People gaze in wonder as rare total eclipse draws shadow across America

The International Space Station is silhouetted against the partially eclipsed sun. Photo / AP

Millions of Americans gazed in wonder through telescopes, cameras and disposable protective glasses as the moon blotted out the sun in the first full-blown solar eclipse to sweep the US from coast to coast in nearly a century.

The temperature dropped, birds quieted down, crickets chirped and the stars came out in the middle of the day as the line of darkness raced 4200km across the continent in about 90 minutes, bringing forth oohs, aahs, shouts and screams.

In Boise, Idaho, where the sun was more than 99 per cent blocked, people clapped and whooped, and the street lights came on briefly, while in Nashville, Tennessee, people craned their necks at the sky and knocked back beers at Nudie's Honky Tonk bar.

At the Nashville Zoo, the giraffes and rhinos started running around crazily when the sun came back. Several minor-league baseball teams - one, the Columbia Fireflies, outfitted for the day in glow-in-the-dark jerseys - briefly suspended play.

It was the most-observed and most-photographed eclipse in history, with many Americans staking out prime viewing spots and settling on to blankets and lawn chairs to watch, especially along the path of totality - the line of deep shadow created when the sun is completely obscured except for the delicate ring of light known as the corona.

The shadow - a corridor just 96 to 113km wide - came ashore in Oregon and then travelled diagonally across the Midwest to South Carolina, with darkness from the totality lasting only about two to three minutes in any one spot.

The rest of North America was treated to a partial eclipse, as were Central America and the top of South America.

With 200 million people within a day's drive of the path of totality, towns and parks had big crowds. Skies were clear along most of the route, to the relief of those who feared cloud cover would spoil this once-in-a-lifetime moment.

The moon's shadow or umbra of the eclipse as viewed from the space station. Photo / Nasa

Nasa reported 4.4 million people were watching its TV coverage midway through the eclipse, the biggest livestream event in the space agency's history.

Astronomers were giddy with excitement. Nasa and other scientists watched from telescopes on the ground and in orbit, the International Space Station, aircraft and scores of high-altitude balloons beaming back live video.

Citizen scientists monitored animal and plant behaviour as day turned into twilight. Thousands of people streamed into the Nashville Zoo to watch the animals' reactions and noticed how they got noisier as it got darker.

The path of totality passed through 14 states, entering near Lincoln City, Oregon, then moving over Casper, Wyoming; Carbondale, Illinois; and Nashville, Tennessee, and exiting near Charleston, South Carolina.

Shawnee National Forest in southern Illinois saw the longest stretch of darkness: two minutes and 44 seconds.

- AAP