Autumnal Equinox 2024 is on Sunday, September 22, 2024: WHAT is the AUTUMNAL equinox?

Sunday, September 22, 2024 is Autumnal Equinox 2024. An equinox occurs twice a year, around 20 March and 22 September. The word itself has several related definitions.

at the March equinox and

An equinox occurs twice a year, around 20 March and 22 September. The word itself has several related definitions.

The Autumnal Equinox signals

is a public holiday in Japan that usually occurs on September 22 or 23, the date of Southward equinox in Japan Standard Time (autumnal equinox can occur on different dates for different timezones).

WHAT is the AUTUMNAL equinox?

The autumnal equinox is when the Sun crosses the celestial equator on it's way to the other hemisphere from your own hemisphere.

Spring equinox is when the Sun is crossing the celestial equator on it's way to your own hemisphere from the other hemisphere.

The celestial equator is an imaginary projection of the Earth's equator onto the sky.

The Sun's path around the sky is called the ecliptic, so the equinoxes are where the ecliptic crosses the celestial equator.

Here is a very good site for finding out about all the different lines and points and times that get defined concerning the celestial sphere.

Scroll down to 'Sun and Seasons'.

For the northern hemisphere the autumnal equinox it's when the Sun is crossing the celestial equator when it's moving south day by day and for the southern hemisphere it's when the Sun crosses the celestial equator when it's moving north.

Spring Equinox..the start of spring, in 2010 is at 1732 hrs GMT on March 20th.

Autumn Equinox...the start of autumn, in 2010 is at 0309hrs GMT on September 23rd.

Real seasons for the northern hemisphere... astronomical dates.

NOTE...the Spring equinox, also called the Vernal equinox, is currently occurring on the 20th March and the Autumn Equinox is currently occurring on the 23rd September, not on the 'traditional' days of 21st-22nd.

The figures are not symmetrical, due to the shape of the Earth's orbit. Likewise, the longest day, the earliest sunrise, and the latest sunset all occur on different days, not on the same day as many people expect.

This year (2010) the Sun crosses the Celestial Equator at 1732 GMT on March 20th, so that is when winter ends and spring starts.

1. Winter....December 22 -March 20..

The sun moves from the southern solstice to the celestial equator

2. Spring..March 20- June 22

The sun moves from the celestial equator to the northern solstice

3. Summer....June-22 - September 23

The sun moves from the northern solstice to the celestial equator

4. Autumn...September 23 - December 22

The sun moves from the celestial equator to the southern soltice

In some years the actual date of any of those events may fall one or two days away from the those given due to a number of astronomical factors.

Scroll down to the table of the dates of the Equinoxes for each year...that's the start of spring and autumn.

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The March Equinox explained. UTC is numerically the same as GMT.

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Those are the astronomical dates. Below is the social and business stuff.

Actual usage may vary, socially and in business, educational establishments, and government department calenders.

For example,November is reckoned by many people to be a 'winter' month because it normally has has 'winter' weather, though 'officially' November is an Autumn month.

March is commonly spoken of as a spring month although most of it falls in the astronomical period of winter, and June as a summer month though most of it falls in the astronomical period of spring.

Mid-summer's Day is June 22nd but is actually the first day of summer astronomically, not the middle.

Likewise, Mid-winter's day is December 22nd, actually the first day of winter astronomically.

Those dates are the times of the sun's highest and lowest declination, and therefore have a good reason for being named as they are, which they have been in Europe for well over a thousand years.

Various organisations have their own usage for the dates of each season. For example a winter bus timetable may start on November 1st for one company and October 1st for another, and schools and colleges may differ by a few days in the start and close of the term times. Spring term may start on January 7th in one college and January 9th or 10th in another, for example, although state-run schools generally share the same start and close times for each term throughout the year.

Below is a section from my answer to a similar Q.

Spring starts when the sun crosses the celestial equator on it's way your own hemisphere. Autumn starts when it crosses again into the opposing hemisphere. So, as the Sun heads north , the first day of spring in the northern hemisphere is also the first day of autumn in the southern hemisphere.That's March 20th currently.

As the Sun heads south again,it crosses the celestial equator on September 23rd, currently, which is the first day of spring south of the equator,and of autumn north of the equator.

Enjoy the lunch break.......

What is the autumnal equinox?

What is the autumnal equinox?

The Autumnal Equinox is the point on the celestial sphere at witch the Sun crosses the celestial equator while moving south (happens around September 22). This is not to be confused with the Vernal Equinox which is the point at which the Sun crosses the celestial equator while moving south (occurs around March 21). The Equinoxes are the days of the year that we experience equal amounts of day and night.

The Equinoxes are different from the Solstices in that the Winter Solstice is the point on the celestial sphere at which the Sun reaches its southernmost position on the horizon (Thereby making this the point at which the Sun will begin to get higher and higher in the sky during the day, bringing the Summer;this occurs around December 21) and The Summer Solstice is the point on the celestial sphere at which the Sun reaches its northernmost position on the horizon (Thereby making this the marking of the point at which the Sun will begin to be lower and lower in the sky during the day, bringing the Winter; This occurs around June 21). The Solstices are the times at which the Sun stops moving either north or south (depending on which solstice is occurring) and reverses its movement as it rises everyday, creating the seasons we experience on Earth.

What is autumnal equinox?

What is autumnal equinox?

Autumnal - means autumn, or the fall (September).

Equinox - means days and nights of equal length.

An equinox is that moment in time when the centre of the Sun can be observed to be directly above the Earth's equator.

The autumnal equinox is September 23 (vernal equinox is March 20).

Holidays also on this date Sunday, September 22, 2024...