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A lunar eclipse occurs whenever the moon passes through some portion of the Earth's shadow. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, the Moon is always full the night of a lunar eclipse. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes. When the sun passes through the dividing line between earth and sky, different waves of light are extinguished in sequence. Light waves on the red end of the spectrum sink from view first. Blue and purple waves are pretty much scattered across the sky (that's what makes the sky blue). Green waves are what's left. When conditions are clear and the eclipse of the Moon is at the correct angle, you will see a momentary spot or ray of green. It's very quick. The color and brightness of the totally eclipsed Moon can vary considerably from one eclipse to another. Dark eclipses are caused by volcanic gas and dust which filters and blocks much of the Sun's light from reaching the Moon. But since no major volcanic eruptions have taken place recently, the Moon will probably take on a vivid red or orange color during the total phase. After the total phase ends, it is once again followed by a partial eclipse as the Moon gradually leaves the umbral shadow. The moon is at an average distance of 238,855 miles (384,400 kilometers) away from Earth. That is about the width of 30 Earths. Because the moon does not orbit Earth in a perfect circle, but instead travels in a slightly elliptical orbit, its distance from Earth varies between 225,700 miles (363,300 kilometers) and 252,000 miles (405,500 kilometers). |
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