If you want, you can also make a phase permanent or turn off moon effects. With default settings, the moon will change each night, but you can change the length of the phases in the Environment section of Game Options.
In total, there are eight phases: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, and Waning Crescent. This excludes locations that might not make sense, like the Magic Realm. Were your Sims set in their nocturnal ways? The moon now has phases within a Lunar Cycle! From now on, you’ll notice that the moon in the sky changes over time, which affects how much light is given off at night in almost every neighborhood across all packs.