The autumn equinox arrived yesterday evening at 9:04p EDT. For those of us in the northern hemisphere, it marks shorter daylight hours and cooler weather. The current indicator of change is that it gets light later in the morning and gets dark earlier in the evening.
Different cultures commemorate the equinox with various customs. I typically notice a shift in the workplace at this time of the year. The looser environment of summer transitions into more of a settled and focused workplace.