May’s Moon, known in legend and folklore as the "Flower Moon," will turn 100% astronomically full on Thursday, May 7, 2020, at 6:45 a.m. EDT.
In most areas of the Northern Hemisphere, flowers are abundant in late spring. Blossoms of brilliant color burst forth in both tree and meadow. Thus, the name of May’s Moon, the Full Flower Moon.
May also marks the end of hard frosts, making this the time of year when farmers begin to seed their fields. This led to May’s Moon also being known as the "Full Corn Planting Moon."
In medieval Europe the first day of May, or Beltane, was the day cows were moved to their summer pastures, providing them with rich nourishment to feed their newborn calves. This is why May’s Moon is also sometimes known as the "Full Milk Moon."
Watch our Flower Moon Folklore video here.
May’s Flower Moon: A Supermoon? Not This Time
Many media outlets are calling May’s Full Flower Moon a Supermoon, but Farmers’ Almanac states that it falls short of earning that moniker, and April’s Pink Moon was our true, and last, Supermoon of 2020.
Supermoons are caused by the shape of the Moon’s orbit, which is not a perfect circle, but an ellipse, or oval, shape. The Moon orbits the Earth once each month, and each month, it reaches a point farthest from the Earth, called apogee, and a point closest to the Earth, called perigee.
According to how a Supermoon is defined, it occurs when the Moon is at least 90% of the way to its perigee position at the same time it is in its "full" or "new" phase.
What’s In A Name?
We've heard from many of our readers on social media that they're tired of hearing the term "Supermoon" so often. It became popular in March 2011 when the Moon's perigee brought it to 221,565 miles of Earth; within 127 miles of the absolute closest that it can come (the absolute closest the Moon can come is 221,438 miles from Earth; an exceedingly rare occurrence).
In actuality, Supermoons should only be applied to "extreme" perigees, in which the full Moon approaches to a distance of 221,472 miles or less. Between the years A.D. 1500 to 2500, this condition is met only 14 times, or on average once about every 71 years. The last time the full Moon came this close to Earth was January 15, 1930 (221,454 miles) and the next time will be on December 6, 2052 (221,469 miles).
But if you follow the 90% rule as noted above, you can have as many as three—and on some occasions even four or five—Supermoons in a single year! Here at Farmers' Almanac, however, we don't like to "water down" the term and believe that a full Moon is truly a Supermoon only when the full phase coincides (or very nearly so) with its closest perigee for a given year. Which happens once. However, Farmers' Almanac realizes that many do enjoy the "Supermoon" terminology and want to celebrate Supermoons more often, so we usually bring attention to two of the closest in any given year.
But Here's Why May’s Full Moon Doesn’t "Add Up" to Supermoon Status
May's Flower Moon:
Moon at perigee on May 5th at 11 p.m. EDT; Distance from Earth: 223,479 miles
Moon turns 100% full on May 7th at 6:45 a.m. EDT; Distance from Earth: 224,432 miles
Perigee comes 31 hours and 45 minutes before the Moon turns full. When it turns full on May 7th, it will be another 935 miles farther away.
Let’s compare it to:
April's Pink Moon:
Moon at perigee on April 7th at 2 p.m. EDT; Distance from Earth: 221,772 miles
Moon turned 100% astronomically full on April 7th at 10:35 p.m. EDT
Perigee occurred 8 hours and 35 minutes before the Moon turned full, with a distance of 221,772 miles.
In April, at the moment it turned full, the Moon was 2,575 miles closer than when it turns full in May. So, as you can see, while May’s Moon is close, it won’t come as close as April's full Moon, which was a "true" Supermoon.
Whatever you call May’s Moon, it will still be a beautiful sight. And even though a full Moon is only in this phase for an instant, it will appear full for a day or two before and after. Here’s hoping for clear skies where you are!