Total solar eclipses have struck awe or fear into hearts for millennia, but scientists are more interested in the unusual mathematics behind the gold-and-indigo lightshow.
Superstition has always haunted the moment when Earth, Moon and Sun are perfectly aligned.
The daytime extinction of the Sun, the source of all life, is associated with war, famine, flood and the death or birth of rulers.
Omen of disasters in ancient China
In ancient China they were often associated with disasters, the death of an emperor or other dark events, and similar superstitions persist.
"The probability for unrest or war to take place in years when a solar eclipse happens is 95 percent," announced an article that attracted a lot of hits on the popular Chinese web portal Baidu.com.
Sanal Edamaruku, president of the Indian Rationalist Association, dismissed such doomsday predictions.
"Primarily, what we see with all these soothsayers and astrologers is that they're looking for opportunities to enhance their business with predictions of danger and calamity," he said.
"They have been very powerful in India but over the last decade they have been in systematic decline."
The ancient Chinese believed that solar eclipses occur when a legendary celestial dragon devours the Sun. It was a tradition in ancient China to bang drums and pots and make loud noise during eclipses to frighten that dragon away.
Indian astrologers predict turmoil
Indian astrologers are predicting violence and turmoil across the world as a result of the total solar eclipse.
In Hindu mythology, the two demons Rahu and Ketu are said to "swallow" the sun during eclipses, snuffing out its life-giving light and causing food to become inedible and water undrinkable.
Pregnant women are advised to stay indoors to prevent their babies developing birth defects, while prayers, fasting and ritual bathing, particularly in holy rivers, are encouraged.
Shivani Sachdev Gour, a gynaecologist at the Fortis Hospital in New Delhi, said a number of expectant mothers scheduled for caesarian deliveries on July 22 had asked to change the date.
"This is a belief deeply rooted in Indian society. Couples are willing to do anything to ensure that the baby is not born on that day," Gour said.
'Eclipse prayers' for Muslims
Muslims pray five times daily, but during eclipses they specially perform the "eclipse prayer" to remember the might and gifts of Allah the Creator.
One of the most important historical solar eclipses is that of the annular solar eclipse of 27 January 632.
It was visible in Medina during the lifetime of Prophet Mohammad, and coincided with the death of his little son Ibrahim.
The Prophet stated explicitly that the eclipses of the Sun and the Moon are not bad omens, but are cosmic spectacles that demonstrate the might and knowledge of Allah the Great.
The science behind solar eclipses
But a remarkable act of celestial geometry explains it all.
When the Moon glides between Earth and the Sun, it casts a cone-shaped shadow, called an umbra, that races from West to East.
The Sun is 400 times wider than the Moon, but it is also 400 times farther away. Because of the symmetry, the umbra, for those on the planetary surface, is exactly wide enough to cover the face of the Sun.
At an eclipse's height, a halo of gold, called a corona, flares around the darkened lunar disc, while the sky turns an eerie dark blue, disorienting birds and causing bats to emerge from their roosts in the belief that night has fallen.
Total solar eclipses are exceptional events, and the one that crosses Asia today is especially so.
A 'monster' eclipse
By eclipse standards, this is "a monster," Espenak and Anderson estimate in the US magazine Sky & Telescope. We will have to wait until 2132 before the totality duration is beaten.
A total solar eclipse usually occurs every 18 months or so. Any given spot on Earth's surface will host a total eclipse on average once every 375 years.
Until now, the most-watched eclipse occurred on August 11, 1999, when the umbra raced from Britain, across Western Europe, part of the Middle East and India.
The last total solar eclipse was on August 1 2008, and also crossed China.
The next will be on July 11 2010, but will occur almost entirely over the South Pacific, where Easter Island -- home of the legendary moai giant statues -- will be one of the few landfalls.
That will be wonderful news to "eclipse junkies," an eclectic army that pursues total eclipses around the world, sometimes hiring seats on planes or ships to get the best view.
Eclipses, even partial ones, should not be viewed with the naked eye or through binoculars, a telescope, beer bottle or photographic film, as this can permanently damage the retina.
Observers should use proper optical filters such as welding-goggle glass, eclipse spectacles or a solar projection kit for their telescope. The safest way to view is on television or the Internet.