There is nothing more romantic than a big, bright moon in the night sky. A few times a year, the moon is bigger and brighter than usual. This natural phenomenon is called a ‘supermoon’. It can appear up to three times the size of an average moon!
Supermoons happen when the Moon, the Earth and the Sun are in a straight line, and when the Moon is closest to the Earth. When these two celestial events happen at the same time, you get a great big Moon in the sky.
THE SCIENTIFIC NAME
‘Supermoon’ is not, in fact, the scientific name of the event. It is actually called a ‘perigee syzygy’. Perigee means ‘closest to Earth’. The Moon orbits the Earth in an elliptical curve; ‘perigee’ describes the closest point in its orbit. The furthest point is called ‘apogee.’
‘Syzygy’, on the other hand, means the alignment of three celestial bodies.
The Sun, the Moon and the Earth are aligned during the full moon and new moon phases. During a new moon syzygy, the Moon is not visible because it is between the Earth and the Sun. This is a lunar eclipse. The supermoons that are visible occur during a full moon syzygy, when it is closest to earth. In other words, a perigee syzygy full moon.
LET’S CALL IT SUPERMOON
Of course, ‘supermoon’ is an easier term to use than ‘perigee syzyzy’. It was coined by astrologer Richard Nolle thirty years ago. His definition was: “a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to earth in a given orbit.” Now it has become the popular phrase among astronomers, as well.
According to Nolle’s definition, the Moon has to come within 226,000 miles of Earth before we can call it ‘super’. The closest it has been recently was on the 14th of November 2016, at a distance of 221,524 miles. This was the closest since 1948 and it won’t come that close again until 2034! However, even the greatest supermoons are only 30 per cent bigger than usual. What makes it truly spectacular is the ‘moon illusion’. Nobody really knows why, but the Moon looks much, much bigger when it is on the horizon. So, when a supermoon touches the horizon, it becomes like something out of a fairy tale.
HOWLING AT THE MOON?
The phrase ‘howling at the moon’ conjures up images of werewolves howling to the heavens, but in fact supermoons do not have any major effect on Earth. Tides are a little bigger, but earthquakes, natural disasters and psychological effects on humans – these are all unsubstantiated myth. So don’t worry and just enjoy the show.