Just wanted to put the song in your head. classic lyrics from Creedence Clearwater Revival just might be what come to mind Saturday evening when the moon is expected to appear red during a full lunar eclipse.

So, just what is a lunar eclipse? Two things have to happen.

First, the moon has to be full, which it is on March 3. Because the moon is directly opposite the sun when it's full, it rises at sunset and is visible all through the night. (This doesn't happen during any other phase of the moon.)

Second, the moon has to pass through some part of Earth's shadow.

There are three kinds of lunar eclipes (eclipsi?).

In a penumbral lunar eclipse, the moon passes through Earth's penumbral shadow. The penumbra is the outer shadow as opposed to the direct shadow. (The graphic on the right explains it. Click it for a larger image.) This kind of eclipse is not terribly interesting to most casual observers because it's really hard to see.

A partial lunar eclipse is exactly what it sounds like. Part of the moon passes through Earth's direct shadow, also known as the umbra.

During a total lunar eclipse, which is what's happening Saturday, the entire moon is in Earth's shadow.

Earth will be blocking the sun's light from the moon, giving the moon a red hue. Some call it a "Hunter's Moon." Others call it a "Blood Moon."

If you want to see it, feel free to look. Lunar eclipses, unlike solar eclipses are perfectly safe to watch. You don't need any special equipment or even a telescope. Just face away from the setting sun. (For those of you who are not directionally challenged, face east.)

Saturday's eclipse, the first total lunar eclipse since Oct. 28,2004, is expected to last about an hour and 15 minutes.

According to NASA, the eclipse will already be underway when the moon rises.

The space agency says the eastern half of North America will have the best view on the continent, but according to its visibility map, we here in Arizona should be able to see something, although it might just be the final penumbral phase. (A total lunar eclipse has three phases -- penumbral, umbral, then another penumbral.)

If you miss it (or couldn't see anything), don't worry. There will be another one this summer, on Aug. 28.

In fact, you might want to mark your calendar, because the western portion of the U.S. should have a stellar view of that event. It will be the first central total eclipse since 2000. From what I am able to translate from NASA-speak, the moon should look huge that evening. (Click here for a visibility map.)

I'll make sure to remind you about it.

If you do watch on Saturday, and happen get a couple of good pictures, send them our way. We'd love to see them and maybe even show them on 3TV.

Back to CCR. Sing with me now!

"Don't go around tonight. Well, its bound to take your life. There's a bad moon on the rise."

Find out more about lunar eclipses!

science.nasa.gov

www.MrEclipse.com