You look up at the bright, full moon and notice there is a little bite taken out of one edge. Take another look a while later and more of it seems to be fading. It continues to fade until it becomes a dim red-orange shadow of its former brilliant self. What happened? It's a full lunar eclipse! A lunar eclipse occurs only when there is a full moon and only when the sun, the earth, and the moon are lined up just right. In this line-up, the earth is between the sun and the moon, thus blocking the sunlight from reaching the moon's surface. Since the moon doesn't produce any light and only reflects sunlight, it darkens.
In the Shadows
There are three kinds of lunar eclipses: penumbral, partial, and total. The earth's shadow has two shades of darkness. The outer part of the shadow is called the penumbra and it is much lighter than the inner part. The inner part is called the umbra, which is very dark. When the moon only passes through the penumbra, it is called a penumbral eclipse. This part of the shadow is so weak that the effect on the moon's surface is barely noticeable. When only a part of the moon passes into the umbra, it is called a partial lunar eclipse. The most spectacular eclipse occurs when the entire moon passes into the umbra and is darkened with a reddish-orange or coppery tint. That is a total lunar eclipse.
Why Red?
You may be wondering why the moon appears a reddish-orange color instead of fading to black during a total eclipse. Some of the sunlight makes its way through the umbra to the moon's surface. To get there, it first passes through the earth's atmosphere where it is refracted, or bent. Particles in the atmosphere scatter the blue and violet colors. Only the reds remain as the sunlight continues on its way to the moon where it casts a reddish tint upon the surface. Occasionally, other particles in earth's atmosphere, such as those from a volcanic eruption, absorb a lot of the sunlight. When that happens, the eclipsed moon may appear gray or even black. Looking at an eclipse through cloudy skies can also make the moon appear gray.
A Lunar Eclipse Is On Its Way
It looks like we may have a coppery moon for the full lunar eclipse that will take place on Wednesday October 27th. It will be visible from North America, South America, Europe, most of Africa and western Asia. The moon will be visible in Canada and the continental United States during all of totality. In Europe, the eclipse will occur early on Thursday the 28th. The schedule for the Eastern time zone is in the box to the right.
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