Long ago, our ancestors relied on the skies above them and shadows on the land to mark the passage of time, using elements of nature as both their clock and calendar.
Even now, as the golden Sierra light deepens in the late afternoon, we are able to watch the location of sunset and sunrise, and note the length of day and night.
Tonight is the autumnal equinox, the astronomical start of the fall season.
Twice a year we have an equinox, in spring and fall, when the Northern and Southern hemispheres of Earth receive the sun’s rays equally, with the sun at a Zenith over the Earth’s equator.
We can see the sun rising later, and sunsets are starting to come a little earlier. We hope for cooler weather, put away the flip-flops and pull out the boots, or at least start thinking about it. The equinox comes at the same moment worldwide, although the clock times vary by time zone.
In the United States this equinox comes on September 22 at 7:29 p.m. PDT.
Note: if you’re already looking forward to that one glorious day of the year when we get an extra hour as we “fall back,” that’s not until Sunday, Nov. 2, when clocks are turned back one hour.
Hang in there, it’s coming!
Everything you need to know about the Equinox from Earth Sky
