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Galaxy Mapping

 

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Overview
Edwin Hubble's proof that the universe is dynamic and that our Milky Way is not the lone galaxy provoked a renewal of questions and theories. Understanding the positions, distances, and distribution patterns of other galaxies not only provides mapping information; it gives perspective on what the earth's relationship is to the overall universal plan; it provides clues about the earth's origin; and it gives a type of structure to an indistinct concept. The Doppler effect can explain the red shifts found in the light from galaxies. According to the Doppler effect, the more that light is shifted to longer wavelengths (meaning toward the red end of the spectrum), the faster the source of the light is moving away from the observer. Edwin Hubble found that the farther away the galaxy, the more its light is red-shifted. This means that the farther the galaxy, the faster it is moving away from us. In other words, the universe is expanding. Consider the universe as a huge ball of bread dough, speckled throughout with raisins, each raisin denoting a galaxy. There is no definite boundary or edge, however. As this model universe is baking in the oven, yeast is making the dough expand. The expanding dough carries the raisins farther and farther apart from each other, but the size of each raisin does not increase. In the same way, space expands the distance between galaxies in the universe, but the galaxies themselves do not get larger. We are on the threshold of new discoveries about the galaxies. Using the latest technology, Margaret Geller and John Huchra are able to analyze "slices" of the universe. If the ball of raisin-bread dough represents the universe, Geller and Huchra so far have mapped only four very thin slices of bread that don't even go all the way through the loaf. Their mapping illustrates a definite pattern to galaxy distribution. Galaxies appear to be positioned in a network of thin, curved walls that surround huge, nearly empty voids. How empty the voids are and how they arose, no one yet knows. The "Great Wall" of the universe is the largest structure known to humans, yet its size, 500 million light years by 200 million light years, poses a challenge to cosmological theories. No one can explain how, if only known forms of matter and known forces were at work, such a large structure was formed in the time since the Big Bang. Newer technologies and continued research promise to introduce new insights into the universe.

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