May's Full Flower Moon Saturday Is, Somehow, a Blue Moon. Here's Why
May's Full Flower Moon Saturday Is, Somehow, a Blue Moon. Here's Why
By Joe Rao 12 hours ago
Sky watcher Austin Moloughney sent in a photo of the moon rising behind Vimy Mountain, Alberta, Canada, on August 18, 2013. (Image: © Austin Moloughney )
We usually associate the term "Blue Moon" with a month containing two full moons. Nothing of that sort happens this month, and yet May 18 brings a Blue Moon nonetheless — at least according to rules drawn up by an almanac's editor nearly a century ago.
A couple of months ago, I wrote about why Easter 2019 should have fallen in March as opposed to April, based on astronomical considerations.
This year, the vernal equinox occurred at 5:58 p.m. EDT (2158 GMT) on March 20, followed less than 4 hours later by a full moon — officially the first full moon of spring.
However, ecclesiastical rules do not recognize spring arriving any earlier than March 21. So Easter, a feast day that is celebrated on the first Sunday after the first full moon of spring, was delayed until after the following full moon, on April 19.
More:
https://www.space.com/blue-moon-may-2019-full-flower-moon-explained.html