They are not normally a major shower, but experts forecast a significant brief outburst on 8 October, centred on a time of 19h 57m (20h 57m BST). Estimates of the rate vary from about 200 per hour to almost 1,000 per hour, with the best guess about 400 per hour, or about 6 or 7 per minute.
Unfortunately there will still be a trace of evening twilight, and a bright gibbous Moon will lie about 20 degrees above the SE horizon, and the meteors are predicted to be fairly faint, so we may not see most of them. However the radiant will be almost overhead at the time of the predicted maximum, so try to find a spot where the Moon is hidden behind some object, and get out a lounger so that you can look up almost overhead.
The radiant will lie just below and left of the head of Draco as you look high in the NW sky. If you don't know Draco, the radiant will be about ¼ of the way from Vega towards the handle of the 'Plough' or tail of the Great Bear, if you prefer. The meteors can of course appear anywhere in the sky, but any Draconids will appear to have come from the area of the radiant: if you trace their paths backwards they should pass close to that part of the sky.
The outburst may last only for ¼ to ½ an hour, but if it's clear I suggest you observe from as soon as the sky gets dark enough to see Vega, until about 20.30 (21.30 BST), just in case! Let me know what you see, if anything.
Astronomers are predicting a sharp maximum of shooting stars to occur during the period from dusk until late evening on Saturday 8th October in the normally weak annual Draconid meteor shower. Between 20 and 100 meteors per hour are expected, with some experts predicting a peak ranging upwards of 500 to 1,000 meteors per hour. Countries of Europe, northern Africa and the Middle East are best placed to see the event. With this in mind the Armagh Observatory is opening for a public meteor watch between 6.30pm and 9.30pm that night. The night of the meteor shower coincides with "International Observe the Moon Night", and assuming the skies are clear there will be an opportunity to see both the planet Jupiter and the Moon.
There will be an introduction to the sky, meteors and the Moon, given by the students of astronomy at the Observatory, and an opportunity, if it's clear, to observe meteors and see telescopic views of the Moon and Jupiter.
The source of the meteors is dust shed by the periodic comet 21P/Giacobini-Zinner, discovered in December 1900 by Michel Giacobini of Nice, France, and in 1913 by Ernst Zinner of Bamberg, Germany. The meteors are called "Draconids" because they radiate from the constellation Draco the dragon.Normally, a maximum of between five and twenty Draconids per hour are seen, but occasionally several thousand per hour may occur, as in 1933 and 1946. The meteor storm that occurred in 1933 was observed from the roof of the Observatory by the Revd W.F.A. Ellison, then Director of the Observatory, who described the meteors as "becoming as thick as the flakes of a snowstorm. The sky was thick with them, wherever one looked" over a period of an hour or so during the evening of 9th October.
Some enhanced displays also occurred in the 1920s, 1950s and 1970s, when the parent comet passed close to the Earth's orbit. This year, on 8th October, there is again the possibility of a significant shower when the Earth passes through a complex of dust trails emitted from the comet in the early and late nineteenth century and in 1900 and 1913. The peaks of any enhanced activity are predicted to occur between approximately 6.00pm and 10.00pm that evening. Unfortunately, it will be daylight when the brightest meteors are expected, and the Moon is in a waxing gibbous phase about three days before Full. Moonlight significantly reduces the number of meteors that might otherwise be seen.
Observations of this rare meteoric phenomenon are keenly sought, and are being encouraged world-wide to determine their numbers versus brightness and time. This will enable astronomers to determine the orbit and activity of the parent comet 21P/Giacobini-Zinner during the nineteenth century, before it was discovered. Mark Bailey, Director of the Observatory, said: "A meteor outburst is an extremely rare phenomenon, and the chance to see one should not be missed — even if moonlight seems likely to reduce the number of visible meteors to a drizzle rather than a sharp shower."
For the best chance to see these relatively slow-moving meteors, face towards the north-west away from the Moon and look about 40 degrees away from the meteor radiant, which lies fairly high in the sky to the west of the North Star, Polaris.
The Observatory will be open to the public from 6.30pm to 9.30pm to view this event. Members of the Irish Astronomical Association will also be in attendance. As with all astronomy observing events it will be necessary to have clear skies. In the event of rain or thick cloud the event will be cancelled. Those who may wish to attend the event should telephone or send an e-mail to Mrs Aileen McKee at the Armagh Observatory, College Hill, Armagh; Tel: 028-3752-2928; E-mail: ambn@arm.ac.uk, and meet outside the main Observatory building at 6.30pm. It will be interesting to see if there will be an exceptional display of shooting stars this year, or just an average number. Other observers should find a dark site, as far as possible from light pollution or the interfering light of the Moon, and should wrap up warm against the cold, and as comfortable as possible, ready to catch the meteors when they appear.
FOR FURTHER INFORMATION PLEASE CONTACT: John McFarland at the Armagh Observatory, College Hill, Armagh, BT61 9DG. Tel. 028-3752-2928; FAX: 028-3752-7174; jmf@arm.ac.uk; URL: http://star.arm.ac.uk/.
Terry Moseley
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