Supermoons

We are going to enjoy a “season” of 3 full moon supermoons on March 9, April 8 and May 7, 2020. Then we’ll have a “season” of 3 new moon supermoons on September 17, October 16 and November 15, 2020.

A supermoon is a new or full moon closely coinciding with the moon’s closest point to Earth in its monthly orbit. A full moon or new moon has to come within 90% of its closest approach to Earth to be dubbed a supermoon. In other words, any full moon or new moon that comes to within 224,865 miles (or less) of our planet, as measured from the centers of the moon and Earth, can be called a supermoon.

Let’s figure out “90% of the moon’s closest approach to Earth” by the year’s closest perigee (moon’s closest point to Earth for the year) and the year’s farthest apogee (moon’s farthest point from Earth for the year). In 2020, the closest perigee is 221,772 miles. The farthest apogee is 252,707 miles. So any full moon or new moon coming closer than 224,865 miles, as measured from the centers of the Earth and moon, counts as a supermoon in 2020.

By the way, the most distant and smallest full moon of the year will fall on October 31, 2020. Sometimes called a micromoon, it’ll be 252,380 miles away. That’s a whopping 30,529 miles farther away than the year’s closest and biggest full moon on April 8, 2020.

The hype aspect of supermoons probably stems from an erroneous impression people had when the word supermoon came into popular usage, maybe a few decades ago? Some people mistakenly believed a full supermoon would look much, much bigger to the eye. It doesn’t. Full supermoons don’t look bigger to the eye than ordinary full moons, although experienced observers say they can detect a difference.

But supermoons do look brighter than ordinary full moons!  So, go outside on the night of a full supermoon, and – if you’re a regular observer of nature – you’ll surely notice the supermoon is exceptionally bright!