Millions of people across the Americas are preparing for an experience like no other on Saturday. The moon will interrupt the sun, casting a shadowy veil from Oregon to Brazil during an annular solar eclipse.
This weekend’s astronomical marvel is set to swoop over the Western United States, through the Yucatán Peninsula and across many nations of Central America, before its sunset finale off the South American coast. Like the solar eclipse in 2017, which crossed 14 American states, people from diverse walks of life will gather for a fleeting reminder that we all share the same home within a vast and infinite universe.
“You have this moment when you see the place of yourself in the universe,” said Franck Marchis, an astronomer at the SETI Institute in Mountain View, Calif., who remembers gazing in astonishment during his first eclipse at an ancient temple in Tokyo.
A solar eclipse occurs when the moon gets between the sun and Earth. Because the moon’s orbit is slightly ovular, rather than a perfect circle, sometimes this alignment happens when it is at its farthest point from Earth. The result is an annular solar eclipse, or the “ring of fire” that viewers will catch this weekend.
In the United States, the annular eclipse will grace the skies above Oregon, Nevada, Utah, Arizona, New Mexico and Texas (as well as small stretches of California and Colorado). It will travel across the 125-mile-wide path of annularity between noon and 1 p.m. Eastern time. People who are not along this strip of land will experience a partial eclipse, including in large cities like Seattle, Los Angeles, Las Vegas and Houston.
Wherever you watch, scientists stress that you should never look at the annular eclipse without the appropriate protective equipment, to avoid damaging your eyes.
In National Weather Service forecast models run early Friday, clear skies were expected between the Sierra Nevada and Rocky Mountain ranges, which could provide viewing opportunities for people in parts of the eclipse’s path through eastern Nevada, western Utah, and northwestern New Mexico. That was also true for most of Central Texas.
But for many other parts of the United States, conditions will probably thwart views of even a partial eclipse, with near-total cloud cover for most of the country midday Saturday.
Outside the path of annularity, eastern Texas, southern regions of Oklahoma and Arkansas and northern areas of Louisiana, Mississippi and Alabama could get a good look at partly eclipsed sun.
Events of all sizes are planned along the path of annularity. Dr. Marchis plans to set up telescopes at an event in Oregon with a live band and breakfast hosted by a community of artists and scientists.
The Exploratorium in San Francisco is livestreaming the eclipse from the Valley of the Gods in southern Utah and sharing Navajo knowledge of the celestial event. Marysvale, Utah, a town on the path that is home to just a few hundred people, has a three-day party planned for an expected influx of visitors.
The Utah Department of Transportation projected more than 300,000 visitors to the state’s central region, along with heavy traffic. Parts of the state will see more than four minutes and 30 seconds of annularity.
And in Roswell, N.M. — the self-proclaimed U.F.O. capital of the world — the four minutes and 41 seconds of the annular eclipse will kick off a daylong science and art festival.
The eclipse will cross Texas from its west to its southeast boundary. The region in and around San Antonio, the nation’s seventh-largest city, has the distinction of being in the path of two eclipses: Saturday’s annular occurrence and a total eclipse next April that will start in Mexico and cross the Southern and Eastern United States before ending in Canada. Excitement among scientists and locals has been building for months.
“It’s unusual for a location to be within the eclipse crossroads — for two solar eclipses, how lucky,” said Kate Russo, who calls herself an eclipse chaser. Dr. Russo is visiting San Antonio to witness her third annular eclipse, in addition to 13 total eclipses she has seen across 11 countries.
While annular eclipses have visited the San Antonio area about six times in the last 500 years, according to Angela Speck, a professor and chair of the physics and astronomy department at the University of Texas at San Antonio, its last total eclipse was in 1397. The next one in San Antonio is scheduled to happen in 2200.
“It’s been a really long time,” said Dr. Speck, who proudly wears a tattoo of an eclipse on her left arm.
Several locations in Central and South Texas have been gearing up for the phenomenon, from Corpus Christi to the Hill Country near Uvalde to San Antonio, which will see more than four minutes of annularity.
Dr. Russo, who is part of the national Solar Eclipse Task Force, arrived in San Antonio about two weeks ago to help prepare the region for the annular eclipse. She’ll be back in April, too.
Seeing an eclipse never gets old, she explained.
“The sudden darkness descends, it’s like boom — you are in another world entirely,” she said. “It’s thrilling, exciting, awe-inspiring, goose-bump-inducing, humbling.”
After the eclipse exits Texas, it will cross the Gulf of Mexico and head to Central and South America. When it reaches the Yucatán Peninsula of Mexico, its shadow will be cast on cities like Campeche and Chetumal as well as the pyramids at the archaeological site of Edzna. Researchers, scientists and local officials have planned events throughout the peninsula. A “Festival of the Sun” in Campeche the evening before the eclipse will include concerts, dance performances and Indigenous traditions.
Schoolchildren will visit an archaeological site on the small island of Jaina to view the eclipse. Local officials in Campeche have warned of a surge of tourists flocking into the area and have opened extra viewing sites at parks, gardens, art centers and even a nursing home. Some of the sites will have telescopes with filters for the public.
“We will be able to appreciate this astronomical phenomenon,” said Daniela Tarhuni, a member of the Yucatán eclipse committee, in a news briefing in August. She also said the region would be celebrating its Maya heritage as the eclipse makes its way through the heart of the Indigenous land. “We are going to be in a place that will allow us to get to know the identity elements of the Maya culture.”
Historically, eclipses were ominous events for the Indigenous Maya people. For the Tzotzil Maya in particular, eclipses were considered a sign of illness in the stars. Others believed an eclipse could harm a pregnant woman’s baby. While those views still resonate in some communities, researchers and organizers said many residents in the peninsula would most likely enjoy the spectacle as an astronomical phenomenon.
Though solar eclipses have been observed for thousands of years, the science on them isn’t all settled.
“There’s a lot left to learn about the sun,” said Amir Caspi, a physicist at the Southwest Research Institute in Boulder, Colo.
On Saturday, some researchers plan to use ham radios to study how solar eclipses affect the ionosphere, the part of Earth’s atmosphere that meets space. Another project in California will measure radio emissions from solar hot spots to study their connection to space weather. Even more experiments are planned for the total solar eclipse in April.
But you don’t have to be a scientist to feel the significance of a solar eclipse.
“It’s a unique chance to see the magical clockwork of our solar system,” said Dan Seaton, a physicist at the Southwest Research Institute who will be working with Dr. Caspi on an experiment to observe the sun’s upper atmosphere.
He also encourages viewers to watch how their surroundings change during the annular eclipse: The air will cool, birds might roost and shadows will sharpen as the moon swallows the sun.
Dr. Marchis recommends documenting as much of the experience as possible this weekend.
“For every eclipse, I have a memory — a story to tell,” he said.
John Keefe contributed reporting.