It’s almost time for a very special day.
Can you guess why?
[Squeaks squeaks]
No, it’s not my birthday … [Squeaks squeaks]
No, it’s not the day of the parade, either.
It’s the longest day of the year … and,
it’s the first official day of summer!
There are lots of days that might seem really
long.
Maybe you’ve felt that way when you were
excited about something that’s going to
happen, like your birthday, or the first day
of vacation.
The day before an exciting event can seem
like it takes a long time.
But even if a day feels that way, it’s not
really any longer.
All days have the same amount of time in them—about
24 hours.
When we say it’s the longest day of the
year, what we really mean is that there’s
the longest amount of daylight, which means
that the sun is up for the longest amount
of time, and it’s dark for the shortest
amount of time.
This special day is called the summer solstice,
and when it happens, it’s officially summer.
Have you ever noticed that in the winter it
gets dark pretty early?
It’s probably dark before you go to bed.
But in the spring and summer, like now, the
sun goes down much later.
[Squeaks squeaks]
Yeah, that’s exactly what you asked about
the other day!
Squeaks asked if he could change his bedtime
so it’s after dark, since he doesn’t like
going to sleep when it’s still light out.
But instead we just changed his curtains so
they make the room darker, and that helped,
right?
[Squeaks squeaks]
We have a summer solstice every year because
of the way our planet moves around the sun—and
how it’s tilted.
Because even though you don’t feel it, the
Earth is always moving!
It takes a whole year for the Earth to go
around the sun one time.
And while it’s moving around the sun, Earth
is also spinning around in place around an
imaginary line we call the axis.
The Earth’s axis runs up and down, right
through the North Pole and the South Pole.
One turn on the Earth’s axis takes 24 hours
— that’s what makes one day.
But there’s something else about the Earth’s
axis: it isn’t exactly straight up and down.
It’s tilted, just a little bit.
… and it’s this tilt that causes the summer
solstice!
Right now, the tilt is pointing the northern,
or top half of the Earth toward the sun.
Which means that during one spin — which
remember, is 24 hours, a whole day and night
— the top half of the Earth spends more
time in the sun than in the dark.
The summer solstice is when the tilt is pointing
us exactly toward the sun.
Here in the top half of the world, that’s
usually on June 21st, although it’s sometimes
on June 20th or 22nd.
Soon, the tilt will start to point more sideways
compared to the sun, and eventually it will
face away from the sun, on what we call the
winter solstice.
That will be the shortest day of the year,
with the least amount of sunlight.
But for now, while we’re pointed toward
the sun, we get long days!
For people who live in the southern, or bottom
half of the world, everything is the opposite.
When the Earth’s tilt points the top half
of the world toward the sun, it points the
bottom half away from the sun.
So for people who live in places like Australia
or South America, it’s about to be the shortest
day of the year, not the longest!
Their winter solstice is the same day as our
summer solstice, and their summer solstice
is the same day as our winter solstice!
Since it's almost our summer solstice and
the first day of summer, I’m going to go
stock up on sunscreen!
Squeaks and I hope you have a happy solstice,
wether it's summer or winter!
Thanks for joining us!
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We’ll see you next time, here at the Fort!
