BANGKOK — 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 tomorrow for about five minutes.

Hawai'i residents will see a partial eclipse starting a little after 5 p.m. today, according to the Bishop Museum. About 10 percent of the sun's disk will be blocked by the moon at the eclipse's deepest; by 6:15, about an hour before sunset, the eclipse will be over.

The times are roughly the same for all the main Hawaiian Islands.

Streams of amateur star-gazers and scientists are traveling to witness the once-in-a-lifetime event. Some astronomers hope the eclipse will unlock clues about the sun.

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. 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 from the sun's surface.

"The corona has a temperature of 2 million degrees but we don't know why it is so hot," said solar scientist Lucie 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."

The previous total eclipse, in August 2008, was 2 minutes and 27 seconds. This one will last 6 minutes and 39 seconds at its maximum point.

"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.