First Day of Fall – Significance of Autumnal Equinox

Today, September 22, is the first day of fall. Often called the Autumnal Equinox, today is special for many reasons, but not because of the length of day as many people believe.

Day and night will be approximately the same length but in reality, the day is still longer. Why you ask? From the Earth, the Sun appears as a disc rather than a single point of light, so when the center of the Sun is below the horizon, its upper edge is still visible. In addition, the Earth’s atmosphere refracts light, so even when the Sun is actually below the horizon, its rays are still visible.

The Autumnal Equinox is still a special event, marking the first day of Fall. It is one of two days  a year (the other being the Spring Equinox)when the sun rises due east and sets due west. It is also the only time other than Spring when the sun will pass a person standing on the Equator directly overhead.

Another interesting fact: If you were standing on the North Pole or South Pole the sun would skim the horizon and signify 6 months of darkness or daylight respectively.

Many facts about the equninox are skewed, as exemplified by the misconception about day and night being equal. Have you heard the claim that only on an equinox day one can balance an egg on its point? It’s not true. De-fact-o.com explains that “one can balance an egg on its point any day of the year if one has the patience.”

Being the first day of fall, mother nature did not skip a beat. In San Diego weather is cooler than normal, giving us a taste of what’s likely to come this season. After a seasonably cool summer, many are wondering if it will ever warm up. The answer is yes. This weekend will bring warmer temperatures so don’t break your your Ugg boots and scarves just yet. The weekend promises to bring sunshine to the coast and inland so you can get your last fix before it’s too late.

Photo from blueshade via Wikimedia