The Full Moon on Saturday, March 31, 2018, is a Blue Moon because it is the second moon occurring within the same month.
This Full Moon is also the second Blue Moon of 2018 after the first Blue Moon occurred on January 31.
Because a Full Moon cycle is 29.5 days and February only has 28 days this year, there was no Full Moon in February 2018. Instead, the next Full Moon fell on March 1 which gave March enough days remaining in the month for a second “Blue Moon” on March 31.
What time is the March 2018 Blue Moon?
This Blue Moon begins with a moonrise over the Atlantic Ocean at 8:01 p.m. Eastern Daylight Time on March 31, 2018, which sets the following morning at 8:08 a.m. (with a few minutes of variation depending on your exact location in Florida or several minutes along the rest of the U.S. east coast).
This Blue Moon will technically be 99.8% full on March 31.
Where to watch the Blue Moon:
The Blue Moon can be seen from anywhere on Earth, unless there is local cloud coverage.
How often is there a Blue Moon?
Blue Moons occur when there is a second full moon in a calendar month or when a season has four full moons. Full moons are separated by 29.5 days but seasons are 88 to 92 days long – so it is possible to fit four full moons into a single season. This happens just over two-and-a-half years, on average. When there are four full moons in a season, the third full moon is considered a Blue Moon.
This is why the phrase “Once in a Blue Moon” is commonly known to mean something rare and offbeat because of the rare occurrence of a Blue Moon.
Is a Blue Moon actually blue?
The date of a full moon doesn’t affect the full moon’s color. The Full Moon on Saturday, March 31, 2018, will be pearly-gray to most locations on Earth, as usual.
According to NASA, the key to a moon appearing blue is to have lots of particles slightly wider than the wavelength of red light (0.7 micron) and no other sizes present in the air. This is rare, but volcanoes sometimes produce such clouds, as do forest fires.
Humans saw blue moons almost every night when the Krakatoa volcano exploded in 1883 with the force of a 100-megaton nuclear bomb. Plumes of ash rose to the very top of Earth’s atmosphere.
Some of those ash-clouds were filled with particles about 1 micron wide – just the right size to strongly scatter red light while allowing other colors to pass. White moonbeams shining through the ash-clouds emerged blue, and sometimes green.
People also saw blue-colored Moons in 1983 after the eruption of the El Chichon volcano in Mexico. And there are reports of blue Moons caused by Mt. St. Helens in 1980 and Mount Pinatubo in 1991.
Why is this Full Moon named the “The Paschal Moon” or “Easter Moon”?
The March 31, 2018 Blue Moon is also called an “Easter Moon” and “The Paschal Moon” because it is the first Full Moon of Spring. A Full Moon in March also has seasonal names such as a “Worm’s Moon” or “Sap Moon.”
Image credit: NASA (blue-enhanced by Brevard Times)