On Monday, Aug. 21, the sun, moon and Earth will align, allowing a narrow band of the country from coast to coast — and the millions expected to travel there — to experience a total solar eclipse.

In Southern Arizona, however, the eclipse will be partial.

The moon will begin crossing the sun at 9:16 a.m. Tucson time and slide in front until the peak coverage at 10:36 a.m. when the moon blocks about 60 percent of the sun’s surface locally. The moon will finally move out of the sun’s glare just after noon.

This is the first total solar eclipse visible from the continental United States since 1979. The next one is in 2024.

Solar eclipses, regardless of how much of the sun is blocked, require eye protection at all times or other precautions, such as using a makeshift pinhole camera, so as not to damage your eyes.

So even in Tucson, with just over half the sun obscured, the event will draw many outside to watch this astronomical event. The local weather should be mostly sunny with some scattered clouds.

There are several public events Monday in Tucson during the eclipse where telescopes will be provided to promote safe viewing practices and also help provide an understanding of the natural phenomenon. (See box on Page A2.)

For those wanting to experience the eclipse from the comfort of their homes, most TV networks plan coverage of the total eclipse and there will be numerous internet sites — NASA.gov for one — livestreaming the event.

The total eclipse

Eclipses aren’t rare, but the path of totality, the strip of Earth’s surface where the moon completely blocks the sun’s light, is narrow and reaching it now could be difficult — large crowds are expected in the areas of the country where there will be a total eclipse.

On average, an eclipse occurs about once every 18 months but over only 1 to 2 percent of land on Earth. Eclipse chasers often have to battle harsh environments, bad weather and monetary and time restraints to see the event.

For people like Glenn Schneider, a University of Arizona astronomer, these obstacles are worth experiencing the thrill of a total solar eclipse.

Schneider is not a solar astronomer, he studies galaxies and exoplanet formations among other topics. He even worked on the Hubble Space Telescope. Eclipse chasing is his hobby.

“It’s actually more of an addiction. It’s not what I do as a profession,” he said.

Schneider was 14 years old when he saw his first solar eclipse in 1970 and has been hooked ever since.

For his first solar eclipse, he prepared for months by reading newspapers articles, magazines and books. He even took a bus all the way from New York City, where he lived at the time, to North Carolina, to reach the path of totality.

His meticulous planning of how he was going to spend time between his camera, telescope and binoculars went out the window the moment totality finally arrived.

He froze for the entire 2 minutes and 54 seconds of strange darkness.

“It was a deer in the headlights kind of moment,” he said. “I was mesmerized.” And when the sun returned, “It took someone to shake me back to mundane reality.”

He decided he wouldn’t let a moment like that slip by him again. Now, almost 50 years later, Schneider has experienced 33 total solar eclipses.

“Every eclipse is the best experience, except for the ones that are clouded out, which are traumatic,” Schneider said. “They’re all different.”

Every environment is unique, the distance between the Earth, sun and moon can change the characteristics and timing of the eclipse and there are unexpected obstacles to overcome.

Schneider has even had to take to the sky many times to avoid being clouded out on the surface. “Every eclipse has its own special unique flavor.”

What can be expected at any eclipse is an eerie and sudden change in environment. Although the change is most dramatic during a total eclipse.

Right before totality, you can see the shadow of the moon rushing toward you, Schneider said. “It’s this giant wall of darkness bifurcating the sky.”

At the last instant of sunlight, you can see the sun peaking over the jagged mountains of the moon, creating a diamond-ring effect, and a phenomenon called Baily’s beads right before totality.

And as the sun disappears, the temperature drops, the wind picks up, the entire sky looks like a sunset and the birds go quiet.

Eye protection can be removed only during totality, and the massive corona, usually hidden by the blinding glare of the sun, can be seen by the naked eye.

“You kind of put yourself in the middle of celestial mechanics in action. It becomes very personal,” he said. “It’s the only way that I know of where you really experience the working and scale of the dynamics of the solar system.”

The big show is only available in the path of totality, a narrow band of land about 65 miles wide, stretching from Oregon to South Carolina.

A group of students from Cienega High School are traveling to the path of totality in Pawnee City, Nebraska, as a part of a citizen scientist group called Citizen CATE.

The nationwide experiment is being coordinated by solar astronomer, Matt Penn of the National Solar Observatory. The goal is to station citizen scientists along the path of totality, collecting images from the total eclipse and stitching them together to create a 90-minute movie of the elusive corona.

Safety tips

Those who want to watch the eclipse, whether it’s full or partial, must take precautions to avoid damaging their eyes.

Never look at the sun directly or through a telescope, binocular or camera lens without a legitimate sun filter. You should only look directly at the eclipse using safe eclipse glasses, which dramatically dim the sun and block damaging wavelengths of light.

Attending one of the local viewing events is probably the best and safest way to see the eclipse.

On Monday morning, Flandrau Planetarium, Steward Observatory, the Lunar and Planetary Laboratory and Optical Sciences, with the aid of the UA’s astronomy club, will be hosting an eclipse viewing event on the UA Mall between 9 a.m. and noon. Telescopes will also be set up in Sabino Canyon by the Mount Lemmon SkyCenter, and local public libraries will also have viewing events. (See box above left.)

There are many other ways to experience the eclipse, besides glasses and telescopes.

  • You can make a pinhole view projector out of a cereal box. You can find a NASA video on how to make one yourself at eclipse2017.nasa.gov/how-make-pinhole-projector-view-solar-eclipse
  • You can also poke a small hole, which doesn’t need to be round, in a sheet of paper and hold another sheet underneath. Like a pinhole viewer box, the image of the sun will be projected on the page beneath.
  • Or look beneath a tree for a different experience. The gaps between the leaves will project hundreds of crescent suns on the ground.

Alternatively, an astronomy professor from Pima Community College will livestream the eclipse on YouTube from the McMath-Pierce Solar Telescope on Kitt Peak, southwest of Tucson, which is the largest solar telescope in the world.

Dennis Just, an astronomy professor at Pima Community College, said he expects to be able to see mountains on the moon during the eclipse.

Don McCarthy, a UA astronomer, said that besides seeing the eclipse, whether it’s partial or total, it’s also important to “listen and feel,” the changes in the world as the moon occludes the sun.

More than half of the sun’s light will be smothered by the moon here. It might get a little darker, and it might get a little cooler. There are many different ways to experience the eclipse, he said.

In 2002, McCarthy prepared the Catalina Sky Survey 60-inch telescope on Mount Lemmon for his astronomy campers who were busy gazing at the partial solar eclipse just outside.

Like many domes, the dome that housed the telescope was punctuated with small holes, possibly from popped rivets.

As the moon slid in front of the sun that day and light from the eclipsing sun peeked in through the holes like a pinhole camera, a kaleidoscope of palm-sized crescent suns were projected around the interior of the dome.

McCarthy laughed at the sight. “I was giddy about it.”

Contact Mikayla Mace at mmace@tucson.com or (520) 573-4158. On Twitter: @mikaylagram.