Conditions were anything but normal on Easter Island, deemed by astronomers the best place to witness Sunday's alignment of sun, moon and Earth for a fleeting four minutes and 41 seconds.

Some weather forecasts, however, warned of cloudy skies, potentially dashing hopes of a clear view there.

The island "has the capacity to absorb this number of tourists," Easter Island Governor Pedro Edmunds Paoa said.

"Logistically, we are prepared so now the only thing that needs to happen is for the people to come, behave well and that there not be so many of them," he said.

Increased security

In the months since the huge earthquake and tsunami that struck mainland Chile on February 27, local authorities have scrambled to inform the global tourism industry that the territory was largely unscathed.

But the island, a Unesco world heritage site inhabited mainly by ethnic Polynesians, was strained even before the eclipse by a growing number of visitors who choose to stay indefinitely and a sharp increase in the non-aboriginal population.

Chile's government last year proposed a law to establish immigration controls on the island and limit the number of tourists to try to protect the local population and fragile ecosystem.

Authorities have increased security for the eclipse, especially around key heritage sites, including the 3,000-year-old large stone statues, or moai, that put Easter Island, a far-flung ethnic Polynesian point of reference, on the world culture map.

During the eclipse, parts of the globe will be plunged into daytime darkness along a
narrow corridor some 11,000 km long across the South Pacific.

The time of greatest eclipse will occur over open water, lasting 5 minutes and 20 seconds.

Solar storm

Scientists will be looking for solar storms forming in the corona, storms with solar winds that can affect space weather and eventually, smash into the Earth's magnetic field. The solar corona goes out more than a million kilometres from the Sun's surface.

"The corona actually extends way out into space and we can see what we call 'coronal mass ejections'  which are these huge massive amounts of material being blown away from the sun at millions of miles an hour," Holly Gilbert, a NASA astrophysicist, told the Associated Press news agency.

A new round of solar storms are slowly building up to a projected maximum period in about four years and could affect electrical systems, satellite communications and some computer networks.

The sun is 400 times wider than the moon, but it is also 400 times farther away. Because of the symmetry, the lunar umbra, or shadow, that falls on the face of the Earth is exactly wide enough to cover the face of the sun. 

In the original islanders' ancient lore, such an eclipse "would have been seen as a very powerful signal of upcoming upheaval," as their world view was rooted in nature, in "the earth, the sea and especially the sky," said Patricia Vargas of the University of Chile.