The September Equinox.
The September Equinox or Southward Equinox is the moment when the Sun appears to cross the celestial equator, heading southward. Due to differences between the calendar year and the tropical year, the September Equinox can occur at any time from the 21st to the 24th day of September. At the equator, the Sun rises directly in the east and sets directly in the west. Before the Southward Equinox, the Sun rises and sets more to the north, and afterwards, it rises and sets more to the south. The equinox may be taken to mark the end of summer and the beginning of autumn (autumnal equinox) in the Northern Hemisphere, while marking the end of winter and the start of spring (vernal equinox) in the Southern Hemisphere.
The traditional harvest festival in the United Kingdom was celebrated on the Sunday of the full moon closest to the September equinox. The Southward equinox was “New Year’s Day” in the French Republican Calendar, which was in use from 1793 to 1805. The French First Republic was proclaimed and the French monarchy was abolished on September 21, 1792, making the following day (the equinox day that year) the first day of the “Republican Era” in France. The start of every year was to be determined by astronomical calculations following the real Sun and not the mean Sun.
The Mid-Autumn Festival is celebrated on the 15th day of the 8th lunar month, often near the autumnal equinox day, and is an official holiday in mainland China, Hong Kong, Taiwan and in many countries with a significant Chinese minority. As the lunar calendar is not synchronous with the Gregorian calendar, this date could be anywhere from mid-September to early October. In Korea, Chuseok is a major harvest festival and a three-day holiday celebrated around the Autumn Equinox. The traditional East Asian calendars divide a year into 24 solar terms, and the autumnal equinox marks the middle of the autumn season. In Japan Autumnal Equinox Day is a public holiday.
The Southward equinox marks the first day of Mehr or Libra in the Iranian calendar. It is one of the Iranian festivals called Jashne Mihragan, or the festival of sharing or love in Zoroastrianism. Credit: Wikipedia.