View over the city of Leiria with the Full Moon just before moonset.
The Moon is about 357 421km from the Earth, called Super Full Moon, because it is in perigee.
The distance between the Moon and the Earth varies because the Earth is not right at the centre of the Moon’s orbit, and the Moon’s orbit is not a circle, it’s an ellipse.
So there will be a lunar perigee when the Moon is closest to the Earth.
If the lunar perigee occurs very close to a full moon, then we see a supermoon.
During a supermoon, the Moon appears up to 14% bigger and 30% brighter than the furthest a full moon can be.
The designation of Super Moon is not an official astronomical term, and is often used to define the phenomenon of Full Moon in Perigee.
The first reference to this name first appeared by an astrologer, Richard Nolle, in 1979. He stated that "a New or Full Moon occurs when the Moon is near or within 90% of its closest approximation to Earth in its orbit ".
Supermoon is not an official astronomical term. It was first coined by an astrologer, Richard Nolle, in 1979.
He defined it as ‘a New or a Full Moon that occurs when the Moon is at or near (within 90% of) its closest approach to Earth in its orbit’.
There are no official rules as to how close or far the Moon must be to qualify as a Supermoon or a Micro Moon.