Placeholder Image

Subtitles section Play video

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

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

  • Some nights, it's a little sliver.

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

  • Well, the moon doesn't actually change shape.

  • But our view of it does change.

  • Why?

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

  • facing the sun, and a part that's not.

  • 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,

  • or moves around, Earth.

  • 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.

  • And there are eight phases of the moon.

  • The first phase is the new moon.

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

  • sun -- is what we can see from Earth.

  • The moon is still up there!

  • 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!

  • The next phase is called gibbous.

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

  • full!

  • And that's what's next!

  • 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

  • right to left too!

  • 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

  • the quarter moon phase again.

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

  • moon.

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

  • can't be seen at all.

  • Now, the moon is a new moon again.

  • It's the same old moon!

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

  • again.

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

  • And in fact, our wordmonthcomes from the wordmoon,” 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?

  • If you can, what phase is it in?k

  • 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

  • trip around the Earth.

  • Thanks for joining us today!

  • 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

  • us an email to kids@SciShow.com!

  • And we'll see you next time!

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

Subtitles and vocabulary

Click the word to look it up Click the word to find further inforamtion about it