October Sky Notes
Tales of Bear Tails
I tend now to view the early autumn night sky with a certain amount of nostalgia, as it was around this time of year I first became interested in identifying the constellations. October, as it turns out, is a wonderful month to begin exploring the heavens anyway, but as a young boy, having just acquired a pair of binoculars, a couple of astronomical books and inspired by the many wonderful tales and legends associated with the constellations, early October seemed particularly suitable.
I took my first tentative celestial steps around one of most familiar star patterns, the Plough, the outline of which resembles a ‘dot to dot’ saucepan. The Plough (or Big Dipper) is really an asterism, a distinctive pattern within a constellation – in this case Ursa Major, the Great Bear. Throughout October evenings, the Plough resides at an observer friendly altitude in the NNW as it endlessly circles the celestial pole.
In Greek mythology Ursa Major represents Callisto, daughter of King Lycaon of Arcadia, who after a liaison with Zeus bore a child, Arcas (Ursa Minor). In order to save Callisto from his enraged wife, Hera, Zeus turned Callisto into a bear. Years later whilst out hunting, Arcas was about to kill a bear when Zeus hurriedly intervened knowing the bear to be Callisto. Turning Arcas into a bear also reunited mother and son who were swung into the heavens out of harm’s way by their tails.
Five of the stars forming the Plough asterism are genuinely associated, sharing the same speed and trajectory through space. These, along with a number of other stars, including Sirius, brightest star in the night sky, are all members of the Ursa Major moving star cluster.
Look at the middle star in the curved handle of the Plough and you should spot a second, fainter star upper left with the naked eye. Binoculars show Mizar and Alcor well, but any telescope will reveal Mizar itself as a striking double star. There are numerous deep sky objects dotted around Ursa Major, most of which require a telescope to spot, but the twin galaxies of M81 and 82 are somewhat brighter, visible as smudges in binoculars.
Ursa Minor, the Lesser Bear, is much less conspicuous than Ursa Major, but does contain Polaris - our present pole star. Use the ‘pointer’ stars in the ‘bowl’ of the Plough to track it down, by sighting up through them and then beyond by a couple of hand spans.
Return back to the Plough and follow round the curve of the handle to locate Arcturus, the brilliant star low in the WNW highlighting the outline of Bootes the Herdsman. To the upper left of Arcturus look for the delicate starry circlet of Corona Borealis - the Northern Crown. Its leading star, Gemma (Latin for jewel) is set in the midst of this pleasing arrangement. According to Greek legend Corona represents the crown of Dionysus, tossed into the heavens to prove his love for Ariadna after she had recently been deserted by Theseus (of the Minataur legend) vowing never to marry a mortal again. Dionysus was a god of course!
Situated below the handle of the Plough lie the Herdman’s dogs, Canes Venatici, marked by two stars. The brighter one, Cor Caroli, meaning Charles’s heart, was named in honour of King Charles II.
My favourite tale for this part of the sky stems from the Iroquois Indians. It ties in Corona, Arcturus and the stars of the Plough or Big Dipper and unfolds as thus. Each spring a giant bear leaves its den or Corona Borealis and is then hunted by seven warriors represented by the stars of the Plough. The bear is tracked throughout the summer, but is not killed until autumn, whereupon its spirit is released - represented by setting Arcturus, whose name means ‘Bear Keeper’. The skeleton of the bear, now represented by the seven stars, remains in the sky until the following spring when a new bear emerges from Corona, complete with renewed spirit and the hunt begins again.
Through the eyes of a small child such stories woven by our ancestors on the grandest of scales not only brought the starry heavens to life, but actively encouraged me in setting out on a voyage of celestial discovery. I hope they still do for a new generation.
Members of the WDAS will be at the Fox and Hounds, Ainthorpe, on 18/19th Oct and at the Danby Moors centre on 2nd Nov.
Further details contact Mark Dawson – firstname.lastname@example.org or go to www.whitby-astronomers.com or contact email@example.com
Whitby & District Astronomical Society
For more information about Whitby & District Astronomical Society see: www.whitby-astronomers.com