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12 December 2010

UK Meteor Fireball 8DEC2010 Video 12DEC2010

UK Meteor Fireball 8DEC2010 video

posted on YouTube by johnnythefixer 93views


This  looks to be a genuine video of this event posted to Youtube by johnnythefixer. The video is taken from a moving vehicle travelling on a bearing of approximately 35 degrees east of north (NNE), along 
Brookside Avenue, Knotty Ash, Merseyside. The video shows a the passage of the meteor from 17:35:09 UT to 17:35:13 UT.



With respect to the fragmenting fireball of 2010 December 08th 17:30 - 17:45 UT, seen from across Britain, Alastair has updated the forum posting detailed above as follows:

I've analysed the available data from 58 reports on the December 8-9 fireball now. The meteor probably happened within five minutes or so of 17:36 UT that evening.

Places across Britain were treated to a view the event, between Swansea in south Wales, Somerset, Dorset and Berkshire in southern England, north to Renfrewshire, Stirlingshire and Fife in central Scotland, as well as across the country from Anglesey off north Wales to the northeast coast of Norfolk in East Anglia.

While the data did not all confirm a single pattern for where the meteor may have been, there was a high probability it had a generally east to west trajectory above central-northern England. Two early reports suggested it had passed almost overhead from the York-Leeds area of Yorkshire. Further analysis indicated a reasonable probability that the fireball had started somewhere above North Yorkshire, the East Riding, or the North Sea offshore of there, as the first point of a "central line" to this broader area, possibly around 10 km east of Filey near 100 km altitude. The visible end was then plausibly over central-western North Yorkshire, or perhaps the adjacent parts of southern County Durham or northern West Yorkshire around the Leeds-Bradford region, centrally again, possibly above the eastern Pennines around the Lofthouse-Masham Moor area of upper Nidderdale, around 55 km altitude. These central line specific locations were around 54.2° N, 0.1° W to 54.2° N, 1.7° W. Likely errors for the heights were at least +/- 10 km, for points along the central line path +/- ~40 km, and for the geographic coordinates,
roughly +/- 0.5°.

This central line is not definitive, merely a best-estimate drawing on what most of the available sightings would at least partly support. However, if we assume it to have been approximately correct, the projected surface path would have been ~105 km long. The fireball's atmospheric trajectory would have been descending at about 23°-24° to the horizontal (or between about 12° to 30° dependent on the error margin), giving an atmospheric path length of ~115 km (or between 108-123 km).

Estimates for the object's visible flight ranged from 1.5 to 10 seconds, according to those who saw all or most of the event, but most (87%), including the few more experienced astronomical observers, favoured a duration of six seconds or less, the majority (68%) between 2 to 4 seconds, with an overall average for all the estimates of 4 seconds. Using this average with the atmospheric path lengths proposed above gives an atmospheric velocity for the meteor, not allowing for deceleration, of ~29 km/sec (error range ~27-31 km/sec), so meteorically slow. This would be consistent with the relatively low start height, as slower meteors tend to ablate lower in the typical ~90-120 km altitude meteor zone.

With this path direction and length, the meteor was likely a sporadic or possibly a late Northern Taurid (recent International Meteor Organization video results have indicated the Northern Taurids probably continue their activity until December 10, rather than ending in late November as we have long supposed). The path direction would have to have been much more northeast to southwest, the estimated velocity somewhat swifter, the path length greater and angled more shallowly to the horizontal for the event to have been a potential Geminid, given that that shower's radiant had barely risen to the northeast when the meteor happened.

Thirty-five observers commented that the object broke apart, probably in a severe fragmentation event quite late in its apparition, producing around 4 to 7 main pieces and likely a lot of smaller sparkling droplets. Seven people suggested the meteor had left a short-lived persistent train for around two seconds, though two people saw no train at all (possibly because of different local observing conditions).

Colours mentioned in the main fireball included white (30%), green and orange (21% each), yellow (19%), blue (7%) and red (2%), while those in the tail or the persistent train (not everyone was clear about the distinction) were orange and blue (29% each), green and yellow (14% each), or red and white (7% each). Nobody in the open air reported hearing any sounds associated with the meteor.

The lack of acoustics and the relatively high end height counted against the possibility of any meteorites having fallen from the event, and increased the difficulty of identifying the more likely fall zone. Any solid objects continuing along the centre line would have splashed-down into the Irish Sea around 20 km offshore of the Barrow coastline of Cumbria. The Irish Sea would have been the more probable fall area overall, or the adjacent lands of the British Isles. No such fall reports consistent with the timing of this event have yet been received, however.

Other links, and any updates that may be possible to this report subsequently, will be found on the SPA's "Recent Fireball Sightings" webpage, at:

http://www.popastro.com/sections/meteor/fireball_sightings.htm 

Many thanks to all contributors so far. Any further reports would still be most welcome!

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
Meteor homepage: http://www.popastro.com/sections/meteor.htm
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, 
please)
-- 
reported by David Entwistle

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