By Staff Reporter (media@latinospost.com) | First Posted: Jul 28, 2015 06:24 AM EDT

"Once in a blue moon," a cliché expression used to describe very rare occasions, will have its definition presented for the world to see as "blue moon" appears in the night sky of July 31.

Tech Times reported that the early definition of a "blue moon" is the appearance of the third or fourth moon of a given season based on The Maine Farmer's Almanac. Modern description of a "blue moon" talked about a phenomenon that occurs when there are two full moons on a single calendar month. Usually, the first full moon occurs on the first two or three days of the month, while the second one happens near the end of the month. This phenomenon was said to occur every two to three years. Using this definition, the last blue moon occurred on August 31, 2012 with the next blue moon scheduled to show by the year 2018.

The phrase "blue moon" has been in use for a very long time - almost 400 years. The course of history resulted in variations of definitions of the phrase. According to Oregon Live, the phrase's core meaning, which is a very rare event, has survived the passing of time.

With all this talk of a "blue moon," does it really show such color in the night sky? According to earlier literature, people have witnessed a blue moon back in 1883. The moons did not necessarily appeared full as there were some occasions of a crescent or half blue moon seen on a nightly basis. On very rare occasions, the moon even appeared green in color. Scientists associated the moon's change in color to the eruption of the Krakatoa volcano in Indonesia. The explosion of the volcano was compared to a 100-megaton nuclear bomb explosion that people from 400 miles away heard the explosion. Volcanic ash covered the skies which turned the moon blue, and occasionally green.

In popular culture, the blue moon brings about a sense of romance and love. Some people go on dinner dates with the blue moon in full view, while others would just lie under the night sky and watch as it rises and falls. For those romantic at heart, mark those calendars and prepare for a special evening with a special someone.

The next blue moon will not occur until January of 2018, so it would be wise to see this year's blue moon as it rises in full view between Thursday night and Friday morning.

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