the moon orbits the earth in the same direction as the earth rotates on its axis, so it takes slightly more than a day—about 24 hours and 50 minutes—for the moon to return to the same location in the sky. during this time, it has passed overhead once and underfoot once, so in many places the period of strongest tidal forcing is the above-mentioned, about 12 hours and 25 minutes. this is analogous to the minute hand on a watch crossing the hour hand at 12:00 and then again at about 1:05½ (not at 1:00).