VERNAL EQUINOX

Vernal equinox, the lovely little Latinate term that means “equal night of spring,” is used to indicate the March-based equinox even in the southern hemisphere, where the event is really the start of autumn. “It’s a very Northern-centric view of things,” said Dr. William Blair, an astronomer at Johns Hopkins University. “Then again, most of Earth’s land mass is in the Northern Hemisphere, so what are you going to do?”

For many cultures throughout history, people got ready to start tilling the fields. Ancient peoples may not have understood orbital mechanics, but they were tireless observers of the Sun, stars and planets and noted with enviable precision how the position of the sunrise shifted on the horizon throughout the year. By tracking solar motions, they kept track of time and could estimate with some security when the last frost had passed and it was safe to plant crops.