The “Great American Eclipse” is coming. In this article I’ll talk about what’s going on, what will we see here in Fountain Hills and (most importantly) how we can observe this amazing natural spectacle safely.

As we all learned in school, a solar eclipse occurs when the moon passes directly between the earth and the sun. The moon then casts its shadow on earth and temporarily blocks some or all of the sun’s light. By coincidence, while the moon is 400 times smaller in diameter than the sun, it also happens to be 400 times closer, so the moon and the sun appear to be the same size in the sky.

During the eclipse the moon’s shadow will sweep across the continental United States at over 1200 mph, taking about an hour and a half to make it from Oregon to South Carolina. The shadow will have two parts – a small dark center portion only about 70 miles wide called the umbra and a much larger and dimmer outer area several thousand miles across called the penumbra. During the upcoming eclipse on the morning of Monday, Aug. 21, Fountain Hills and most of the US will be in the penumbra.

The full beauty of the eclipse will be visible only to people standing in the narrow zone travelled by the umbra. This zone is called the path of totality since in this narrow strip of land the moon will totally obscure the sun. Millions of people are planning to make the trip into the path, and hotel rooms where available are going for “astronomical” prices. (For folks here in Arizona the closest states crossed by the path of totality would be Idaho, Wyoming and Nebraska.)

The experience of totality is truly an “out of this world” thrill. During those two minutes or so the sky darkens, stars and planets come out, birds (confused by the sudden appearance of dusk) go to roost, the wind may stop blowing, and the sun’s beautiful outer atmosphere (called the corona) becomes temporarily visible around the dark circle of the moon. Eclipse chasers travel the globe for the experience.

However, from here in Fountain Hills and from the rest of the US outside the narrow path of the umbra, the moon will cover only part of the sun. This is called a partial solar eclipse.

First, let’s talk about eye safety. From here in Fountain Hills the moon will never cover the entire sun, so the sun will be almost as bright as it always is. Therefore, you must at all times use special eclipse safety glasses to watch the eclipse.

Eclipse safety glasses are available for free from the Fountain Hills Library. (Put them right over your regular glasses if you wear glasses or right on your face if you don't). Don’t try to observe the eclipse with sunglasses, exposed film or anything except the eclipse safety glasses you get from the library or from other reliable sources. Also, don’t even think about using binoculars or a telescope to look at the sun during the partial eclipse or at any time – instant, irreversible eye damage will result. Eclipse glasses will keep you safe.

From our area the moon will appear to first “touch” the sun at about 9:14 a.m. MST. Watch for that first tiny sliver of the sun to disappear and then watch the moon take a bigger and bigger bite out of the sun. (You can see an animation of the full event at timeanddate.com/eclipse/in/usa/phoenix.) The eclipse is a “slow motion” event, and won’t be over until 12:01 p.m. so you can take plenty of breaks as you view it. And don’t forget sunscreen.

Another safe way to watch the eclipse is to use a pinhole to project an image of the sun and moon onto white cardboard for everyone in the family to watch together. You can find instructions on doing this easy project at timeanddate.com/eclipse/make-pinhole-projector.html. It’s a great project for the grandkids. (A colander also makes a great way to create lots of little eclipse images.)

If it’s cloudy around here on the morning of the 21st you might want to consider checking satellite maps and taking a drive to someplace where it’s clear. However, if you miss this one don’t worry, by great luck another total eclipse will cross the US from Texas to Main on April 8, 2024; only seven years away.

Enjoy the event and please practice safe observing.

Learn more about the eclipse at the following websites: eclipsewise.com;

eclipse2017.org;

greatamericaneclipse.com; astronomy.com/great-american-eclipse-2017; eclipse.aas.org; and on Facebook at facebook.com/greatamericaneclipse.

(Ted Blank is a part-time Fountain Hills resident and founder of the Fountain Hills Astronomy Club. An amateur astronomer, he serves as a volunteer Solar Ambassador for NASA)