Two men watching an annular solar eclipse in China in January 2010
9:47am UK, Wednesday May 16, 2012
Early risers in some parts of China and Japan will see a rare solar eclipse at the weekend.A partial solar eclipse - which will see the moon completely block out the sun but for a ring of fire around the moon's edge - is set to slink across a narrow swathe of the Earth on May 20 and 21.
The event, which scientists call an annular eclipse, will also be visible at sunset in western parts of the United States.
Depending on where people are in the eclipse's path, some may be able to witness an annular eclipse, while others will see the sun as a crescent, partially obscured by the moon, for a period of around four to five minutes.
Some will see an annular eclipse and others will see a crescent
It will continue onto the Pacific Ocean, passing south of Alaska's Aleutian Islands before reaching the coastlines of southern Oregon and northern California where it will be visible in Nevada, Utah, New Mexico, Arizona and Texas.
It will be the first time in 18 years that such an eclipse is visible from the US, according to Fred Espenak, a longtime solar eclipse expert with Nasa.
"What is unusual about this particular annular eclipse is that it goes over the western US," Mr Espenak said.
"People always think that eclipses are extremely rare but there are at least two solar eclipses every year. Each of these annular eclipses covers a very small fraction of the Earth's surface."
The next time the Earth will witness a total eclipse of the sun, a more dramatic event than a partial or annular eclipse, will be August 21, 2017