Millions of people across Asia will witness the longest total solar eclipse that will happen this century, as vast swaths of India and China, the entire city of Shanghai and southern Japanese islands are plunged into darkness Wednesday for about five minutes.
Streams of amateur stargazers and scientists are traveling long distances to witness the once-in-a-lifetime event.
Astronomers hope the eclipse will unlock clues about the sun, while an astrologer in Myanmar predicts it could usher in chaos. Some in India are advising pregnant relatives to stay indoors to follow a centuries-old tradition of avoiding the sun's invisible rays.
The eclipse will appear first at dawn in India's Gulf of Khambhat just north of the metropolis of Mumbai.
It will move east across India, Nepal, Myanmar, Bangladesh, Bhutan and China before hitting the Pacific. The eclipse will cross some southern Japanese islands and be last visible from land at Nikumaroro Island in the South Pacific nation of Kiribati. Elsewhere, a partial eclipse will be visible in much of Asia.
For astronomers, it will be a chance for a prolonged view of the sun's corona, a white ring 600,000 miles (1 million kilometers) from the sun's surface. The previous total eclipse, in August 2008, was two minutes and 27 seconds. This one will last 6 minutes and 39 seconds at its maximum point.
Solar scientist Lucie Green is aboard an American cruise ship heading for that point near the Japanese island of Iwo Jima, where the axis of the moon's shadow will pass closest to earth.
Passengers paid $2,599 to $3,643 for the cruise run by Mayhugh Travel, a California company that specializes in astronomy vacations, according to the company's website.
"The corona has a temperature of 2 million degrees but we don't know why it is so hot," said Green of University College London. "What we are going to look for are waves in the corona. ... The waves might be producing the energy that heats the corona. That would mean we understand another piece of the science of the sun."
Scientists are hoping data from the eclipse will help explain solar flares and other structures of the sun and why they erupt, said Alphonse C. Sterling, a NASA astrophysicist who will be following the eclipse in China.
"We'll have to wait a few hundred years for another opportunity to observe a solar eclipse that lasts this long, so it's a very special opportunity," said Shao Zhenyi, an astronomer at the Shanghai Astronomical Observatory.
Man has been recording solar eclipses for 4,000 years, and even today they inspire a combination of fear, fascination and wonder.
One astrologer in Myanmar, also known as Burma, predicted in a magazine that the eclipse would trigger wars, instability and natural disasters for the next several months.
Liang Wei is among more than 40 members of a Chinese solar eclipse fan club traveling to Shanghai to see the event.
"Even though I'm not a scientist, it's an experience I've waited all my life for," said the 29-year-old Guangzhou native, who works at a lighting company and operates an online fan site for eclipse enthusiasts.
In India, hundreds of scientists are gathering in the village of Taregna in Bihar state. One team, led by Dr R.K. Sinha of Patna University, will study bird behavior.
"The researchers will observe whether they suddenly move back to their nests, sound differently and behave in an unusual manner due to sudden darkness," he said.
A travel agency in India is running a charter flight to watch the eclipse by air.
Some families have advised pregnant relatives to confine themselves to curtained rooms, following long-held fears that the invisible rays would harm the fetus and the baby born with disfigurations, birthmarks or a congenital defect.
"I've been told to lie straight on the bed with my eyes open and to chant prayers and verses from the Hindu holy texts during the eclipse," said Sonya Chadha, a New Delhi accountant who is seven months pregnant and plans to take the day off. "If even a tiny sliver of light falls on me, it could harm my child."
In Japan, where the last total eclipse happened in 1963, people are flocking to the small southern island of Yakushima, which is holding a two-day festival with fireworks, dancing, grilled squid and cotton candy. The island's 180 hotels are fully booked. A partial eclipse will be visible in Tokyo.