A chilly, midday darkness fell across North America on April 8 as a total solar eclipse raced across the continent, thrilling those lucky enough to behold the spectacle through clear skies.

Eclipse mania gripped all of Mexico, the U.S. and Canada, as the moon swept in front of the sun, blotting out daylight. Almost everyone in North America was guaranteed at least a partial eclipse, weather permitting.

It was the continent’s biggest eclipse audience ever, with a couple hundred million people living in or near the shadow’s path, plus scores of out-of-towners flocking in.

Clouds blanketed most of Texas as the total solar eclipse began its diagonal dash across land, starting along Mexico’s mostly clear Pacific coast and aiming for Texas and 14 other U.S. States, before exiting into the North Atlantic near Newfoundland.

Just east of Dallas, the hundreds gathered at Mesquite’s downtown area cheered and whistled as the clouds parted in the final minutes before totality. As the sun finally became cloaked, the crowd grew louder, whipping off their eclipse glasses to soak in the unforgettable view of the sun’s corona, or spiky outer atmosphere, and Venus shining brilliantly off to the right.

City officials reminded everyone that the last total solar eclipse in these parts was the 1870s, making this one all the more special. Eclipse-themed music was turned off as the big moment approached.

“Oh God, it’s so dark,” marveled Aiyana Brown, 14, who watched alongside her grandfather, Mesquite Mayor Daniel Aleman Jr. “I’m a huge science nerd, and this is amazing.”

The weather also cooperated at the last minute near Austin. “I will never unsee this,” said Ahmed Husseim of Austin, who had the eclipse on his calendar for a year. Husseim and his family were among hundreds who gathered on the lawn of Southwestern University in Georgetown, Texas, with blankets, lawn chairs and country music.

Arkansas and northeast New England were the best bets in the U.S., going into Monday’s spectacle. New Brunswick and Newfoundland in Canada also looked promising.

The show got underway in the Pacific before noon EDT. As the darkness of totality reached the Mexican resort city of Mazatlán, the faces of spectators were illuminated only by the screens of their cellphones.

The cliff-hanging uncertainty added to the drama. But the overcast skies in Mesquite near Dallas didn’t rattle Erin Froneberger, who was in town for business and brought along her eclipse glasses.

“We are always just rushing, rushing, rushing,” she said. “But this is an event that we can just take a moment, a few seconds that it’s going to happen and embrace it.”

A festival outside Austin wrapped up early on Monday because afternoon storms were in the forecast. Festival organizers urged everyone to pack up and leave.

Sara Laneau, of Westfield, Vermont, woke up at 4 a.m. Monday to take her 16-year-old niece to nearby Jay Peak ski resort to catch the eclipse after a morning on the slopes.

“This will be a first from me and an experience of a lifetime,” said Laneau, who was dressed in a purple metallic ski suit with a solar eclipse T-shirt underneath.

At Niagara Falls State Park, tourists streamed in under cloudy skies with wagons, strollers, coolers and lawn chairs. Park officials expected a large crowd at the popular site overlooking the falls.

During Monday’s full eclipse, the moon slipped right in front of the sun, entirely blocking it. The resulting twilight, with only the sun’s outer atmosphere or corona visible, would be long enough for birds and other animals to fall silent, and for planets, stars and maybe even a comet to pop out.

The out-of-sync darkness lasts up to 4 minutes, 28 seconds. That’s almost twice as long as it was during the U.S. coast-to-coast eclipse seven years ago because the moon is closer to Earth. It will be another 21 years before the U.S. sees another total solar eclipse on this scale.

It will take just 1 hour, 40 minutes for the moon’s shadow to race more than 4,000 miles (6,500 kilometres) across the continent.

Eye protection is needed with proper eclipse glasses and filters to look at the sun, except when it ducks completely out of sight during an eclipse.

The path of totality — approximately 115 miles (185 kilometers) wide — encompasses several major cities this time, including Dallas; Indianapolis; Cleveland; Buffalo, New York; and Montreal. An estimated 44 million people live within the track, with a couple hundred million more within 200 miles (320 kilometers).

“This may be the most viewed astronomical event in history,” said National Air and Space Museum curator Teasel Muir-Harmony, standing outside the museum in Washingon, awaiting a partial eclipse.

Experts from NASA and scores of universities are posted along the route, poised to launch research rockets and weather balloons, and conduct experiments. The International Space Station’s seven astronauts also will be on the lookout, 270 miles (435 kilometres) up.

Washington:

Just a single, unguarded glance at a solar eclipse can result in a lifetime of vision loss, eye health experts warn.

On Monday, tens of millions of spectators across Mexico, the United States and Canada will witness the Moon completely obscure the Sun’s light, a rare celestial spectacle that won’t be visible for most of North America again until 2044.

Medical literature is teeming with examples of people who suffered damage to their retinas — the layer of light-sensitive tissue at the back of the eye — and health professionals are offering advice on how to avoid becoming the next cautionary tale.

Aaron Zimmerman, a clinical professor of optometry at the Ohio State University, told AFP that the dangers of sungazing during eclipses were discussed by the ancient Greek philosopher Socrates, but it wasn’t until recently that science really caught up with how eye injury happened.

When it comes to eclipses, he explained, the main damage comes from “photochemical toxicity,” where short, high-energy wavelengths of light — blues, violets and non-visible ultraviolets — trigger chemical reactions that damage the rods and cones of the retina.

Cue visits to the emergency department by people with complaints of blurry vision, changes in color perception, and blind spots, with the outlook for recovery far from certain.

Human beings inherently look away from the Sun because of the discomfort it causes, but during eclipses “you can psychologically override” that instinct, explained Zimmerman.

A famous journal report about the 2017 US solar eclipse involved a woman in her twenties who presented to the New York Eye and Ear Infirmary after looking at the solar rim “several times for approximately 6 seconds without protective glasses” and then later with eclipse glasses.

Hours later, objects started to look fuzzy and out of shape, colors became distorted, and she developed a central black spot in her left eye.

An advanced imaging technique was able to show the damage at the cellular level which persisted on her follow up six weeks later.

‘Permanent blank spot’

Young adults might be more susceptible, the authors of the paper said, because of larger pupils, clearer eye structure, or “poorer recognition of the dangers” of viewing eclipses with improper eyewear.

“In some cases, it’s just partially damaged and it may resolve so that you don’t notice it anymore,” Neil Bressler, a professor of ophthalmology at Johns Hopkins University and editor-in-chief of JAMA Ophthalmology told AFP. If recovery happens, it’s normally within the first six months.

“But in other cases, it can leave a permanent blank spot… and we don’t have a treatment to reverse that. It’s like brain tissue, once you lose it, it won’t grow back,” added Bressler.

The best way to view the eclipse is with eclipse sunglasses, which block out 99.999 percent of light. Always go for genuine products. To test if your glasses are up to standard, “find the brightest light bulb in your home — and then look at that from up close and you should barely be able to see the light,” said Zimmerman.

If it’s too late to procure specialist eyewear, then there are indirect methods, such as punching a pinhole into a cardboard and letting the light shine onto another surface, or even using the humble kitchen colander to the same effect. NASA’s webcast is another option.

Those fortunate enough to be in the “path of totality,” under which the Moon will fully block out the Sun, can look up without glasses and admire the Sun’s outer atmosphere, or corona, glowing from behind the silhouette of the Moon.

But, said Bressler, the danger is not having protection before and after those precious moments, which can last anywhere from seconds to a few minutes, depending on your location.

“You must know when it begins and use protection before that, and you may be enamored by looking at all this, but you must have some alarm to tell you it’s about to end,” he warned.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

As the Solar Eclipse, also known as Surya Grahan, is set to take place on April 8, the US Federal Aviation Administration (FAA) has issued a warning for flying ahead of this celestial event. In a press note, the US government civil aviation agency advised that aircraft should be prepared for possible delays, reroutes, and changes in departure schedules for all the domestic (Instrument Flight Rules) IFR flights. The FAA’s website also listed the airports in the path of the upcoming Solar Eclipse that will be affected. 

“The purpose of this notice is to inform airmen of the possible impacts to air traffic and airports along the eclipse path during the period April 7, 2024, 1000 UTC through April 10, 2024, 0400 UTC,” the press note read. 

“Aircraft should be prepared for potential airborne holding, reroutes, and/or Expect Departure Clearance Times (EDCTs) that may be issued for all domestic IFR arrivals and departures. Traffic Management Initiatives (TMIs) are possible,” it added. 

According to NASA, the April 8 Solar Eclipse, also known as the “Great North American Eclipse”, will be visible in several countries, including the United States, Mexico and Canada. The eclipse will cross North America, creating a spectacle for observers. As a result, air traffic is expected to intensify, particularly between Texas and New England, as skygazers prepare to witness the rare event, the FAA said. 

“There may be a higher traffic volume than normal anticipated at airports along the path of the eclipse. Traffic should anticipate delays during peak traffic periods. Parking may be limited – particularly at the smaller, uncontrolled airports,” the aviation agency added. 

Also Read | What Scientists Hope To Learn From Total Solar Eclipse In US

Further, the agency recommended early planning and vigilance for both pilots and airports to mitigate potential challenges during this period. “Special security provisions may be in effect for this event, including, but not limited to, Temporary Flight Restrictions (TFRs), two-way radio communications, and discrete transponder requirements,” it said. 

Notably, the Solar Eclipse will not be visible in India. It will be visible in Texas, Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire, and Maine. Small parts of Tennessee and Michigan will also experience the eclipse. The eclipse will then move to Canada before exiting North America on the Atlantic coast. Hundreds of schools across the United States are set to close on April 8th due to a total solar eclipse.