'Credit'; http://homepages.wmich.edu/~korista/ss-images/lunar-apogee-perigee.jpg


It was set to appear in our skies on the 14th of November and to be the biggest and brightest supermoon since January 26th 1948. Unfortunately for most of us in the southwest it didn’t live up to expectations because our skies were overcast; nor did the slightly smaller appearances of the same moon appear at any time over the following days. So, again, English weather has taken it upon itself to ruin something awesome for the sake of it’s own agenda, making people miserable in the winter.

The science behind supermoons is interesting and has to do with the occurrence of a coincidence between there being a full moon and the moon being at the perigee (closest point), as opposed to apogee (farthest point), on it’s orbit from Earth. The correct astronomical term for this occurrence is a perigee-syzygy of the Earth-Moon-Sun system, but popularisers of science to describe the phenomenon have adopted the term supermoon.

Due to the full moon cycle and the nature of the way in which the moon aligns with Earth, a supermoon will occur once in every fourteen full moons. To give the technical terminology this means that one every 13.9 synodic months (about 411 days), which is the length of the full moon cycle, one of these alignments between the moon and the Earth at the perigee of the moon’s orbit will occur. In addition to this, after about 18 full moon cycles or after about 20 years, the moon will appear to be especially large, as in the case of the 14th this month.

The effect that supermoons have on the tides can also be felt, at the perigean spring tides. For example the tide can increase by up to an inch. As tides follow an inverse cube law, this can cause rises of up to 19%. There have even been attempts to link this phenomenon to natural disasters, such as the Tohoku earthquake and tsunami in 2011, although the links thus far have been shown to be tenuous.

So, if you did manage to see the supermoon, good for you. If however, like the rest of us you didn’t manage to see it then you’ll have to wait until 2034 for the next time when it will be as close to Earth. So, if you’re a supermoon enthusiast you’ll have to wait.

By Sam Cottle