It has been reported that second full moon will occur on July 31. And it will happen for the first time since August 2012. Every month a full moon appears, but the lunar cycle and the calendar year do not continue in perfect manner so it is approximately every three years that two full moons appear in the same calendar month.

However, it will almost certainly not look blue in any way. In general, when a moon takes on a bluish hue, it is as a result of dust or smoke in the atmosphere.

This kind of thing occurred in 1883; during that time eruption of the Indonesian volcano Krakatoa took place and it sent out ash into the atmosphere so much so that the moon appeared with a cerulean touch for years. Following the huge explosion, the volcanic debris led to vivacious red sunsets and the moon was having a bluish tint. According to scientists, the explosion was comparable to a 100-megaton nuclear bomb.

As per reports, the dark blue tone of sky in the evening could also have an influence on the coloring that is perceived. According to NASA's National Space Science Data Center, the phrase "once in a blue moon" was used in this matter so as to indicate that one will feel lucky to see this rare event in his lifetime.

In September 1950, the most recent blue moon occurred that had truly blue hue. It appeared in Edinburgh, Scotland. As per reports, the next blue moon won't appear until 2018.