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Facts & Faith, Second Quarter 1997 IssueA key to discovering the structure and scale of the universe was discovered by the ancient Greeks and is still taught in high school trigonometry. The distance from the base of a triangle to its vertex (or top angle) can be calculated with just three pieces of information: the length of the base, the angle between the base and the left side of the triangle, and the angle between the base and the right side of the triangle.
Using the diameter of Earth’s orbit around the sun as the base of a triangle (186,000,000 miles), the Greeks were able to calculate the distances from Earth to the other planets in our solar system. The stars were so far away, however, that the angles from the left side and right side of the triangle’s base out to the stars always appeared the same: 90 degrees.
With the advent of the telescope, this ancient theorem could at last be used to measure the distance to nearby stars. And with the application of more theorems to these measures, astronomers could calculate, at least roughly, the dimensions of galaxies and galaxy clusters, the distances to stars and galaxies, the ages of stars and galaxies, the expansion rate of the universe, and the shape and dimensions of the universe.
No scientist likes to depend on rough calculations, however. The more precise the measurements, the more secure the conclusions. And in 1989, an important and expensive step was taken toward obtaining the more precise measurements. In that year the European Space Agency launched a satellite called Hipparcos armed with a telescope capable of measuring the angles to stars with one hundred times the precision of ground-based instruments. Last month the Hipparcos research team announced its first set of measurements, precise distances to 120,000 stars.
These preliminary results from Hipparcos indicate that the galaxies are slightly farther away (by about 10%) than our ground-based calculations suggested, that the universe is expanding at a slightly slower rate (10% more slowly) than we had thought, that the universe is a little older (about 2 billion years older) than we had thought, and that the oldest stars in some globular clusters are slightly younger (by about three billion years) than we had thought.1
Having a more accurate measure of the time gap between the beginning of the universe and the formation of the first stars will help scientists discern which creation model best fits reality. With results still coming in, researchers hope to publish, perhaps before the end of 1997, a recalibration of the burning cycles of several different kinds of stars. This recalibration will enable astronomers to determine in much greater detail how and when stars and galaxies formed. Knowledge of our universe’s origin will be significantly advanced.
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Facts & Faith, Second Quarter 1997 Issue