For some people, Monday’s eclipse will literally mean the world.

“It’s impossible to describe how exciting it is. You just have to experience it,” says Dr. Jay Pasachoff, an astronomy professor at Williams College in Massachusetts, who has seen 65 eclipses in his lifetime.

Pasachoff is referring to the rare cosmic event to take place on Monday, August 21st — an event known as eclipse “totality.” It will pass in a matter of minutes as the moon fully blocks out the sun, shrouding observers in complete darkness.

The last time totality was seen in American skies was 1979. At the time, amateur astronomer and science writer Dave Dickinson was just 10 years old.

Now, a hardened eclipse veteran, Dickinson will take in the spectacle from the Pisgah Astronomical Research Center in the Smoky Mountains, about an hour’s drive from Asheville, North Carolina.

“I’m going to hold onto my wife, and we’ll just watch. She’s never seen one either,” Dickinson says, referring to total eclipses. He has seen partial ones, however — including that eclipse back in 1979, albeit not from a vantage point to see totality. He remembers the anticipation he felt for Monday’s event — a save-the-date 38 years in the future.

And then there’s Len Ellis of New York, who, unlike Pasachoff and Dickinson, has no ties to the scientific community. He’s a husband and father of two girls, who harbors an obsession for chasing the sun. It’s an obsession that has inspired him to bring 150 of his closest friends to Jackson Hole, Wyoming, to gaze at the skies in wonderment.

“Umbraphiles” are defined as “[people] who love eclipses” — and are willing to go the distance to experience them. While people all across the contiguous United States will glimpse a few fleeting minutes of partial eclipse, only those who either live or travel to a narrow 70-mile-wide swathe of land that cuts across the American landscape will be in optimal position to witness totality.

Map of the eclipse’s path of totality. Source: NASA.gov

That strip of terrain slices through states including Oregon, Wyoming, Missouri, and North Carolina. It’s the reason why people like Pasachoff have brought a dozen of his students to a remote destination in Salem, Oregon — along with over two tons of sophisticated scientific equipment — to watch the show.

Pasachoff hopes to recreate the same sense of amazement he felt as a student in his freshman year at Harvard University, when his astronomy professor, Donald Mendel, flew his class in a rented Northeastern Airlines plane to glimpse an eclipse out the window. “Four years later, when I had just graduated from Harvard, I went to see an eclipse on the ground. It was even better,” Pasachoff remembers.

Since then, he’s been to China, Russia, Paula New Guinea, Gabon, and a remote archipelago near Norway — all in the name of watching and studying eclipses.

Clearly, umbraphiles are are hard core eclipse groupies. “My grandparents … went all over the world,” to chase eclipses, Ellis said. “The first one they saw was in the middle of nowhere in Canada in the 50s or 60s.” The only total eclipse he has seen was with his wife Nicky, in a remote desert in Turkey in 1999. But on Monday, that will change.

For Dickinson, he’s been making plans for this eclipse for the past five years, and knows others who have been arranging their trips for a decade. “People are dropping more than $10,000 just for this weekend.”

One umbraphile he knows is flying in from Malaysia, and Dickinson has heard reports of AirBnb units in the path of totality renting for over $2,000 a night.

He personally spends “maybe a few thousand a year,” on the hobby, but “[knows] people who spend comfortably in the five digits just flying,” to eclipse sites.

Once the roughly two and half minutes of lunar shadow come to an end, it will be down to business, planning for the next solar events that these devoted observers can’t miss. For Ellis and his friends — a group he has codenamed “Hole in the Sky” — that means decamping in Peru in 2019 for a total eclipse in South America, and for Dickinson, it’s returning to his hometown in Maine to see one in 2024.

But as the nation stands still on Monday and stares at the sky, how do they plan to watch?

“I’m going to bring a little solar scope on a tripod, set up the GoPro, and sling a DSLR [camera] over my shoulder,” Dickinson says.

But you don’t need all that equipment yourself. Just bring a pair of eclipse glasses, and Dr. Pasachoff’s advice: “Just enjoy yourself.”