Name: Why Does the Moon Change?
Uploaded: 2018-01-18T14:18:46.000Z
Duration: 3 min 49 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

If you ever look up at the moon at night sky
-- say, before you go to bed -- you've probably

Present continuous

noticed that, as the days and weeks go by,
the moon looks like it's changing shape.

And some nights, a few weeks later, it's
a big bright circle!

Well, the moon doesn't actually change shape.

Well, the moon, just like the Earth, has a
day side and a night side -- a part that's

So when we see a little sliver of bright moon,
we're seeing a little part of the moon that's

facing the sun, while the rest of the side
that's facing us, is dark.

And the size and shape of that little sliver
of lit-up moon changes, because the moon orbits,

It takes the moon about one month to make
a one full orbit around the Earth.

And as it moves around our planet, the day-time
side of the moon -- the side that's lit

up from the sun -- is facing in different
directions, as we see it from Earth.

This means that, every night, we get a slightly
different view of the moon!

And during its month-long trip in orbit around
the Earth, the bright part of the moon appears

to grow, and then shrink, from right to left!

The different shapes that we see, of the lit-up
part of the moon, are called phases.

This is when the nighttime side of the moon
-- the side that's facing away from the

But because its dark side is facing us, we
can't see it during the new moon phase!

The next phase is called the crescent phase.

This is when the moon looks like a little
sliver, kind of like the tip of your fingernail!

After the crescent comes the quarter moon
-- this when the moon looks like half-circle!

A gibbous moon is when it's missing just
a little sliver of light, and it's almost

The moon is at its brightest at the full moon.

That's when the fully-lit side of the moon
is facing us, so we see a big, bright circle.

But we're only halfway through our phases!

After the full moon, the lit-up part of the
moon appears to shrink.

And just like how it grew from right to left,
the sunny side of the moon will shrink from

So, after the moon is full, it starts to shrink
back down to a gibbous moon.

But this time, you'll notice that the left
side is shining bright instead of the right!

And after the gibbous phase, the moon will
look like half circle again, when it reaches

And then after a few days, it shrinks down
to a little sliver again ... the second crescent

After that, the tiny sliver shrinks all the
way down until the lit-up side of the moon

But it's gone through a month-long cycle
of phases, and is ready to start all over

Like I said, it takes a month for the moon
to go through all eight phases.

And in fact, our word “month” comes from
the word “moon,” because it takes a month

for the moon to go from new moon, through
all of its phases, and back to new moon again.

So, tonight, before you go to bed, take a
look out the window.

If the sky is clear, can you see the moon?

Is the bright part on the right side or the
left side?

Keep an eye on it as the days go by, and watch
how the moon looks like it's changing shape.

You can even make drawings to keep track of
how it changes from day to day.

Now you know that the moon itself doesn't
really change shape.

We just see different amounts of the sunny
side of the moon, as it makes its monthly

We love getting questions here at the Fort!

So if you have one...ask a grownup to help
you leave a comment down below, or to send