Wednesday full moon, supermoon and partial lunar eclipse explained

A supermoon will coincide with a partial lunar eclipse on Wednesday, in a rare astronomical event. But what you see will depend on where in the world you live.

A supermoon will coincide with a partial lunar eclipse on Wednesday, in a rare astronomical event.

But in bad news for Aussies, the unusually dim moon will only be visible to people in countries on the opposite side of the world, because the eclipse will occur in our daytime.

Dr Rebecca Davies from Swinburne’s Centre for Astrophysics and Supercomputing said that supermoons were the biggest full moons and normally the brightest, occurring when the moon was within 90 per cent of its closest approach to Earth.

It means the moon on both Tuesday and Wednesday nights over Victorian skies will be huge, but not dimly-lit as it will be for those in Europe and the Americas.

Occurring close to the autumnal equinox, the supermoon Australians would see was also known as a harvest moon, she said.

Supermoons are usually bright, but this one will be unusually dim. Picture: Jonathan Ng

It is rare for a partial lunar eclipse to coincide with a supermoon, as it will on Wednesday September 18, and has not occurred for several years.

“Lunar eclipses occur when the Earth blocks light from the sun and casts a shadow on the full moon. The September 18 eclipse will be a partial one, covering the top 8.4 per cent of the moon at its peak,” Dr Davies said.

“Unfortunately, the eclipse will not be visible from Australia because it will occur during our daytime — the eclipse will begin at 10.41am on Wednesday … peak at 12.44pm and end at 2.47pm. However, there will be online live streams available for keen sky-watchers to catch a glimpse of this exciting event.”

Dr Davies said the next lunar eclipse clearly visible from Australia would happen on March 14, 2025.

When is the best time to see the supermoon?

The moon will rise around about 6.26pm in Melbourne. As long as the skies are clear, this will be the best time to see it.

What is the difference between a full moon and a supermoon?

The full moon is an astronomical event where the full face of the moon is visible from Earth. This monthly event happens when the moon and sun are aligned on opposite sides of Earth, meaning that 100 per cent of the moon’s face is illuminated by the sun, making it appear extra big and luminescent in the sky.

A full moon gets upgraded to supermoon status when it’s at the closest point to Earth during its orbit. According to NASA, September’s supermoon will be the biggest of the year, but there will be another on October 17.

What is a harvest moon

The harvest moon is the full moon that occurs closest to the autumnal equinox. This year, it falls on Wednesday September 18, so we will have a harvest moon.

Unlike other full moons, the harvest moon rises almost immediately after sunset for several days in a row, allowing for more prolonged periods of light in the evening.

Folklore also surrounds this particular full moon. In some cultures, it’s believed that the harvest moon brings good fortune, while others see it as a time for reflection and new beginnings.

Originally published as Wednesday full moon, supermoon and partial lunar eclipse explained