The total "supermoon" lunar eclipse, also known as a "blood moon" is one that appears bigger and brighter than usual as it reaches the point in its orbit that is closest to Earth.
"There’s no physical difference in the moon. It just appears slightly bigger in the sky," planetary geologist Noah Petro, with NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said.
The two-hour eclipse is visible, depending on weather conditions, from North and South America, Europe, Africa and parts of West Asia and the eastern Pacific.
Unfortunately for Australians, it will not be visible here.
Images of the eclipse have flooded social media, with users describing it as "magical", a portent of evil.
It has been more than 30 years since a supermoon combined with a lunar eclipse, said NASA. The next total lunar eclipse will not be until 2018. The next supermoon-lunar eclipse combination will not happen until 2033.
For more than an hour, Earth’s shadow will blanket the full moon as the planet passes between the sun and the moon. The brilliant white glow of the moon will slowly transform into a dim red. The coloring is caused by Earth’s atmosphere scattering sunlight into the shadow.
Because the moon is not perfectly round, its distance from Earth varies by about 31,000 miles (49,900 km) as it circles around the planet every 27 days.
At its closest point, known as perigee, the moon comes as close as 225,622 miles (363,104 km) from Earth. At apogee, the most distant point, the moon is 252,088 miles (406,696 km) away.
