Sky-watchers from the South Pacific to the Americas will witness the first solar eclipse of 2005 on Friday when the moon blots out part of the sun.
It will be a partial eclipse rather than a total one, in which the Earth is cast into darkness. But it will be the last partial solar eclipse visible from the continental United States until May 20, 2012.
Solar eclipses occur when the Earth, sun and moon line up in such a way that the moon casts a shadow over Earth.
Friday's eclipse will last from a few minutes to over an hour, depending on one's location. In much of the continental United States, people will see what looks like the moon taking a bite out of the sun, with the bite bigger over the South.
In Central America and the northern portion of South America, the sun will be reduced to a narrow ring of fire.
Astronomers warned people not to stare directly at the sun without eye protection.
"It's neat to see the moon take a bite of the sun," said Tom Fleming, an astronomer at the Steward Observatory at the University of Arizona in Tucson. "Each eclipse is different because I remember who I was with and where I was when I was watching it."
The path of the eclipse will stretch about 8,800 miles through a corridor beginning near New Zealand and extending across the Americas.
In the United States, people living north of a line extending from southernmost California to central New Jersey will see no dimming of the sun at all.
The maximum eclipse visible from the continental United States will be in Miami, where nearly half of the sun's diameter will be covered at 6:20 p.m. EDT.
For a while, the sun will be blotted out completely as the eclipse moves across the open Pacific, but it will be visible only to people at sea.
The next solar eclipse will be Oct. 3, crossing the Iberian Peninsula to Africa.