There are 8 moon phases. The moon goes through a complete cycle, known as a lunar month, which takes approximately 29.5 days. During this cycle, the moon goes through different phases, including the new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, and waning crescent. Each phase represents a different amount of the moon's illuminated surface that is visible from Earth. Therefore, the correct answer is 8.