So long summer!

The season officially ends at 10:49 a.m. Saturday. That's the moment when the Autumnal Equinox occurs in the Eastern United States.

The Old Farmer's Almanac explains what's happening:

On the first day of fall—the autumnal equinox—day and night are each about 12 hours long (with the actual time of equal day and night, in the Northern Hemisphere, occurring a few days after the autumnal equinox). The Sun crosses the celestial equator going southward; it rises exactly due east and sets exactly due west.

Here are two ideas to help you mark the day:

• Become a locavore by dinner: Buy Local Greater Lehigh Valley is a great resource for celebrating the fall harvest with your wallet.

• Argue with a friend that Golden Delicious is the superior apple for pie: Find a great orchard right near you with this u-pick guide for Eastern PA. Your favorite not listed here? Tell us in comments. 

Do you know of other events to mark the start of fall? Hosting one yourself? Add them in the comments section below.