The Age of the Universe
Andrew Fraknoi, who chairs the Astronomy Dept. at Foothill College in California, has pointed me towards this website of the American Astronomical Society. They have prepared a twenty-page booklet explaining how we know the universe is ancient. The booklet is entirely non-technical, and is intended primarily for school boards, students parents and teachers. The booklet is available for download, in PDF format, at the link above. I have only read a small piece of it so far, but it looks excellent. Here's a brief excerpt from the introduction:
In the past 150 years, scientists have greatly advanced our understanding of the natural world. We know that we live on an ancient planet, that life on Earth has evolved in its diversity and complexity, and that the universe itself has evolved from a hot and dense early state. These assertions are supported by a web of evidence, and the ideas behind them can be and have been tested, with a wide range of experiments. The understanding of our place in the universe and our place in the scheme of living creatures is one of the greatest achievments of the human intellect.
Many good books and articles have been published for teachers and the public on the scientific basis for evolutionary ideas in biology. But rather little is available to help explain how we know that the galaxies, stars and planets are really old. In this booklet we want to give you some of the background on how scientists have been able to measure ages so vast that human history is a mere blink of an eye in comparison. We also provide some references to classroom activities, and resources for further exploration of some of the astronomical ideas we discuss.