The biggest Supermoon in 70 years is set to light up the night sky tonight.

ANU astronomer Dr Brad Tucker said when a full Moon was closest in its orbit to Earth, or at perigee, it was called a Supermoon. 

"This Supermoon is special as it is very close to the Earth, the closest in 70 years," said Dr Tucker from the ANU Research School of Astronomy and Astrophysics.

"Perigee syzygy is the technical term, syzygy being straight alignment, but Supermoon is easier to say."

The Moon did not orbit the Earth in a perfect circle and varied by about 50,000 km, Dr Tucker said. 
 
"This is the second of three Supermoons in a row. The full Moons of October 16th, November 14th and December 14th are Supermoons, but the November one is the 'superest' of the three." 

Dr Tucker said while the perigee would occur at 12:53am AEDT on Tuesday 15 November, the best time to view the Supermoon was at sunset tonight.

"To view it best, you need a clear view to the eastern horizon."