A pair of supermoons, culminating in a rare blue moon, will offer a double feature for sky-gazers in August.
On Tuesday evening the full moon rises in the south-east, appearing slightly brighter and bigger than normal.
That is because it will be closer than usual, just 357,530 kilometres away.
The moon will be even closer the night of August 30 — only 357,344km distant.
Because it is the second full moon in the same month, it will be what is known as a blue moon.
“Warm summer nights are the ideal time to watch the full moon rise in the eastern sky within minutes of sunset. And it happens twice in August,” said retired Nasa astrophysicist Fred Espenak, known as Mr Eclipse for his expertise.
The last time there were two full supermoons in the same month was in 2018.
It will not happen again until 2037, according to Italian astronomer Gianluca Masi, founder of the Virtual Telescope Project.
Supermoon shots from around the world - in pictures
Mr Masi will provide a live webcast of Tuesday evening’s supermoon as it rises over the Colosseum in Rome.
“My plans are to capture the beauty of this … hopefully bringing the emotion of the show to our viewers,” he said.
“The supermoon offers us a great opportunity to look up and discover the sky."
This year’s first supermoon was in July. The fourth and last will be in September. The two in August will be closer than either of those.
If the skies are clear, binoculars or backyard telescopes can enhance the experience, Mr Espenak said.
The event will reveal such features as lunar maria – the dark plains formed by ancient volcanic lava flows – and rays from lunar craters.
According to the Old Farmer’s Almanac, the August full moon is traditionally known as the sturgeon moon.
That is because of the abundance of that fish in the Great Lakes in August, hundreds of years ago.