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Celestial Geometry

June 2, 2012

A lunar eclipse is a result of celestial geometry — it’s all orbits, angles, and timing. The Moon lines up opposite the Sun just as the Moon’s orbital path crosses Earth’s path around the Sun. Depending on just how good that alignment is, it allows Earth’s long shadow to cover all or part of the lunar disk.

And in fact, there’s a so-so alignment coming up before sunrise on Monday. The southern third of the Moon will pass through the shadow, so it’ll look as though something were taking a “bite” out of the lunar disk.

In times gone by, most cultures took that “bite” quite literally — they thought something was devouring the Moon. And it often required immediate action to save the Moon.

Just what was eating the Moon varied. Many people saw it as a dragon, others as a wolf. And still others saw the work of a werewolf, a vampire, or a witch.

Regardless of the culprit, though, many of the remedies were alike — they were attempts to scare the demon way. One was to make a lot of noise — a lot of shouting and banging. Another was to build up a big bonfire. And yet another was to throw rocks or fire arrows into the sky.

Some ancient cultures, such as those of Babylon and China, could predict when eclipses might occur. They weren’t always right, but they were at least on the right track. Through careful observations, they began to see eclipses for what they are — the results of celestial geometry.

More about Monday’s eclipse tomorrow.


Script by Damond Benningfield, Copyright 2012


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