August 30th saw the largest supermoon to be recorded this year (Image from the Independent)
Supermoons have been regarded as an auspicious omen throughout human history. Whether it signified a change in the gods’ emotions or the coming of an agricultural disaster, supermoons were revered and treated as a mythological phenomenon which no one knew the answer to.
Our moon’s cycle contains a slight eccentricity: meaning, they follow elliptical orbits rather than an exact circular path. This creates a disparity in the moon’s distance from the Earth throughout its cycle. In other words, the moon may be sometimes closer to the Earth, and sometimes further. Our moon maintains a distance range of 360,000 to 400,000 kilometres from our planet.
Supermoons are defined as a new or full moon whose distance from the Earth is within 90 percent in its elliptical orbit: in order words, if the moon was closer to the Earth than was the ordinary (i.e. at a perigee), then it was classified as a supermoon. August 30th saw the largest supermoon to be recorded this year, at just 222,043 miles (357,344 km) away from Earth.
Although a less commonly used term, the moon, at the furthest point away (i.e. at an apogee) forms a micro-moon, a moon that appears to be smaller in size than normal. When the Moon is at this point, it appears around 14% smaller than when we would see a supermoon. However, scientists say that this difference, being of little significance, cannot be easily discerned by the human eye.
Then, what differences can we see on nights when a supermoon rises? Because the moon is closer to our planet than usual, more of the Sun’s ray that reflect off the surface of the Moon reach the Earth. Thus, the moon may appear to be brighter (up to 30%) than on normal nights. Moreover, as the ocean’s tides are caused by the gravitational forces of both the Sun and the Moon, as the Moon approaches the Earth, the gravitational force from the Moon would act more strongly on the ocean. However, the change would be minimal, a few centimetres of change in the tide at most.
How often do supermoons occur? As the moon’s orbits are not perfectly circular, not every full or new moon coincides with a perigee: although the moon’s cycle follows a monthly pattern, a supermoon follows an approximate yearly pattern, producing supermoons during consecutive months each year.
The next supermoon is predicted to occur on the 18th of September 2024. Why not take a look outside and watch the ‘little cosmic dance’ starring the Earth and moon?
Seowoo (Cathy) Kim