What exactly is a lunar eclipse?
NASA's website purports the final lunar eclipse of 2011 will be a total lunar eclipse. That means the moon will be completely darkened by the shadow of the earth. The alignment must be perfect for the moon to pass behind the earth. The National Weather Service states a lunar eclipse can only happen during a full moon. There are different stages of the eclipse as the moon slowly moves into the earth's shadow and blocks the sunlight that reaches our closest heavenly body. The next total lunar eclipses will happen in 2014 and will be able to be seen over the entire North American continent.
What factors may prevent seeing the eclipse?
When the moon sinks below the horizon, the eclipse will be unreachable to those on the ground. If you happen to be on an airplane flying west at the time of the eclipse, you will have a prime viewing spot to see the darker colored moon. Weather and cloudy skies may also hide the eclipse from ground-based earthlings. NASA's Lunar Reconnaissance Orbiter will have a unique perspective on the events of Dec. 10. Cameras and sensors on the probe will get a close-up view of the shadow as well as take temperature readings of moon rocks.