What is the September Equinox?
The September equinox marks the beginning of autumn in the Northern HemisphereThe September equinox, also called southward equinox, is the moment in time (not a day-long event) when the Sun stands directly above the equator while crossing from the north to the south. For the Northern Hemisphere (where nearly 90% of the world's population live) it is the autumnal equinox (fall equinox) as it is the moment when summer ends and autumn (fall) begins, while for the Southern Hemisphere it is the vernal equinox (spring equinox), the moment when winter ends and spring begins. Up until the September equinox the Sun rises and sets more to the north of the equator, and afterwards it rises and sets more to the south. The September equinox usually occurs every year on September 21 to 23. Very occasionally it can also fall on September 21 or 24. The dates given on this page are based on Coordinated Universal Time (UTC), which for practical purposes is equivalent to Greenwich Mean Time (GMT). While the September equinox occurs at the same moment in time all over the world, the date and local time differ from place to place depending on the year and a location's time zone. For locations that are ahead of UTC (further east) it may fall on the day after, and for locations that are behind UTC (further west) it may fall on the day before. To find out the exact date and time of the September equinox 2018 in your area use this seasons calculator. The September equinox is one of four days (two equinoxes and two solstices) throughout the year that mark the beginning of a new season. The other days are the March equinox, the June solstice and the December solstice. The word "equinox" is derived from Latin and means "equal night". On the day of an equinox, day and night are of approximately equal length all over the world, as the Earth's rotational axis is neither tilted away from nor towards the Sun. At all other times the length of day and night will be different.