Full Moon tonight: Friday the 13th brings a rare Micromoon – What is a Micromoon?

Astronomy and superstition collide tonight when an unusual Full Moon coincides with an inauspicious date – Friday the 13th. September’s Full Moon has been given the anachronistic name of The Harvest Moon. And this year’s Harvest Moon will be all the rarer because it will be a Micromoon.

A Micromoon is the cosmic occurrence when a Full Moon or a New Moon coincides with apogee – when the Moon’s orbit takes it farthest away from our planet.

The Moon travels around Earth in an elliptical orbit, meaning one side of its trajectory is closer to the Earth than the other.

The point in the Moon’s orbit closest to Earth is technically called perigee, while the converse point, when it is farthest from Earth is apogee.


The average distance between Earth and the Moon is 237,700 miles (382,500km).

When a Full Moon – or a New Moon – occurs around apogee, it is dubbed a Micromoon.

Other names for this phenomena include Minimoon or Apogee Moon.

A Full or New Moon occurring around perigee, meanwhile, is known as a Supermoon.


There are no concrete rules as to how far away the Moon must be to qualify as a Micromoon.

However, there are commonly accepted definitions used by most astronomers.

A micromoon is a Full Moon or New Moon taking place when the Moon’s centre is farther than 251,655 miles 405,000km from the centre of Earth.

Supermoon, meanwhile, is a Full or New Moon occurring when the Moon’s centre is less than 223,694 miles (360,000km) from the Earth’s centre.

READ  Scientists create stunning gifs of Mars' sand dunes to understand what conditions impact them 

READ MORE: Astronomers announce first ever video of black hole M87

Realistically, the difference between a Supermoon and a Micromoon is difficult to detect.

Sky & Telescope magazine senior editor Alan MacRobert said: “It’s not enough to notice unless you’re a very careful Moon-watcher.”

The term “Supermoon” actually only appeared in the lexicon in 1979.

And it was not until a spate of three Supermoons in 2016 that the term was popularised.

What does a Friday the 13th Full Moon mean?

Though a dimmer-than-usual Full Moon may make Friday the 13th feel creepier, you should refrain from being g afraid.

Full Moons have occurred on Friday the 13th innumerable time before with no effect.

The majority of research suggests humans are unaffected by the cycle of the Moon.

Contrary to popular myth, people will not experience an increased likelihood of giving birth, have seizures or go mad in the presence of a Full Moon.


Leave a Reply