Equinox – The term equinox means “equal night,” when day and night are supposedly an equal length of 12 hours each.
- 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.
Equilux – 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. This means that the time when day and night are actually equal happens before the equinox.