This is our 2nd full moon that occur in the month of July 2015. We call it blue moon, because its the 2nd time to have another full moon in one calendar month. Its not actually turning into color blue, but the saying "once in a blue moon" might originated from this astro event.
Actually,I didn't even know that the full moon that I captured last July 31, 2015 is a blue moon, I was amazed how the moon rises above the BGC sky and its so big!!! Its like the full moon is much closer but that's only an illusion due to the horizon level of the sky from my location.
I was in Ayala-EDSA waiting to cross the highway when I spotted the moon, Im glad that my Olympus E520 with 55-150mm lens is with me that night.
I did some research and I learned that the next blue moon is on year 2018. (source)