--a sight not to be missed

http://spaceweather.com/


Incredible Holmes Comet grows bigger than the sun
The Sun is no longer the largest object in our solar system. The recently visible-to-the-naked-eye Holmes comet has achieved that distinction today. The comet has a larger gas and dust cloud known as the coma, and consequently it has a larger diameter than the sun according to astronomers at the University of Hawaii. Scientists don't seem to have a guess as to how big it will ultimately become.

The Holmes coma's diameter on Nov. 9 was 869,900 miles (1.4 million kilometers), based on measurements by Rachel Stevenson, Jan Kleyna and Pedro Lacerda of the University of Hawaii Institute for Astronomy. The sun's diameter, stated differently by various sources, is about 864,900 miles (1.392 million kilometers).Holmes is still visible to the naked eye as a fuzzy star anytime after dark, high in the northeast sky. You can find it by using this sky map.

On Monday, Nov. 19, the comet will create a unique sky watching event according to the Web site Spaceweather.com: "The comet will glide by the star Mirfak [also called Alpha Persei] and appear to swallow it-a sight not to be missed.

"NASA's Hubble Space Telescope has watched the bright core of Comet 17P/Holmes, which mysteriously brightened by nearly a millionfold in a 24-hour period beginning Oct. 23, 2007. "This amazing eruption of the comet is produced by dust ejected from a tiny solid nucleus made of ice and rock, only 3.6 kilometers (roughly 2.2 miles) in diameter," The Hawaiian astronomy team wrote in a press statement. The new image from the Hawaiian observatory also shows a modest tail forming to one side, now just a fuzzy region to the lower-right. That's caused by the pressure of sunlight pushing on the gas and dust of the coma. But the comet is so far away-149 million miles (240 million kilometers), or about 1.6 times the distance from Earth to the sun-that even Hubble can't resolve its nucleus.

Comets have gotten a lot of attention this year. For example, in October NASA said one of its satellites captured the image of a solar hurricane ripping off the tail of a passing comet. The resulting collision saw the complete detachment of the plasma tail of Encke's comet, which was traveling within the orbit of Mercury, NASA said. The comet is only the second repeating, or periodic, comet ever identified and has the shortest orbital period - about 3.3 years - of any known comet. Halley's comet was the first.
http://www.networkworld.com/community/node/21947
 

Luis França

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Um zoom ao interior do cometa Holmes:



E ele só passa para o hemisfério sul em meados de 2009...
 
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Luis França

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Já está visível no céu o cometa 8P/Tuttle

" It was clear 2 nights ago, and my first attempt to spot the comet Tuttle was successful. But it was just visible, only as a very faint smug, no condensation detected, and an estimate of mag 11. But he will become easier, reaching mag 6 in January. This time he is very close to the pole star, so it was not comfortable seeking it with an equatorial mount. Both comet 17P/Holmes and 8P/Tuttle will be riding the skies within naked eye, or simple binocular view at the same time.

Comet 8P/Tuttle is a Halley-type comet in a 13.6-year orbit, passing just outside of Earth's orbit. It will make its appearance on January 2nd just after the 2008 New Year celebrations. 8P/Tuttle is likely to be one of the brighter objects for visual observers in 2008. It could be a binocular or even naked eye object at the beginning of the New Year as it makes a close pass of the Earth at 0.25 AU."

Uauu :surprise:

11-24-07tuttle_holmes.PNG
 

Luis França

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Cometa 17P/Holmes 25nov 10.15 pm


The coma is mot brightening It had actually slightly decreased in integrated magnitude and is now at about magnitude 3 (making it quite a lot dimmer in total magnitude than the Mirfak SURFACE magnitude (which is the way it appears to the naked eye) is quite a lot lower than this.

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Luis França

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The comet 17P/Holmes has astronomers scratching their heads in confusion. The heavenly body just keeps getting bigger - and is now twice the diameter of our sun.

Comets, of course, are no rarity. And it seems like every couple of years or so, one becomes big and bright enough that it can easily be seen from Earth. But the behavior of 17P/Holmes has mystified both hobby astronomers and professionals around the globe.

Rather than shrinking as it gets farther from the sun as most comets do, this one just keeps getting bigger and brighter. At the beginning of the week, the cloud of dust and gas surrounding the comet's core - called the coma - had already grown larger than the sun. Now, just a few days later, the coma's diameter is twice that of the sun - the dust cloud measures some 2.7 million kilometers across whereas the sun is just 1.39 million kilometers across. And there is no sign that it is finished.

"The comet is now a long ways away, but the dust cloud is still growing," Dr. Maciej Mikolajewski from the Torun Center for Astronomy at Nicolaus Copernicus University told SPIEGEL ONLINE. "It's the first time I've ever seen such a thing. I've never seen such a bright comet in my life."


link


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Italian scientist discovers a new comet, to be visible in June, 2008