Have you ever wondered if the Earth is really round like a ball? Teachers, scientists, and even astronauts who have been to the Moon tell us that it is. They have taken pictures from space showing the Earth as a big, blue sphere. But when you step outside, everything looks flat. So, what’s going on? Are the pictures real? Let’s find out!
A long time ago, people didn’t know what shape the Earth was. In ancient China, some thought it was shaped like a giant cube. In Europe, the Norse people imagined it was flat like a pancake surrounded by water. Without pictures from space, they had to guess, and many guessed wrong.
One of the first people to suggest that the Earth might be round was a thinker named Pythagoras. He looked at the Moon and wondered if the Earth could be a sphere like the Moon. Later, when telescopes were invented, astronomers saw that other planets like Mars and Jupiter were round too. This made more people think that the Earth must be round as well.
But how can we know for sure? One clue comes from something called a lunar eclipse. This happens when the Earth moves between the Sun and the Moon, casting a shadow on the Moon. The shadow is round, which means the Earth must be round too! You can see a lunar eclipse without a telescope if you know when to look.
Another clue comes from watching ships at sea. When a ship sails away, it doesn’t just get smaller and smaller. Instead, the bottom of the ship disappears first, then the top. This happens because the ship is going over the curve of the Earth, just like a friend would disappear over a hill.
You can also learn about the Earth’s shape by talking to friends or family who live far away. If you video chat with someone in another country, ask them what time it is. It might be nighttime for them while it’s daytime for you. This happens because the Earth is round and spins, so different parts face the Sun at different times.
Even though the ground looks flat, there are many clues that show us the Earth is round. From lunar eclipses to ships disappearing over the horizon, and even video calls with friends far away, we can see the evidence for ourselves. It’s important to ask questions and explore the world around us. Stay curious and keep discovering!
Here’s a sanitized version of the provided YouTube transcript:
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(telephone rings)(horn beeps softly) – Hi, it’s Doug. Teachers have told you that the Earth is round like a ball. Scientists have told us that the Earth is round. Astronauts who’ve been to the Moon have told us that the Earth is round. They took pictures. And yet, when you walk outside, everything looks totally flat. What’s the deal? Are teachers trying to trick us? Are the pictures from space fake? And is there any way to even know for yourself? I mean, unless you become an astronaut and go to space, it seems impossible to ever know this for yourself.
Someone named Amalee has a question about the shape of the Earth. Let’s give Amalee a call. (telephone rings)(horn beeps softly) – Hey, Doug. – Hi, Amalee. – I have a question for you. How do we know the Earth is round? – Ooh, that’s a really interesting question. Today, we have photographs of the Earth from space, but think about it. Thousands of years ago, people had no idea what shape the Earth was. People in ancient China thought the Earth was shaped like a giant cube. Over in Europe, the ancient Norse people thought the Earth was flat like a pancake and surrounded by water. Since ancient people had never seen pictures of the Earth, they just had to guess at what shape it was. And they were guessing wrong.
Before I go on, though, I’m curious. Besides pictures, are there any other ways to know that the Earth is round? What do you think? Now would be a good time to pause the video and discuss. Okay, you ready? One of the first people to come up with the idea that the Earth was round was a person by the name of Pythagoras. He spent a lot of time looking up at the Moon and wondered, could the Earth be a round sphere like the Moon is? Later, when the telescope was invented, astronomers began to discover other round spheres in space, like Mars and Jupiter, and more and more people began to think, hey, if the Moon and other planets are round, then the Earth must be round, too.
But just because the Moon and Mars are round doesn’t mean the Earth is round, too. I mean, what if the Earth is different from other planets? That could be possible, right? It could be, but the shape of the Moon and planets isn’t the only reason people began thinking the Earth is round. A long time ago, astronomers began to notice something strange. Every once in a while, they could see a shadow on the Moon. For hundreds of years, people wondered what’s going on up there. Eventually, astronomers figured out where the shadow was coming from. It was coming from the Earth. And the amazing thing was the shape of the Earth’s shadow was round. Some of these ancient astronomers realized, wow, if the Earth’s shadow is round, then the Earth itself must be round.
Now, when this happens, it’s what’s called a lunar eclipse. It happens when the Earth moves between the Moon and the Sun, and you don’t need a telescope or binoculars to see one. In fact, if you know when to look for a lunar eclipse, you can see the Earth’s round shadow on the Moon for yourself. A lunar eclipse happens every couple of years or so, but you don’t need to wait till the next lunar eclipse in order to see for yourself that the Earth is round. There are other things you can notice, too, like if you get a chance to visit any place where you can watch boats coming and going.
Now, what could boats have anything to do with the Earth being round? Well, take a look at this ship. This is something people first noticed a long time ago. Every time a ship is sailing away from you, once it gets really far, it doesn’t just look smaller and smaller until you can’t see it anymore. It actually looks like the bottom of the ship disappears first, then the top. This might seem surprising, even weird, but it makes perfect sense if the Earth is round. Part of the ship is disappearing because it’s sailing over the round curve of the Earth. Just like part of a friend would seem to disappear if she walked over the top of a round hill. If the Earth were flat, that wouldn’t happen.
Now, you might not get to see a lunar eclipse for a while or see a ship coming or going towards the horizon. But there’s still an even easier way to tell that the Earth is round. Have you ever done a video chat with a friend or family member who lives far away from you, like someone who lives in another state or even another country? If you have, here’s something to try to notice next time you talk to them. Ask them what time of day it is where they are. Have them show you a clock or, better yet, have them show you the view outside their window. It might be late at night for them while it’s still daytime for you. Think about why that is. If the Earth were flat, then when the sun comes up, it’d be morning for everyone on Earth at the same time. And yet video chatting with far away friends and family can show you that that’s not the way it is.
See, since the Earth is a sphere, we don’t all see the sun at the same time. With a sphere, that means it’s only daytime when your side of the Earth is facing the sun. When it’s daytime for you, the other side of the Earth is in nighttime. So, while you may be facing the sun and having breakfast in North America, kids on the other side of the sphere, like in Japan, are already sound asleep.
So in summary, when we look out in front of us, the ground really does look flat. The idea that the Earth is round? It makes sense why it can be hard to believe. But don’t just take someone’s word for it. It’s important to ask questions and try to understand things for yourself. There are a lot of different clues which can help you to know for yourself that the Earth is round, from lunar eclipses to ships to video calls with far away friends. That’s all for this week’s question. Thanks, Amalee, for asking it. Now for the next episode, I reached into my question jar and picked out three questions sent into me that I’m thinking about answering next. When this video is done playing, you’ll get to vote on one. You can choose from: What was the first cartoon? Are teeth made of bone? Or, how does a faucet change from cold to hot water? So submit your vote when the video is over. I want to hear from all of you watching. There are mysteries all around us. Stay curious and see you next week.
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