Moons are (usually) near-spherical sattelites orbiting a planetary body. These moons reflect light, usually sunlight. Somewhere in the reflective process, the light carries Bluntz Waves, which transform Saiyans that have tails.
On full moons, the concentration is so high that the Saiyans become Oozari, the plural for Oozaru, the Great Ape.
Earth- 1st, 15th of each month
Vegeta- 1st of each month
Namek- Never
Uberia- 15th of each month
Glacian- 1st, 15th, 28th of each month
Majin- 1st of every other month
Heaven- Second Tuesday of every month
Nova Roma- Constantly
Sometimes, a strange event that no one quite understands happens. Crimson, or Blood, Moons. These can sometimes happen at random, and will not only turn even the strongest, most disciplined Saiyan feral, but also works on tailess Saiyans! The Powerlevels of these Oozari are tripled, but their speed is halved.