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DaveOrion · 10-30-2007, 02:37 AM

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2007 Outburst
Between October 23–24, 2007, the comet grew significantly brighter, going from magnitude 17 to magnitude 2.8 in just a few hours, while in the constellation of Perseus.[4][5] The first person to notice anything happening with 17P/Holmes was A. Henriquez Santana on the island of Tenerife in the Canary Islands; minutes later Roman Naves in Barcelona noticed the comet at magnitude 7.3.[5] It became easily visible to the naked eye as a bright yellow "star" in the northeast sky within Perseus.[6][7] 17P/Holmes appeared as the third brightest "star" in Perseus by October 25.[5]

While large telescopes showed fine-scale cometary details, naked eye views of the object revealed a view similar to looking at a star until October 26.[6] After October 26 the object began to appear more comet-like to naked eye observers.[6] During the 2007 outburst, its orbital position took it to near opposition with respect to Earth: Since comet tails point away from the Sun, this means Earth observers were looking nearly straight down along its tail, making it appear as a bright sphere in telescopes. To the naked eye it was easily visible as a fuzzy yellow dot in the sky..

Based on orbital computations, and luminosity before the comet's 2007 outburst, its nuclear diameter is estimated at 3.4 km [8] In late October 2007 the diameter of its coma increased from 3.3 arcminutes to over 13 arcminutes, about half the diameter the the Moon subtends in our sky. At a distance of around 2 AU, this means the true diameter of the coma swelled to around 1 million km, or about 70% of the real diameter of our Sun.[citation needed] If the nucleus of this comet had been located at the centre of the Earth, the edge of its coma during the 2007 outburst would have have been found to be twice as far away from us as our Moon.

http://en.wikipedia.org/wiki/17P/Holmes

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Tim Hickman, an amateur astronomer in Timonium, working from the back yard of his home in Timonium, has captured a nice image of Comet Holmes. The once-dim comet brightened suddenly last week and has stirred excitement among backyard stargazers around the world.

Here's what Tim had to say last night about seeing the comet:

"Frank: As you have undoubtedly heard, Comet 17P/Holmes suddenly brightened to a naked-eye comet on Oct. 24th. After several nights of rain, we in Baltimore got a chance to view it tonight. Naked eye, it looks like a new star in Perseus. Its brightness appears to be between alpha and delta Perseus (ED: two stars of the constellation Perseus) which, with it, form a triangle. It's easy to see even with the moon up. In binoculars you can see it is a fuzzy ball and not a star-like point.

"With my 12.5" Starmaster telescope it shows up as a very unusual object. It has a small, star-like nucleus with a large glowing ball around it, inside of which is an off-centered bright area which could be the beginning of a tail. I have attached a photo of it I took in my back yard in Timonium tonight at 10 p.m. Cheers, Tim Hickman."

http://weblogs.marylandweather.com/2...phed_from.html