Going through some Facebook memories this morning, a friend (and now Patreon supporter) asked a few years ago: “Could you lay down some vernal equinox parameters for us? My ephemeris says March 21. My sweetie is a Pisces. So are a couple of our friends. Help?!” (edited slightly)
What she meant here was the all of the friends that she mentioned have birthdays on March 21. But they all have the Sun in Pisces. So if the vernal equinox — the day the Sun enters Aries — is March 21, then how could they be Sun-sign Pisces?
Crazy old books
My friend mentioned her ephemeris, which is a book that lists where all the planets are at midnight (or midday, pick your version) Universal Time (which most people still know as Greenwich Mean Time). The word “ephemeris” comes from Greek, and was originally a medical term that meant “daily.” The Greek word for “day” is hemera and the “epi” means “on, upon.” So originally, the term referred to a fever or other medical condition that lasted only a day. Today we use the word “ephemeral” to mean something like “not long-lasting” or “changing.”
Indulgent Language Geek AsideThe plural of “ephemeris” is “ephemerides” (pronounced eff – eh- MERR – i – deez). This is similar to the “proper” plural of “octopus,” which is “octopodes” (ok – tip – oh – deez). The mistaken plural “octopi” comes from the incorrect assumption that the -us on the end is from the Latin masculine ending, where the plural would (likely) be -i. But the “us” is not at all part of the ending, it’s part of the root. The ancient Greek word pous means “foot,” and we see it in words like podium and pedestal (the places where you stand, you know, with your feet).
That said, the actual “proper” way to make plurals in English from words that have been borrowed from other languages is to use standard English pluralization, or the original plural form. So either “octopodes” or “octopuses” is perfectly fine. Just not “octopi” (unless you really do mean 8 x 3.1415926535…).
Another one of the crazy old books that astrologers used to use was a table of houses. But today, most of us just flip on the computer and fire up the ol’ software, or go to sites like Astrolabe or Astro.com to generate a free chart.
So back to the vernal (spring) equinox (in the Northern Hemisphere, at least). The equinox is when the celestial equator and the path of the Sun intersect. The celestial equator is simply the Earth’s equator extended into space.
When the Sun aligns with the equator, western astrology calls this moment the beginning of Aries, which is considered to be the first sign of the zodiac. (Though one can question whether a circle has a beginning or end.) But the moment that this happens each year shifts slightly. Calendars tend to list it generally on the 20th or 21st of March. But it moves forward about 6 hours each year, until leap year happens and it resets to earlier.
Leap year weirdness
You’re probably familiar with why we have an extra day in the calendar every four years. It’s because the calendar can’t account for the approximate 1/4 day extra that it takes for the Sun to reach the same point in the sky each year. Stellar events like this don’t repeat themselves in whole numbers, like our calendars do.
But leap year isn’t quite that simple. In order to keep the calendar aligned with the solar journey, we need a few more tweaks. Every time a year ends in double zero, we don’t have a leap year. Unless that year is divisible by 400. So we didn’t have a leap year in 1700, 1800, 1900, even though they were those “fourth years” that should have been leap years. But we did have a leap year in 2000, because that’s divisible by 400 (the other century years mentioned are not).
Obvious side note: Anyone reading this won’t have to worry about it in the coming future.
Forbes has a good, if at times technical, article on this, and why leap year 2020 is the earliest since 1896.
Determining the equinox
Aside from the issues mentioned above, we have to consider where we are on the planet at the moment of the equinox. Here in the Eastern Daylight Time Zone, the 2020 Spring Equinox was about 10.5 minutes before midnight, daylight time, on March 19. But the UK was four hours ahead of us, so it was already the 20th there. What’s a calendar maker to do?
So while horoscopes and other calendars will usually list the equinox as March 20 or 21st, it’s not always that simple. However, if you were born in a given year when the Sun was still in Pisces on the 20th or even the 21st, then rest assured that it doesn’t change for you.
If you insist on calling yourself “a Pisces” (another mistaken assumption dealt with elsewhere on the blog), there’s nothing that should stop you from doing so now. Except some more sophisticated astrological education 🙂 .