A ‘Blue Moon’ is an rare phenomenon that entails the looks of an additional full moon inside a given interval. Just lately, the time period Blue Moon has been utilized to the second full moon in a single calendar month. There are roughly 29.5 days between full moons, making it uncommon for 2 full moons to suit right into a 30- or 31-day-long month.

October this yr will witness the uncommon incidence of a second full moon, known as the ”Blue Moon”, about which we talked above, on Saturday. October already has seen a full moon and the following full moon falls on 31 October, mentioned Arvind Paranjpaye, director of Nehru Planetarium, Mumbai.
“When there are two full moons in a calendar month, the second full moon is named the Blue Moon,” he mentioned.

What Is a Blue Moon? | Space

What’s The Maths Behind The Blue Moon?

There’s a little bit of arithmetic concerned on this. “Period of a lunar month is 29.531 days or 29 days, 12 hours, 44 minutes, and 38 seconds. Therefore, with the intention to have two full moons in a month, the primary full moon must be on the first or 2nd day of the month,” Paranjpaye explains. This further time accumulates over the months. After about 30 months there will likely be one further full moon within the yr, Paranjpaye mentioned.

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The director of Nehru Planetarium, Delhi, N Rathnashree mentioned this time period is a calendrical time period. “It’s too unusual to have a Blue Moon in a month of 30 days,” she additional mentioned. The final Blue Moon in a month with 30 days was on June 30, 2007, and the following Blue Moon will likely be on September 30, 2050, Paranjpaye mentioned.

There have been two such occurrences in 2018. The primary one was on January 31 with the second adopted on March 31. “This was as a result of the previous month February had solely 28 days,” Paranjpaye mentioned. He additional advised that the following Blue Moon will seem on August 31, 2023.

Why Can’t India Predict It?

A scientist with Vigyan Prasar, T V Venkateswaran, an astronomy fanatic, mentioned this phenomenon is basically bounded to the Gregorian calendar which is used worldwide.
Venkateswaran mentioned, “You’ll not see this look of two full moons in a month in Tibetian or Islamic calendars or those being adopted in giant components of India as a result of these are based mostly on lunar actions”.

A rare phenomenon: Blue Moon is all set to grace the sky on October 31 - Once in a blue moon | The Economic Times
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The phrase ”As soon as in a Blue Moon”, denotes some occasion that doesn’t occur very ceaselessly got here from this phenomenon, Venkateswaran added.