So here you have two definitions of a blue moon but the one for a calendar blue moon does not describe the true meaning of a blue moon. Here's why:
However, the astronomers will require more HST observations in order to obtain accurate measurements in order to determine if the moon's orbit is circular or elliptical. Preliminary estimates suggest that if the moon is in a circular orbit, it finishes a circle around Makemake in 12 days or longer.
Discovered on March 31, 2005, by a team of planetary scientists led by Dr. Michael E. Brown of the California Institute of Technology (Caltech) in Pasadena, Makemake was initially dubbed 2005 FY 9, when Dr. Brown and his colleagues, announced its discovery on July 29, 2005. The team of astronomers had used Caltech's Palomar Observatory near San Diego to make their discovery of this icy dwarf planet, that was later given the minor-planet number of 136472. Makemake was classified as a dwarf planet by the International Astronomical Union (IAU) in July 2008. Dr. Brown's team of astronomers had originally planned to delay announcing their discoveries of the bright, icy denizens of the Kuiper Belt--Makemake and its sister world Eris--until additional calculations and observations were complete. However, they went on to announce them both on July 29, 2005, when the discovery of Haumea--another large icy denizen of the outer limits of our Solar System that they had been watching--was announced amidst considerable controversy on July 27, 2005, by a different team of planetary scientists from Spain.