This video from NASA shows how the Earth was illuminated between 9/19/2010 and 9/19/2011 from the vantage point of a geosynchronous satellite.
Groups of people have long celebrated this day marking the beginning of fall for us norther hemisphere dwellers. The equal hours of day and night for which the day is named is slightly dependent on latitude because of how sunrise and sunset are defined (the edge of the sun passing the horizon vs. the center of the sun). For all of us, today is the day that the tilt of the Earth points neither toward nor away from the sun. We pass through this balance point as the sun’s most direct rays pass from the northern to the southern hemisphere. Instead of the moon rising 50 minutes later than the day before, there is a period around the equinox that it only rises 30 or 40 minutes later, leading to more light earlier in the night, traditionally good for harvests.
The equinox is the harbinger of change, as days shorten and nights lengthen and warm seasons become cool. Now is the time for harvest, reaping the rewards of the seeds you planted earlier, for deciding what is important enough to you to protect for the coming winter, and cutting away the things that won’t weather. Let us honor this day by choosing a recent victory or achievement to celebrate and finding one thing to donate, throw away, stop doing or otherwise choose to let fall away. It takes a lot of compost to grow a beautiful garden.