Cometa 17P/Holmes brilha nos céus

Luis França

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The description for a photo on Nov 27th says that it was eight times the volume of the sun. Keep in mind, that is volume not diameter.

"Going, going, but not quite gone... Compare how Comet Holmes has increased in size and decreased in brightness in these two identically scaled images. Holmes was as voluminous as the sun in the November 11 image, but eight times the volume in the November 27 photo. Canon D40 images."
 

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Continua deslumbrante (a 4 de Dezembro) e também "entra em cena" na conjunção de 23 Dezembro, juntamente com o Tuttle e o Boattini. :)

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Para alguns o cometa já deu o que tinha a dar; não será bem assim pois ele só passa para o hemisfério sul em meados de 2009 e como continua a crescer deixo aqui algumas valores medidos por astrónomos:

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7/P Holmes coma Diameter = roughly 3.9 million km
17/P Holmes coma Surface Area = 47.78 million square km
17/P Holmes coma Volume = 31.06 million cube km

VOLUME OF 31.06 MILLION!!!

Heres a reference, the Sun.

Suns equatorial diameter = 1.39 million km
Suns Surface Area = 6.07 million square km
Suns Volume = 1.406 million cube km

So that means comet 17P is actually 22x's larger then the Sun when we consider its volume. Which I believe would be the most accurate form of relationship in 3d measurements.

17P - 31.06
Sun - 1.40

IT IS 22x's the size of the sun. People say its 3x's bigger then the sun but thats only the diameter measured cross, a 2 dimensional relationship. If you calculate the volume of both the Sun and Holmes Coma using thier diameters given you will get holmes coma 22.09 times larger, in volume that is. However, I'm not declaring Holmes is denser then the sun, the sun still holds its crown as the heaviest object in the solar system so no, the sun isn't going to change its galactic orbit over this. But, it IS 22 times larger in scope. No, this comet doesn't have a tail, the coma is still egg shaped so these calculations hold a good value for sheer size if it were placed next to the sun.

What I feel might, might happen....Comet holmes goes through another outburst in late Dec, early Jan 08. If this happens, I wonder if the current coma would glow bright in the sky. Knowing the coma is larger then the moon from naked eye observations means it would be a fantastic light show in the night sky.



Já agora Rog, a magnitude mantém-se 3.0 e continua visível no céu (equivalendo a Sirius em brilho).
Por estas e por outras, este é um cometa "sui generis" de que ninguém fala na imprensa. Não seria conveniente, por razões óbvias...

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E neste link podem ver-se o Holmes e o Tuttle :
 

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11 Dezembro 2007

Continua com a magnitude de 3.1 ... (estranho! dizia-se há um mês que ia enfraquecer como costuma acontecer com os outros "cometas" mas pelos vistos enganaram-se; este é diferente!!)


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Missing comet baffles scientists

University of Hawaii astronomers and colleagues from around the world have searched in vain for a missing comet that was supposed to appear by October.

The cosmic mystery forced the rescheduling of NASA's Extrasolar Planet Observation and Deep Impact mission to the comet 85P/Boethin. The EPOXI mission will now go to a different comet.

"We were astonished when it wasn't there," said UH astronomer Karen Meech, who led the effort to try to find Boethin.

The Subaru 9-meter telescope and 3.6-meter Canada-France-Hawaii Telescope on Mauna Kea, both with sensitive wide-field cameras, joined observatories worldwide in the futile hunt for 1-mile-long, half-mile-wide Boethin.

Although there is a chance Boethin could be observed next fall, astronomers needed to find it now to put the Deep Impact spacecraft on the right trajectory, Meech said.

Comet Hartley 2, Boethin's substitute for the $40 million mission, is just as interesting scientifically, said Tom Duxbury, EPOXI project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. But it will take two years longer to reach, he said.
 

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Os indianos estão e sempre estiveram muito mais "à frente" do que nós. Um exemplo da imprensa diária:

Sun no longer the biggest body in the solar system

The Sun is no longer the largest object in the Solar System: That honour has fallen temporarily to a previously innocuous comet. The comet, called 17P Holmes, shot to prominence in late October when its brightness suddenly increased roughly a million-fold.

Since then, both its size and its profile have grown — earlier this month astronomers at the University of Hawaii Institute for Astronomy declared that its diameter had outstripped that of our Sun.

Many ancient cultures interpreted comets as portents of doom. Should we be worried? Aren’t comets supposed to be small? It seems ridiculous that the titanic Sun could be dwarfed by a comet.


Os srs. jornalistas nacionais deviam seguir o exemplo.
 

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O Holmes a passar perto das Plêiades no dia 15 de Dezembro.

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E ainda a sua rota até Janeiro 2008:

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"Comet 17P Holmes is fading away. I could not see it in the moonlight and I can barely make it out by stacking 6 photos with Registax stacking software. This photo was produced by stacking six 20 second exposures. Comet Holmes is just barely visible."

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As notícias não são muito claras mas parece que o Holmes já tem cerca de 8x o diâmetro do Sol.
Mais uma fotocomposição desde o início do fenómeno com a última imagem de 27 Dezembro:

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Ainda é possível observar o Holmes a seguir ao por-do-sol, olhando para Norte:

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"The comet is easy to see with the naked eye from dark-sky sites and is growing more gigantic every day," he says. Indeed, the main problem with telescopic observations is fitting the oversized comet in the eyepiece. Binoculars and small telescopes work best. Look north after sunset.

"Comet 17P/Holmes is still big and beautiful," reports Chris Schur of Payson, Arizona. "Here is the latest deep exposure from last night."

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O Holmes está gora avermelhado mas ainda visível com telescópio. Uma fotografia do dia 1 de Janeiro 2008.

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TIME BOMB? Tick-tock, tick-tock. It's been 71+ days since Comet 17P/Holmes exploded on Oct. 24, 2007, brightening almost a million-fold to naked-eye visibility. This means it could be time for another explosion. To understand why 71 days is significant, we turn back the clock to the year 1892.
Comet Holmes was discovered on Nov. 6, 1892, by astronomer Edwin Holmes while he was making observations of the Andromeda Galaxy. He noticed the comet not far from Andromeda when it "exploded"--a brightening akin to that of Oct. 2007. It was quite a sensation as observers around the world suddenly were able to see the comet with the naked eye. Interest faded as the comet expanded and dimmed, but then, 71 days later on Jan. 16, 1893, Holmes exploded again! Deja vu?

No one knows why Holmes occasionally explodes. Theories range from tiny moonlets crashing into the comet's icy surface to great comet-caverns collapsing under the stress of sunlight. The interval 71 days may have no significance at all. But on this anniversary of a double explosion, it reminds us to keep an eye on Comet 17P/Holmes.

Finding the comet is easy. Tonight, after sunset, take your binoculars outside and scan the northern constellation Perseus: sky map. Holmes is readily visible as a big pale fuzzball near the variable star Algol. On January 21-23, the comet will pass directly in front of Algol; the view through a backyard telescope should be dynamite!

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