Get Ready for the Equi…lux!
The September equinox is upon us. But did you know that day and night are equal on a different date? Find out why and when.
Equinox Is Next Week
Day and Night Won’t Be Equal
It’s often said that day and night are equal at the two equinoxes (there’s another one in March). After all, the term equinox translates from Latin as ‘equal night.’
The moment when day and night are actually equal falls on a different date. That date is called the equilux.
“The difference in day length between the equinox and equilux is only a matter of minutes—it’s not something we tend to notice,” says Graham Jones, timeanddate’s resident astrophysicist.
“Having said that, the difference is real, and it’s fascinating to see it show up in our sunrise and sunset data.”
Equilux Is Today (But Not Everywhere)
So, when is the equilux? Well, the date depends on where you live.
In the Southern Hemisphere, the equilux happens a few days before the September equinox; for Northern Hemisphere dwellers, it is a few days after the equinox.
Find Your Equilux Date
- Go to our Sun Calculator and search your city.
- Scroll down to the table and find the date when the duration shown in the ‘Length’ column is closest to 12:00:00.
Example: The Equilux in Los Angeles
Day lengths in Los Angeles:
- September 24: 12:04:05 (4 minutes and 5 seconds longer than 12 hours)
- September 25: 12:01:59 (1 minute and 59 seconds longer than 12 hours)
- September 26: 11:59:53 (only 7 seconds shorter than 12 hours)
- September 27: 11:57:47 (1 minute and 59 seconds shorter than 12 hours)
On September 26, the day length is closest to 12 hours. This means that the equilux in Los Angeles happens on that day.