Autumnal Equinox 2017

When is the Autumnal Equinox 2017?

What is the Autumnal Equinox?

In the Northern Hemisphere, the moment in time when the Sun stands directly above the equator while crossing from the north to the south is called autumnal equinox (also known as fall equinox, September equinox or southward equinox). It is the moment summer ends and autumn (fall) begins in the Northern Hemisphere (where nearly 90% of the world's population live). For the Southern Hemisphere, it is the vernal equinox (also called spring equinox) as it is the moment winter ends and spring begins.

In the Northern Hemisphere the autumnal equinox occurs every year on September 22 or 23. 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 autumnal 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 autumnal equinox 2017 in your area use this seasons calculator.

The autumnal 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 vernal equinox (beginning of spring), the summer solstice (beginning of summer) and the winter solstice (beginning of winter).

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.


The exact moment of the autumnal equinox through the centuries

Graph demonstrating the movement (caused by leap shifting) of the exact moment of the autumnal equinox between 1900 and 2520. X axis (bottom, horizontal): Calendar years, Y axis (left, vertical): day in September (21st to 24th).

In a non-leap year, the moment of the autumnal equinox is about 5 hours 49 minutes after that moment in the previous year (in UTC), and in a leap year it is about 18 hours 11 minutes before that moment in the previous year, as can be seen in this graph. In this way the time of the autumnal equinox constantly shifts back and forth so it always stays around September 22 or 23. This four year cycle is clearly visible in the graph.

To adjust for the gradual movement backwards on the calendar (as visible for the period 1900 to 2099), in years divisible by 100 (1900, 2100, 2200, 2300 and 2500 on the graph), which should be leap years as they are divisible by 4, the leap day is omitted (except when they are divisible by 400, eg. 2000 and 2400) and the moment of the autumnal equinox moves forward in time compared to the same moment in the year before.


For more information see September equinox on Wikipedia.

When is the Autumnal Equinox 2018?

Dates for the Autumnal Equinox from 2010 to 2025

The next occurrence of the Autumnal Equinox is marked in red.

When is ...?	Date	Day of the week	Days away
Autumnal Equinox 2010	September 23, 2010	Thursday	2436 days ago
Autumnal Equinox 2011	September 23, 2011	Friday	2071 days ago
Autumnal Equinox 2012	September 22, 2012	Saturday	1706 days ago
Autumnal Equinox 2013	September 22, 2013	Sunday	1341 days ago
Autumnal Equinox 2014	September 23, 2014	Tuesday	975 days ago
Autumnal Equinox 2015	September 23, 2015	Wednesday	610 days ago
Autumnal Equinox 2016	September 22, 2016	Thursday	245 days ago
Autumnal Equinox 2017	September 22, 2017	Friday	in 120 days
Autumnal Equinox 2018	September 23, 2018	Sunday	in 486 days
Autumnal Equinox 2019	September 23, 2019	Monday	in 851 days
Autumnal Equinox 2020	September 22, 2020	Tuesday	in 1216 days
Autumnal Equinox 2021	September 22, 2021	Wednesday	in 1581 days
Autumnal Equinox 2022	September 23, 2022	Friday	in 1947 days
Autumnal Equinox 2023	September 23, 2023	Saturday	in 2312 days
Autumnal Equinox 2024	September 22, 2024	Sunday	in 2677 days
Autumnal Equinox 2025	September 22, 2025	Monday	in 3042 days
Data provided 'as is' without warranty

Dates of the Autumnal Equinox 2017 and surrounding years as downloadable image file

Christian (and related) Advent Advent Sunday All Saints' Day All Souls' Day Ascension Day Ash Wednesday Black Saturday Boxing Day Bright Saturday Bright Week Candlemas Christmas Christmas Day Christmas Eve Christmastide Corpus Christi Easter Easter Day Easter Eve Easter Friday Easter Monday Easter Saturday Easter Sunday Eastertide Easter Week Easter Weekend Epiphany Epiphany Eve Fat Tuesday First day of Lent Good Friday Holy Friday Holy Saturday Holy Thursday Holy Week Jesus' Birthday Lazarus Saturday Lent Mardi Gras Maundy Thursday Orthodox Easter Palm Sunday Pancake Day Pascha Pentecost Pentecost Sunday Pentecost Monday Shrove Monday Shrove Tuesday St. Andrew's Day St. David's Day St. George's Day St. Patrick's Day St. Stephen's Day Theophany Three Kings Day Trinity Sunday Twelve Days of Christmas Twelfth Night Whit Sunday Whit Monday

US federal holidays New Year's Day Martin Luther King Day Presidents' Day     (Washington's Birthday) Memorial Day Independence Day Labor Day Columbus Day Veterans Day Thanksgiving Day Christmas Day Australian holidays ANZAC Day The seasons Spring Vernal equinox (spring equinox, March Equinox) Summer Summer solstice (June solstice) Autumn / Fall Autumnal equinox (fall equinox, September equinox) Winter Winter solstice (December solstice)

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