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Jessi and Squeaks are really excited about the total solar eclipse on August 21st, so they're revisiting all the amazing things they've learned about the sun, the moon, and how eclipses happen!
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(SciShow Kids intro)

Hi everyone.  Squeaks and I were just making plans for August 21st.  Do you know why that day's going to be so special?  You're right, Squeaks, that's when we're going to have a solar eclipse.  That means something very unusual is going to happen to the Sun.  It's going to look dark for a little while.  That's because the moon is going to get right between the Earth and the Sun and block it from our point of view.  We haven't seen that happen in two years, so Squeaks and I were just reminding ourselves what happens during an eclipse.  That's a great idea, Squeaks.  Do you guys want to learn about eclipses, too?  Let's take a look back at the 2015 solar eclipse first.

The Sun is one of those things that you can always count on being there.  Well, at least during the daytime.  Usually, whenever we look up into the sky during the day, we can see the Sun shining down on us, giving our planet heat and light.  But sometimes, you can also see the moon during the day.  The moon moves around the Earth, making a full trip all the way around our planet once every month, and during some of that month-long trip, you can see the moon only at night, but at other times, you can see it during the day, and every now and then when you can see both the moon and the Sun in the sky during the day, cool things can happen, and this week is one of those times because our planet is going to experience a solar eclipse.

A solar eclipse happens when the moon gets right smack dab between the Sun and the Earth.  When the moon does this, it blocks out some of the Sun's light and casts a gigantic shadow on the Earth.  It doesn't last for very long, just a few minutes really, but when the moon blocks the light from the Sun, it can make the sky appear as dark as night, even though it's still daytime.  

Now, not all eclipses are the same.  They can look different depending where on Earth you are, and where the moon's shadow is.  A total solar eclipse is when, from where you're watching, the moon completely covers the Sun in the sky, and then there's also the partial solar eclipses, when the moon passes over just a little bit of the Sun.  

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When this kind of eclipse happens, the sun looks like a little chunk is missing -- like a cookie with a big bite taken out of it! Now, it’s not very often that sun, moon and the Earth line up in just the right way to create a solar eclipse. But the next one is going to happen on March 20! Not everyone in the world is going to be able to see it -- only people who happen to be in the path of the gigantic moon shadow. So where I live, in the United States, we won’t be able to see the solar eclipse. But people in Europe -- especially in the northern parts -- will get the best view. Those folks will get to see the total eclipse. Right around breakfast time, they’ll have a few minutes of darkness, almost as dark as night. People in the rest of Europe, and also parts of Asia and Africa, will see a partial solar eclipse. For them, it will look like a little bite has been taken out of the sun. And as the minutes pass, that bite will get smaller and smaller until the sun is back to its old self again.

Now it’s important to remember, you should never try to look directly at an eclipse, because the rays from the sun can really damage your eyes, even when it’s partially covered up. So the next time you go outside during the day, see if you can find the moon. What does it look like? We’ll be keeping an eye out for it too here at SciShow Kids.

Awesome.  Now I'm even more excited to see what happens on August 21st.  You're right, Squeaks, another kind of eclipse happens sometimess, too.  The eclipse on August 21st will be a solar eclipse, but sometimes, we see a lunar eclipse.  'Solar' means 'sun' and 'Lunar' means 'moon', so can you guess what a lunar eclipse is?  That's right, during a lunar eclipse, the moon goes dark, because the Earth blocks he light from the Sun from reaching the moon.  Let's learn more about it.

Hi it’s Jessi here in the observatory! This is where we come to look at the night sky, just to see what we can find. But there are lots of things up there you can find without needing a telescope at all. The moon is easy to spot, and you’ve probably noticed that it can look different at different times of the month. Sometimes it looks like a crescent. Other times, it’s big and round in the night sky, glowing white. You can also sometimes see the moon during the day. But have you ever seen a red moon? 

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This happens during a lunar eclipse, which will be appearing in the night sky very briefly this week! “Lunar” is the word we use to describe things that have to do with the moon. And an eclipse is when one objects blocks, or gets in the way of, another. So let’s use those two ideas to figure out what happens up there in the sky to make a lunar eclipse take place. If you’ve ever noticed that you can see the moon in different parts of the sky at different times, that’s because the moon orbits, or goes around, the Earth. It makes a full trip around us once a month. And at the same time that the moon is orbiting the Earth, the Earth is also going orbiting around the sun.

So at different times, the sun, moon and Earth are in different positions. And every once in a while, the Earth happens to get right smack-dab in between the Sun and the moon. And they end up in a straight line. When they all line up this way, the Earth blocks some of the sun’s light and casts a big shadow on the moon. That, my fellow sky-watchers, is a lunar eclipse. But the shadow that the Earth casts on the moon isn’t black. It’s not even really that dark! Instead, during a lunar eclipse, the moon can look red! That’s because when sunlight shines from behind the Earth, it travels through our atmosphere. And that light bends when it shines around the Earth. Those bent rays of sunlight then create a red color on the moon. Lunar eclipses are famous for turning the moon red, but they can be other colors, too like yellow, orange, or brown. What color you see depends partly on where you are when you’re watching it. And not everyone on Earth can see the eclipse -- only people who happen to be on the side of the Earth that’s facing the moon when it happens can see it. Generally, that’s the side where it’s nighttime. Unlike solar eclipses, which can hurt our eyes, we can look at lunar eclipses directly. You can even take pictures of them with your camera. The lunar eclipse will be visible all over the western United States, Canada, and most of Mexico, plus in eastern Australia and Japan!

Now, lunar eclipses don’t happen that often, maybe twice a year if the Sun, moon and Earth line up just right. 

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But if you can’t catch this one, don’t worry! There will be another one in September. So go to bed early the night before and check out the moon before breakfast! That’s what we’re gonna be doing! 

So during a solar eclipse, the moon has to be out during the day, but why can you sometimes see the moon during the day and sometimes you can't?  Oh, yeah, we have learned aobut this before, haven't we?  Let's check it out.

Hey guys! Squeaks and I love looking up at the sky. Clouds, airplanes, the Moon, there's so much to see! And one clever Sci Show viewer recently asked us a really interesting question about the daytime sky. 8-year-old Dawson wants to know: Why can I see the Moon in the daytime?

Great question Dawson. It does seem kind of strange. Sometimes we think of the Moon as something we only see in the night sky. But that's not true. The moon is always hanging around. Sometimes it's out at night and sometimes it's out during the day. And much of the time it's visible for parts of both the day and the night. That's because the moon is on the move, and so is Earth.

You probably know that our planet, the Earth, is spinning around in place, kind of like a toy top. As it spins half of it faces the Sun and the other half faces away from the Sun. The part facing the Sun gets the Sun's light and for that part of the world it's daytime. And the part facing away from the Sun doesn't get any light. There it's nighttime. But things don't stay like that for long because the Earth is always spinning and every time our planet spins all the way around that's one day.

Okay. So the Earth is always spinning which makes different parts of the world go through day and night. But what's the Moon up to?

Well the Moon is also moving. It's travelling in a path around the Earth. We call this movement orbiting and it takes about a month for the Moon to orbit the Earth one time. So the Earth is spinning and the Moon is orbiting. But the most important part about why we can see the Moon is... the Sun! That's right the Sun makes it's own light, sending heat and warmth to us here on Earth but the moon doesn't.

The only reason we can see the moon, is because it's also getting light from the Sun. 

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That light bounces off the Moon and comes down to us. So in order to see the Moon, we have to see the side of the Moon that's being lit up by the Sun. Just like the Earth, the Sun only lights half of the Moon at a time. And since the Earth is spinning and the Moon is orbiting, we see that lit up half of the Moon in different parts of the sky and at different times of the month.

Sometimes, the lit up side of the moon is facing the nighttime side of Earth. So people there can see the moon in their night sky. But as the moon slowly moves in its orbit, day by day, it swings around, so that more of its lighted half is facing the daytime side of Earth. And when that happens, we can see the moon during the day.

Now remember, it takes about a month for the moon to go all the way around the Earth. That means that for part of the month, you'll see the moon more in the daytime. And, for the other part, you'll see it more at night.

And maybe you've noticed when you look up at the sky that the moon doesn't always look like a big circle. Sometimes, the moon looks like a cookie with a bite taken out of it. Other times it looks like a thin little fingernail clipping. And sometimes it looks like a big round plate.

But the moon isn't really changing shape. It's just very slowly moving around the Earth, giving us different views of the side of the moon that's being lit up by the sun. So if you're a sky-watcher like Dawson and Squeaks and me, then keep an eye out for the moon. During the day, and at night. 

So the sun shines on the moon and the moon orbits the Earth so we can see the moon at different times.  That's true, the moon does look different sometimes.  The moon can look like different shapes depending on how the sun is shining on it and how it moves around the Earth.

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. 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. 

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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. 

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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 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?

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. 

I feel like I know a lot more about the Sun and the moon now.  Squeaks, how about you?  And how about you?  Are you feeling more ready for the solar eclipse on August 21st?  Squeaks and I are going to research this particular eclipse now, and we'll be back to tell you more about it before it happens, so make sure to hit the red subscribe button so you can learn right along with us.  Thanks, and we'll see you next time here at the Fort.