What compels people to travel from all over the world to see a total solar eclipse? The experience is hard to describe. You can see stars in the daytime. The sun's shimmering corona is visible to your naked eye. You get to observe how something happening up in the heavens has an immediate effect on the world around you. If you are lucky enough to be in a natural setting, the effect is even more striking.

On the Path to Totality

I saw my first solar eclipse on February 26, 1979, at Farnum Elementary School in San Diego, when I was 11 years old. For my classmates and me, it was only a partial one, but thousands of others living farther north had gotten to see the full spectacular show.

“There won't be another total solar eclipse in the United States until August 21, 2017,” my sixth-grade teacher told us. Though most of the class paid little attention to the date (time would stop in 1999 as far as we were concerned), I did, because August 21 is my birthday. I immediately started planning.

In 1991, I was hiking through Lassen National Park, on my way from Mexico to Canada on the Pacific Crest Trail, when I stopped on July 11 to observe my second partial eclipse. I perforated the cover of my guidebook to build a makeshift pinhole camera, and with it, I was able to watch the crescent sun cast shadows onto the smooth bark of a dead tree. The eclipse was total for people watching in Hawaii, but the continental United States would have to wait.

That will change on August 21, when the moon's shadow will cross the United States from Salem, Oregon, to Charleston, South Carolina. The moon is four times smaller than the earth, but it is 30 earth diameters away, so during the eclipse, its shadow will be a scant 100 kilometers, or roughly 60 miles wide. This diagonal stripe, known as the "path of totality,” is the place to be. If you are outside of it, you’ll only see a partial eclipse.

I’m as excited now to see this total eclipse as I was as a kid, even though it won’t be my first. In December 2002, I observed one while I was in Australia researching exoplanets. I and a few other astronomers drove for hundreds of miles into the outback, passing through a vast stretch of emptiness before abruptly coming upon hundreds of people parked along the side of the road with telescopes, binoculars, and cameras. Some had come from the farthest corners of the planet for an experience that lasted 43 seconds.

The Big Picture

Eclipses have always played an outsized role in the human psyche. Archaeologists have unearthed written records of them dating back to 1375 BCE (from the Syrian city of Ugarit). According to historians, they have even ended wars.

Scientists have used solar eclipses to discover the element helium and confirm Einstein's theory of gravity. Writers from Mark Twain to Annie Dillard have included eclipses as key elements in literature.

Some people consider eclipses to be spiritual events that tune us into cycles of the sun and moon beyond the normal calendar of days, months, and years. For example, there’s the Saros Cycle, in which nearly identical "cousin" eclipses occur in the same part of the world 54 years, 33 days apart. The August 2017 eclipse is the Saros cousin to an eclipse that occurred July 20th, 1963, in Canada and the northern United States, just after the Cuban Missile Crisis. If you are old enough to remember that, you may have a grandchild young enough to witness the next repeat in 2071.

Where to Go on August 21

The good news is that once you make it to the path of totality, you don’t need to be anywhere special to witness the effects of the eclipse. But being out in nature does make the experience more profound. If you like the great outdoors, this is an excellent excuse to get there.

Campers and hikers will be soaking up the darkness in places like Mt. Jefferson Wilderness in Oregon, Lake Cascade State Park in Idaho, Grand Teton National Park in Wyoming, Onondaga Cave Park in Nebraska, and Great Smoky Mountains National Park in Tennessee. You can check NASA's detailed eclipse maps to find other natural spots.

The bad news is that most of the hotels and campgrounds directly on the eclipse path have long been booked. If you are just starting to plan now, you’ll need to think creatively. Staying an hour’s drive away from the path of totality is a good option, since the eclipse occurs at the comfortable time of midmorning. Just be sure to account for traffic because others will probably be making the same trek.

What You’ll Need

You don't need expensive gear to have an amazing eclipse experience. Because the partial phases—before and after—will each last about an hour, you'll want a pair of eclipse viewing glasses. (If you can afford it, why not buy a few extra to hand out?) A pinhole camera is another effective way to observe these phases. You can also look for the crescent sun's image in the dappled shadows of trees. As the first partial phase progresses, you'll see the moon take a bite out of the sun, then gradually cover more and more of it. When the sun completely disappears, lower your protective glasses and enjoy a few minutes of profound darkness.

How to Be Safe

You've no doubt heard safety warnings about looking directly at the sun. Fortunately, human instincts protect our sensitive eyes, and documented cases of accidental long-term solar eye damage are exceedingly rare. But you should still be aware of heightened risk in the partial phases of the eclipse. The total phase, which only lasts minutes, can be viewed with your naked eyes, but just as totality ends, your eyes may be dilated and let more light in. So, be ready to put those eclipse viewing glasses back on immediately.

Also, during the partial phases, you may get a chance to look through a telescope. If a solar filter has been installed at the entrance to the scope, this can be done safely without eye protection. But don't automatically assume it is safe to put your eye to an eyepiece. Some telescopes are configured to project the sun's image, in which case no filter will be used. To be safe, simply put your hand where your eye would go. If you see a bright light or can feel the heat of the sun, then your eye doesn't belong there. 

I’ll be celebrating the once-in-a-lifetime experience of a total eclipse coinciding with my birthday in a cabin in Idaho’s Sawtooth Mountains with my family and friends. But for anyone living in the United States, this is the celestial event of a lifetime. See you in the path of totality!