Rare 'True' Blue Moon to appear on August 22; Here's all you need to know

If the skies are clear this weekend, the full moon on Sunday, August 22, will be a 'Blue Moon,' according to the American Astronomical Society. A blue moon is an extra full moon that appears in a year's division: the season's third of four full moons. Blue Moons are a rather uncommon occurrence. 

What is Blue Moon? 

The term 'Blue Moon' is now commonly used to refer to the second full moon in a month (the most recent of which was on October 31, 2020), but this was not always the case. This colourful term is actually a calendar blunder that first appeared in the pages of Sky & Telescope in March 1946 and quickly spread throughout the world. The classic astronomical definition can be traced back to the Maine Farmers' Almanac in the late 1930s, according to Sky & Telescope editors and authors. The phrase was always used by the Almanac to refer to the third full Moon in a season with four Full Moons rather than the normal three.

Blue Moon date & timing

"Introducing the 'Blue' Moon meant that the traditional full Moon names, such as the Wolf Moon and Harvest Moon, stayed in synch with their season," said Diana Hannikainen (pronounced HUHN-ih-KY-nen), Sky & Telescope's Observing Editor. When the cycle of lunar phases leads the full Moon to appear within a few days of an equinox or solstice, we have a 'genuine' Blue Moon. The last time this happened was in February 2019, and the next one will be in August 2024.

What is the significance of Blue Moon?

A 'Sky & Telescope' Blue Moon happens when the full moon comes on the first or second night of a month with 30 or 31 days; this sort of Blue Moon cannot occur in February because full Moons occur 29.5 days apart. The next Blue Moon will occur in August 2023, which will be the second full Moon in a month. This month, after the Moon has set as seen from the US East Coast, the Moon will be exactly full at 8:01 a.m. Eastern Daylight Time (12:01 Universal Time). This means that on August 21-22 and August 22-23, watchers in the Americas will experience nearly full Moons on two consecutive nights, with the Moon looking closest to full before dawn and again after nightfall on August 22.

Spiritual meaning of Blue Moon

Historically, the name 'Blue Moon' was not always associated with astronomy. It's often used as a metaphor of grief or loneliness in older ballads, while "once in a blue moon" refers to a rare occurrence. When volcano eruptions or forest fires throw large amounts of smoke and fine dust into the atmosphere, the Moon will turn blue in our sky.

With inputs from ANI

IMAGE: UNSPLASH