Location: Chemistry/Physics Building, MUN
Time: 8:00 pm
Doug gave his usual introduction.
Lots of clouds.
Phil was going to speak about the 1904 Shelbourne meteorite, but these events seemed more topical. Over the course of about a month he was involved in two events: the "Fergus" (October 15), southern Ontario, and "Buzzard Coulee" (November 20/21), Alberta and Saskatchewan bolides. The Mary Cornfield fragment of the Shelbourne meteorite was shown in a slide to familiarise people with the appearance of a meteorite. Phil explained the basics of meteorites.
On October 15, 5:30 am, 7 all-sky cameras in Ontario detected a bolide. At an estimated 17km/s, it could possibly drop fragments. Phil showed us some sample camera shots. These were made into a video with about 40 shots stacked to make one video frame. The bolide appeared to be -4 in magnitude and had a rough north to south path. The group solved this to obtain an orbit for "Fergus" with an aphelia around Mars, and a high inclination to the ecliptic of 20 degrees. Probably 1-2 kg fell, and a fall ellipse was determined. About 250 notices were distributed on properties in this area.
However, reports from people in the fall ellipse indicated seeing the meteor in unexpected directions. From these it would appear to have fallen somewhere south of the 401 highway, instead of the original fall area, which was to the north. The group determined this turn of events occurred because the meteor was lost in the clouds near the horizon. Unfortunately, this new fall area can't be determined with any great accuracy. No fragments have been found yet.
The event on November 20/21 ended up being more fulfilling. This was a bright fireball, with a huge area over Alberta and Saskatchewan during evening rush hour. Phil showed us some videos. The hilight was the lady at the Husky gas station, rushing to put the nozzle back in the pump after the night became bright daylight! Many of these can be found on YouTube.
There were several measurements available. According to infrasound measurements (some were over 2000 km away) the energy was equivalent to 0.4 kton of TNT. The all-sky cameras were too far away. There was one uncalibrated radiometer. From videos, the speed was estimated to be 14km/s. The mass was estimated at 10 000 kg. If the meteoroid was spherical, and of the typical stony composition, it would have been about 1m in radius. From the videos it had a rough north to south path and probably ended up 30 km south of Lloyd (a 60 degree entry angle).
A search team was organised. Initially, nine fragments were found on or near a frozen cattle pond at Battle River, south of Lone Rock, Saskatchewan. Graduate student Ellen Milley spotted the first on the lake as they were driving by. The largest fragment recovered from this fall weighed in at 13 kg. Phil explained how the initial days worked out, and how later a larger group searched the surrounding fields (with the farmer's permission). A fellow by the name of Warren Wiley found a 7 kg fragment, after spending nearly 3 days looking for a piece for his son. So far, 70 fragments have been found.
[Here is a short article from the National Post.]
There followed a short question and answer session. Phil donated a book on Canadian meteorite falls to our library.
Chris announced the Ioptron has arrived and Joe is in the process of checking it out. We got this mount and accompanying small scope to fulfill a donation from Admiralty House.
The iconoclastic John Carter presented a book by Henrik Svensmark and Nigel Calder, "The Chilling Stars". The book is based on the hypothesis that the sun's influence on cosmic rays has a greater effect than any anthropogenic global warming.
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