What is Autumn Equinox and why does it happen?

The Autumn Equinox means summer is now officially over

Sabrina Barr
Saturday 23 September 2023 09:33 EDT
Comments
Related: Modern pagans celebrate autumn equinox at Stonehenge

Your support helps us to tell the story

From reproductive rights to climate change to Big Tech, The Independent is on the ground when the story is developing. Whether it's investigating the financials of Elon Musk's pro-Trump PAC or producing our latest documentary, 'The A Word', which shines a light on the American women fighting for reproductive rights, we know how important it is to parse out the facts from the messaging.

At such a critical moment in US history, we need reporters on the ground. Your donation allows us to keep sending journalists to speak to both sides of the story.

The Independent is trusted by Americans across the entire political spectrum. And unlike many other quality news outlets, we choose not to lock Americans out of our reporting and analysis with paywalls. We believe quality journalism should be available to everyone, paid for by those who can afford it.

Your support makes all the difference.

After a suprise September heatwave in the UK, when temperatures rose as high as 33.5C, autumn has now officially set in.

The change in seasons is the result of the autumn equinox, which arrives this year on Saturday 23 September.

What is the autumn equinox and why does it happen?

The autumn equinox always takes place in September, either falling on the 22nd or 23rd day of the month.

An equinox occurs twice in the year when the sun "sits right above Earth’s Equator", National Geographic states.

The Royal Observatory in Greenwich, London, explains that the Earth, which tilts on its axis, orbits the sun.

“As it orbits the sun, the sun illuminates the northern or southern hemisphere more depending on where the Earth is along its orbit,” the museum states.

“However, at two points in the year the sun will illuminate the northern and southern hemispheres equally. These are known as the equinoxes.”

This also means that, in the northern hemisphere when autumn officially begins, spring is commencing in the southern hemisphere at the same time.

Encyclopædia Britannica adds that the autumn equinox in the northern hemisphere marks just one of two times of the year when “the sun is exactly above the Equator and day and night are of equal length”.

The autumn season lasts until winter, which begins this year in the northern hemipshere on 21 December.

When is the spring equinox?

The spring equinox in the northern hemisphere is the second of the two times of the year when day and night are of equal length.

The 2024 spring equinox, marking the official start of spring, will take place on Monday 20 March.

Join our commenting forum

Join thought-provoking conversations, follow other Independent readers and see their replies

Comments

Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged inPlease refresh your browser to be logged in