AFP - The longest total solar eclipse of the 21st century cast its shadow over western India Wednesday and headed for China on a path that was plunging hundreds of millions of people into temporary darkness.
Ancient superstition and modern commerce came together in a once-in-a-lifetime opportunity which could end up being the most watched eclipse in history, due to its path over Earth's most densely inhabited areas.
After forming over the sea west of India, the lunar shadow or "umbra" made landfall in India's Gujarat state shortly before 6:30 am (0100 GMT) and quickly swallowed the city of Surat, the country's diamond polishing centre.
By eclipse standards, this is "a monster," NASA eclipse expert Fred Espenak and University of Manitoba meteorologist Jay Anderson wrote in the US magazine Sky & Telescope.
After an eight-minute journey across central India, it was to squeeze between northern Bangladesh and the eastern tip of Nepal and then slice through some of China's biggest cities, including Chengdu, Chongqing and Wuhan, before arriving at Shanghai, a city of 20 million souls.
The umbra then flits across the islands of southern Japan and veers into the western Pacific, where at one point the duration of totality -- when the solar disc is wholly covered -- will be six minutes, 39 seconds.
If the clouds hold back, it could be the most-watched eclipse in history, and we will have to wait until 2132 before the totality duration is beaten.
The total transit will obscure the sun by 50 percent or more for an estimated two billion people, from the salt flat farmers of Gujarat to herdsmen in the foothills of the Tibetan Himalayas.
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.
Desperate for an explanation, the ancient Chinese blamed a Sun-eating dragon. In Hindu mythology, the two demons Rahu and Ketu are said to "swallow" the sun during eclipses, snuffing out its light and causing food to become inedible and water undrinkable.
Ahead of Wednesday's eclipse, some Indian astrologers had issued predictions laden with gloom and foreboding, while superstition dictated that pregnant women should stay indoors to prevent their babies developing birth defects.
A gynaecologist at a Delhi hospital said many expectant mothers scheduled for July 22 caesarian deliveries insisted on changing the date.
For others it was an auspicious date, with more than one million Hindu pilgrims gathering at the holy site of Kurukshetra in northern India, where bathing in the waters during a solar eclipse is believed to further the attainment of spiritual freedom.
Those who could afford it grabbed seats on planes chartered by specialist travel agencies that promised extended views of the eclipse as they chased the shadow eastwards.
Travel firm Cox and Kings charged 79,000 rupees (1,600 dollars) for a "sun-side" seat on a Boeing 737-700 aircraft before dawn from New Delhi for a three-hour flight.
Thick cloud and heavy rain were likely to ruin the party for millions of people hoping to watch the solar blackout in Shanghai and other parts of eastern China, meteorologists said.
But the Hyatt hotel on Shanghai's waterfront Bund said its eclipse breakfast event remained fully booked out despite the weather concerns.
"People are just looking for a reason to get together," hotel spokeswoman Meg Zhang said. "You can tell your boss: 'It's only once in 300 years'."
The next total solar eclipse 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.