Spring equinox myth busted: You can stand an egg on its end today – and any other day

What is an equinox? The science behind the astronomical seasons explained

The vernal equinox marks the beginning of astronomical spring and occurs in the Northern Hemisphere around March 20th, whereas the autumnal equinox falls around September 22nd.

Every time the first day of fall or spring rolls around, you might hear of the neat trick you can "only" do on the dates of the equinox: Stand an egg up on its end.

It turns out it's true. You can stand an egg on its end on the equinox.

And on your birthday.

And on Flag Day.

And your anniversary.

Or any of the other 361 days (or sometimes 362 – it works on Feb. 29, too).

FILE – An egg stands up on the autumnal equinox.

(Brian Donegan / FOX Weather)

Suffice to say, you can stand an egg up on any day of the year, provided the egg is in the proper condition. 

On the vernal equinox in March and the autumnal equinox in September, the equator (0 degrees latitude) is aligned directly with the Sun. Therefore, everywhere on Earth experiences an equal 12 hours of daylight and darkness because the Sun rises due east and sets due west.

The myth that standing an egg up is an equinox-only event seems to stem from an idea that not only is daylight equal on the planet, but that gravity is somehow balanced, too.

FIRST DAY OF SPRING IS MARCH 20: HERE'S THE SCIENCE BEHIND THE VERNAL EQUINOX

"(Sounds) like science, but it isn't," wrote National Weather Service meteorologists in Birmingham, Alabama. "There are many forces acting on an egg when you try to stand it on end on a flat surface. Some people think that the gravitational pull of the Sun becomes balanced with that of the Earth to allow for this phenomenon to occur."

JINING, CHINA - MARCH 20:  A tourist balances her egg on end to welcome the Spring Equinox day on March 20, 2018 in Jining, Shandong Province of China. The old legend tells us that it's easier to balance an egg on end on the Spring Equinox than on other days of the year. 

(Visual China Group / Getty Images)

But the NWS says the Moon exerts a much stronger gravitational effect on the Earth than the Sun, dominating the ebb and flow of the ocean tides. 

"The Moon's effects are different at each of the equinoxes, however," they said. "The most dominant force of gravity on a standing egg is the one between the Earth and the egg itself. This is determined by the weight of the egg and the force pulling the egg to the countertop."

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And this is one scientific experiment you can prove to yourself at home.

"Take a fresh, uncooked egg and hold it with the larger end resting on a table or countertop. Wait for the fluid content of the egg to settle, then carefully test the balance," the NWS said. "Be patient as you find the point where you can ever so gently let it go to remain standing on end."

Feel free to give it a go on the first day of autumn. And again on Halloween. Or Thanksgiving. Or Jan. 19…