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Mar 13, 2018

Image:Vernal Equinox -

Tuesday the 20th brings the spring equinox according to the Old Farmer's Almanac. If this date next week surprises you because you associate vernal equinoxes as occurring on the 21st, you’re dating yourself.

Spring arrived on the 21st during most of the 20th century. They slide 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 keeps, unless you believe in reincarnation and want to check back in the 22nd century. In a few more decades, the vernal equinox will sometimes start landing on the 19th.

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, Monday’s midday sun stands 43 from precisely overhead. 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 palpable 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.

Spring Equinox Fun Facts

Equal day/night: 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, meaning before this weekend!

East/West phenomenon: The equinox is also when every place on earth rotates perpendicularly into our planet’s —terminatorits day-night shadow line. As a result, on Monday 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 Monday’s 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.

Sunlight changes: This is also the week when sunlight changes at its maximum annual rate, with 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.

Five Ancient Sites Aligned with the Solstice & Equinox

Across time, people have marked the changes of seasons—sometimes in dramatic ways! Here are five amazing ancient sites aligned with the solstice and equinox.

Our ancestors lived amidst nature more than most of us do today. They observed the universe, marveling in its rhythms. They used the Sun and the Moon as a sort of calendar, tracking the Sun’s path across the sky. Here are some examples of the ancient sites and monuments that aligned with the solstice and equinox.


Machu Picchu is the transcendent City of the Incas. This archaeological site is perched atop a mountain overlooking the Urubamba Valley in Peru.

There is a giant stone at the top of this sacred mountain called Intihuatana, which means “the place when the sun gets tied.” Amazingly, the stone is perfectly positioned so each corner sits at the four cardinal points (north, south, east and west). The stone serves as a solar clock to mark the dates of the equinoxes and solstices.


Every year on the summer solstice, thousands of people travel to Stonehenge, England, a place with huge stones that were arranged in a circle around 3000 B.C.
The huge monument celebrates the relation between the Sun and the seasons.

At what is now Chichen Itza (“CHEE-chen-EET-sa”), Mexico, Mayans built a huge pyramid around the year A.D. 1000. The play of the Sun’s light on it signals the beginning of the seasons.
On the spring equinox, for example, the light pattern looks like a snake. Mayans called this day “the return of the Sun serpent.”

In today’s Chaco Canyon, New Mexico, Anasazi Indians, who were expert sky watchers, carved spiral designs into rock to track the seasons and record the passage of time.

In this canyon is a petroglyph called the Sun Dagger because of the way the Sun’s wedge-shape beams strike it in midday during the summer and winter solstices.


Around 3200 B.C., ancient people in Ireland built a huge mound of dirt and surrounded it with stones. Today, the knoll is called Newgrange.

For five days over the winter solstice period, a beam of sunlight illuminates a small room inside the mound for 17 minutes at dawn. The room holds only twenty people at a time.

Every year, thousands enter a lottery in hope of being one of the hundred people allowed to enter.

There are many ancient sites around the world. We welcome your comments about other ancient sites—and how you mark the seasons!

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