Mapping the eclipse: A journey through darkness
On April 8, 2024, a total solar eclipse will enshroud North America in shadow. What lies along its path?
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Solar eclipses have captivated human fascination since antiquity — and on April 8, 2024, a total solar eclipse will cast a shadow across a swath of North America. In a breathtaking display of celestial alignment, the Moon will slip in front of the Sun, blocking its light and momentarily transforming day into night along a cosmically prescribed path stretching from Mexico to Canada.
Solar eclipses occur when the Moon passes directly between the Sun and Earth. The Moon momentarily blocks the Sun's light, casting a shadow — or an umbra — on the planet below.
During a total solar eclipse (like the one in April 2024), the Moon's elliptical orbit carries it close enough to Earth so that it appears to block out the Sun completely. Annular eclipses occur when the Moon is farther from Earth, and appears just large enough to block the Sun's central disk. And during a partial eclipse, the Moon’s shadow merely grazes the planet.
A conceptual diagram of a total solar eclipse. Not to scale.
"Each eclipse is different," says longtime astronomy enthusiast Michael Zeiler, who has witnessed 11 total eclipses in person and runs the website greatamericaneclipse.com . "But they're all unspeakably beautiful."
The April 8 eclipse will first appear over the South Pacific Ocean, before making landfall near the Mexican city of Mazatlán around 11:10 AM local time.
Moving faster than the speed of sound, the Moon’s shadow — an oblong ellipse roughly the size (if not the shape) of Massachusetts — will continue along a northeast trajectory, entering the United States around 1:30 PM CDT. (Mexico does not observe daylight saving time, hence the two-hour time change.)
The shadow of the Moon will trace a path up to 123 miles wide as it moves across the continent.
The total eclipse will last up to 4 minutes and 28 seconds near the center of the path of totality. But the duration of the total eclipse is considerably shorter near the edge of the path of totality.
Consider the case of Greater San Antonio, Texas, a metropolitan area of roughly 2.5 million people that straddles the path of totality. While some central neighborhoods may experience 25 or 30 seconds of totality, the city's northwestern suburbs — which lie deeper within the path — may experience more than 4 minutes of totality.
Outside of the path of totality, the eclipse will still be visible over much of the continent — but viewers will only experience a partial eclipse.
In Chicago — a couple hundred miles from the path of totality — the Moon will appear to block up to 90 percent of the Sun during the eclipse's peak. But in Portland or Seattle, the Moon will block only about 10 percent of the Sun.
Total solar eclipses aren’t especially rare: they typically occur every 18 months or so. But most are only visible from remote areas. In contrast, the April 8 eclipse will pass over an estimated 32 million Americans in the path of totality — nearly a tenth of the country's population — along with millions more people in Mexico and Canada.
In fact, the April 8 eclipse will pass over more people in Texas alone than the passed along its entire transcontinental route.
This map shows major urban areas within 10 miles of the path of totality, with taller spikes representing more populous cities. The , , , , , and metropolitan areas fall partially (if not entirely) within the path of totality.
Millions more will travel to the path of totality to witness the dramatic event firsthand. About 140 million Americans live within a 5-hour drive of the eclipse’s path; some 200 million live within a 10-hour drive.
Zeiler, the eclipse enthusiast, will be among those making the trip. A former GIS professional, he has crunched the numbers and expects at least 4 million people to travel to the eclipse — and that’s a conservative estimate.
These numbers are bolstered by soaring public interest in eclipses. “There was a 38-year drought of total solar eclipses in the United States before 2017,” observes Zeiler, “so there wasn't much of a national memory of what a total solar eclipse was.” This time around, no one wants to miss out.
The April 8 eclipse will arrive during a period of heightened solar activity, and may put on an especially dazzling show. “The Sun has an 11-year sunspot cycle, and we're very close to the maximum,” notes Zeiler. As a result, “we have a very good possibility of seeing some very dramatic fireworks on the Sun.”
A conceptual illustration of the corona during a total solar eclipse. Not to scale.
These may include prominences and coronal mass ejections, which are concentrations of plasma and magnetic field that are ejected violently from the Sun.
Such features contribute to the otherworldly appearance of the Sun’s outer atmosphere, known as the corona. Only visible to the human eye during a total solar eclipse, the corona is "like nothing you’ve seen before,” according to Zeiler. “It’s a beautiful ghostly diaphanous thing, and it has a different appearance each time.”
Of course, these captivating coronal features will only be visible in cloudless areas. This map shows the average cloud cover for the month of April over the past five years; brighter areas on the map are more likely to be obscured by clouds.
As the eclipse glides over the American heartland, it may encounter weather far more sinister than overcast skies: Its path skirts Tornado Alley, and its arrival coincides with the active storm season.
This map shows the tracks of all tornadoes in April from 1950-2022. The width of each path represents the tornado's magnitude, while the brightness of each path corresponds to its recency.
Today, astronomers can predict future eclipses, and reconstruct historical ones, with remarkable accuracy. In fact, scholars have used eclipses to identify or corroborate the dates of historic events.
Shown here are two centuries of total eclipses over North America; those rendered in orange occurred in the past, while those in purple are expected to arrive in the next 100 years.
The April 8 eclipse also reminds us of the significance these cosmic events have held throughout history.
In 1806, the Shawnee spiritual leader Tenskawatawa accurately predicted a solar eclipse over the Ohio Valley. This prophecy bolstered his reputation and authority among the indigenous peoples of the area, which Tenskawatawa used to attract followers to a growing anti-expansionist movement.
This movement, led by Tenskawata and his older brother, Tecumseh, grew into a formidable confederacy that would later challenge the U.S. Army.
The April 8 eclipse will cross the path of the 1806 eclipse — or Tecumseh's Eclipse, as it's sometimes remembered today — around 3:06 PM, near Indianapolis.
Twelve minutes later, the eclipse will pass over Niagara Falls and skirt past Toronto. Hewing to the contours of the U.S.-Canada border, the Moon's shadow will darken Montreal beginning at 3:26 PM.
And finally, at 5:13 PM Newfoundland Time, the eclipse will depart North America for good. Minutes later, it will be swallowed up by nightfall over the North Atlantic Ocean.
All told, the Moon's shadow will cover more than 3,200 miles over land in just under an hour and a half.
In a modern world marred by division and discord, total solar eclipses like the one on April 8 offer a fleeting moment of shared wonder — and a poignant reminder of humankind’s insignificance, and fragility, in the grand cosmic scheme.
Fortunately, if you happen to miss the April 8 total solar eclipse, you have plenty of time to prepare for the next ones: they're not scheduled to arrive until March 30, 2033 (Alaska only), August 23, 2044 (Canada, Montana, and North Dakota), and August 12, 2045 (California to Florida).
