The super harvest moon

A supermoon – known by astronomers as a perigee full moon - occurs when the moon comes closer to the Earth than normal allowing it appear 14 % larger and 30 % brighter. This recent supermoon was the third this summer, or as National Geographic calls it, the ‘last act in a cosmic play’.

According to National Geographic, the moon was closest to the Earth on the night of 7 September when the ‘silvery orb’ was a mere 358 398 kilometres from us sky-watchers. However the full phase of the moon occurred officially occurred on 8 September.

What exactly are the ‘cosmic mechanics’ of the supermoon? National Geographic explains the supermoon phenomenon: ‘The moon orbits the Earth on an egg-shaped orbit, with our planet sitting a bit off center. This means that once a month in its orbit, the moon reaches its closest point to Earth, known as its perigee. This is when the moon looks the largest in diameter. At the same time, the moon is also at the point in its 28-day-long orbit around the Earth that it passes opposite the Sun.’

Once in a while, a perigee and a full moon coincide to create a perigee full moon or supermoon. This gives us a brighter and larger-than-normal full moon. The opposite of a supermoon is a micromoon which is when a full Moon occurs near the furthest part of the Moon's orbit so that it appears smaller and dimmer than usual.

There is no need for us to fear anything from the epically-named supermoon looming close to the Earth. Dr. James Garvin, chief scientist at NASA's Goddard Space Flight Center, says that supermoons have only a minor effect on our planet. He notes, ‘the Earth has stored a tremendous amount of internal energy within its thin outer shell or crust, and the small differences in the tidal forces exerted by the moon (and sun) are not enough to fundamentally overcome the much larger forces within the planet due to convection (and other aspects of the internal energy balance that drives plate tectonics). Nonetheless, these supermoon times remind us of the effect of our 'Africa-sized' nearest neighbor on our lives, affecting ocean tides and contributing to many cultural aspects of our lives (as a visible aspect of how our planet is part of the solar system and space).’

September’s supermoon is particularly special because it’s also a harvest moon. Although we usually associate the harvest moon with autumn, this year's version is actually the last full moon of the summer season. Discovery News tells us that the harvest moon is important because instead of rising its normal average of 50 minutes later each day, the moon rises only a little later each night, providing farmers with extra moonlit evenings to reap their crops.

So this year’s super harvest moon provided a special treat for farmers and sky watchers alike!