RALEIGH, N.C. (WNCN) — The Sun rose Tuesday on the last day of 2023 where we’ll see more daylight than nighttime in the Triangle.
The fall equinox arrived early Saturday morning, meaning Earth’s axis was completely vertical, with sunlight directly hitting the equator. But, contrary to what the word may initially imply, the fall equinox is not the day with an equal 12 hours of daylight and nighttime.
That day is the equilux, which happens today; three days after the equinox. Equilux means “equal light” in Latin. There are a few different reasons why the two words are different, mainly centered around one scientific phenomenon.
That phenomenon is light refraction. Earth’s atmosphere refracts sunlight about half a degree upward, meaning we see the sunrise before the Sun is actually above the horizon. Sunset sees the same phenomena; we still see the Sun after it has physically set.
Latitude also impacts when the equilux occurs. The lower the latitude (closer to the Equator that you go), the later the equilux.
The final reason is the shape of the Sun. When talking about when sunrise or sunset exactly occurs, we refer to the moment the center of the Sun crosses over the horizon. There’s obviously still half of the sun to still see!
We saw 12 hours and 19 seconds of daylight Tuesday and that number keeps dwindling until the winter solstice on December 21st when we’ll see just under nine hours and 44 minutes.