The first day of spring is a really special day.
And not just because it’s when we start thinking about flowers blooming, and the days
warming up, and birds coming back from their winter homes.
It’s because the first day of spring is also when something special happens -- something
called an equinox.
Isn’t that such a cool word?
But what does it mean?
Well, before we can understand exactly what an equinox is, we’ll need to learn a little
bit about the Earth...specifically, how the Earth moves.
Even though you don’t feel it, the Earth is always moving.
In fact, it’s moving in two different ways.
First, right now, the Earth is moving around the Sun like this.
It takes a whole year for the Earth to go around the Sun one time.
And secondly, at the same time, the Earth also spins around in place, like this!
if you’ve ever played with a top, then you know the top spins around its center.
So does the earth!
It spins around an imaginary line we call the axis.
The Earth’s axis runs up and down this way -- right through the North Pole and the South
Pole.
But the Earth’s axis isn’t exactly straight up and down.
It’s tilted, just a little bit.
So, for most of the year, one half of the Earth is tilted toward the Sun, and the other
half of the Earth is tilted away from the Sun.
And that little bit of tilt makes a lot of difference down here on the ground.
That’s because, the half of the earth that’s tilting toward the sun gets more direct sunlight.
That means it’s warmer there, and the days are longer.
When that half of the Earth is tilting toward the sun as far as it can go, it’s summer
there!
And at the same time, the half that’s pointing away gets less direct sunlight.
So, the days are shorter, and colder.
There, it’s winter!
Now, as the Earth moves this way, around the sun, the top half and the bottom half of the
Earth change which way they’re tilting.
After a few months, the part that was tilting toward the Sun starts to tilt away, and the
part that was leaning away starts to lean toward it.
This whole cycle -- with different parts of the Earth getting more, and then less, direct
sunlight throughout the year -- is why we have seasons!
BUT!
There are two times of year when /neither/ side of the earth is pointing right toward
the sun.
Halfway between when /one/ half is tilted toward the Sun, and when the /other/ half
is titled away from the sun ... the part that’s getting the most direct light from the Sun
is right in the middle!
Around the middle of the Earth, there’s an imaginary line, called the equator.
And when the equator is getting the most direct light from the Sun, then both halves of our
planet get the same, or equal, amount of sunlight.
And hey, ‘equal’ kind of sounds like ‘equinox’!
And on an equinox, /everything/ is kind of in the middle — temperatures are often warmer
than they were in winter, but not as warm as they will be in summer.
And the days are longer than they were in the winter, but not as long as they’re going
to get in summer!
Sounds like this describes spring perfectly!
The spring equinox happens around March 21.
And where I live -- up here -- this part of the Earth starts to tilt more toward the Sun,
and gets more direct sunlight.
This means we’re leaving the colder, shorter days of winter, and starting to get the warmer,
longer days of spring and summer.
Now, there’s another equinox, too!
Because, remember, I said there are /two/ times a year when neither half of the Earth
is pointing toward the sun.
After summer’s over, the part of the Earth that was leaning /toward/ the sun starts to
tilt away.
Right around September 21, the most direct sunlight hits the Earth at the equator … again!
And as that part of the Earth continues to tilt away, it will head into autumn, and eventually
winter.
But, for now, where I live, we’re looking forward to our part
of the Earth tilting toward the sun!
Which means
that warmer weather and longer days are
on
the way!
So until next time—happy spring equinox!
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