It will be a once in a lifetime opportunity for Australian stargazers to see a super blue blood moon, but cloud cover means many people could have a tough time catching a glimpse of the extremely rare event.
It's been 150 years since the last triple lunar event where a total lunar eclipse turns the moon a brooding, dark red, as it coincides with both a supermoon and a rare blue moon.
It will happen again on Wednesday night, but clouds will blanket much of NSW and the ACT, as well as South Australia, making the triple lunar treat difficult to see, the Bureau of Meteorology said.
Stargazers have slightly better prospects in parts of Tasmania, anywhere north of the Sunshine Coast and inland areas of the Northern Territory, where cloudy skies are forecast but breaks could expose the phenomenon.
The best views will be from coastal parts of Western Australia as well as most of Victoria with the exception of Melbourne's western suburbs.
"It's pretty cloudy across much of the country," a bureau spokesman told AAP on Wednesday.
"Coastal Western Australia should have beautiful clear skies but Sydney and Brisbane might not see anything at all."
The total lunar eclipse - which is often referred to as a blood moon because the moon appears red - will be visible in Australia, Asia, parts of Europe and the United States.
"Tonight, we have three lunar events happening simultaneously; the moon will be at perigee (the closest point in its elliptical orbit to Earth), it will be a blue moon for most of the world and - most spectacularly - it will be a total lunar eclipse," Penrith Observatory manager Raelene Sommer said in a statement.
The observatory, in Sydney's west, will live stream the event.
Astrophysicist Alan Duffy said the random event was a rare trifecta, with the moon appearing bigger and a third brighter before it turns red when the moon passes into the Earth's shadow and reflects the sun back at the Earth.
Astronomer Sarah Reeves said for the three phenomena to coincide was "really very special".
"I don't think we've had another of the same three things for more than 150 years now," she told SBS News.
The entire process will take about three-and-a-half hours but Ms Reeves said staying for the 'blood moon' was worth staying up for.
"[The 'blood moon'] is caused by light from the sun, even though it can't hit the moon directly, refracting or bending through the earth's atmosphere, and some of that red light hitting the moon and making it appear that colour," she said.
Australians witness a total lunar eclipse about once every 2.8 years on average but when it occurs with both a supermoon and blue moon the lunar event becomes a true rarity.
Here's what stargazers are in for:
Total lunar eclipse
From late on Wednesday night, when the moon is full, it will slide entirely into the earth's shadow.
This will turn the moon a brooding, dark red due to light being bent or refracted onto its surface by the earth's atmosphere. This effect is commonly referred to as a blood moon.
Australians can witness a total lunar eclipse about once every 2.8 years, on average.
But here is where the super moon and the blue moon come in, and elevate this lunar event to a true rarity.
Supermoon
Wednesday night will also be a supermoon when the full moon will be closest to the earth on its orbital journey - a mere 360,198km away.
Blue moon
In some parts of Australia, Wednesday night's full moon will also be a blue moon, which has nothing to do with the colour blue.
A blue moon is simply the second full moon in any calendar month.
When to view the total lunar eclipse (weather permitting)
ADELAIDE:
Totality begins 11.21pm, ends 12.38am
BRISBANE:
Totality begins 10.51pm, ends 12.08am
DARWIN:
Totality begins 10.21pm, ends 11.38pm
HOBART, MELBOURNE, SYDNEY AND CANBERRA:
Totality begins 11.51pm, ends 1.08am
PERTH:
Totality begins 8.51pm, ends 10.08pm
*All times are given in local time
