The Moon finds itself in this position roughly every 29 days, which is the length of the monthly lunar cycle.
And we only see the Moon at night because it reflects the Sun’s light back at us.
The US space agency NASA said: “If we could magically look down on our solar system, we would see that the half of the Moon facing the Sun is always lit. But the lit side does not always face the Earth
“As the Moon circles the Earth, the amount of the lit side we see changes.”
These changes are known as the lunar phases and they repeat every month.
This Full Moon is also known as the Fruit Moon as many fruits ripen around this time of the year.
September’s Full Moon is also sometimes known as the Barley Moon or Harvest Moon as it falls near the autumn equinox.
Mr Johnston said: “This Full Moon corresponds to the Chinese Hungry Ghost Festival.
“The seventh month of the Chinese calendar is the Ghost Month and the fifteenth day of this month – a Full Moon day – is called Ghost Day, on which ghosts and spirits, including those of deceased ancestors, come out to visit the living.”
When are the Full Moons this year?
January 10 – Wolf Moon
February 9 – Snow Moon
March 9 – Worm Moon
April 8 – Pink Moon
May 7 – Flower Moon
June 5 – Strawberry Moon
July 5 – Buck Moon
August 3 – Sturgeon Moon
September 2 – Corn Moon
October 1 and October 31 – Hunter’s Moon
November 30 – Beaver Moon
December 30 – Cold Moon