17 July 2014
The Short Answer (TSA)
The Supermoon gets a lot of attention. But it’s opposite, the “Micromoon,” is often neglected. A Supermoon is any Full or New Moon that happens when the Moon is closest to the Earth.
The Moon has an “irregular” orbit around the Earth. So, sometimes, the Moon is much closer than at other times. The Moon is said to be at its “perigee” when it is closest to the Earth. And when the Moon is both (1) a Full Moon and (2) at its closest approach to the Earth, it is called a Supermoon. A Supermoon is worth looking at because, as the the Moon gets closer, it gets visibly bigger in the night sky.
A Micromoon & Supermoon as seen in the Night Sky
But the opposite also happens. When the Moon is farthest away from the Earth, it is said to be at its “apogee.” And, when the Moon is both (1) a Full Moon and (2) at its farthest from the Earth, it is called a Micromoon.
Why does the Micromoon get so little attention?
First, “the smallest Moon you could ever see in the sky” just seems like a “smaller” event than “the biggest Moon you could ever see in the sky.”
Second, Supermoons are wrapped up in a controversy. When the Moon is close to the Earth, it exerts more gravitational pull on the Earth. For example, the ocean tides are stronger when the Moon is closer.
Some believe that the Super Full Moon causes earthquakes and volcanic eruptions on Earth. The theory is that, when the Sun and Moon are on opposite sides of the Earth, they are “pulling” in opposite directions. This gravity “tug-of-war” puts extra strain on the surface of the Earth. And, when there’s not only a Full Moon, but the Moon happens to be at its closest approach to the Earth, the increased gravity is more likely to cause earthquakes or volcanic eruptions.
Some believe that more stress is put on the Earth’s surface at the New Moon, when both the Sun and Moon are together on one side of the Earth. And, when the New Moon is also a Supermoon (at its closest approach to the Earth), the gravity pulling on the Earth’s surface is at its very strongest. So, does gravity from Super New or Full Moons cause earthquakes and volcanic eruptions?
Although there seems to be logic to the idea that more gravity could affect the surface of the Earth, science says no. Studies have not produced any evidence that the Sun and the Moon, even when the Moon is at its closest, produce enough “extra” gravity to cause anything like an earthquake or volcanic eruption. But, others disagree.
At any rate, the forgotten Micromoon is the smallest (not the biggest) “moon” visible in the night sky. And, because the Micromoon is farthest away, it has the weakest gravitational pull on the Earth. No one thinks the Micromoon could cause any trouble. So, there is no controversy — with the result that Micromoons gets very little attention.
Any Full Moon, when the Moon is more than 250,000 miles away, is a Micromoon. When it comes to Micromoons, only Full Moon’s count. New Moons seem to be ignored. So, a New Moon more than 250,000 away, isn’t called a Micromoon or anything else. No one seems to notice or care.
The next Micromoon happens on 5 March 2015.
M Grossmann of Hazelwood, Missouri & Belleville, Illinois
Lots of Moons & Music 