A First Step
There's a tendency to think that the flashier things in life are the most important - from cars to stars. We'll let you decide for yourself if that's true with transportation. But it's definitely not true with the stars.
An example is 61 Cygni. It's part of Cygnus, the swan, which is high overhead this evening. 61 Cygni appears fairly close to Deneb, the star that marks the swan's tail.
Although 61 Cygni isn't very bright, it's one of the most important stars in astronomy history: It was the first star other than the Sun whose distance was accurately measured. The measurement established a technique that astronomers still use today. And it allowed us to begin to understand the true vastness of the universe.
Freidrich Bessel made the discovery in 1838. He'd been watching the star at different times of the year, as Earth moved in its orbit around the Sun. He found that 61 Cygni appeared to move back and forth a tiny bit compared to other stars. By measuring how far the star appeared to move, he calculated its distance: about 10 light-years. Modern observations show that he was off by just 10 percent.
Until then, astronomers knew that the stars were far away, but they didn't know how far. 61 Cygni's back-and-forth movement is greater than that of almost any other star, so it's one of our closest stellar neighbors. Almost all the other stars are much farther - indicating that the universe is vast indeed.
More tomorrow.
Script by Damond Benningfield, Copyright 2005
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
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