What is spring equilux and when is it? Difference to equinox

Signs of spring are appearing all around us, from juicy green leaves sprouting on tree branches to the sun rising earlier each day.

But ahead of the spring equinox taking place in a few days, what is the spring equilux which is happening today (March 17)? Let’s find out what the difference is between them.

What is the spring equilux?

Today is the Spring #Equilux 🌷 which means the length of day and night are equal

Days will now be longer than nights until the Autumn Equilux

Here are some of the sunrise/sunset times across the UK today 👇 pic.twitter.com/ehSF446JX4

— Met Office (@metoffice) March 17, 2024

The equilux is when day and night are equal and occurs a few days before the spring equinox, and a few days after the autumn equinox.

The Met Office explains: “On the equinox, the length of day and night are only nearly equal. This is because the Sun appears as a disk in the sky, and the top half rises above the horizon before the centre.

“As well as this sunlight is refracted by the Earth's atmosphere. The Sun, therefore, appears to rise before its centre at the horizon, giving more daylight than you might expect (12 hours 10 minutes on the equinox).”

What is the difference between the spring equinox and equilux?

📸 Thank you for sharing some great weather pictures today

Here are some of our favourites from @JanetteHall in Preston, @Over50Bloke in Eastbourne, @liam_lovell in Brampton, and @Jacksweatherch1 in Atterton 👇 pic.twitter.com/w0Xyk69w89

— Met Office (@metoffice) March 16, 2024

The equilux can often be confused with the spring equinox but what is the difference?

The spring equinox marks the beginning of spring and from this day forward the day is longer than the night, reports the Met Office.

This is compared to the equilux which is when day and night are equal.

“Similarly, the autumn equinox marks the start of autumn as the night becomes longer than the day.”

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The weather experts add: “The Equinox in the Northern Hemisphere occurs twice a year around 20 March (the spring equinox) and around 22 September (the autumn equinox).

“They occur between the summer and winter solstices marking the point the Sun crosses the equator's path and becomes positioned exactly above the equator between the Northern and Southern Hemisphere.

“During the equinox, day and night will be around the same length which is evident in the word's origin derived from the Latin equi (meaning 'equal') and nox (meaning 'night').”

When is the spring equinox 2024?

This year, the spring equinox will take place in the UK on Wednesday, March 20.