Earth on a date with "Blue Moon"

Planet earth on a date with "Blue Moon," which will take place on Friday night, corresponding to the phenomenon of 31 July

This phenomenon occurs when the moon is complete appears twice in the same month, while the moon cycle lasts 29.5 days.

It was the first full moon of this month, appeared on the second of July, while it was the last time you saw the sky Earth this phenomenon occurs in the August 31, 2012, and the phenomenon will occur next time in January 2018.

Astronomers say that the phenomenon generally occurs on average once every two to three years.It is noteworthy that the "Blue Moon" does not mean literally change color to blue moon, but it shows that the full moon appears twice in the same calendar month.

In a few cases, parts of the moon might appear in blue, and in case there was a volcanic ash in the skies of the region, according to the British newspaper The Telegraph reported.