[Theme Music]
You've seen the sunset. Right? And if you get up early enough maybe you've seen it
rise too. But have you ever wondered if the Sun rises every day and sets every night
where does it go when we can't see it?
Well, nowhere. It's actually us that
goes somewhere because we're on the earth and our planet is always turning,
or spinning, on its axis.
Imagine a line passing through the center of the earth that goes both
through the North Pole and the South Pole.
We call that invisible line the axis. Earth spins around on this axis like a top
This spinning movement is called the Earth's rotation and, the Earth's
rotation is what gives us day and night everyday, all year. If you're on the side
of the earth that's facing away from the Sun as the earth is spinning,
it's night. If you're on the side facing the Sun it's, you guessed it, day.
Now hold on tight because the earth is actually moving in more ways than one.
At the same time that the Earth spins on its axis it also orbits or revolves
around the Sun. This movement is called its revolution.
One full orbit all the way around the Sun is one revolution and
the earth takes 365 days, or one year, to
complete a revolution. So have you got all of this so far?
The earth is rotating
on its axis, creating day and night and the same time its revolving all the way
around the Sun. Now here's the thing: as the earth is both rotating and revolving
it's not sitting straight up and down. Its axis is actually tilted just a
little. It's not all that much, but this tilt causes one part of the earth to
lean towards the Sun, while another part of it is leaning away. This means that
different parts of our planet surface gets different amounts of sunlight and heat.
So why am I telling you all of this?
Well, as the earth travels around the Sun it
creates a pattern throughout the year.
This pattern happens over and over again and i'm sure you've noticed it.
At certain times of the year you see the northern hemisphere leans towards the
Sun and the southern hemisphere leans away, and at other times the southern
hemisphere leans towards the Sun and the northern hemisphere leans away. That
pattern, my friend, is what makes seasons. When the part of the world that you're
living in is leaning towards the Sun it's warm and the days are long: summer.
When you're on the part that's leaning away from the Sun
it's cold in the days are short: winter. In between it's spring or autumn.
If the earth were tilted we would have the same season all year long.
So, revolution, rotation, orbit. Is your head spinning?
Let's do a demonstration to shed a little light on these concepts.
Okay you're gonna need a globe in a table lamp without a shade.
Plus a table to put them both on. Put the lamp in the center of the table and turn
it on, put the globe on one side of the table. Now hit the lights. The globe is
earth- makes sense right?
The lamp at the center of the table is the Sun at the center of the solar
system.
Now slowly spin the globe as the Earth rotates the Sun lights up one side of
the planet better than the other.
It's day where the light is shining more brightly on the globe and night where
it's not.
Now let's see what the Earth's revolution around the Sun looks like.
Give the globe a few spins with one hand while slowly pushing the globe in a
circle around the Sun or the lamp with your other hand. So do you notice how the
earth keeps rotating as it revolves around the Sun? If this were the real Sun
and Earth by the time you get back to where you started
the global have completed 365 rotations or days and that's another year gone by.
So what does all this show us?
It shows that what looks to us to be the motion of the Sun in the sky is really
caused by the motion of the earth. So now you know when you look up and see the
sun setting or rising,
it's not going around us it's sitting pretty much at the center of the solar
system while we and the seven other planets go around it.
That sun, always going to be the center of attention.
[Theme music]