On Sunday at 4:30 PM, Councilmember Tom LaBonge will lead the annual Fall Equinox Hike in Griffith Park. Meet at the top of Fern Dell (Western Avenue Entrance) off Los Feliz Blvd. Cars will park in lot 9. Hikers are encourage to bring food and drinks for a pot luck dinner at the summit. Vans will be provided to transport items and persons who need assistance.

The day is marked by different religions worldwide. According to Mike Nichols on the site Global Oneness:

In many mythologies, this is the day the Sun God, the God of Light, is killed by his rival and dark twin, the God of Darkness — who was born at Midsummer, reached puberty at Lammas, and lives a mirror-image life of the Sun God.

From this mid-Autumn day forward, darkness will be greater than light, just as night becomes longer than day. So it is a festival of sacrifice, including that of the Sun God in his aspect of Spirit of the Fields, John Barleycorn — for this is the final grain harvest.

The Christian religion adopted it as ‘Michaelmas’, celebrated on the alternative date September 25, the old equinox date (Old Harvest Home). (The Welsh word ‘Mabon’, meaning ‘son’, is used by some Witches for the name of this holiday, although such usage is recent and not attested historically.)

As far as what actually occurs celestially, according to Wikipedia,

The actual equinox is a single moment in time — it does not take the whole day. Because the Sun is a sphere and not a point source of light, the actual crossing of the Sun over the equator takes approximately 2 and 1/2 days. The equinox occurs halfway through the transit when the center of the Sun is directly over the equator.

Thumbnails from Wikipedia