During the total lunar eclipse, which will last several hours, the Earth will pass between the sun and the moon.
As it happens, the moon will reflect sunlight scattered in the Earth's atmosphere, taking on a red hue.
The early phase of the eclipse began at 1330 IST, or 4:00 am local time, on the east coast of the United States, and will continue until sunrise.
In Hong Kong, the eclipse will begin shortly after moonrise at 1000 GMT or 6:00 pm local time, with the total eclipse phase emerging half an hour later and lasting for around an hour before moving to a partial eclipse.
In Tokyo's Roppongi fashion and entertainment district, enthusiasts were planning to perform yoga exercises under the blood moon. Many others had climbed atop the city's skyscrapers to view the sky.
On Australia's east coast, a live video feed set up by the Sydney Observatory was pointing to cloud cover less than an hour ahead of the moon's move into Earth's shadow.
In New Zealand, the moon will be close to its highest point in the sky, according to Auckland's Stardome Observatory & Planetarium, holding out hope of a view of the spectacle unobstructed by buildings.
NASA's lunar experts are answering questions ahead of the celestial event via live web chat from 0700 GMT.
"NASA moon experts will be up all night on October 8 to answer your questions," the space agency said.
The eclipse is the second of four total lunar eclipses, starting with a first "blood moon" on April 15, in a series astronomers call a tetrad.
The next two total lunar eclipses will be on April 4 and September 28 of next year.
The last time a tetrad took place was in 2003-2004, with the next predicted for 2032-2033. In total, the 21st century will see eight tetrads.