Supermoon or super hype?

This month’s full Moon is set to be the ‘biggest’ in about 70 years. But what can observers actually expect to see, and should we believe the hype?

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Peter Louer sent us this incredible image of the Moon, taken from the north of Tenerife on 16 October 2016. Peter used a Canon EOS 700D DSLR camera and 55-250mm lens. Image Credit: Peter Louer

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On Monday 14 November the Moon will pass by Earth at a distance closer than it has done since 1948, making it appear larger in the sky than any other full Moon of the year.

But is this month’s full Moon anything to get really excited about?

While many know this phenomenon as something called a ‘supermoon’, the correct term is a ‘perigee syzygy Moon’; perigee meaning the closest point the Moon comes to Earth in its orbit of our planet (in comparison to ‘apogee’, which is the farthest point) and syzygy meaning the alignment of three celestial objects, in this case the Sun, Moon and Earth in that order.

Perigee and apogee occur because the Moon’s orbit is an ellipse rather than a circle.

As a result, its distance from Earth changes.

The effect is that the Moon will appear almost 15 per cent wider and marginally brighter than the full Moons in May or June 2017, which occur when the Moon is at apogee, but only about seven per cent wider than October’s full Moon.

In other words, the spectacle will not be anything to get particularly worked up about, and certainly nothing near that of a total solar eclipse or the peak of an impressive meteor shower.

“I encourage people to go out and take a look,” says Jim Lattis, director of the University of Wisconsin-Madison’s astronomy outpost Space Place, “but I wouldn’t wake the kids up at 3 a.m.

If you could stack up full Moons next to each other, there is a difference. It is a question of expectations.”

If you would like to see for yourself, simply stepping outside on the evening of the 14th and talking a look with the naked eye will allow you decide whether the lunar disc appears any larger.

It may also be interesting to consider that you are observing the Moon at a proximity to Earth that will not be matched until November 2034.

You could even try imaging the full Moon with a digital camera and comparing it to another taken of at apogee in May next year, to see if you can spot any difference.

You can learn more about the perigee Moon on 14 November and what you can expect to see from The Sky at Night TV show’s Pete Lawrence in our monthly podcast.

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And you if do decide to capture an image of it, be sure to share it with us via Facebook, Twitter or by uploading to our online Hotshots gallery.