Thousands of people are planning viewing parties for the upcoming annular solar eclipse, a rare event in which the sun will appear as a thin ring behind the moon.
The eclipse will begin over Asia on Monday morning, when it will be visible in southern Japan and southern China.
In the United States, the eclipse will be visible on a path from northwestern Texas through New Mexico, northeastern Arizona, southern Utah, Nevada, northern California and southwestern Oregon late Sunday.
"I recommend anyone who has the chance to see this, because while they do happen occasionally, it's a fairly rare event," said Jeffrey Newmark, a solar physics specialist with NASA. "It's a neat thing to see."
During an annular eclipse, the moon does not block the entirety of the sun, but leaves a bright ring of visible light at the edges, according to NASA.
"For the May eclipse, the moon will be at the furthest distance from Earth that it ever achieves meaning that it will block the smallest possible portion of the sun, and leave the largest possible bright ring around the outside," the agency said on its website.
The last annular eclipse appeared in the United States in 1994. The next solar eclipse will be on November 13, and is expected to be visible over northern Australia, according to NASA.
In western United States, more than 1,000 people may flood the small town of Kanarraville, Utah population 300 to get one of the best views of Sunday's event, said Bonnie Char, spokeswoman for the Cedar City-Brian Head Tourism Bureau.
The town is calling the eclipse "the ring of fire."
The Brian Head Resort in Utah is opening its ski lift so people can watch the eclipse from atop a mountain peak of more than 11,000 feet. For $8, visitors will get a ride up the mountain and solar glasses, Char said.
And instead of football fans, the University of Colorado Boulder's Folsom Field will be occupied by astronomy enthusiasts on Sunday.
"In order to provide the best viewing angles, attendance for the event is limited to 13,000 inside the stadium," the university said on its website.
The whole eclipse will last for a couple of hours as the moon passes in front of the sun, creating a partial eclipse. The actual annular portion, in which the sun appears as a thin ring, will be about four minutes long, Newmark said.
More than 80% of the sun will be blocked out during the apex, he said. Outside of the eclipse's narrow path of less than 200 feet (61 meters), people will be able to see only a partial eclipse.
"This will cause less change in the daylight than you might think," said Alan MacRobert, a senior editor at Sky & Telescope magazine. "Moderately thin clouds would dim the sunlight more. And if you're where the eclipse is only partial, the dimming will be less."
Newmark said people should not peer up at the sky to view the solar event without special viewing equipment. Looking at the sun with the naked eye can cause blindness.
Eclipse glasses, dark welder's goggles or an astronomer's filter made for sun viewing are recommended if people want to look skyward.
Another way to view the eclipse is by using binoculars and telescopes to project an image of it on the ground, Newmark said. Point the binoculars or telescopes at the sun without looking through the lenses and aim the other end onto a piece of paper or cardboard.
In northern Utah, "ecliptomaniacs" are planning to travel south to view the event, said Patrick Wiggins, a NASA ambassador in Salt Lake City.
He said astronomy club members "realize they could either drive four hours to see the eclipse or wait 11 years for the next one."
Wiggins said he always looks forward to seeing people's reactions to an eclipse.
"You get everything from stoic, staring into the sky ... to people breaking down and crying, they're just so moved," he said.