This will be a rare event not to miss for those living in the western third of the U.S. -- a total lunar eclipse on Saturday that's the last one the United States will see for almost three years.

The moon will be immersed in the earth's shadow, said a Chicago astronomer, and it will happen in full between 6:06 a.m. and 6:57 a.m. PST, after beginning at about 4:45 a.m.

[T]o see totality you have to be somewhere in the western states like Nevada and California, Larry Ciupik, an astronomer with the Adler Planetarium in Chicago, told Reuters.

Residents of Hawaii will see the moon higher in the sky, which could yield an even better viewing spectable.

The total eclipse will be North America's first total lunar eclipse this year, as the moon turns into an incredible photo opportunity and spectacle.

It's called a selenelion, when an eclipsed moon sets as the sun rises and both can be observed at the same time.

If clear skies prevail, the moon should be cast in a big shadow, appearing bright red and oversize. Beyond the United States, those in places such as Winnipeg in Manitoba, Guam, Australia, and eastern Asia will also be able to see it.

If skies remain clear, which only looks like a toss-up right now, it could provide some spectacular photo ops, meteorologist Jan Null of Golden Gate Weather Services said in an interview with USA Today.

Others in the United States may see the total lunar eclipse as well, but it would be those in the central portion of the country, and they won't be able to see it as well as those in the west. Those in the eastern portion of the nation who want to see the total lunar eclipse will be out of luck. For them, the moon will have set before the total lunar eclipse begins.

It will be the last opportunity for Americans to see a total lunar eclipse from the United States until April 15, 2014. The most recent total lunar eclipse occurred on June 15, but it wasn't visible in the United States.

A total lunar eclipse occurs when the moon travels completely within the Earth's umbra. NASA scientists say this one will be worth watching.

Not only will the moon be beautifully red, it will also be inflated by the moon illusion, NASA scientists said in a statement. For reasons not fully understood by astronomers or psychologists, low-hanging moons look unnaturally large when they beam through trees, buildings, and other foreground objects.

According to Space.com, atmospheric refraction makes it possible to see the rising sun and fully eclipsed moon at the same time.

Atmospheric refraction causes astronomical objects to appear higher in the sky than they are in reality. For example: when you see the sun sitting on the horizon, it is not there really. It's actually below the edge of the horizon, but our atmosphere acts like a lens and bends the sun's image just above the horizon, allowing us to see it, Space.com reported.

The same holds true with the moon, as well.