The length of day and night are at an exact equal today. From now until the winter solstice around December 21st or 22nd the days will be shorter and shorter and the nights longer and longer.
This definitely marks the beginning of fall as now our days will be shorter, nighttime will be coming sooner and cooler weather will be heading our way. This is Kristen's favorite time of year!
This illustration, which shows an example of the September equinox, is not to scale.
For a more detailed explaination for the September Equinox click HERE to visit Time and Date website.