Astronomy Benalla
Reports - 2013
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Astronomy Benalla  Meeting Presentations - Wednesday 20th November 2013 Constellation of the Month - Taurus                   Presenter: Jeff Knight As summer approaches, the wonder of our southern skies continues to enthral us.  As a young lad I remember vividly, gazing up at the beautiful black backdrop of the summer sky for nights on end.  I would try and make out patterns by ‘connecting the dots’; the bright pinpoints of light.  I knew nothing of the constellations back then, but some asterisms, like the ‘Saucepan’, just hit you.  As did the ‘Rocket’, just left of the Saucepan, and the ’Seven Sisters’ just beyond that.  Of course it wasn’t really a ‘rocket’, but to my eye it later became a very useful reference point for finding the constellation of TAURUS.  The upside down ‘V’ was the very snout of the Bull.  In time I would learn that this was actually an open star cluster known as the Hyades, and pronounced very similarly to that of the Pleiades, the more well-known and beautiful open star cluster, universally known as the ’Seven Sisters’, and situated in the left shoulder of the charging bull.  I deliberately have to force myself to see these pictures upside down in the night sky, as most books and periodicals usually show these constellations from the northern hemisphere (and certainly ‘original’!) perspective.  Taurus’ mighty horns therefore extend down toward the horizon, as marked by the second brightest star in this constellation, El Nath (“The Butting Horn”).  The principal star of Taurus (alpha Tauri) is the very eye of the bull, known in ancient times as ‘Al Debaran(‘The Follower’, because it followed the Pleiades presumably!), and by even earlier names, ‘I-ku-u’ (‘Leading Star of Stars’), ‘Gis-da’ (‘Furrow of Heaven’), and ‘Dilgan’ (‘Messenger of Light’).   It is a fiery orange giant over forty-four times the diameter of our sun, and just over 65 light years away.  While it appears, from our perspective, to sit supremely in the Hyades open cluster, it is in fact completely unrelated to the cluster, sitting about half way between us and them.  When considering this orange giant, I can’t help but wonder whether the term “Bulls Eye” may have been coined in antiquity after the famed Al Debaran, the eye-catching, focal centre of Taurus! As a child I particularly marvelled at the beauty of the ‘Seven Sisters’ (being so near to the ‘Rocket’), although I really could only count six.  I learned in time that it was a cluster of possibly over one thousand stars, and that people with exceptional eyesight could see up to eighteen in the right conditions.  When I inherited my first pair of binoculars, this was definitely one of the first objects on my ‘must see’ list.  I was not disappointed!  Through my 7 x 50’s the Pleiades looked like the most beautiful collection of jewels I had ever seen; and, not only could I see the ‘seventh sister’, I could now see scores of her family.  What I particularly find intriguing is that in every culture this star group is known by virtually the same name.  Even our Australian aborigines cite a legend where the ‘missing’ queen was snatched away by a crow infatuated with her beauty.  They didn’t have the benefit of our viewing equipment, so how did they know there was another?  Caleano, in Greek mythology, is known as ‘the lost pleiad’, as it is too dim to be seen with the naked eye. Taurus is unique among the zodiacal constellations.  It alone sits in that part of the heavens where it is crossed by all three of the ‘galactic equator’ (the plane of our galaxy), the ‘celestial equator’ (the projection of the earth’s equator onto the heavens), and the ‘ecliptic’ (the path of the sun across the sky from our perspective) It also hides a number of deep sky objects that are worth seeking out (though some of these are only discernable through the ‘Hubble’!).  The most famous of these is the Crab Nebula (M1), situated near the tip of the bull’s right horn.  Lying around 6000 light years from us, it appeared as a bright explosion in 1054 AD, according to ancient Chinese chronicles, and could be seen even in the daytime for twenty-three days before it disappeared.  Charles Messier’s observation of it, in 1758, stimulated him to compile his Messier List, being the first entry, M1. The Crystal Ball Nebula (NGC 1514) is a planetary nebula about 4 degrees below the rising Pleiades.  It was discovered by William Herschel in 1790, describing it "A most singular phenomenon" and forcing him to rethink his ideas on how the heavens were constructed. As a result, he came to understand that the ‘cloudy’ nebula was not at all made up of masses of stars too remote to resolve, but rather was a “faintly luminous atmosphere".  The Merope Nebula [Tempel’s Nebula] (NGC 1435) is located in the Pleiades star cluster. It surrounds the star Merope (23 Tauri) and is illuminated by the star’s light.  The nebula is a suspected supernova remnant, and was discovered by the German astronomer Wilhelm Tempel in 1859.  It is approximately 440 light years distant from us. Hind’s Variable Nebula (NGC 1555) is another ‘reflection’ nebula, like that of Merope, but it exhibits variations in luminosity as a result of changes in its star.  It lies 400 million light years away, beside the star T Tauri, (very near the left ‘eye’ of Taurus) and is illuminated by the star’s light.   The nebula was first discovered by the English astronomer John Russell Hind in 1852. NGC 1409 (right) and NGC 1410 (left) are a pair of colliding galaxies 300 million light years from us.  They are to be found just above the (upside-down!) left hoof of Taurus.  The two galaxies are connected by a pipeline of gas spanning over 20,000 light years that is being funnelled from one galaxy to the other.  They are gravitationally bound and will eventually merge into one. Prepared, with special acknowledgement to:        Wikipedia Constellation Guide Starry Night Enthusiast CosMos Astronomy EarthSky, Science news Star Names, Richard Hinckley Allen, 1889 CoraSkywalker's Blog Anne‘s Astronomy News
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