Millions of people across Indonesia and the Pacific are about to be treated to a total solar eclipse.
Beginning late on Tuesday (GMT), the Moon will pass directly in front of the Sun, fully eclipsing the solar disk.
This will block all direct sunlight, turning day into night.
The eclipse will be total in Indonesia and the Central Pacific, while parts of Australia and east Asia will experience a partial one.
People along a 150km-wide strip running through Sumatra, Borneo and Sulawesi – the path of eclipse totality – will experience a blackout from about 07:00 to 11:00 local time.
Astronomers reiterated advice not to look directly at the Sun with the naked eye, or through a telescope. Experts recommend using either a professional solar filter in front of a telescope or camera, or special eclipse-viewing glasses.
The partial eclipse will commence at 23:19 GMT and the total eclipse at 00:15 GMT, with the moment of maximum shadow at 01:59 GMT.
The celestial event will end at sunset, local time, north of Hawaii (04:34 GMT).
Because the eclipse path crosses the International Date Line, in the local time zones it will begin on Wednesday 9 March and end on Tuesday 8 March.
Skywatchers in southern China, south-east Asia, Australia, Hawaii and Alaska will experience a partial eclipse when the Moon's penumbra – the outer region of the shadow – catches them. This will look as if a just a chunk of the Sun has been blacked out.
For eclipse watchers outside these regions, a number of astronomy institutes are hosting live streams of the event.
Scientists at Nasa said they planned to use the event to study solar physics.
From Indonesia, they will use an instrument called a polarization camera to capture 59 exposures of the Sun in just over three minutes, collecting data on the innermost parts of the sun's volatile, superheated atmosphere.
This region can only be observed during total solar eclipses when the Sun's bright face is completely blocked by the Moon.
The lower part of the sun's atmosphere, the corona, is thought to hold the keys to several solar mysteries, including the birth of explosive clouds of solar material called coronal mass ejections and the mystery of why the corona is actually hotter than the surface.
"The Sun's atmosphere is where the interesting physics is," said Nelson Reginald, from Nasa's Goddard Space Flight Center in Maryland.
The most recent total solar eclipse took place in the far northern hemisphere on 20 March 2015.