Whenever there’s a full Moon, things get pretty exciting at the Farmers’ Almanac office. Our staff and readers alike enjoy all of the Moon’s phases, but we get especially enthusiastic about the folklore surrounding each full Moon. But what if there was no monthly full Moon? In February 2018 that’s exactly what’s happening—we won’t have a full Moon. But to make up for it, January and March will be “double full Moon months,” meaning that during both of these months, there will be two times that the Moon reaches its full phase.
When we have two full Moons in a single month the second of these is popularly called a “Blue Moon,”although a Blue Moon can also be the third full Moon in a season.
Is A No-Moon Month Rare?
We often describe an unusual event as happening “once in a Blue Moon.” This expression was first noted back in 1821 and refers to occurrences that are uncommon, though not truly rare — they happen on average once every 3 ½ years. But what about a month with no Moon at all? That is a bit more rare. A “No-Moon” month happens about once every 19 years. The last time February didn’t have a full Moon was in 1999 and then again in 1980.
The timing of the full Moon is related to the “Metonic Cycle,” named by the Greek astronomer, Meton, who discovered this phenomenon around 500 B.C. He noted that a given phase of the Moon usually falls on the same date at intervals of 19 years.
Why Are We Having A Month With No Full Moon?
There doesn’t seem to be name for a month that lacks a full Moon, but the only month where this can happen is in February, the shortest month. The other 11 months must have at least one full Moon.
The reason February is a “No-Moon” month is really quite simple: our Gregorian calendar isn’t synching up with the lunar calendar, which is 29.53 days long. It usually synchs up nicely, giving us at least one full Moon each month, but with February being a short month, sometimes things don’t line up. So, of course there will be a Moon in the sky in February — and it might even appear full — it just won’t reach the moment where it’s 100% astronomically “full” until March 1 (at 7:51 pm EST) on our calendar.
As for the two months with two full Moons this year, there is no real name for when this happens either, but you may notice that these months seem a bit “crazier” than normal!