Asteroids, comets, meteors and impacts
Third Meeting Of The Third Season
The third EAAS meeting of the new season took place on Monday Nov 6th with a rich gathering of attendees and a selection of new members. The meeting began with our chairman Mark Stronge informing members of the latest sky events and news on the up and coming Leonid meteor shower outburst and a possible but yet unconfirmed enhancement of the Monocerotid minor shower which will take place in the days after its famous counterpart. Before our guest speaker took to the stage Mark introduced the first of a new series of short talks by EAAS members aimed directly at beginning observers.
An Introduction To Constellation Mythology
A ‘keye’ highlight (excuse the pun) was his fascinating in depth coverage of the mythology which surrounds these famous star figures, a story which was underlined by vivid narrative and imagery, some of which was not for the faint of heart I can tell you! Even experienced armchair and visual astronomers learned something new from his talk. It was evident that Eamonn had done extensive research into his topic and rehearsed his delivery thoroughly before taking to the stage. Thanks to Mr Keyes for starting this new trend and we very much hope to hear future talks from our new engaging and pro-active observer.
Introducing Dr. David Asher
Dr Asher is one of the world's leading experts in Near Earth Objects (NEOs), currently dividing his time between Armagh and Japan where, at the invitation of the Japan Spaceguard Association, he is working at the Bisei Spaceguard Centre, Japan. However, in recent years has also worked closely with Robert McNaught of the Australian National University, in predicting so precisely, the Leonid Meteor Storms to within a few minutes.
Dr Asher was born in Edinburgh, and between school and university got a kind of student vacation job with Dr Victor Clube and Professor Bill Napier at the Royal Observatory, Edinburgh. It was here that he gained his interest in astronomy. Later, he did his research degree under Clube, and his D.Phil. thesis was on the Taurid meteor stream. He then went to work with Dr Duncan Steel's near-Earth asteroid programme in Australia, (since closed down by the Australian Government), learnt what a telescope was, (his words!), and got to know Robert McNaught. It was during his time in Australia that he discovered a number of asteroids one of which has recently been named (16693) Moseley in honour of Terry Moseley, former President of the Irish Astronomical Association, and good friend of the EAAS.
His current job at Armagh is to work with the Director, Professor Mark Bailey, doing theoretical (computational) studies in solar system dynamics. The research project is about sun grazing and Jupiter grazing objects in particular, such as comets and asteroids.
A Superb Talk From An Imminent Man
A Bananarama Leonid Meteor Shower Outburst!
Comets (Dirty snowballs – a term coined by Fred Whipple) or as David informed us ‘Icy conglomerates’ if you want to sound smart are the source of meteor showers. Dust particles (meteoroids) are not ejected from a cometary nucleus uniformly but instead are ejected from its parent body in the form of jets or fans which, over time, form a trail around the Sun. Once (in some cases twice) a year the Earth swallows up these dust particles which burn up in our atmosphere and flare to incandescence due to friction producing a meteor or ‘shooting star’. Sounds simple enough however it is quite a complex process as Dr. Asher introduced us to the world of orbital dynamics. Due to non gravitational forces and perturbations of the major planets the Leonid meteoroid trail can spread out diffusely, or can have a dense morphology when calculations take into consideration the number of revolutions the stream makes around the Sun (age). Making these calculations with comparison to the behaviour of previous streams during the 1960’s David was able to provide us with a forecast for this years Leonid meteor shower. On Nov 18/19th at 04.45 UT his modelling predicts that the Earth will encounter a dense stream of small particles during the predawn hours producing a brief outburst of meteors with a ZHR of approximately 120 and what’s more, observers in N. Europe are perfectly placed for the encounter!
Dr. Asher explained this process in a very clear and easy to understand fashion and even used an unorthodox method to engage his audience. Like a meteor, he produced a bunch of bananas seemingly from nowhere and chose the straightest banana in the bunch which he peeled in front of his startled audience. Next he produced a large kitchen knife and carefully cut a cross section through the banana at an angle, then held it face on to the crowd to give us a visual demonstration of the shape of the dense Leonid meteoroid stream we would encounter. This was a very delightful and humourus way to educate society members – and it worked!
The Earth As A Dart Board
From Meteors To Occultations
The talk ended with a fascinating question and answer session. I think everyone would agree that Dr. Asher delivered an outstanding and fascinating talk which was fuelled by passion and a professional manner which could only come from a true master of his field. On behalf of the EAAS I wish to thank Dr. David Asher for a memorable and fascinating night!
Next month's meeting will take place on Monday Dec 4th and our guest speaker will be Dr. John Eldridge of Queens University Belfast who will deliver a talk on ‘Making Models of Stars’.
See you there
Martin Mc Kenna.
David Asher’s Asteroid discoveries
Dr. Asher’s Leonid meteor predictions
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