Act 2 - the Basic Constellations
Welcome to Sumner Skies Planetarium! Hows that for an entrance. Nothing like retracing the birth and evolution of the whole universe to set the stage for the stars in all their beauty and glory. We're looking at the sky you can see tonight from middle Tennessee, gorgeous isn't it? But actually, this is the sky you could see if everything was perfect outside after dark - no clouds, no moon, and no light pollution. Everyone knows you can't see through clouds, and the brightness and romance of the moon are actually hindrances to seeing the multitude of faint objects we see here. But clouds and the moon can be avoided. Its the third enemy of the stars, light pollution, that not many people know about. Its easy to understand though when you consider how much development there has been around these parts. As brightly lit cities sprawl outwards unchecked, as lights shine not only down where they're needed but up where they're not, the horizon glow gets brighter and brighter until our beloved sars are all but lost in the glare. This sadly is the state of affairs in all metropolitan areas now, including here in Gallatin. There is a movement towards low sodium, top shielded outdoor lighting, but it may be a losing battle. Still, we can drive to the country far away from the city and see the stars as they were truly meant to be seen.
The sky we see above tonight is virtually unchanged from the sky seen by our distant ancestors 2,000 years ago - stars move ever so slowly across our skies not because they themselves move slowly, but because they are so distant. So tonight here in the planetarium you are looking at virtually the same stars the cavemen saw as they struggled for survival. Today of course we have the thousands of yearold legacies of the constellations, or star pitctures - patterns in the sky in which the anicents thought they saw all manner of legendary and everyday beasts, birds, and objects from their world and myths. The beautiful cards encircling the walls of the planetarium depitc thse trantastic imaginings. More recently, we have star classifications applied to the brightness of the stars we can see above - from the brightest zero magnitude stars to the faintest 5th magnitude stars. We see the famous Milky Way, a faint band of light that one must have truly dark skies to even see at all - sightings from Gallatin now are reserved for the darkest, clearest nights. This is our own galaxy seen from within, the one we saw born out of the Big Bang when we began. The Milky Way is not milk at all, it is the co-mingled light of billions of stars too far and numerous to be seen with the naked eye. Ancients referred to the Milky Way as the 'backbone of the night', and its easy to see why.
The stars at night appear to move from east to west across our dark sky, much as the sun does across the brilliant skies of daylight. This of course, as in the case of the sun, is the result of the earth's rotation, not the stars movement. The stars do appear to rotate about the north celestial pole in the sky, a point directly over the North Pole of Earth. Marking the North Pole is the famous pole star, Polaris, tail star of the Little Dipper. The Little Dipper is faint, in the dead north of the sky, and it takes a clear night to make out. More famous is her big brother, the Big Bear, circling nearby. You may know her by her most famous portion - the Big Dipper. The Big Dipper is visible most nights of the year - note how the so-called pointer stars of the Big Dipper point to the North Star. Joining the stately Dippers of the North are the King and Queen of the night sky, King Cepheus and Queen Cassiopeia of mythology. Cepheus looks like a house shaped figure skirting the Milky Way. Cassiopeia is shaped like an M or W flying round the pole. Need help seeing these four famous figures? Now can you see them? (at this point utilize constellation projectors and demonstrate other seasonal points of interest)
Monday, March 1, 2010
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