Special darkened glasses were selling out in Japan as anticipation built ahead of a “ring” solar eclipse above one of the most densely populated parts of the planet.
A swathe of the country will be able to see the annular solar eclipse, when the moon passes in front of the sun, blocking out all but an outer circle of light.
Astronomers say the greater Tokyo area, home to more than 30 million people, will be a prime spot to see the event, which has not been visible in the capital for 173 years.
Eclipse-viewing glasses were flying off the shelves and television stations were planning live broadcasts amid stark warnings not to look directly at the sun.
One of the most ambitious projects to mark the moment was being mounted by electronics giant Panasonic, which had sent an expedition to the top of Mount Fuji to film the phenomenon using solar-powered equipment.
The path of the eclipse will span “a 240 to 300 kilometer-wide (150-185 mile) track that traverses eastern Asia, the northern Pacific Ocean and the western United States”, according to the US space agency.
The eclipse begins at sunrise in southern China at 2206 GMT Sunday and swiftly travels eastward to the southern coast of Japan, NASA said.
However, Japan’s weather agency has been giving a slightly different warning — the event might not be visible at all.
According to historical data, China and Japan are likely to be swathed in cloud at the time of the eclipse.