America’s Great Total Solar Eclipse, Aug 21, 2017

This summer America will witness a total solar eclipse along a 71-mile-wide strip stretching from South Carolina, through the Midwest and over the Rocky Mountains to Oregon.

Solar eclipses are awesome and creepy and weird and utterly beautiful. If you have never seen one, stop what you are doing right now and plan a summer vacation to see it. You will experience the most spectacular astronomical event you will ever see in your life. Exaggeration?

Hardly. Our sun will disappear before your very eyes. That’s right, the moon will cover it up. Gone. Not there, just a black hole in the sky surrounded by the ghostly solar corona.

Like anything the sun shines on, the moon casts a shadow. When the shadow falls on the earth, we have a solar eclipse. There are two parts to every shadow, the umbra and the penumbra. The umbra (as in umbrella) is the darkest part of the shadow and is what we normally think of as “the shadow”, in this case where the path of totality falls. The penumbra is a brighter part of the shadow where only part of the sun is covered up. Here in Topanga we will only see a partial (penumbral) eclipse, which is interesting but will be hardly noticeable.

The whole event will last several hours but totality only about two minutes as the shadow of the moon sweeps across the nation. When the moon takes its first bite out of the sun, you won’t notice any dimming. Only after about 80% of the sun is covered will the landscape seem a bit darker.  Birds, however, will think sunset is coming and start to nest. When the sun is 95 percent hidden you’ll get the feeling that something really strange is happening.

As the very beginning (and end) of totality, a brilliant “diamond ring” emerges just for a moment.  The “diamond” is a razor thin crescent of the sun and the “ring” is the now slightly visible corona surrounding the dark moon.

And then it’s show time. The corona and brilliant cherry red prominence pop into view. Prominence can be seen hugging the edge of the moon. These are actually enormous solar storms shot upward from the sun, and are much larger than the entire earth. But it’s the ghostly white corona that steals the show. Too faint to be visible outside an eclipse, it’s the hottest thing you can see with the naked eye, well over two million degrees F.

Due to the narrow 71-mile width of the eclipse path, the sun will still be shining on the atmosphere a few dozen miles away. During totality, this will create a lovely yellow 360° twilight sky on the horizon.  

Before and after totality, watch as the normally round sun dapples on the ground beneath trees and take on the shape of the partially eclipsed sun, ultimately into a field of overlapping crescents.  Tiny gaps between leaves cast “pinhole” images of the sun. These are normally round and we don’t notice them until an eclipse.

There are lots of things you can do to enhance your views. A sun filter for watching the partial phase as the moon creeps across the sun. A patch over one eye starting about twenty minutes before totality will let that eye darken and adapt, so during totality, you can take it off and see much more of the corona.

All you have to do is be at the right place at the right time. The right place is any cloud-free location on the centerline of the eclipse. Being on the centerline is important because the duration of totality will be less away from it. With good maps, you need only pull off the road to see it. And there are thousands of miles of roads in the path of totality.

Plan on arriving at your chosen site before first contact, i.e., the moment the moon takes the first bite out of the sun. At this instant, you enter the penumbra. The first diamond ring and totality (second contact) will begin a few hours later. At the end of totality (third contact) and the second diamond ring (third contact), totality ends and you are back in the penumbra.  

Logistically, it’s best to be mobile. Keep track of the satellite weather maps and decide where the sky will be clearest on eclipse day. Plan your vacation to be near the eclipse path a day or two before the big event and do some sightseeing or visit friends and family.

For first-time viewers, my advice is to park yourself in a comfortable lawn chair and just watch it. Don’t worry about taking pictures; plenty of people will do that for you. Or set up a wide-angle video camera and start it about a minute before totality, then jump back into the lawn chair. Don’t get distracted by camera gear, just listen to the people whoop and holler and enjoy the show.

For more information, google “MrEclipse,” or “solar eclipse.”

Pinhole images of the partially eclipsed sun. Photo courtesy of Ed Morana, Livermore, CA,, used with permission.


By David K. Lynch


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