Millions of Americans across the mainland USA, spreading across 41 of 50 states, will witness a partial to total solar eclipse on Saturday as the celestial spectacle of the blacked out sun with ring of fire around the moon unfolds.

The direct path of the eclipse extends to portions of eight states from Oregon to Texas, while a partial eclipse minus the ring of fire, will be visible in all 41 of the other continental states including Alaska, media reports said.

The NASA will stream live the solar eclipse as seen from its telescopes on its website. An annular eclipse is one in which the moon passes between the Sun and Earth, close to its farthest point from the planet. Since the earth is 400 times smaller than the Sun, it cannot envelop the star completely thus producing the image of a dark disk on top of a larger, brighter disk leading to a fiery ring around the moon, multiple US media outlets reported quoting agency reports .

Eclipse watchers in remote US were up early, or camped overnight, to try to get the best view possible.

At Bryce Canyon national park in southern Utah, lights were visible before sunrise along a well-known trail. “I just think it’s one of those things that unite us all,” said John Edwards, a cancer drug developer who travelled alone across the country to try to watch the eclipse from Bryce Canyon. “It’s seeing these unique experiences that come rarely are what got me here. This is about as rare as it gets.”

The last solar eclipse occurred in North America in 2012 and the next will happen in in 2039 over Alaska, and 2046 in the lower 48 states, astronomers predicted .

Eclipse festivals and watch parties were taking place at numerous planetariums, science museums, schools and other venues across the country. NASA has urged safe viewing avoiding a direct look at the eclipsed Sun as it can lead to partial to complete blindness depending on how long you look at it. Watch through special eclipse glasses, a solar viewer, or solar filters on a telescope, NASA said in an advisory as it alternatively recommended indirect viewing through pin hole projector.

Scientists are using the opportunity to study the temperature differences when sunlight dips affecting the upper atmosphere. Three NASA “sounding rockets” will be fired into the shadow of the eclipse from the White Sands missile range in New Mexico to record atmospheric changes, media reports said.

After passing over Alaska, the annular eclipse will be visible in central and southern Oregon beginning at approximately 9.13 a.m. PT, following a south-east path across portions of California, Nevada, Idaho, Utah, Arizona, and New Mexico, before covering a swathe of area from Texas and into the Gulf of Mexico.

The event in the US will last about one hour. The Yucatan peninsula, and several central and South American countries from Belize to Brazil also lie in the path of eclipse shadow.