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Posted 11 months ago
A Closer Look at a Few Myths About Stars
How common are myths about stars? Well, there are more than 6,000 true stars visible to the naked eye on a clear night, and it sometimes seems that each has spawned its share of myths. Why? The reasons are complicated, and mostly boil down to the fact that we've only just begun discovering the truth about stars.
Sure, we know now that stars are basically huge fusion reactors in the sky, big balls of flaming plasma that have lives and lifespans of their own, and that in fact our sun is just an average star. But that's the fruit of the last century of science, and before then people came up with some pretty interesting ideas about them.
Myth 1: Stars are eternal
This myth about stars is true only on a human timescale. In fact, stars are born, age, and die, just as we do, and nearly all the stars we know of don't even belong to the first generation of stars to exist in this universe. The larger and hotter a star is, the shorter its lifespan -- though it's still measured in millions of years.
A star begins as a ball of hydrogen gas that falls in on itself and ignites due to gravity. But it can only exist as long as its fuel supply lasts, whereupon it throws off its outer layers and shrinks to a tiny rotating body (this explanation simplifies the process terribly, of course). Some stars even explode violently when they die.
Myth 2: Stars always stay in one place
This myth about stars doesn't even come close to reality. All stars move gradually in relationship to each other as they rotate around the center of their galaxy. So eventually, the seemingly fixed positions of stars will move, though it may take thousands of years for any noticeable differences in position to appear.
For example: the 12 traditional Western zodiacal constellations are no longer where they were thousands of years ago, when they were initially defined. Some have even become noticeably distorted, and astronomers have been obliged to add to their star maps a 13th, Ophiuchus, to account for modern reality.
This myth about stars is also untrue because Earth itself slowly moves, making the apparent positions of the stars change. Case in point: the North Star is currently Polaris, but we know that 5,000 years ago, it was Thuban. Iota Cephei will get the honor about AD 5200, and Vega will replace it around AD 14000.
Myth 3: Our star is special, or unusual
Not really. Some folks don't think of the Sun as a star, but of course it is: astronomers classify it as a G-class yellow star. While it's perfect for our kind of life, as a singleton star (many are binaries) it lies somewhere in the middle of the scale, color- and temperature-wise, and so is pretty much average.
In fact, our star is kind of staid. It's quiet, easy to live with (thank goodness!) and at about 5 billion years old, it's basically middle-aged. Nor it is specially situated, being located out on the edge of one arm of a not-so-special pinwheel-shaped spiral galaxy. If this myth about stars is true at all, it's only because we live here!