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IAM1
B.V. Info-a-holic
Joined: Sep 01, 2006
Posts: 5474
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 Posted: Tue Nov 13, 2007 9:24 pm Post subject: Comet Holmes Bigger Than The Sun! |
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Comet Holmes Bigger Than The Sun
Nov. 9, 2007
By David Jewitt
'Spectacular outbursting comet 17P/Holmes exploded in size and brightness on October 24. It continues to expand and is now the largest single object in the Solar system, being bigger than the Sun (see Above Figure). The diameter of the tenuous dust atmosphere of the comet was measured at 1.4 million kilometers (0.9 million miles) on 2007 November 9 by Rachel Stevenson, Jan Kleyna and Pedro Lacerda of the University of Hawaii Institute for Astronomy.'
Summary
Formerly, the Sun was the largest object in the Solar System. Now, comet 17P/Holmes holds that distinction.
They used observations from a wide-field camera on the Canada-France-Hawaii Telescope (CFHT), one of the few professional instruments still capable of capturing the whole comet in one image. Other astronomers involved in the UH program to study the comet include Bin Yang, Nuno Peixinho and David Jewitt. The present eruption of comet Holmes was first reported on October 24 and has continued at a steady 0.5 km/sec (1100 mph) ever since. The comet is an unprecedented half a million times brighter than before the eruption began. This amazing eruption of the comet is produced by dust ejected from a tiny solid nucleus made of ice and rock, only 3.6 km (roughly 2.2 miles) in diameter.
Caption: (Left) Image of comet Holmes from the 3.6-meter Canada-France-Hawaii telescope on Mauna Kea showing the 1.4 million km diameter coma. The white ''star'' near the center of the coma is in fact the dust-shrouded nucleus. (Right) the Sun and planet Saturn shown at the same scale for comparison. (Sun and Saturn images courtesy of NASA's SOHO and Voyager projects). [The same image (much larger) is available here as a 300 dpi tif file at link below.]
http://www.ifa.hawaii.edu/faculty/jewitt/images/holmes_jewitt_071109.tif
holmes_jewitt_071109.tif (image/tiff Object)
The new image also shows the growth of a tail on comet Holmes (the fuzzy region to the lower right in the comet picture), caused by the pressure of sunlight acting on dust grains in the coma. Over the next few weeks and months, the coma and tail are expected to expand even more while the comet will fade as the dust disperses. Comet Holmes showed a double outburst in November 1892 and January 1893. It is not known if the present activity in the comet will follow the pattern from 1892, but continued observations from Mauna Kea are planned to watch for a second outburst. Most comets show small fluctuations in brightness and some have distinct outbursts. The huge event on-going in comet Holmes is unprecedented, however.
The orbit period of comet Holmes is about 6 years, putting it in the class of Jupiter Family Comets whose orbits are strongly influenced by Jupiter. These objects are thought to have spent most of the last 4.5 billion years orbiting the Sun beyond Neptune, in a region known as the Kuiper Belt. Holmes probably was deflected into its present orbit within the last few thousand years and is losing mass as it evaporates in the heat of the Sun. In another few thousand years it is likely either to hit the Sun or a planet, be ejected from the Solar system, or simply die by running out of gas.
http://www.ifa.hawaii.edu/faculty/jewitt/kb.html
Kuiper Belt Kuiper Belt Kuiper Belt Kuiper Belt Kuiper Belt Kuiper Belt K uiper Belt Kuiper Belt Kuiper Belt |
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dangermite
B.V. VIP - Contributor
Joined: Jun 25, 2006
Posts: 3586
Location: Land o´ Lincoln
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| Posted: Wed Nov 14, 2007 7:38 am Post subject: |
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| Pretty cool, IAM1. Just gonna move this over to the Space Forum. Might be more appropriate there. |
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_________________
. . . et in Arcadia ego . . . |
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IAM1
B.V. Info-a-holic
Joined: Sep 01, 2006
Posts: 5474
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| Posted: Tue Nov 20, 2007 11:39 am Post subject: |
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| dangermite wrote: |
| Pretty cool, IAM1. Just gonna move this over to the Space Forum. Might be more appropriate there. |
Thanks dangermite! Glad you like it!  I must have been tired when I posted this. It definitely belongs in the forum you're moving it to  . |
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IAM1
B.V. Info-a-holic
Joined: Sep 01, 2006
Posts: 5474
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| Posted: Mon Nov 26, 2007 11:31 pm Post subject: |
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Comet Holmes and the case of the Disappearing Tail
Perseus and the Medusa. The beautiful comet 17P near the Mirfak. The sky is very bright (80% Moon).
By Anton Wylie
Published Sunday 18th November 2007
The Web is abuzz about Comet Holmes.
Comet 17P/Holmes had been expected to make just another routine ultra low visibility departure from perihelion passage this year. But in a record for a comet, it unexpectedly brightened by a factor of around a million on October 24, making it more reminiscent of a stellar nova explosion.
"Amateur astronomers the world over have been stunned and amazed by the weirdest new object to appear in the sky in memory," wrote Sky and Telescope .
"The comet shocked skywatchers as it went from a dim 17th magnitude then suddenly to 3 magnitude" wrote Theo from the Pacific Northwest.*
Holmes brightened from below the threshold of binoculars to being clearly visible with the unaided eye. The outburst presented as a circular fuzzy patch in the constellation of Perseus, and has proceeded to grow in size. The comet was then reported to have spawned a tail.
More drama was to come.
Spaceweather currently reports that "last Friday, astronomers watched in amazement as the comet's tail broke off!".
And Comet Holmes may yet make further news, should this be a prelude to the full-on fissioning of the comet's core into several pieces. The comet is expected to remain visible to the naked eye for some weeks.
Why did Comet Holmes flare up?
Yet Comet Holmes has brightened up unexpectedly on a previous occasion: that of November 1892 led to its discovery by E. Holmes in England. It was subsequently determined to be a periodic comet, with a revolutionary period of about every seven years. You can see its orbit in relation to other planets courtesy of Larry's animation here.
Much less, though, has been made of the fact of where it was when the current flare-up occurred. The Armagh Observatory's website puts the comet at some 230m miles from the Sun - a distance from, and quite a long time after, its closest point to the Sun, which occurred on May 4, 2007.
In the accepted view, comets are thought to comprise rocky and icy solids in a mixture termed "rocky snowballs" by some and "icy rockballs" by others. They get brighter and sprout tails as the "icy" component is thought to sublimate from solid to gaseous state under the influence of solar heating, which typically begins affecting them at a point just inside the orbit of Jupiter. This gives rise initially to an expanding light-reflecting aura known as the coma, which is then "blown away" in the opposite direction from the sun by the solar "wind".
Multiple repeated thermally-induced mechanical stresses are thought to give rise to a cometary aging process, whereby a large single core disintegrates after multiple closer solar encounters into much smaller fragments. When such orbiting debris intersects the Earth's orbit, it can give rise to meteor showers.
Professionals, however, are well aware of exceptions.
Comet Wirtanen fragmented in 1957 when it was just inside the orbit of Saturn. Conversely, in December 1680, the eponymous comet studied by Halley and Newton passed intact within 100,000km of the Sun.
Things took a more serious turn, as reported in 1990 by New Scientist.
The object named Chiron, discovered in 1977 as an asteroid orbiting between Jupiter and Neptune, had begun to "look like a gigantic comet".
Forget for a moment the stuff comets are made of - here, the very categories of astronomy were under attack. |
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BloodStone
B.V. Info Seeker
Joined: Apr 29, 2005
Posts: 1942
Location: Poconos, USSA
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| Posted: Tue Nov 27, 2007 12:20 am Post subject: |
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could this be what brought down the towers?
you seem to believe everything else ,I just thought I would ask,and keep your name on every topic . seems you like the attention. 
BloodStone... |
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IAM1
B.V. Info-a-holic
Joined: Sep 01, 2006
Posts: 5474
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| Posted: Mon Jan 07, 2008 6:53 pm Post subject: |
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| I like sharing information with others, which you've obviously got a problem with that. You seem to enjoy harassing and belittling others, is that a hobby or does it just come naturally for you? |
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