First day of spring 2023: What to know about the vernal equinox - mlive.com

First day of spring 2023: What to know about the vernal equinox - mlive.com

"...It’s actually the astronomical beginning of a new season, occurring at the moment when the Earth’s axis is tilted neither toward nor away from the sun, resulting in a nearly equal amount of daylight and darkness at all latitudes...

All four seasons on our calendars begin with astronomical events: 

• The two equinoxes mark the start of spring and fall, and 
• the solstices, which occur in June and December, are the official beginning of summer and winter.

(Unless, of course, you’re marking the seasons by the meteorological method, in which case spring began on March 1. More on that here.)
Interestingly, the Vernal Equinox fell on March 21 during most of the 20th century, but due to the 400-year Gregorian calendar cycle, the event occurs a tiny bit earlier every year...