How rare is supermoon?

How Rare is a Supermoon?

A supermoon is the term given to a full moon that occurs when the Moon is at or near its closest point to Earth, known as perigee. This alignment of events creates a particularly bright and striking sight in the sky. But how rare are these special moon events, and what’s the criteria for calling a moon super?

SupermoonFrequency

Supermoons actually occur relatively frequently, especially when considering that there’s a full moon every few days. On average, a supermoon occurs every 6 months, but this average can vary slightly due to the Moon’s elliptical orbit. The Moon revolves around Earth in approximately 29.5 days on average, which affects the frequency of supermoon occurrences.

Here’s the breakdown of how often full moons occur, including supemoons, in table form:

Types of Rare Moons

There’s more to a supermoon than just a full Moon at perigee! Let’s break down its rare-ness into these categories:

• Traditional Supermoons: ~3% of full moons, meaning 40-50 traditional supermoons in 20 years.
• Blue Full Moons (i.e., a second full moon in a single calendar month): 1 event every 2.67 years, with an aggregate frequency of about 21 events in 20 years.
• Second Blue Moons or Pseudobulpe: even rarer, with only 9-12 occurrences in the 21st century
• Total Lunar Red Moon: very rare combination of a lunar eclipse along with a blue moon:

• ~1 blue moon in 2-3 years, and further divided into partial, Total, or Partial Lunar eclipses
  Why Do We Care so Much about Supermoons?

For many around the world, supermoons become special events mainly due to the increased perception of the moon’s magnified brightness, making each appearance seem even more prominent. Supermoons grab attention for these reasons among others:

• Marketing and Social Media: companies and news outlets often prioritize these rare celestial events when they happen to generate popular interest.
• Eclipse Mania: interest in astronomy grows during astronomical events like total lunar eclipses, sometimes causing the phenomenon to overlap with blue or super-full moons.
• Calendar Alignments: super-moons coincide with other peculiar celestial occurrences like planetary arrays, asteroids passing close proximity, and unique planetary transitions.

Final Thoughts – Rare is Not Always Endangered

With the occurrence of approximately 4+ supermoons per annum, and supermoons happening 8-12 times within the next lunar cycle, this phenomenon while rare is by no standards endangered. To put their frequency into perspective, with the world having witnessed its 24th super- moon of this century this year (Aug 5, 2019 [1]) as of December 2019, many people already live through relatively rare moon cycles.

How rare is a super-moon? Answer: Very rare but regular enough still. Enjoy each unique time to catch your super Moon!

[1] Supermoon Alert! The second supermoon of the Year, NASA | August, 5th, https://www.nasa.gov/feature/2019-nasa-issued-supermoon-alert-second-supermoon-of-2019-hits-north-half-of-north-american-map.