September 2010 Meeting Notes
For our September meeting, we tried a modified schedule, with setup and casual conversation from 6:45 p.m. to 7:00 p.m., then a brief business meeting, followed by a 10 minute Introduction to the Autumn Constellations, and our main program starting at 7:30 p.m. This seem to work well and we will continue with this schedule unless some conflicts appear.
Introduction to Autumn Constellations - Daryl Doughty
One of the reasons for modifying our meeting schedule was to allow us to include a short, 10 to 15 minute introduction to some astronomical topic each month. Starting off this new Introduction to… series, Daryl Doughty presented a brief introduction to some of the autumn constellations to watch for in the coming months. In describing these constellations, Daryl also touch on the importance of the celestial equator (the projection of the Earth's equator onto the sky), the ecliptic (the apparent path of the planets, sun and moon across the sky) which is inclined about 23.5° to the celestial equator, and the spring and autumn equinoxes, where the celestial equator and the ecliptic cross.
Using his own astrophotos as visual aids, Daryl explained how to identify The Pleiades and its adjacent constellation Taurus, Ursa Major which contains the Big Dipper, Sagittarius and the Navigator's Triangle. The Pleiades, rising in the northeast during autumn nights, is a compact and distinctive asterism that some see as a little dipper. Not to be confused with THE "Little Dipper" which contains Polaris (the North Star) at the end of its handle, The Pleiades is an open cluster of relatively young stars. Long exposure photos reveal wisps of faintly glowing clouds that are remnants of the gas and dust from which the Pleiades were formed. A short distance to the south and east is Taurus, one of the Zodiacal constellations that lie along the ecliptic. Taurus was an important constellation in ancient Egyptian mythology, with the sun located there on the first day of spring about 3000 BC. Precession of the Earth's polar axis has steadily moved the equinox west and out of the constellation, since that time. Taurus contains another relatively young open cluster of stars called the Hyades, though it's not as young as the Pleiades.
Ursa Major, the Big Bear, is a constellation that can be seen setting along the northwestern horizon early in autumn evenings. The most visible stars in the constellation form the easily identifiable Big Dipper. The two outer stars of the bowl of the Big Dipper (opposite the handle) are appropriately called the "Pointer Stars", because a line drawn through them points approximately toward the North Star. Daryl's photo of the Big Dipper clearly showed that the center star in the handle is actually a double star. Although legend suggests that these two bright stars, Mizar and Alcor, are close enough together that they served as an eye test for Roman soldiers, they are actually separated enough that most people with average eyesight can distinguish them.
Daryl's third astrophoto included the beautiful glow of the Milky Way stretching toward the southwestern horizon, where it blended into a distinctively teapot shaped constellation of stars named Sagittarius. In Roman mythology this was known as the Archer. Sagittarius is another of the Zodiacal constellations and has the distinction of containing the center of our Milky Way Galaxy.
The final stop in Daryl's introduction to autumn constellations is nearly overhead in the early evening this time of year. The three bright stars, Vega in the constellation Lyra, Deneb in Cygnus and Altair in Aquilla, are the points of a large overhead triangle called the Navigator's Triangle. In the past, ship and aircraft navigators used sitings on these stars to determine their location on Earth. With the advent of GPS positioning, the navigational utility has declined, but the triangle is still there, now often referred to as the Summer Triangle.
Winter Solstice 2012: Celestial Cycles, Hype and Intrigue - Arden Strycker
During the past couple of years there has been increasing confusion and misinformation about claims that the Mayan "long count" calendar will come to an unequivocal end on December 21, 2012, triggering unprecedented global consequences. In his presentation, Arden laid out the major claims, explored the truth about these claims and the reality of the celestial phenomena underlying them, and carefully dismantled the unfounded hype and misleading claims that have given this doomsday scenario far more credibility than it deserves.
An abundance of doomsday rumors have been fueled by recent books, TV shows, internet websites and movies. Of these, the movie 2012: Doomsday, has played a major roll in escalating the hype. Some of the doomsday scenarios include collision with a rogue planet, violent solar storms, reversal of Earth's magnetic field and a "galactic" alignment. Arden explained the details of the possible interpretations of the Mayan Calendar, showing the supposed end of the 13th B'ak' tun to be of no particular significance.
Addressing some of the major scenarios, Arden carefully analyzed the claims and evaluated the conclusions. Although there are occasional small Earth approaching asteroids that might pose an impact risk far in the future, anything large enough to qualify as a rogue planet would have long since been detected by astronomers. At first glance, the claim of violent solar storms in 2012 might seem to have some credibility, since the 11 year solar cycle is building toward a maximum some time in 2013. However, the most recent NASA analysis (July 2010) indicates that the sunspot maximum will likely be considerably lower than that of the past cycle 11 years ago.
Geologic evidence suggests that magnetic field reversals occur about every 400,000 years with no obvious global catastrophes. Despite the fact that there is a normal, minor polar "wandering" of the Earth's rotational axis from year to year, NASA finds that there is no evidence for a dramatic shift of the poles any time soon.
And what about some mysterious galactic alignment of the Sun and the center of the galaxy? Arden pointed out that, by coincidence, the ecliptic passes across the galactic equator, as seen in the sky, near the central bulge of the Milky Way. Since the Sun makes a complete circuit around the ecliptic every 12 months, this means that it will necessarily pass near the galactic center once a year. The fact that it will do so on December 21 in 2012 is of no particular significance.
Arden's explanation of Milankovitch cycles, which compare variations in the precession of the Earth's poles, the obliquity and eccentricity of the Earth's orbit, with solar forcing and estimated periods of past glaciation, triggered a vigorous and interesting discussion. Although these factors can cause truly global changes in climate, the time scales are so long that they play no part in the short term concerns of 2012.
The clear and thorough explanations that Arden presented demonstrated that not only is there no justification for any of the 2012 Doomsday prophesies, but that and advantage of studying science at any level is that it teaches us how to think logically and critically about topics of concern, such as the unjustified hype about the Winter Solstice of 2012.
Monday October 4, John Land, of the Astronomy Club of Tulsa, will present "The Astronomical League", in the Bartlesville Public Library Meeting Room. For more information, see the meeting announcement on our website home page at <http://sites.google.com/site/bartlesvilleastronomyclub/> .
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