Research is one of the fun things about writing. When I was imagining my young adult novel, The Labyrinth of Time, I became intrigued by the idea of “double blue moons.” In recent times, we generally say the second full moon in a calendar month is a blue moon. A few times each century, you have two blue moons in one year, which is called a double blue moon.
On March 30, we’ll have the second blue moon of 2018, following one on Jan. 31. The last double blue moon happened in 1999, and the next will be in 2037.
The idea of double blue moons inspired the “prophecy of the Peruvian elders” that’s at the heart of the adventure story in The Labyrinth of Time:
Beware the second blue moon’s rising. Stones will speak to men, and the song of Pachamama and Inti will fill your hearts. Tremble at the dark moon, which heralds the Light’s return. Only those who tread the Path of Knowledge may rise among the First Men and quench the flames of doom.
I took some liberties with the “dark moon” reference. There is a total lunar eclipse during this cycle, but it occurred on Jan. 31, 2018, rather than March 30 when the story occurs. And the next total eclipse visible in Ica, Peru, is Jan. 21, 2019, which is not part of a double blue moon pair…and that was too long for Jade and Felix to wait for the comet’s return.