Blue Moon July, 2015

There was a full moon on July 2 and last Friday, July 31, the second one appeared.  When there are two full moons in one calendar month, the second is described as blue.

The term blue moon,  has nothing to do with the color of our satellite,  but  refers to the succession of two full moons in the same month of the calendar, something which happens approximately every three years. In fact it is not blue. It is one full moon, like any other, of the same color as are most full moons: between pale gray, silver or milky white.  Here are two amazing photos of the Blue Moon.

People gathering to watch the blue moon rising over Glastonbury Tor.

  

Here, a group of friends pose like the Beatles as the moon rises above Penny Lane in Liverpool.

Read more:  Daily Mail 

The reason why it is possible to have two full moons in the same month is due to the fact that  the full moon cycle is approximately every 29.5 days.  If the full moon occurs the first day or the second of the month, it is more likely  that a second full moon would appear in the same month, what we would call a blue moon.

Does the Moon look blue?  In general, no. To make the moon appear with a  bluish tone copper, it  must be influenced by the ashes and smoke.  For example, in 1883, the explosion of the volcano Krakatoa (Indonesia) covered the clouds with ashes. The particles of ashes that absorbed a small amount of light tinted the atmosphere,  hence the moon could be seen as blue through the ash covered clouds.  Source:  Science Magazine Muy Interesante

The same was repeated in 1983, as explained from NASA, with the Mexican volcano El Chichón eruption. Source:  Hipertextual

Source of photo:  Hipertextual

We call the second full moon occurring in the same month as  blue Moon because of its rarity, as it is not an astronomical phenomenon that is usually observed.

The term Blue Moon actually had no scientific sense. James Hugh Pruett was the writer who baptized  the third full moon in a quarter that counted with four full moons.

Many cannot hear the expression without remembering a melody.  Blue Moon is also an American song by Richard Rodgers and Lorenz Hart, one of the many versions of a story by performers such as Frank Sinatra and Elvis Presley.