By Felix Andrew and agencies
OPTOMETRISTS have warned people intending to view solar eclipse later this month in major parts of United States to use protective glasses.
They say that viewing the solar eclipse with naked eye could harm the most dangerous human being parts.
On Monday, August 21 this year the sun, moon and Earth will line up in an act of cosmic serendipity that will turn day into night across the 2,680-mile width of the US.
It will be the first time that has happened in nearly a century, and never will a total solar eclipse be so heavily viewed and studied.
Experts say at any point when the eclipse is partial, even if only a sliver of the sun is visible, it would burn the back of your eyes to look at it.
"Unfortunately, I think it is probably true that during every solar eclipse, there's bound to be somebody who does get hurt," said Ralph Chou, an optometry professor and leading authority on eye damage from eclipse viewing.
From Oregon in the west, to South Carolina in the east, there will be festivals and flamboyant eclipse viewing parties.
As one astronomer put it: "This will be the most photographed, most shared, most tweeted event in human history."
How unusual an event is this?
Full solar eclipses, when the moon positions itself smack between the sun and the Earth, happen every few years but often in remote areas or over the ocean.
This will be the first total solar eclipse in 99 years to cross the US coast-to-coast, and the first to pass through any part of the lower 48 states in 38 years.
Where is it happening?
The path of totality - where the light of the sun is completely blocked out by the moon - is 70 miles wide and stretches from Lincoln City, Oregon, to Charleston, South Carolina, passing through 14 states and 21 National Parks
The total eclipse will last about 90 minutes as the lunar shadow sweeps across America at more than 1,500 mph beginning about 10.15 am west coast time. On the east coast it will end at 2.49 pm east coast time.
States like Wyoming and Idaho could fare better. Ideally, the best option is to be somewhere remote with access to a fast car and clear roads in case a cloud settles overhead.
It varies in different places, Darkness will last just under two minutes in Oregon, gradually expanding to a maximum two minutes and 44 seconds in the Shawnee National Forest in southern Illinois, and into Kentucky, then dwindling to two-and-a-half minutes in South Carolina.
Minneapolis will see 86 per cent of the sun covered, Miami 82 per cent, Montreal 66 per cent, and Mexico City sees 38 per cent.