Vernal Equinox Oddities

Fun Facts about the March Equinox

Mar 21, 2018
March Equinox Fun Facts
Josephine Wall


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This year, the vernal equinox falls on Tuesday, March 20. Are day and night equal today? Does the Sun rise exactly east and set exactly west? Learn about the March equinox from Bob Berman, Almanac astronomer.

Why Does the Spring Equinox Fall on Different Dates?

If you thought that the Spring Equinox was only on March 21, you may be dating yourself.

Spring arrived on the 21st of March during most of the 20th century, but the event slides earlier and earlier during the 400-year Gregorian calendar cycle. The final March 21 equinox was in 2007, even if we use Greenwich Time as many almanacs do.

Now the 21st is gone for the rest of our lives, unless you believe in reincarnation and want to check back in during the 22nd century. In a few more decades, the vernal equinox will sometimes start landing on the 19th.

See our March Equinox: First Day of Spring page!

Sun Grows More Intense

In the Northern Hemisphere, plants and animals start feeling the Sun’s energy, though its intensity depends on our latitude. 

The equinoctial Sun always misses your zenith (or straight overhead point) by the same number of degrees as your latitude. In Bennington, Vermont, latitude 43°, the midday Sun stands 43° from precisely overhead on the day of the equinox. Essentially, it’s halfway up the sky. It’s a gratifying change from just a month ago, and a dramatic shift since December, when the midday Sun only climbed an anemic one-fifth of the way up the sky. Since solar rays are stronger the higher up it is, you can now palpably FEEL the Sun’s growing intensity.

And it’s not finished: Watch the sky at 1:00 PM each day, and you’ll see that the Sun manages to climb four of its own diameters higher each week. This rapidly ratchets up its intensity. This is the year’s greatest solar-energy boost for those who live north of the equator.

Vernal Equinox Fun Facts 

  • Are day and night equal at the equinox? The equinox is famously the time of balance, with theoretically 12 hours of sunshine and 12 hours of non-Sun. In practice, the atmosphere bends the Sun upward so that the real date of sunlight equality is three or four days ahead of the equinox. 
  • Does the Sun really rise due east and set due west? Yes, it really does. The equinox is also when every place on earth rotates perpendicularly into our planet’s “terminator”—its day-night shadow line. As a result, on the day of the equinox, the sun will rise precisely due east and set exactly in the west, and this is true everywhere. It’s the best time to observe the cardinal compass directions. (Well, not quite everywhere. From both poles, you’d see the equinoctial Sun hovering fully above the horizon, never setting, but moving horizontally. At the north pole, the Sun moves rightward, and it chugs along leftward for the folks at the South Pole research station, rolling atop the horizon like a red rubber ball.)
  • How does sunlight change? This is the week when sunlight changes at its maximum annual rate! There are three extra minutes of daily Sun from typical US cities, but nearly seven daily minutes for the folks in Fairbanks, Alaska. That may be the equinox’s greatest gift, and worthy of an early morning Sun Salutation. Check it! See your day length times on the Almanac sunrise/set calculator.

Here’s MORE equinox facts and folklore.

Wherever you are, take a few minutes to enjoy this year’s vernal equinox—and all the good things that come with it. 

Image Credit: Josephine Wall. Enjoy more art on her Web site.

About This Blog

Welcome to “This Week’s Amazing Sky,” the Almanac’s blog on stargazing and astronomy. Bob Berman, longtime and famous astronomer for The Old Farmer’s Almanac, will help bring alive the wonders of our universe. From the beautiful stars and planets to magical auroras and eclipses, he covers everything under the Sun (and Moon)! Bob, the world’s mostly widely read astronomer, also has a new weekly podcast, Astounding Universe

Reader Comments

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painting by Josphine Wall

The picture is lovely. As a fan of Gaia, was wondering if it is possible to obtain a print?

spring image

Hi Sandra, See Josephine Wall’s beautiful work on her Web site here:


I also love that beautiful painting. It could be the cover of a Moody Blues album.

I was thinking that same thing.

One of the best concerts I ever attended.

Great column......

Also would like to know title of painting at top.

spring equinox

The painting by Wall is titled, “Breath of Gaia.” Gaia, a Greek goddess, personified Mother Earth and brought renewal to the land.


The equal day/ night actually was Saturday, March 17th, wasn't it? Is this due to a slowing of the rotation? Is it an unusual occasion or is this a normal occurance?

Stunning Painting to Illustrate the Article


Very much enjoyed your column on the vernal equinox. I would love to know the title of the painting by Josephine Wall that introduces it. Thanks!

Really enjoyed this. Thanks!

Really enjoyed this. Thanks!

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