Funny, I always thought that the day of the equinox was 12 hours of daylight and 12 hours of dark. Apparently my understanding was a little off; sunrise today was at 6:32 AM and sunset at 6:40 PM, giving us a day that is 8 minutes longer than 12 hours. Hmm...
I went looking for information and found the page What is the September Equinox? It showed that the equinox at my location was today, September 23, 2015, at 4:22 AM. I found the definition interesting:
Sun Crosses Celestial Equator
The September equinox occurs the moment the Sun crosses the celestial equator – the imaginary line in the sky above the Earth’s Equator – from north to south. This happens either on September 22, 23, or 24 every year.
information courtesy of www.timeanddate.com