While most of us are sleeping, the Earth and sun will cross paths in a way that will officially mark the start of Fall. The autumnal equinox occurs a bit after 3:20 am on Wednesday September 23, 2015. Fall can officially begin as early as the 21st and as late as the 24th, depending on the calendar. Like the spring equinox, it is a time when the sun's rays are shining directly on the equator, resulting in equal day and equal night around the world. However, the Earth does not follow a perfect circle and as a result the half and half day may occurs a few days after the official start of Fall. In Minnesota, our day of equal night and day will be on September 26th. Here in the Northern Hemisphere we start tilting away from the sun, resulting in less and less daylight and eventually colder and colder temperatures.