To see this month's total solar eclipse, the first one to be visible from the contiguous United States in nearly 40 years, all Donald Liebenberg will have to do is open his front door and step outside.
"It's a really special treat to be able to have one in my driveway," says Liebenberg, who has trekked to Turkey, Zambia, China and Pukapuka, a remote island in the Pacific, to see past eclipses.
Some, like Liebenberg, are attracted by the chance to scientifically observe the outer atmosphere of the sun. Others are emotionally drawn to an experience they describe as overwhelming and otherworldly.
Liebenberg, an adjunct professor of astronomy at Clemson University in South Carolina, has seen 26 total solar eclipses. He has spent more time in totality, which is when the moon completely blocks the sun, than anyone else on Earth.
Totality is normally a brief event, when you see it from one spot. "The longest eclipse time on the ground is just shy of eight minutes, says Liebenberg. But he has always wanted more.
That is why he helped pioneer the use of airplanes to move along with the shadow of the moon as it swept over the landscape. In 1973, French officials even let him fly in the brand-new Concorde. It streaked across North Africa to keep up with the moon's shadow.
"Now remember, this plane is going at Mach 2, or more than a thousand miles an hour, and the eclipse is going a thousand miles an hour," says Liebenberg. "It was beautiful."
And it let him spend an astonishing 74 minutes in totality. That special trip is one reason why Liebenberg holds the world record for the most time spent in the moon's shadow — no one else is even close.
And the umbraphiles definitely keep track of records like this one.
Glenn Schneider, an astronomer at Steward Observatory at the University of Arizona, has been to 33 total solar eclipses. "I'm an eclipse junkie. I'll admit that," says Schneider. "People talk about eclipse addiction, and I think I'm probably up here on the top of eclipse addicts."
Don't ask him to pick a favorite. "I don't have a ranking," says Schneider. "Any one of them is one of the top events in my life. The one that I'm seeing at the moment is the best one."
The story of how he got hooked is pretty typical: It started with the unexpected impact of the first. As another eclipse chaser notes, "your first time is always special."
For Schneider, that came in 1970, when a total solar eclipse was visible from the East Coast. He was a teenage amateur astronomer who eagerly planned how to spend the brief window of totality. "I had a number of telescopes and binoculars all set up and had practiced and rehearsed for months on end," Schneider recalls.
All of that was forgotten the moment the sun blinked out.
"Staring up at that hole in the sky, I just literally froze," Schneider says. "I couldn't move. It was just such a literally awe-inspiring moment."
You may intellectually understand the workings of our solar system, and the vastness of time and space, he says, "but a total solar eclipse makes you feel it."
"With the darkening of the sky, the movement of the moon's shadow, and you sort of at the bull's-eye of the confluence of where this is happening," he says, "it really is overwhelming."
If you're willing to go anywhere on Earth — and the umbraphiles are — a total solar eclipse is visible every 18 months, on average. Schneider still laments the one eclipse he didn't manage to get to: It was in 1985, in a remote, inaccessible part of Antarctica.
"That's the one that escaped," he says. "Terrible thing! Nobody could see it."
But the next year, he and some pals got in a plane and managed to see a brief total solar eclipse off the coast of Iceland. Only nine people on Earth saw that eclipse, he says: "The nine that were in our airplane."
"There are some that are pretty remote and that you do go to a lot of trouble for," says Schneider. "Fortunately, there are none coming up in the rest of my lifetime that I think are off the chart for being able to get there. But there will be difficult ones again."
Jay Pasachoff, an astronomer at Williams College who also has traveled to see 33 total solar eclipses, still regrets the one time he didn't try to go.
"I stayed home the one in November in 1976 because I was up for tenure at the time, and I'm still sorry that I missed it," he says, recalling that he would have headed to Australia for it. "I console myself by the knowledge that it was cloudy where I would have gone."
Clouds drift in and out of eclipse chasers' stories. They talk of clouds that magically parted at the last second or of a random little cumulus cloud that wandered in and ruined everything.
"If it's clear, I guarantee you're not going to be let down," says Pasachoff. "The real worry is the weather. And that's why I chose my location by the cloudiness statistics."
For chasers like him, planning to see an eclipse means consulting maps that show historical weather patterns and making contingency travel plans.
Fred Espenak, aka "Mr. Eclipse," is a retired astrophysicist who has witnessed 27 total solar eclipses. In the days leading up to this month's eclipse, he'll be in Casper, Wyo. "If the forecast is bad for Casper, I'll be ready to travel a thousand miles east or west on Sunday — the day before the eclipse — to get to a better location," says Espenak.
After all, what's a thousand miles to a guy who once spent weeks on a Russian icebreaker to see a total solar eclipse? He says his fellow eclipse chasers often bump into each other, in airports in Istanbul or Beijing.
"We all tend to be science geeks, a good number of us," he says.
But Espenak says you don't have to be a nerd to appreciate a total solar eclipse. He calls it the most beautiful natural phenomenon anyone can experience.
"I have seen people witnessing their first eclipses. And after totality, they are down on their knees, weeping," says Espenak. "It's just an incredibly moving event."
So moving that some of the millions of Americans watching this next one may be instantly transformed into umbraphiles.