Now how

How does a supermoon occur?


The Earth and the moon


The full moon doesn’t have the power to turn people into vicious werewolves. It’s not controlled by a moon goddess that can bring about floods and powerful storms as the Mayans believed. It doesn’t call out mermaids from the ocean, and it doesn’t give people superpowers once a month. What it can do, though, is become a beautiful sight in the nighttime sky and sometimes become enhanced and enlarged into a “supermoon.”


Approximately once a year, the full moon shines brighter and swells up to a size larger than the average full moon. It’s an amazing sight to observe as it rises from the horizon and is a worldwide phenomenon that is captured beautifully in many creative photographs. On June 23, 2013, the Earth had its brightest view of the moon of the year, but don’t fret if you missed it! There is a way to calculate exactly when your next viewing opportunity will be.


The moon orbits the Earth in approximate one-month cycles but rather than following a perfectly circular trajectory around our planet, it traces out an elliptical shape. As a result, it is not always equidistant from the Earth; the point when it is closest to the Earth each month is called perigee and the point when it swings farthest away is called apogee. When the full moon falls on the same day as the perigee, this orb in the sky appears larger and brighter than usual, creating a “perigee full moon.”

Judging from previous observations, it takes a cycle of one year, one month, and 18 days for the perigee and full moon to coincide. Generally, the perigee full moon also aligns with the proxigee, the closest point the moon reaches to the Earth in an entire year. Before June 23, the last time the full moon and perigee aligned was on May 6, 2012 and prior to that, on March 19, 2011.

There have been several misconceptions that have arisen about the larger-than-normal full moons. Technically, all perigee full moons are supermoons, but not all supermoons are perigee full moons. The requirements for a supermoon are strictly that the full moon must be “at or near (within 90% of) its closest approach to Earth” (McClure and Byrd).

At perigee, the moon can come as close as 363,000 km to Earth, while on apogee, the moon is as far as 405,000 km away. On average, the distance from Earth to the moon is 384,000 km (“How Far is”). A perigee full moon can be as much as 14% wider and 30% brighter than apogee full moons (Phillips).


The next supermoon will take place on August 10, 2014. Make sure you have your camera ready because I definitely would have loved to unleash my creativity with pictures like these:

supermoon2 supermoon1

 Written by Constance Kaita

Works Referenced

Images courtesy of (

“How Far is the Moon?” n.d. Web. 25 June 2013.

McClure, Bruce and Deborah Byrd. “Most ‘Super’ Supermoon of 2013 on June 22 – 23.” EarthSky. n.d. Web. 25 June 2013.

Phillips, Tony. “Super Full Moon.” NASA Science. n.d. Web. 25 June 2013.

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