Saturday, March 20, is the spring equinox – officially at 4:45 p.m. CST.
On the equinox, night and day are nearly exactly the same length – 12 hours – all over the world. This is the reason it’s called an “equinox,” derived from Latin, meaning “equal night.”
In the northern hemisphere, the March equinox occurs when the sun crosses the equator line, heading north in the sky. This event marks the start of spring in the northern half of the globe. After this date, the northern hemisphere begins to be tilted more toward the sun, resulting in increasing daylight hours and warming temperatures. (In the southern hemisphere, it’s the opposite: the March equinox marks the start of autumn, as the southern hemisphere begins to be tilted away from the sun.)