September 21 is the 265th day of the year in the Gregorian calendar, marking the approximate beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere. It matters because it's often associated with the autumnal and vernal equinoxes, when day and night are nearly equal length across the globe.
AI-generated from the Wikipedia summary — may contain errors.
September 21 is the 264th day of the year (265th in leap years) in the Gregorian calendar; 101 days remain until the end of the year.
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Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).