On the night of 31 January will come the super blue blood moon, or the purple eclipse. That’s a blue moon, a blood moon or lunar eclipse, and a supermoon.
None of the events are rare in themselves. But the collision of lunar phenomena is – nothing like it has been seen since 1982.
The vision will be seen all the way from the west of North America to the east of Asia. And for everyone else, some will be seen, if only through the various live streams that will be run on the day.
The overlap of a blue moon – the second full moon in a calendar month – with a lunar eclipse, while the moon is at its closest approach to the earth, is the first such celestial trifecta since 1982, says Noah Petro, a research scientist at Nasa’s Goddard Space Flight Centre outside Washington DC.
“Just having these three things simultaneously occur is unusual,” he adds. “A blue moon is not extremely rare but it’s a nice coincidence that it happens in conjunction with these other two.”
The moon will reach its fullest on Wednesday at 8.27am EST (13.27 GMT).
A blue moon normally occurs about once every two and a half years. This month’s first full moon was on 1 January.
The blue moon also will be a supermoon, which occurs when it is at or near its closest point to the earth, or perigee. A supermoon is about 14 percent brighter than usual. Wednesday’s moon will be the second closest of 2018 after the one on New Year’s Day.
The lunar eclipse, which takes place when the moon passes in the Earth’s shadow, will last almost three and a half hours. It will start at 6.48am EST (11.48 GMT) and peak at 8.29am EST (13.29 GMT), Nasa says.
The total eclipse will be visible from the western United States and Canada across the Pacific Ocean to most of Australia and China, as well as northern polar regions. The eclipse will give the moon a reddish colour known as a blood moon.
“I’m calling it the purple eclipse because it combines the blue moon and a red eclipse,” Rich Talcott, a senior editor at Astronomy magazine, says.
Petro said the eclipse is also a scientific opportunity for researchers in Hawaii, who will study what happens to the moon’s surface when it quickly drops from 100C in sunlight to minus -153C in darkness. The speed of cooling can show what the surface is made of, such as rock or dust, he says.
More about: moon
