Spider webs decorated with dew, Autumnal equinox is here already

Spider Webs, Decorated With Countless Tiny Dew Droplets, are a beautiful sight on foggy autumn mornings. Look for them in San Diego’s wild canyons and park areas, or in your own back yard.

The Recent Weather Has Given Us A Glimpse Of Fall, but the season officially begins at 11:50 pm local time this Saturday, September 23 — a great reason to throw a celebratory Saturday night party. The event is also known as the autumnal equinox. Technically, this means that at that exact moment, the sun will be shining directly down somewhere on the Earth’s equator. The autumn season will continue for three months until the sun “moves” to its farthest southerly point on the winter solstice, December 21.

Twice a year the sunset lines up perfectly with the water channel at the Salk Institute in La Jolla: on the Fall Equinox and the Summer Equinox.

Equal Days and Nights Everywhere On Earth, 12 hours each, is only one of the noticeable consequences during the time of equinox, either autumnal or vernal (spring). Another is that the sun at equinox always rises from a point on the horizon due east and later sets due west. You could calibrate a compass this way if you had access to a true (unobstructed) horizon. A more subtle consequence is that at mid-latitudes like ours, morning and evening twilight periods are shortest during equinox. In San Diego, the duration of twilight this week is about 80 minutes; last June, it was about 100 minutes.