Why a Perigee Full Moon is Referred to as a Super Moon

When a full moon appears to be of greater size than usual, it is beautifully bright and clear and details of the moon’s surface can be detected by the naked eye. This is what is known as a super moon.

According to Andrew Fazekas, commenting on photos of the 2012 Supermoon for National Geographic, the term “supermoon” has only been around since 1979.  Previously it had been referred to as a blue moon.

Scientific explanation of a super moon

It really is quite simple, as earth science teacher David Dickinson explains in his article on the Universe Today website. What really happens when a super moon appears in the sky is a full moon during the time when the lunar orbit brings the moon closest to the earth.

The reason why the moon moves closer to us is due to the fact that the orbit of the moon forms an oval. It is not on a circular orbit.

A super moon is known in astrology as a Perigee Full Moon. Another term that has been used to describe the appearance of a bigger moon, because it’s  nearer to the Earth, is a Proxigean Moon.

The opposite of a perigee is an apogee. At the apogee of the lunar orbit the moon is farthest from the Earth. A super moon appears to be larger and brighter, and when the moon is at its apogee it will seem smaller and duller.

Viewing a super moon

The dates when a super moon will occur can be predicted, because a full moon will appear during its perigee once every 14 lunar months. The next super moon will be visible on August 10, 2014.

The best time to view a super moon is when it begins to rise and is at its most spectacular. The moon will always appear to be slightly larger when it’s close to the horizon. This is known as the “moon illusion”. When it is setting the moon will also appear larger, just before it sinks below the horizon.

Myths about a super moon

In recent years super moons have become associated with dangerous high tides, earthquakes and other natural disasters. NASA denies that any of these happen more frequently during a super moon, but accepts that tides do rise slightly higher than normal during the moon’s perigee.

Some media reports continue to warn that some sort of disaster could be set off by the occurrence of a super moon.

Once in a blue moon

Because a super moon appears less than once a year, the phrase “once in a blue moon” has come to indicate something that will only happen rarely. The moon might appear blue when it’s closest to the Earth, but it can also appear yellow or red according to atmospheric conditions.

A super moon is a rare site that makes a big impression, with its brightness, size and clarity. The scientific explanation is easy to understand, but that does not prevent people being excited at the sight of a super moon.