Capital Weather Gang’s Angela Fritz explains how math is used to determine the timing and location of the total solar eclipse crossing the U.S. on Aug. 21. (Claritza Jimenez,Daron Taylor,Angela Fritz/The Washington Post)

This one’s different. This one’s somehow bigger and brighter, eclipsing all previous eclipses. There’s a total solar eclipse roughly every 18 months somewhere on the Earth, but the United States shares Monday’s spectacle with no other country (not for nothing is it branded the Great American Eclipse of 2017). Many of the total eclipses in recent years have happened in remote parts of the planet, and eclipse chasers have had to travel to desolate atolls and guano-covered rocks amid lonely seas. This one saunters down Main Street. The path of totality — the 70-mile-wide strip of America from Oregon to South Carolina in which the moon will, for a couple of minutes, block the sun — crosses the homes of an estimated 11 million people.

The sun and the moon haven’t changed, but Americans have. We’ve never been so populous, so mobile, so digitally wired, so GPS-savvy and so ready for a big event that has nothing to do with Washington politics.

The eclipse will attract hardcore eclipse chasers who have been prepping for years and who know all the lingo about the diamond ring, the Baily’s beads, the First Contact and the Second Contact and the Third Contact, etc. But this time they’ll have to take evasive action to avoid the crowds of eclipse rookies — the improvisers who perhaps haven’t quite grasped that totality is not when you put the eclipse glasses on, but when you take them off.

They probably don’t even know the difference between the umbra and the penumbra! [Pause while reporter Googles this.]

Here in the high desert of central Oregon, the focal point of Eclipse Mania is the town of Madras, population 6,200. This weekend the town expects roughly 100,000 visitors. This place is just about perfectly situated on the centerline of the path of totality, and most importantly, it’s climatologically gifted in late August, having a lower probability of cloud cover than any other place in America along the eclipse’s path.

The problem is smoke. You can see a long tongue of smoke extending from the Cascades, coming from a wildfire near a small town called Sisters. It’s wildfire season, so this is all completely normal — except that on Monday, anything that interferes with eclipse perfection will be completely unacceptable.

The smoke situation will probably be just fine. That’s the official word from experts monitoring the situation. The wind is supposed to shift this weekend and ensure blue skies. But make no mistake, the standards for this eclipse here in the Oregon desert are astronomically high.

Lupe Enriquez, 33, the barber at the Bada Bing Barber Shop, said he senses a divine element at work here in his home town: “God wanted me to see it. First hand. Front-row seat.”

The state expects an influx of 1 million people. Already there’s been a 15-mile backup on a country road leading to a remote lake in mountains east of here, where a total-immersion music festival called the Symbiosis Gathering is expected to draw more than 30,000 “authentic seekers of awe and truth and beauty,” as the event’s website puts it.

In Madras the big camp-out began several days ago. Just north of town is a vast field that suddenly has a population of many thousands. It’s called Solartown. The RVs are in one area, the luxury tents in another. The beige canvas tents go for $1,500 each for the weekend — pre-positioned, with cots. They’re clustered in orderly rows as if part of a military encampment.

“We don’t care if we never leave this campsite,” said Kathleen Spencer, 62, of Whittier, Calif., who drove here with her husband, Carl, 68, and massive supplies of bacon, hamburger meat and hot dogs, 10 gallons of water, a gas stove, flashlights, head lamps, a solar-powered cellphone charger and playing cards.

Solartown should not be confused with Solar Port, an RV and tent complex near the airport, or with Solarfest, a festival at the fairgrounds that has featured Native American drummers, gospel and country music, and, on Saturday, a string of tribute bands (Foreigner, Aerosmith, Pat Benatar, Heart).

Visitors have been warned that there could be an apocalyptic lack of decent cellphone coverage (in other words, Eclipsemageddon.) Traffic is a serious concern, as there are only a couple of ways in and out of town. State officials warn that on Eclipse Day, it could take seven hours to drive what would normally be a one-hour distance on roads leading to Madras.

Lysa Vattimo, the solar eclipse plan facilitator for Madras, points out: “It’s not like the Olympics, where money is pouring in and you get to widen your roads.”

Locals have prepared for the influx as if an earthquake is about to hit, stocking up on food and water and gasoline. And entrepreneurs are renting out their farms and ranches as campsites. Downtown, Black Bear Diner owner Joe Davis has simplified his menu and added extra capacity, boasting, “I’ve got enough food for five weeks.”

Connie Damberger, 55, a resident for three-and-a-half decades, stopped by the art studio of Mayor Royce Embanks and questioned him about whether some of this eclipse-generated local revenue could be used to pave the road in front of her house. The mayor said no. The revenue from renting campsites at the airport will be used for cleanup, he said.

Damberger said she has mixed feelings about the eclipse: “It’s good. I just hope people go when they’re done. I like my small town!”

The eclipse is geographically generous: Everywhere in the continental United States will have at least a partial eclipse. One does not need to travel to the ballyhooed path of totality to see the celestial event. Dark-filtered eclipse glasses (cheap-looking things akin to what you might wear in a 3-D movie) are absolutely necessary to avoid eye damage.

Even in a partial eclipse, the moon and sun demonstrate an extraordinary coincidence of scale: The sun is about 400 times wider than the moon but about 400 times farther away. From our perspective, they’re matching orbs. And an eclipse is one of those events that absolutely will go off on schedule, down to the second.

“It’s inevitable. It’s celestial mechanics, and we have no control over that. And this is how we understand how vast the universe is, and we are so insignificant,” said Kate Russo, a psychologist and eclipse chaser who is the author of the book “Being in the Shadow.”

The experts have been emphatic that, compared with a partial eclipse, totality provides a soul-stirring grandeur. Grasping for a metaphor, we might say the difference is night and day.

Russo, 44, plans to lead an expedition of eclipse chasers by gondola up the slope of Grand Teton in Wyoming, right in the path of totality. Russo said the vantage point will permit a contemplation of the movement of the moon’s shadow across Teton Valley as it heads to the east.

“I always say to people, ‘Look above you, and around you, and within you,’ ” she said. “Just be there. You don’t need any other special equipment.”

Ryan Milligan, a solar physicist affiliated with the University of Glasgow, said he’ll observe from a ranch near Alliance, Neb., and is determined to avoid the disaster he experienced in 2015. That year he journeyed to the Faroe Islands to see a total eclipse, only to miss it when clouds rolled in.

He later learned he could have driven to a clear spot. At the crucial moment, he froze.

“I’m kicking myself to this day,” he said. “They don’t call it eclipse chasing for nothing. You can’t sit around and wait for it to come to you. You have to be prepared to move.”

To move or not to move: That’s the question as Eclipse Day gets close and people scan the weather reports and the wildfire news. And there’s another issue, a subtle one: What do you do if you’re in the path of totality but not very close to the centerline of that path of totality? The closer you are to the center, the longer the moon’s full shadow passes over you.

“This area is in the center of totality,” Amy Mullen, 39, of Portland, said as she sat in the dwindling shade of her tent at Solartown. “Right here I think it’s going to be two minutes and 9 seconds.”

The difference is only a matter of seconds, but the situation can generate Totality Envy.

Consider the case of Christopher and Diana Rulon, retirees from Albany, N.Y. They went to their first solar eclipse in Australia in 2012 and had a classic cloud catastrophe. Clear skies, the moon comes in, and right before totality, a cloud blots out the show.

“It’s going to come again. Keep it on the bucket list, and we’ll try it again,” Diana remembered saying after the disappointment.

So they’re here, in an RV, but in a location south of Madras where totality will last only 1 minute and 40 seconds, they say. Should they move? Get another 20 seconds or so? Risk calamitous traffic jams?

Fortunately there was an expert at the Solarfest who could help them out: Dean Pesnell, a NASA solar physicist. He’s a veteran eclipse chaser. This weekend he’s dispensing expertise at the fairgrounds.

Stick with what you got, he advised the Rulons: “The extra 20 seconds is probably not going to be worth the hours of traffic.”

Pesnell describes an eclipse as a group experience: “If you’re there with your family, try and talk about what you see. Everybody sees it a little differently. Do you see things coming out of the top of the sun? Do you see things coming out of the bottom of the sun? Try and work with each other.”

But about those wildfires: Around Madras, the smoke is noticeable on the horizon, at times completely obscuring the magnificent volcanic cone of Mount Jefferson to the west. But the sky directly overhead has been clear and blue. By the time the moon starts to pass in front of the sun on Monday, it’ll be well into the morning, the sun high in the sky. Totality starts at 10:19 a.m. here.

Farther south, the big Cascade fire has sent a shelf of smoke over the town of Redmond. A lingering haze could create an eclipse buzz kill, but the state Department of Environmental Quality expects the wind to shift this weekend. Greg Svelund, a spokesman for the department, said winds should blow the smoke to the west before Eclipse Day. “Cross your fingers,” he said.

Other than smoke, the weather forecast is immaculate: Nothing but brilliant sunshine is expected Monday.

Until the moon makes its move.