The Moon represents the emotional flow, the “Mood” of the day, the nature of our day-to-day human interactions.
When the Moon walks in the front door of a sign, it “stirs up” that sign’s energy. As the Moon proceeds through the sign, it will engage in aspects with the Sun and other planets and temporarily take on their energies. Once the Moon has checked in with every planet it’s going to, it’s off duty. Done. For the rest of the time the Moon is in that sign, the “mood” is disconnected from the rest of the planets, a.k.a. void of course.
You may notice a “drifty” quality to your interactions when the Moon is void of course. Void of course = off course. I see it as a cosmic time-out or resting period. A musical rest before the next harmony begins.
When the Moon is VOC, the “mood train” has left its track— and it will tend to go in the same direction and back onto the track you intended if you just leave it be. But if you push it too hard, it can go off your intended track and end up on another track– one you didn’t intend. You have little power to influence the track your boxcar ends up on (no steering mechanism). That’s why you’ll probably do well to take a “time out” from the big actions and decisions when the Moon is VOC.
Depending on how the rest of the planets are situated in their respective signs, the VOC period can last as little as a few seconds or more than two days. The VOC period ends when the Moon enters a new sign.
My free astrology calendar includes Moon void of course dates and times.
Pro tip: you can use the Moon VOC to make plans that you don’t really want to keep. My friend Lynn mails her tax returns when the Moon is void of course! She says it helps her avoid an audit.