Inspriration | Equilux

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25/09/2026 - Astronomical autumn has officially started after the equinox took place in the early hours of Wednesday. It is the precise moment in time when the Sun crosses the celestial equator and neither hemisphere is tilted towards or away from the Sun, meaning day and night are roughly equal in length across the world. At the equinox, the daylight measurement is taken from the point when the centre of the Sun is at the horizon, and is 12 hours sunrise to sunset and 12 hours sunset to sunrise.

However, it is the top edge of the Sun which is visible first at sunrise and last at sunset.

Because of light refraction - light being bent by the atmosphere - there is still light for a time when the Sun is not directly visible. This adds extra time to daylight hours.


In autumn, this means that the time when day and night are actually equal happens after the equinox.


This is known as the "equilux", which means equal light.