The official start of the Autumnal Equinox will be this Saturday, at 10:50 a.m. The equinox occurs when the tilt of the axis of the earth is vertical in relation to the sun, the earth is neither tilted toward or away from the sun, with the sun is centered on the earth's equator.
So on Saturday, the day and night will be very close to 12 hours each. Today we had a sunrise of 7:22 and sunset of 7:34, so you can see the days are getting close to 12 hours right now. On the day of the autumnal equinox, the sun rises and sets around 6 a.m. and 6 p.m. (the time varies for several reasons and increases as you go toward the poles) everywhere on earth. Here, it will rise around 7:23 a.m. due to the fact we follow Daylight Savings Time, without it, the sun would be rising at 6:23 a.m.
If you're a meteorologist, fall started on Sept. 1 and this is called Meteorological Fall which will last from September though November.
On a little side note, Fairbanks Alaska is losing around six minutes a day of sunlight right now, where we are only losing about two minutes a day, so it could be worse here!