BLOOMINGTON — There have been total solar eclipses before. But the one that arrives Aug. 21 is the first in nearly 40 years to be visible in North America and the first in 99 years to be visible across the entire contiguous United States.
And that's not all.
In this era of Instagram, Facebook and YouTube, the internet is expected to be inundated with solar selfies. Communications companies are placing temporary cell towers in key rural locations along the "path of totality," but still warn that connections may be slow or non-existent.
In fact, so many people are expected to travel to see this historic celestial event, it's being described as “the largest single day mass migration of humans in history,” said Tom Willmitch, director of the Illinois State University Planetarium.
Willmitch will be one of those joining the migration, traveling to southern Illinois with a group of Bloomington-Normal astronomy buffs.
They are heading down a few days early, giving programs at a place called Camp Ondessonk and staying put, unless weather reports the day before suggest finding another spot.
But they don't want to be on the road any time near the eclipse itself.
“It's going to be a dangerous place to be,” said Carl Wenning, former ISU Planetarium director, who will be part of the Twin City group at Camp Ondessonk.
He is not talking about the danger of eye damage from looking at the sun without proper eye protection. He is referring to the potential for traffic accidents.
The Illinois Department of Transportation said an estimated 100,000 to 200,000 people are expected to visit the prime viewing areas in southern Illinois.
Do not park along the shoulder of a road, highway or interstate, warned IDOT. Instead, get off the road and park in a safe area away from traffic.
IDOT also advises people to turn on their headlights if driving during the eclipse and watch out for pedestrians.
Meanwhile, back home
So what about those of us staying put in Central Illinois?
About 93 percent of the sun will be blocked by the moon at the peak of what's considered a major partial eclipse in Bloomington-Normal.
“There will just be a thin sliver of sun visible” at the maximum point at 1:18 p.m., said Willmitch.
“You're going to see it get darker. You're going to see it get eerie. But it's not going to get dark,” said Wenning.
With the mid-day partial eclipse, Willmitch said, “The light just takes on a flat sort of hue. … It's hard to describe, and creepy.”
But don't be lulled by the dimmer light into looking directly at the sun without eye protection. The visible light and ultraviolet rays are still harmful in a partial eclipse, experts warn.
And, there still are interesting phenomena to observe during a partial eclipse.
Dappled sunlight passing through small openings in the tree canopy will create little crescents, said Willmitch. Another way to observe the odd crescent-shaped shadows is by taking a kitchen strainer or colander outside during the eclipse and have the sunlight shine through the openings, suggested Wenning.
But even with 93 percent of the sun obscured, “it's nothing, nothing compared to a total eclipse,” said Wenning, who has seen several.
When he saw a total eclipse in Bolivia in 1994, one man repeatedly exclaimed, “Wow, wow, wow for six minutes,” recalled Wenning.
“It's an indescribable delight,” said Wenning. “The first time I saw an eclipse, I didn't know what to expect. But once I did, I knew I had to go again.”
Both Willmitch and Wenning said people also shouldn't get caught up in trying to take photos of the eclipse.
“Don't be looking at your feet or camera. Just experience it. Take it in,” said Willmitch.
Wenning agreed: “You don't want to miss the big event.”