Millions are expected to gaze at the cosmic spectacle that will begin at 10:24 a.m. local time (1824 GMT) in the South Pacific and sweep along a path 6,800 miles (11,000 kilometers) across open waters to Chile and Argentina, the only places that the total eclipse will be seen aside from an uninhabited island out in the ocean.
The eclipse is expected to make its first landfall in Chile at 3:22 p.m. (1922 GMT) in La Serena, a city of some 200,000 people where the arrival of more than 300,000 visitors forced the local water company to increase output and service gas stations to store extra fuel. Police and health services were also reinforced.
The total eclipse will begin there at 4:38 p.m. and last about 2½ minutes.
"I came to La Serena to watch the total eclipse with a friend following a recommendation," said Stephanie Bouckurt from the United States. "They told me that nothing compares to a solar eclipse, so that's why we're here. We're super excited."
Northern Chile is known for clear skies, and some of the largest, most powerful telescopes on Earth are being built in the area, turning the South American country into a global astronomy hub.
The town of La Higuera will also be plunged into total darkness.
"We hope this milestone will transform (our town) into a tourist attraction, so that visitors ... can come to La Higuera and take a picture where there once was a total sun eclipse," Mayor Yerko Galleguillos said.
Town officials distributed more than 2,000 cardboard-frame protective eyeglasses at local schools and community centers while workers built statues of huge sunglasses and a darkened sun on a local square.
"These glasses are going to give (students) the opportunity to protect themselves and witness this spectacle that we've all been waiting for so eagerly," said Alejandra Zuñiga, director of the Juan Pablo Muñoz school in La Higuera.
A solar eclipse occurs when the moon passes between the Earth and the sun and scores a bull's-eye by completely blocking out the sunlight.
"It's going to be very dark and we're going to have a Milky Way in its full splendor," said Chilean astronomer María Teresa Ruiz. "I invite you to look at hundreds of thousands of stars."
Thousands of visitors also trekked to neighboring areas of Argentina where the eclipse also will be total.
The San Juan provincial government installed telescopes and public viewing areas. Meanwhile, astronomers in Buenos Aires province planned to offer yoga and meditation classes during the eclipse, which will also be partially visible in other South American countries.
Total eclipses are relatively rare for a particular spot. In 2017, millions of people in the United States witnessed the phenomena, with a full solar eclipse visible in parts of 14 states and a partial eclipse seen in nearly the entire country. It was the first such widespread eclipse in the U.S. since 1918.