There’s a once-in-a-lifetime eclipse coming. Here’s what you need to know

UPDATE: Since this story was originally prepared, the Discovery Center at 1944 N. Winery Ave. in Fresno decided to provide an eclipse-viewing. A solar telescope will be available there from 9 a.m. Monday through the end of the eclipse at 11:45 a.m.

What would it look like if a celestial electrician installed a dimmer switch on the sun? Fresno and the Valley will get a hint of that when a solar eclipse creeps across North America on Aug. 21.

We won’t get the best of what the eclipse has to offer. The experience of a total eclipse – when the moon passes between Earth and sun and completely obscures the sun for two minutes or more – is reserved for a 70-mile-wide path crossing the continent from Lincoln City, along the Oregon coast west of Salem, to the Atlantic coast north of Charleston, South Carolina.

Local stargazers say a total eclipse is a spectacular phenomenon, a once- or twice-in-a-lifetime experience for those living in the United States. And many are hitting the road to stake out a prime viewing position somewhere in the “path of totality.”

The farther you get from that path, the less of the sun that is blocked by the moon. In Fresno, about 750 miles south of Salem, the eclipse will be noteworthy if not spectacular. According to information from NASA’s Solar Eclipse 2017 website, the moon will start nibbling at the edge of the sun at 9:03 a.m. and, at its peak at 10:19 a.m., will obscure about 72 percent of the sun’s disc. After that, the moon will get out of the sun’s way, completing its transit at 11:42 a.m.

For the Valley, “this one is going to be very similar to one in October 2014,” said Steven White, a physics professor at Fresno State and director of the university’s Downing Planetarium. “It’s actually going to be a little better than the one a few years ago, which was about 46 percent. It’ll be noticeably dimmer, kind of like an overcast day.”

Road tripping

Greg Eckes, president of the Tulare Astronomical Association, said he and many other members of his amateur astronomy group are going to Oregon and elsewhere to experience the full eclipse.

“It’s very significant,” Eckes said. “There’s an eclipse somewhere on this Earth every year, and sometimes it can even be twice a year. But this is the first one over the continental U.S. with a path of totality across the whole country in something like 100 years.”

NASA reports that the last total solar eclipse visible from the contiguous U.S. was in February 1979, when the path went across five northwestern states and several Canadian provinces. But no total solar eclipse has crossed the entire U.S. from the Pacific Ocean to the Atlantic since June 1918.

Plenty of members from Fresno-based Central Valley Astronomers likewise are heading north. “They’re leaving the state and going to Oregon to see the eclipse in totality instead of 72 percent,” said Lynn Kliewer, the club’s president.

If work or school commitments prevent you from making a 12-hour road trip, your eclipse-viewing choices may be limited. The Discovery Center, Fresno’s go-to place for hands-on science education for children, will have a solar telescope set up for the public starting at 9 a.m. and continuing through the nearly three-hour duration of the eclipse. Neal Bourzac, education and outreach specialist at the center, said there will also be other educational activities related to the eclipse. The Discovery Center is at 1944 N. Winery Ave. in Fresno.

Because so many members of the Tulare and Fresno astronomy groups are hitting the road, however, neither will host eclipse events. Nor will the Downing Planetarium at Fresno State because folks who work there also want to see the total eclipse firsthand.

White, the Fresno State professor, was in college in Oregon when the 1979 total eclipse happened. While some of his friends traveled to eastern Oregon for the eclipse, an economics test kept him on campus in Salem, “and there were thick gray clouds so you couldn’t even tell the sun was out.”

“I’m not going to miss it this time,” White said. “Everybody’s going, so we’re going to be closed” at the planetarium.

Eye protection

For those staying in the Valley, eye protection and safety are of critical importance. NASA, the American Astronomical Society, the American Academy of Ophthalmology and the California Academy of Eye Physicians and Surgeons all declare that people must not look at the sun unless they are equipped with specially designed solar eclipse glasses or viewers.

“The only safe way to look directly at it is with special solar filter glasses,” White said.

NASA recommends buying eclipse viewing glasses from any one of five companies: American Paper Optics, Baader Planetarium, Rainbow Symphony, Thousand Oaks Optical and TSE 17. American Paper Optics is the largest of those companies, with sales reaching 500,000 pairs of glasses per day in the weeks leading up to the eclipse, according to published reports.

NASA also recommends eclipse viewers ensure that the ISO certification number 12312-2 and the manufacturer’s address are printed on viewing glasses.

Solar eclipse glasses can be bought in stores, including some Walmart and Lowe’s home improvement stores, according to the American Astronomical Society, which helped NASA compile a list of reputable manufacturers. But glasses from companies not recommended by NASA are readily available online, where it is sometimes hard to tell the difference between safe and potentially risky glasses.

If you can’t find a pair of approved eclipse glasses, White recommends making a simple “pinhole projector” with cardboard, aluminum foil, and a straight pin.

“Take a piece of cardboard, cut a hole, cover that hole with foil, and then poke a pinhole in it,” he said. Once that’s done, hold the cardboard so the sun shines through it and projects an inverted image of the sun onto a piece of white paper. “And one thing you can do that’s kind of fun is poke the pinholes in a design, and when you hold that screen up, every single pinhole will make an image of the eclipse,” he added. “It’s a way that kids can get creative with it.”

NASA will also stream the eclipse live on its website www.nasa.gov/eclipselive from locations across the country so people can watch on their computers, tablets or smartphones.

History and mythology

For centuries, solar eclipses were the stuff of mythology and superstition as ancient people witnessed the daytime disappearance of the sun. Often, eclipses were considered bad omens. Historians note that eclipses were represented as a creature or demon consuming the sun – a dragon in China, a giant turtle in Vietnam, a jaguar in Latin America, and more. In some cultures, people beat on drums or whatever they could to make enough noise to chase away what was attacking the sun.

“The Chinese were especially aware of eclipses because they thought the most important things in the sky were changes,” White said. “New stars, comets and eclipses were very important, and they developed an ability to predict eclipses.”

There are stories of at least two astronomers from ancient China who were executed because they had failed to predict solar eclipses, White added.

The ancient Greeks also developed an understanding of eclipses as celestial shadows. “They knew a solar eclipse was the moon blocking the sun temporarily, and lunar eclipses happened when the moon passed through the earth’s shadow,” White said. “Aristotle said we knew the earth was round because you could see the curve of the shadow on the moon. And they figured that out without telescopes or even a rudimentary understanding of physics.”

After Aug. 21, the next total solar eclipse that will be visible from anywhere in the U.S. will be April 8, 2024. Elsewhere on the globe, future total eclipses will be on July 2, 2019 and December 14, 2020, both in South America, and Dec. 4, 2021, in Antarctica, according to the website GreatAmericanEclipse.com.

No total eclipse will be visible from anywhere in California until Aug. 12, 2045, and even then it will only be visible in totality in the northern reaches of the state.

This story was originally published August 15, 2017 at 6:00 AM with the headline "There’s a once-in-a-lifetime eclipse coming. Here’s what you need to know."