(NEW YORK) -- Look in the western sky Saturday morning before dawn, and if the weather is clear and you're in the right place, you will be rewarded with the last lunar eclipse of 2011.
For just under an hour, the disk of the full moon will almost disappear, turning a dark, rusty red. The catch for Americans is that you'll miss almost everything unless you're west of the Mississippi. Totality -- when the moon is completely consumed by Earth's shadow -- begins at 6:06 a.m. Pacific time on Saturday, and ends at 6:57 a.m. Even on the Pacific coast, dawn will start to brighten the sky before the eclipse is over.
Depending on the atmospheric conditions where you are, the moon may turn a rich orange, or it may become hard to pick out in the sky. The reddish hue comes from sunlight that is bent by Earth's atmosphere.
From the Rocky Mountain states or the West Coast, the moon may seem larger than usual, since it will loom close to the western horizon, creating a common optical illusion, since you'll have trees or buildings to which you can compare it.
Clearer views will be from places like Hawaii, Alaska and Guam, where it will be the middle of the night, and from Eastern Asia and Australia, where it will be Saturday evening. Earth's shadow will start to slide across the moon's face about an hour and 20 minutes before the moon becomes totally covered.
A lunar eclipse takes place when the moon, following its orbit around us, passes directly behind Earth as seen from the sun. It is the opposite of a solar eclipse, when the moon passes between the sun and Earth. Since the moon's orbit is slightly tilted, the bodies do not align perfectly during most months -- but the rules of orbital mechanics are such that in any given year, there will be at least two and no more than seven solar or lunar eclipses.
If you miss Saturday's eclipse, there will be a partial one on June 4, 2012. There will not be a total lunar eclipse again until April 15, 2014.
Copyright 2011 ABC News Radio