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EAAS Meeting 4th November 2002 Ballyrobert
|The last meeting of the East
Antrim Astronomical Society took place on Monday November 4th. The guest speaker Mr
John McFarland from the Armagh Observatory, spoke on the subject of Meteors and the 2002
Every November, the Earth passes through the trail of debris created by Comet Temple-Tuttle, producing the Leonid meteor shower.
|After the meeting
John mingled with members of EAAS (shown below) who enjoyed a light supper following his
|During his talk
John McFarland gave details of how the Leonids emanate from the trail of
CometTemple-Tuttle which swings past the Sun every 33.2 years, and during each close
approach it emits a dense stream of dust and small particles. Over time, these dust trails
extend along the whole length of the comet's orbit, but the trails remain very narrow and
concentrated in space taking hundreds of years to spread out.
Every year, between 15th and 20th November, the Earth meets a broad stream of ancient debris, leading to an annual meteor shower visible in the early morning hours towards the Northeast after midnight between these dates. The cometary dust particles move in very similar orbits and the resulting meteor shower appears to radiate from a point in the constellation of Leo, hence the term Leonids.
Comet Temple-Tuttle revolves around the Sun in the opposite direction to the Earth, so when the Earth encounters the trails of particles, they enter the atmosphere at very high speeds, about 160,000 miles per hour. Most of the dust grains are very small, and vaporise in the first few seconds at heights of more than 60 miles.
Prediction of meteor storm activity was for many years a rather uncertain science, but techniques developed by Dr David Asher of Armagh Observatory and Rob McNaught of the Anglo-Australian Observatory over recent years have enabled storms to be forecast accurately to within minutes.
This year, their calculations indicate two Leonid storms, the first being visible from western Europe and western Africa at 4.00am on the morning of the 19th November, and the second being visible at 5.30am in North America. During the European storm, under ideal conditions, (rarely realised) up to 2000 meteors per hour may be seen for an hour or so either side of the maximum. However, the moon will be nearly full, fairly high up in the west, washing out the light from the fainter meteors.
Those who wish to observe the Leonids are advised to find a clear, dark site, wrap up well in several layers of warm clothing, a flask of something warm, and recline in a comfortable chair with your back to towards the moon.
John McFarland has had a long-standing interest in astronomy, one of his earliest recollections being the television images showing the far side of the moon taken in October 1959 by the Russian spacecraft Luna 3.
He worked at the Armagh Observatory as a Summer Student from 1969 - 1973, during which time he graduated in Mathematics from Queen's University, Belfast in 1972, followed by a Physics Honours Degree in 1973.
In 1973/74, he studied for a Master's degree in Physics, and obtained a Master's Degree in Astronomy from Queen's University in 1981, John has been employed at the Armagh Observatory since 1982, and is currently Curator of Archives and PRO.
At the close of the meeting Chairman, John McConnell gave a vote of thanks to Mr McFarland and commended members to the expected fine display of meteors on Nov the 19th.