Monday 26 August 2019

The Alpha Aurigid Meteors.

The Alpha Aurigid Meteor shower occurs each year between 25 August and 6 September, peaking between 11.30 pm GMT on 31 August and 0.30 am GMT on 1 September. However the shower is notoriously hard to observe, having been recorded only in the years 1911, 1929, 1930, 1935, 1979, 1980, 1986, 1994 and 2007 (some of these observations occurred before the 'official' discovery of the shower by Cuno Hoffmeister and Artur Teichgraeber in 1935, but have subsequently been linked to the shower). The shower has its radiant (the point from which the meteors appear to radiate) in the constellation of Auriga, making it more-or-less impossible to see from the Southern Hemisphere, and only produces about six meteors per hour at its peak; though as the New Moon occurs on 30 August this year, there should be very little light interference from that source, giving astronomers in the Northern Hemisphere a chance of glimpsing these meteors.

The radiant of the Alpha Aurigid Meteors. Copper Mountain Mesa.

Meteor showers occur when the Earth crosses the orbit of a comet or similar body, encountering millions of tiny particles left behind in that body's trail, even if it is not close by itself. The Alpha Aurigid Metoers are thought to originate from the tail of the comet C/1911 N1 (Kiess). This is a Long Period Comet (comet with a period of longer than 200 years), thought to visit the inner Solar System only once every 2497 years, last having done so in August 2011, when it came to about 0.2 AU from the Earth (i.e. about 20% of the distance between the Earth and the Sun). The orbit of C/1911 N1 (Kiess) is highly elliptical, and tilted at an angle of 148° to the plane of the Solar System (or 58° with a retrograde orbit - an orbit in the opposite direction to the planets) and takes the comet from 0.68 AU from the Sun (68% of the average distance between the Earth and the Sun, slightly inside the orbit of Venus) to 367 AU from the Sun (367 times as far from the Sun as the Earth, or 20 times as far as Neptune, but within the inner part of the Oort Cloud).

 The orbit and current position of comet C/1911 N1 (Kiess). JPL Small Body Database Browser.

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