Q&A: Utah’s eclipse view and what to expect Saturday

While residents and tourists are heading to southern Utah for a full view as the moon passes in front of the sun Saturday morning, the Clark Planetarium says those who stay on the Wasatch Front will see nearly 90% of the moon’s coverage.

The annular eclipse’s “path of totality” will cover Torrey, Richfield, Lake Powell and other areas, and the Utah Department of Transportation is warning that it expects heavy traffic on central and southern Utah highways.

Richfield is expected to draw at least 300,000 visitors, with maximum obscurity there at 10:28 a.m. on Saturday, UDOT said. The heaviest traffic is expected in that area and near Mexican Hat, though drivers throughout the region should expect delays from Friday through Sunday, it said.

Worried about the impact on her small town, Bluff Mayor Ann Leppanen is urging people: “Don’t try to come here.”

What will the annular eclipse look like?

An annular eclipse occurs when the moon passes directly in front of the sun, but appears to be smaller than the sun.

It’s different than a total eclipse, explains Paul Ricketts, observatory manager at the University of Utah, because “the moon is farther away, and so it doesn’t block out the sun fully. You basically see a ring of sunlight around the moon.”

Don’t get distracted, he advises — the full annularity (when people can see the ring) will last less than five minutes, depending on where one sees it. He describes it as “a quick thing that you never forget.”

Where is the full view?

The path of annularity — where the entire disc of the moon moves in front of the sun — is expected to be a narrow band, around 125 miles or so in width.

It will start in southern Oregon, skirt the northeast corner of California, pass over northern Nevada, cross southern Utah to the Four Corners area (snagging bits of Arizona and Colorado), go through New Mexico and finally across southwest Texas. The band will then travel down the length of Central America, and cross through Colombia and Brazil.

In Utah, the annularity will just miss Zion and Arches national parks on either side of the band, but hit the other three of the “Mighty 5.” Towns in the middle of the band, such as Richfield and Torrey, will see the annularity for more than 4 minutes. The parts of Utah outside the band will see the moon cover at least 80% of the sun’s rays.

While an annular eclipse can occur somewhere on Earth once or twice a year, “the rare part is it landing where we are,” Ricketts said. “The path for them is so thin that only a small slice of any country actually gets to see it.”

According to the website GreatAmericanEclipse.com, all of the lower 48 states will see the moon obscure at least part of the sun. The National Aeronautics and Space Administration estimates the eclipse will be visible for millions across the Western Hemisphere.

How do you safely watch the eclipse?

People wanting to watch the eclipse should take safety precautions, Ricketts warned. “We’ll actually see so much light from the sun that it’s still not safe to look at without solar glasses,” he said.

Glasses, telescopes, binoculars and cameras should have solar filters that have a high enough optical density to blockout the sunlight properly, Ricketts said. NASA recommends using only solar filters built specifically for those devices; rigging up your own version could lead to eye damage.

“What you want to do is, initially, use them to look at the sun, and if it’s uncomfortable any way — like if it feels too bright or something — immediately stop using them,” he said.

Clark Planetarium has eclipse glasses available for safe viewing, while supplies last, at 110 S. 400 West in downtown Salt Lake City. It is also offering viewing parties Saturday in Salt Lake City, Magna and Cottonwood Heights.

NASA has further safety guidelines on catching a glimpse of the eclipse, at solarsystem.nasa.gov/eclipses.

— Tribune editor Sheila R. McCann contributed to this report.