Most people believe that moonlight is a reflection of sunlight, but some astronomers have refuted this theory with the fact that moonlight is visible even during dual lunar eclipse.
Five millennia ago the planet of Terra attempted to assimilate Gaia to save its weakening crystal. The Fusion was a failure and the planets only partially merged with Terra shifting inside the planet of Gaia.
As a result of the failed Fusion, Terra's red moon moved on Gaia's orbit, giving the planet two moons. Each moon radiates the color of its planet's crystal, and as Gaia's crystal radiates blue light, and Terra's crystal radiates red light, the moons acquire their colors.
The lunar monthEdit
Explained in the Final Fantasy IX Ultimania, as the two moons orbit every sixteen days their positions switch, and the moons appear to overlap in a phenomenon similar to a solar eclipse. Only the Gaian moon's radiance is strong enough to be seen when it is directly behind Terra's moon. This is seen on the night Alexander is summoned. Because Terra's crystal is weak, the red moon doesn't glow as brightly, and when Gaia's moon covers Terra's, the red moon is left in shadow.
In an old development memo Hironobu Sakaguchi shared online, the play Tantalus Theater Troupe is about to perform at the beginning of the game is a "special play at night when two moons are full once a year". In the final game, I Want to Be Your Canary is being performed to honor Princess Garnet's birthday.
Location: Luscious Ellie at Treno/Card Stadium (disc 3), Genome at Black Mage Village/Entrance (disc 4), Strong Phantom at Memoria/Lost Memory, Rare Phantom at Memoria/Time Warp
The moons are not named beyond being the "twin moons", but they allude to Final Fantasy IV where the Earth has two moons, the Red Moon originally belonging to an alien race. The Red Moon is the Indian name of the full moon seen during the month of August, the full moon's names were given in the Farmers' Almanac. The Moon may also appear red during a lunar eclipse.
- When Ark is summoned its full-length summoning sequence shows it appearing from Terra's red moon. Ark itself seems to be some form of prototype airship of Terran design, seeing that it resides in Oeilvert that houses airship concepts.
- At the end of the ending credits the two moons appear to merge and become one, seemingly transforming into the crystal that is the logo for Final Fantasy IX.