Lesson video

Hello, and welcome to today's lesson, from the Unit "Earth, Sun, and Moon." This lesson today is called "the Shape of Objects in Space." Hi, my name is Mrs. Waller, and in today's lesson, you are able to consider evidence from space and describe the shape of the Earth, Sun, and Moon.

Let's take a look at the key words we'll be using in the lesson today.

Earth, Sun, Moon, spherical, and evidence.

Now, I'm sure you've heard most of these or all of these words before.

So take a moment to think for yourself.

Do you know what these words mean, or do you think you might need a little more help in today's lesson? Today's lesson is in two parts.

In the first part, we'll be thinking about the shape of objects in space, and then we'll be moving on to consider evidence from space.

We know that throughout history, for many years now, people have disagreed about the shape of objects in space, and this includes the shape of planets, the shape of Moons, and the shape of stars.

Take a look at some of these ideas that people have had throughout history.

"The Moon gets thinner as it is eaten by the sky." What do you think about that one? That's an interesting one, isn't it? How about this one? "Objects in space are flat, with a dome for the sky." Do you agree with that one? Do you disagree with that one? And finally, some people may think that the Sun is a huge ball of fire, so it has no shape.

Do you agree with any of these ideas? Have a chat with somebody else about your own ideas and the ideas in front of you here.

In the daytime, we see the Sun in the sky.

Now be careful with this one.

We know that the human eye is extremely sensitive, and it is dangerous to look directly at the Sun.

But we know that the Sun is up there in the sky during the daytime.

Have a think about this.

What shape is the Sun? The Sun is very important to us.

It's the centre of our solar system.

It gives out heat and light, and therefore it is a star.

Some people think that stars are pointy shapes.

We may have seen images in children's books, in nursery rhymes, "twinkle, twinkle, little star." And sometimes other people might think that the Sun is completely flat, like a pancake.

But the Sun is actually a sphere.

Some scientists believe that the Sun is the most perfect sphere ever observed in nature.

Moving on now to another object in space, something else that we often see in the sky, we often see the Moon.

So same question for you.

What shape is the Moon? Yes, you've guessed it.

The Moon is also a sphere.

So, if we have a look at this photograph of the Moon, it doesn't look like a sphere here, does it? How would you explain this photograph of the Moon with regards to its shape? Well, it's a tricky one, but actually the Moon stays a sphere.

It's always a sphere.

But sometimes it appears to change shape at different times of the month.

We've covered quite a lot of science so far, haven't we? So let's take a break, and it's time for me to check your understanding from the first part of today's lesson.

The Sun is our nearest star.

What shape is a star? A star has five points.

A star is a sphere shape.

A star is a tiny dot.

Which one do you think? It's B.

A star is a sphere shape.

Now we know that the Sun is a star, and lots of people don't realise that, but it's a star because it gives out its own heat and light, and we know that stars are sphere shaped.

How about this one? Which of these statements about the shape of the Moon is true? The Moon is never a sphere.

The Moon is only a sphere for a few days a month.

Or the Moon is always a sphere.

Well done, yes.

The Moon is always a sphere.

Now this is another tricky one, isn't it? Because it doesn't always look like a sphere, because we know if we look up to the night sky over the period of a month, the Moon appears to be changing shape.

But actually, it is always a sphere.

Let's put this into practise now.

Choose from the words to describe the Earth, Sun, and Moon.

So we have our sentence starters.

The Earth is, the Sun is, and the Moon is.

And we've got some different words for you to choose from.

Pointy, circle shaped, star shaped, spherical, and flat.

And what I'd like you to do is pause the video, and think about which word you would use to describe each of the Earth, Sun, and Moon.

Are there any other words that you would use to describe the shape of the Earth, Sun, and Moon? Are there any words that you would use that are not in this list? And what words might they be? It's time to take a look at which words we would choose to finish our sentences.

The Earth is spherical, the Sun is spherical, and the Moon is, is this going to be a different one? Spherical.

Yes, well done! It was kind of a trick question.

I was wondering if you were going to choose different words to finish the descriptions of the Earth, Sun, and Moon.

But we do now have evidence to show us that objects in space, including the Earth, the Sun, and the Moon, are spheres.

So well done.

Did you think of any other words to describe the shape of the Earth, Sun, and Moon? I was thinking maybe round, ball-shaped, but I'm definitely going to stick with spherical.

Did you have any other ideas? Alex has decided to use a pizza to represent the Sun, a hot cross bun to represent the Earth, and an egg for the Moon.

Talk to someone about Alex's choices.

Do you think he's made good choices? Do you think a pizza, a hot cross bun, and an egg are good items of food to represent the Sun, the Earth, and the Moon? Think about what other objects, maybe not food this time, can you suggest that would make a more accurate model? So let's start off by thinking about our model Sun.

We know that Alex has chosen a pizza, and I'm wondering if you can suggest anything else that might be more accurate for our model.

And I was thinking maybe to use something like a beach ball, a large ball of some sort, because I think a pizza is a good choice for the Sun.

It's large, and it is circular, but it's a flat 2D shape, isn't it? And I think it needs to be a sphere.

So a large ball like a beach ball would be better.

What do you think? Did you have other ideas? Let's think about the Earth now.

I think a hot cross bun is a 3D shape, so that's a good choice for the Earth.

And it's kind of rounded, isn't it? It's not a perfect sphere though, would you say? Maybe something like a tennis ball is more spherical in shape for the Earth.

How about what you thought? Did you have similar ideas, or something different? And moving on now for our egg to represent the Moon.

Now, is that a good choice? Well, the egg, it's not flat, so that's the first thing that's good.

But it's still not a sphere, is it? So something like a small sphere, maybe a marble would be better for the Moon? As we know that the Moon is a sphere.

How about your ideas? So here's my final ideas for my suggested model of objects in space.

I've got a beach ball Sun, and a tennis ball Earth, and a marble Moon.

Take some time to compare your ideas to mine, and do you think that you came up with a model that was a more accurate representation? Moving on to our second part of today's lesson, and we're going to be looking at evidence that's been collected from space, that helps us to understand more about the shape of objects in space, such as the Earth, the Sun, and the Moon.

Our first piece of evidence comes from Captain Albert Stephens and Captain Orvil Anderson from the American Army.

And they were involved in a really brave mission to travel up to an extremely high distance above the Earth in a helium balloon, named Explorer Two.

Now, they actually attempted this mission the year before, in 1934, but unfortunately, the balloon ripped open just after the launch, and the gas from the balloon mixed with the gas in the air, and the balloon exploded.

Now, luckily, they were able to parachute safely back down to Earth.

But like all great engineers, they decided to have another go.

In 1935, they actually reached a distance of 22 kilometres.

That's just over 22,000 metres, above the surface of the Earth.

And they travelled up in this helium balloon, and this meant that they weren't yet actually in what we would call space, but they were high enough to collect the most amazing evidence.

And this evidence showed that they'd gone so far away from the Earth, 22 kilometres away from the Earth, they were able to take photographs which showed the curved surface of the Earth.

And this was the very first time that people had been able to travel so far away from the Earth, and actually capture that evidence in a photograph.

These stories are pretty inspirational, aren't they? In 1946, another team of scientists and soldiers in America, they launched missiles into space.

And these missiles were carrying a very early type of video camera.

And the reason for that is they were hoping to capture video footage from high up into space, that would look back down onto the Earth, and would show us its actual shape.

And these missiles did return the first images of the Earth from space.

And you can see they're quite old looking images.

They're black and white, and they're rather grainy looking.

But how incredible to have this? This was the first time that video images were used, and this provided further images for a spherical Earth.

So you can see that further back in history, when the aeroplane wasn't invented, certainly when space flight wasn't invented, when we didn't have cameras, when we didn't have videos, we weren't able to have such incredible evidence to help us to understand the shape of objects in space.

But since the 1960s, spacecraft have been able to return photographs and videos and images from ever greater distances away from our planet.

We know that today's astronauts, they aren't just taught how to carry out scientific experiments in space.

They are also fully trained in photography.

In more recent decades, we now have the most amazing images from space.

And you may have heard of the International Space Station, and astronauts who've been able to actually go outside of the spacecraft, and take a space walk.

And we have images of this, to show the most amazing developments in technology, and these incredible images looking back down to the Earth.

Let's take a look at a few more examples.

Today, satellites, probes, and people in space, have taken amazing images.

And with modern technology, we are now able to take really accurate measurements, so that we can be even more certain about a spherical Earth, Sun, and Moon.

Let's take a look at these satellite images taken from space, looking down from a really great distance away from the Earth, so that we can see its curved shape.

You can find lots more images like this on the internet.

You might want to take a look, and find some more evidence for yourself.

I'm now going to check your understanding of the second part of today's lesson.

From the Earth, the Moon looks like a circle.

Astronauts tell us this is not its real shape.

What shape is the Moon? Is it oval, semicircle, sphere, or cylinder? Yes, that's right.

The Moon is a sphere, and we keep coming back to that word, sphere, don't we, as a representation of a circle shape, but a sphere is round like a ball.

Now, which two answers explain why we only have photos from space in the last 200 years? Is it because 200 years ago spacecraft wasn't invented? Or cameras were not invented? Or cameras only took black and white photos? Or people were too scared to fly that high? Which two answers do you think? Yes, that's right.

Over 200 years ago, there was no spacecraft, and also no cameras.

It's now time for you to have a go at this practise task.

We know that there are now many famous images of the Earth from space, and I'd like you to carry out your own research to collect more evidence for a spherical Earth.

Now, I'm going to give you some starting points here.

So a great image for you to research and for you to start with, try searching for an image that was taken in 1972, and it's called "The Blue Marble." And when you're carrying out your research, it would be brilliant if you could find out what was so special about "The Blue Marble" image, and how did "The Blue Marble" image provide evidence for a spherical Earth? Pause the video and off you go, and carry out some research of your own.

I hope you found it fascinating, working like a scientist, and carrying out your own research.

And it's brilliant to have a look at all the evidence that's out there.

There's so much out there, isn't there? In order to collect information in support of the idea that the Earth is spherical in shape.

So what did you find out about "The Blue Marble"? Well, you might have found out that "The Blue Marble" is a very famous photograph of the Earth, and we know that it was taken in 1972, but did you know that it was taken by the crew of the Apollo 17 spacecraft, on their way to the Moon, and it was taken at a really high altitude at a distance of around 29,000 kilometres away from the Earth? Wow.

Did you know that "The Blue Marble" was the first photograph taken of the whole round Earth? And because of that, it's believed to be the most reproduced image of all time.

This photo provided evidence that we live on a tiny ball in space, just like a tiny marble.

That's why it was called "The Blue Marble".

And it made people realise that we really are floating alone in space.

And I'm sure by now, you've seen an image of "The Blue Marble" photograph.

It really is the most incredible image to be taken.

And again, don't forget, this was used as evidence that the Earth is a sphere.

I'm going to ask you two final questions now, and these are really deep thinking questions, so take your time.

These aren't questions that I think you're just going to answer immediately in the click of your fingers.

So take your time, gather your thoughts, think about everything that you already know and understand about the Earth, the Sun, and the Moon.

And think like a scientist.

Have you ever thought about why the Earth, the Sun, and the Moon are spherical? So we have this evidence now that shows us that they're the shape of spheres, but have you thought about why that might be? What reasons might you be able to give for this? Now, don't worry about getting it right or wrong.

The important thing here is just for you to think scientifically and give some scientific possibilities.

Have a go.

And my second deep thinking question, we're working hard today, aren't we? Is that scientists tell us that the Earth, Sun, and the Moon, are approximately spherical, and they use this word "bodies", so they're bodies in space.

They are approximately spherical.

So they're not saying that they're exactly spherical.

Why do you think they include the word "approximately?" Just have a go at this, and maybe talk to somebody else about your scientific ideas.

Well done.

They were tricky questions, weren't they? I'm going to give you some ideas that might help.

So I think that objects in space are spherical, and that's due to gravity.

Now we know that gravity pulls from the centre, so gravity pulls equally from all sides.

And if you imagine a shape that's being pulled equally in every direction from all sides, then that's going to pull the shape into a shape that's round, like a ball.

Is that similar to what you thought? Don't worry if it isn't.

It'll be great to hear your ideas too.

Moving on to our second tricky question.

I think scientists say "approximately spherical" because objects in space are spinning.

So their shape might change very slightly, but they're still round.

So we're not saying exactly spherical.

They're approximately, pretty much almost, more spherical than any other shape.

And also don't forget that objects in space are very, very far away.

So their surfaces might be rough and bumpy.

So not actually a perfect sphere, but approximately like a sphere.

Are my ideas similar or different to yours? Don't worry if they're different, but again it would be brilliant for you to share your ideas with somebody else, and listen to what they thought, too.

Let's summarise our learning today.

We know that there have been disagreements for many years about the shape of stars and planets and Moons, objects in space.

What else have you learned today? That's right.

The Earth, the Sun, and the Moon, are round like a ball.

And we know what we call this shape, don't we? We call this shape a sphere.

And finally, images and measurements from space, so in more recent decades, they've helped us enormously, haven't they? They've helped scientists to gather evidence that stars and Suns and Moons are all spherical.

Fantastic work today, everybody.

Well done.

Congratulations.

You've reached almost the end of the lesson, and all that remains now is for you to have a go at the exit quiz.

I'll see you in the next lesson.