Cloudy conditions over much of Australia could spoil our view of the biggest supermoon in almost 70 years.
Source: AAP
It will be the biggest and brightest moon in decades but many Australians likely won't be able to see it.
A so-called supermoon will light up the night sky on Monday, coming closer to earth than any full moon since 1948. NASA says we won't see another like it until 2034.
But Australians hoping to catch some dazzling night-time rays may be disappointed, the Bureau of Meteorology is predicting cloudy conditions for most capital cities.
Only Brisbane and Perth can expect clear skies on Monday night, while Hobart might be lucky with breaks in the clouds.
Astronomers suggest if sky-watchers take a photograph of the moon on Monday night and then again in a few weeks' time they'll appreciate the difference in scale.
"Unless you are really paying attention it's going to be hard to notice," Associate Professor John O'Byrne from the University of Sydney's physics school told AAP.
"(But) the moon will look genuinely fully illuminated with no hint of a shadow at the edges.
"The difference between the moon at its minimum and maximum is 14 per cent in diameter and that translates to about 30 per cent in area."
That larger surface area means a supermoon reflects almost a third more light than when the moon is farthest from earth. Hence it appearing so bright.
Prof O'Byrne says the moon will be at its brightest after midnight in the early hours of Tuesday.
But because it appears bigger the closer it is to the horizon, he suggests moonrise on Monday evening is a good time to try to see the phenomenon.
