"The blue moon will occur on Aug. 30," astronomer Elmor Escosia of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) told The STAR yesterday.
According to Escosia, the blue moon is the extra full moon, or the 13th instead of only 12 full moons this year and the second full moon this month after the one that occurred last Sunday, Aug. 1.
The period from one full moon to another is 29.53 days, the astronomer said.
"The last time we had a blue moon was in Dec. 30, 2001," Escosia said.
He said this intriguing astronomical phenomenon — when two full moons manage to position themselves and appear in the same month — occurs every two and a half years.
Astronomers say that two full moons in one month may occur in any month except February, which is shorter than the lunar cycle. The more recent phenomenon, where the blue moon is considered to be the second full moon in a calendar month, last occurred on Nov. 30, 2001 in the western hemisphere and Dec. 30, 2001 in the Philippines.
Over the next 20 years, there will be a total of 17 blue moons but no such rare moons in the years 2006, 2011, 2014 and 2017, astronomers say.
Was there ever a time the moon literally turned blue?
Escosia said really blue moons were actually caused by volcanic ash and other fine particles tainting the atmosphere.
"The moon turned blue after the June 15, 1991 eruption of Mt. Pinatubo and the observation was reported worldwide. The smoke from the destructive Canada forest fires in September 1950 also made the moon turn blue in color," he said.
Records also show that the great explosion of Krakatau volcano (Krakatoa, east of Java) on Aug. 26, 1883 in Indonesia also made the moon blue.
"Dust and ash from this eruption encircled the earth in 13 days forming a cloud that, by Sept. 9, 1883, had covered completely the upper atmosphere along a belt in the equatorial zone. Three months after the eruption, this belt of fine volcanic dust and particles had spread to higher latitudes causing unusually spectacular red sunsets and other interesting atmospheric effects. Blue and green suns were also observed. Blue moons, too," records say.
The intriguing blue moon phenomenon has inspired the writing of poems and songs, even the creation of paintings.
Or come up with the phrase "once in a blue moon," which no longer means never, but rather "every now and then," or more precisely, every two and a half years.