What time is the Harvest Moon tonight, what does it mean and how often do they occur?

13 September 2019, 21:20

A harvest moon over Tyne and Wear in 2016
A harvest moon over Tyne and Wear in 2016. Picture: PA
Nick Hardinges

By Nick Hardinges

A harvest moon will appear over UK skies tonight on Friday 13th in a rare phenomenon.

Tonight's moon will take place at the same time as an especially rare "micromoon"- meaning it will appear 14 per cent smaller than usual.

A full micromoon appearing on Friday 13th happens roughly every 20 years, with the next not taking place until August 2049.

But tonight, stargazers will be treated to an even more unique experience with a harvest moon and a micromoon, also known as a Perigean moon, taking place together.

With harvest moons taking place once a year, and micromoons on Friday 13th once every two decades, the chances of both occurring at the same time is extremely small.

Harvest moons occur once a year between September and October
Harvest moons occur once a year between September and October. Picture: PA

The Professor of Public Understanding of Science at the University of Brighton, Professor Hal Sosabowski, told Global's Newsroom that as the universe is roughly 14 billion years old and Earth is between four and five billion years old these occurrences are inevitable.

However, he added that these are "very interesting" events, comparing their likelihood to that of "winning the lottery."

What is a harvest moon and what does it mean?

A harvest moon is a full moon that takes places closest to the Autumn Equinox, which means it is the full moon nearest to the day that is the astronomical start of autumn.

It can take place on any day between September and October and it usually means that cooler weather is on the way and daylight hours begin to dwindle.

The name 'harvest moon' comes comes from the satellite usually appearing bigger and brighter in the sky, which helped farmers extend their day and work by the light of the moon during the harvest.

Harvest moons happen once every year.

This year's Harvest moon and micromoon will appear in the early hours of Saturday morning
This year's Harvest moon and micromoon will appear in the early hours of Saturday morning. Picture: PA

What is a micromoon?

Micromoons occur because of the moon's elliptical orbit around Earth, due to something known as Kepler's laws of planetary motion.

What this means is that the moon does not orbit round Earth in a perfect circle, instead it orbits in a more oval-like shape.

As a result, there are times when the moon is further away from our planet and this is when micromoons appear.

What time is the harvest moon tonight?

According to US space agency NASA, the full moon will peak around around 5:33am on Saturday morning in the UK, however stargazers will get a good view of the moon across the weekend.

To the untrained eye the moon will appear roughly the same size across the weekend, however veterans will be able to note its change in shape.