Stargazing Challenges

-Hi, I'm Jem.

-And I'm Helen. And we are mad about science.

There's just so much to find out about the planets and the stars.

We thought we'd show you of our favourite demonstrations

to help you understand how the solar system works.

'Coming up in today's show,'

Blue Peter stars Helen and Barney

set us six sensational stargazing challenges.

I wonder how the Earth, sun and moon move around each other.

Why do we have seasons?

I'd actually like to know how to make my own rocket.

With our young astronomers' help, we work on teasers,

including how the Earth orbits the sun.

It can't be that difficult.

The Earth does it all day every day and never complains.

-Discover why we see the moon in different shapes.

-I've got it!

And reach for the stars as we make a home-made rocket.

Wow, that would be awesome!

I'm here at the observatory in East Sussex,

and I've got lots of young astronomers here to help me out.

Come on down. We've got our challenge. Come and have a look.

The distances between the planets are so massive it's hard to picture them.

What is the best way to describe the distances involved?

Can anyone tell me what the planets are?

Mars, Venus, Earth, Mercury,

Uranus and Saturn.

And Jupiter. And Neptune.

Almost there. That's brilliant.

Does anyone know which is the furthest planet from the sun?

-Neptune.

-That's right, yes.

The solar system is made up of eight planets.

The four rocky planets are Mercury, Venus, Earth and Mars.

Jupiter, Saturn, Uranus and Neptune are known as the gas giants.

The temperature of a planet

is affected by how close to the sun it is.

The temperature on Venus can get up to 460 degrees Celsius,

hot enough to melt metal,

while the temperature on Neptune is minus 220 degrees Celsius.

The problem we have is that the size of the planet is tiny

compared with the enormous distances between them.

But I have a system that will help us understand those two things.

For that, I'm going to need some fruit

and some spices and some loo roll.

My solution to this challenge is a loo roll solar system.

We need to know how big the planets are.

What's the biggest planet?

-Jupiter.

-It is Jupiter. Now what's the biggest piece of fruit

you think we could use to represent Jupiter?

-Watermelon.

-It is.

We'll use a watermelon to represent Jupiter because that's large.

What's a small thing we could think of to represent the smallest planet?

-Grape.

-A grape. A grape's not bad.

-Can anyone think of anything smaller than a grape?

-A raisin.

Getting close. What we're going to use is a peppercorn.

A tiny, tiny little thing for the smallest planet.

As our young astronomers gather the essential equipment,

there's one thing missing.

Now, the sun is 99% of everything in the solar system.

So, all of the planets and the comets and asteroids

only make up a tiny fraction - 1% - of everything.

So, our sun, compared with what's in everyone's hands, is massive.

We've got another young astronomer who's going to bring it out to us.

Alex, you can bring it out now.

# Rubber ball I come bouncing back to you

# Rubber ball, I come bouncing back to you-u-u-u-u. #

BOING!

So, I've got my loo roll ready

to measure the distances of the solar system.

Each piece of toilet roll represents 16 million kilometres.

It's a long, long way.

The first planet, Mercury, is 3.5 pieces of toilet roll in.

So, Mercury, hold out your planet so we can see what have you got there?

The peppercorn. The next planet is Venus,

which is one, two, just around three further out.

So we've got Venus. What have you got? A cherry tomato for Venus.

The next planet is us - it's Earth.

We're about 2.5 pieces of toilet paper further out.

Put your foot on that and hold out the Earth.

The last rocky planet is Mars.

That is five pieces further out.

Here you go.

Now, these are all the rocky planets.

We're heading out into the asteroid belt.

The next planet is much further away.

8, 9, 10, 11, 12...

31, 32, 33, 34.

So, now we're ready for the first of the gas giants, Jupiter.

The biggest planet in the solar system. OK.

So we're going to keep going out now towards Saturn.

35, 36, 37, 38, 39, 40.

Saturn. Hold out your planet.

So, we got a grapefruit representing Saturn,

which is 1.4 billion kilometres away from our sun over there.

We've got further to go, so let's keep going.

88, 89, 90.

We've got to Uranus. Brilliant! We've got one more planet to go.

This one is even further that way.

Off we go!

So we've come to the end of the second roll of toilet paper

but there are only 20 more squares needed.

So we're going to have the next one.

So here we are - our last planet - Neptune. Represented by a lime.

This is 280 squares of loo roll down the line from the sun.

In the solar system, that distance is 4.5 billion kilometres,

and this isn't even the edge of the solar system.

It's just where the last planet out is.

In fact, the planets are very rarely lined up like this.

They're all spread out, going on their orbits around the sun.

But the experiment gives you an idea

of the distances between those orbits.

So, that's our challenge complete.

Hopefully you've now got an idea of the size of the solar system

and the scale of the planets.

Hopefully it's also something

you can try for yourself at home or at school.

We're at Herstmonceux Observatory,

waiting for another challenge to come through.

I've got my junior astronomers - Ellie, Matthew and Kain.

I've got our challenge coming in right now.

I love watching rockets blast off into space.

In fact, I'd actually like to know how to make my own rocket.

So, rather than me getting my hands dirty,

I'd like you to make me a rocket.

Yeah, that would be awesome!

You don't get a better challenge.

I've made a few rockets. It's always exciting.

How high might a rocket need to go to get to the edge of space?

Millions of miles.

Millions of miles.

Believe it or not, it's only about 20 miles. Up to the edge of space.

When was the first rocket launched up to space?

Well, the first one that was powerful enough to get up into space

was made by the Germans in the 1940s.

It was called a V2 rocket.

However, people have always played with launching things.

Chinese gunpowder rockets are the basis of modern-day rocketry.

They were invented in the 13th century.

700 years later, rockets enabled us to get to the moon.

Five, four, three, two, one...

The thrust from the space shuttle at takeoff is greater than that

from 30 jumbo jets put together.

For today's challenge, we need some little camera film cases.

We need some water. We need some kind of fizzy vitamin tablets

and probably some card and scissors.

-Do you reckon you can get that?

-I know where to get them.

-OK, go on.

So, how does it actually work?

This water and these tablets,

they combine together to make the fuel of the rocket.

When these tablets get dropped in water, they start fizzing.

That fizzing is them giving off a gas called carbon dioxide.

Now, if we confine that inside here,

then the gas pressure keeps building up.

When the gas pressure gets sufficiently high, bang!

It bursts the little launchpad off and your rocket heads skywards.

Oh, are they your fins?

So, we've got some amazing-looking rockets now.

But it's the moment of truth. We've got to see how they fly.

You've got to take the bottom off your rocket.

Very nice.

Then you get your fuel tablet, break it up into little pieces,

-then you've got to decide what's the right amount of fuel.

-All of it.

You've put the lot in. Oh, my life!

I'm staying this end of the table.

The next big decision

is to decide how much water you're going to put in.

Water does two jobs.

One, it reacts with the rocket fuel to produce the gas.

The other, it provides the weight,

the mass for the rocket to throw out the back, to jet itself forwards.

-I'm cunningly watching what you guys do.

-Three quarters.

Yours is going to go off pretty quick.

You don't want to lose that power, so make sure your lid is handy,

and, as quickly as possible, put the lid on and jam it closed.

As soon as you've done it, turn it over, step back.

Most rocket engines use either a solid or a liquid fuel.

This is burned to create hot gas,

which is forced out the bottom of the rocket.

This creates an opposite upward force called thrust.

Our home-made rockets work on a similar principle, creating thrust.

-Everybody ready to fuel up their rockets?

-Yeah.

This is absolutely crucial now that we get this right. Ready?

Three, two, one. Lid on.

I've done it.

Are you snapped on? Agh, we have a fuel leak!

There you go, rescued.

LID POPS

Aw! Aw! Look at that one!

Oh, that's fan... Yes. Fantastic!

There you go, Barney.

You wanted us to build a rocket, we've just built loads of them.

They're really not that difficult to make, so I reckon, make them at home,

make them at school. To be on the safe side, launch them outside.

That way, the sky's the limit.

With me are two young astronomers - Tiani and Dzhem.

They're going to help me with my next challenge.

Here it is. Let's have a look.

We've all seen different types of weather at different times of year,

but why do we have seasons?

Do you know why it's warmer in the summer and colder in the winter?

-Is it because of the axis of the world?

-It is.

The Earth has an axis

that spins around and is tilted over.

The Earth orbits the sun and is tilted by about 23 degrees.

Countries near the equator don't have four seasons like we do.

They often have just two - a wet and a dry season.

Now to solve this challenge,

what we've got are some very simple things.

We need the globe, a torch and some whiteboard markers.

So, let's get started.

The torch represents the sun

and the sun shines sideways at the Earth from over here.

Can you see, if you come round, you can see that the torch

is shining a circular light on the globe.

This torch is giving out fixed amounts of energy.

All the energy coming from the torch is landing on that circle there. OK.

What I want you to do is to draw a circle around

where the light is falling on the earth.

Can you see an oval? I'm going to try and hold the torch steady.

You see if you can draw around it.

Brilliant! So, this is winter.

In the summer, the Earth has come all the way around the sun,

all the way around here.

So, in the summer, Earth is here, and the sun is over here.

Now, could you draw around the light that falls on the earth now?

OK, so what's the difference

between those two shapes in the summer and the winter?

-The summer's smaller?

-That's right.

So in summer, we only have to share the energy the sun's giving out

with this smaller area here.

In winter, we have to share that same energy with all of this

so we get much less energy for ourselves.

That's why it's colder in the winter and warmer in the summer.

Sometimes people think that we have seasons

because the tilt of the Earth changes direction. That's not true.

The Earth is always tilted so that the North Pole

points towards the pole star.

As it goes around the sun, it still points towards the pole star.

When it's on one side, it's tilted towards the sun,

and when it's on the other side, it's tilted away from the sun,

meaning we get different amounts of light at different times of year.

So that's the solution to our challenge.

Hopefully you can try that for yourself at home or at school.

I've got two assistants, Lauren and Castor.

We've just got our challenge. So let's have a look.

I've always wanted to take a closer look at the stars and planets

but I don't have a telescope. Can I make one at home or at school?

Have you used telescopes before? Do you know what they're used for?

Telescopes are useful for looking into space and looking at stars.

Lots of things to look at out in space.

I saw a glimpse of Jupiter once at this observatory.

-What could you see?

-It was a big round ball with a red dot on it.

So, you saw the Great Red Spot of Jupiter,

like a pimple on the planet. Telescopes are arrangements

of lenses that we use to look at things out in the sky.

They use optics. They've been around for hundreds of years.

The first optical telescope was constructed in 1608

by the Dutch optician Hans Lippershey.

His children were playing with lenses

and realised that when they put two together,

a faraway church tower appeared much closer.

The following year, Galileo Galilei

built the first astronomical telescope

from a tube containing two lenses.

With this telescope and several following versions,

Galileo made the first telescopic observations of the sky

and discovered mountains on the moon

and that the Milky Way was actually a huge number of stars.

Since then, telescopes have increased in size

and produce much better images.

There is a special telescope that orbits the Earth

known as the Hubble space telescope.

It can photograph objects with ten times more detail

than Earth-based telescopes.

Our two astronomers go and collect what we need -

a selection of lenses of different thicknesses, something to look at,

some tubes, scissors and sticky tape.

So now we have all the things we need.

I'm going to take a pair of magnifying glasses

and Lauren, could you take those two there?

What's the difference between those two lenses?

-One is definitely thicker.

-One's thicker than the other.

What you want is to think about the thick one first.

We've got a globe over there. That's what we're going to be looking at.

What we're going to do first is work out approximately

where our lenses need to be.

So, what you need to do, is to hold up the thicker one

and put the thin one behind it.

Move them around a little bit. Move them further and closer to you.

-Can you see the globe?

-Mmm-hmm.

-Is it in focus?

-Yeah.

-What does it look like?

-It's upside down.

-It is upside down.

That's how telescopes work. You're always seeing upside down.

Now what we need to do, Castor's going to measure the distance

between the two lenses when they're in the right place.

-So, how far apart are they?

-30 centimetres.

-Brilliant, OK.

The next thing you need is a cardboard tube.

Astronomers can't stand around all night holding lenses.

Castor's going to take a tube there. I'm going to use the tube here.

You'll need to do is get some help.

Get some help cutting slots in the right place in a tube.

How are you going to make your telescope?

We're going to take the thicker lens and pop it in this slot.

And then what happens next, Castor?

-Then you measure it, put the cardboard bit in.

-What's that for?

That's to hold the glass in place.

Where should the small lens go down?

-Here.

-OK. Now let's see if we can get the telescope

to work inside the tube.

Come back over here.

Now, this thin lens may not be in exactly the right place first time.

What you may need to do is just adjust it a bit.

-Can you see the globe?

-Yes.

Is it in focus or do you think it could be better?

-In focus.

-Perfectly in focus first time.

-What can you see on the planet, Castor?

-I can see all sorts.

-Can you see any countries?

-Yeah.

-What do you think, Castor?

I think it's pretty amazing when you've just made it by home-made.

-It is pretty good.

-It's really easy to do, isn't it?

-Yeah.

How about you, Lauren? What do you think?

I think it's a good idea

that you can look at the stars with just a little telescope.

It makes things bigger.

All those things that are so far away, makes them seem closer.

We can't see any stars now because it's still daylight.

But we're all ready with our home-made telescopes

to have a look at the cosmos this evening.

You can do the same if you make your own home-made telescope.

We're here at an observatory in East Sussex

with a group of superb young astronomers

and we're waiting for a challenge to come in.

It should be coming in any moment.

I've always wondered how the Earth, sun and moon move around each other.

People used to think the sun moves around the earth

but that's not true, is it?

Does the sun go round the Earth or does the Earth go round the sun?

-The Earth goes round the sun.

-Like I said, superb young astronomers!

But how far away from the Earth do you reckon the sun is? 100 metres?

A million kilometres?

150 million kilometres? What do you reckon?

150 million kilometres.

Astonishing! We truly do have superb young astronomers.

The Earth is orbiting the sun at an amazing 108,000 kilometres per hour.

That's much faster than the average space rocket.

Of course, we cannot see the sun at night.

This is because the Earth's rotating

at the same time as it orbits the sun.

So different places on the planet face the sun at different times.

Seems like a bit of a massive challenge. Are you up for it?

-ALL: Yes!

-Excellent.

You've got to make yourselves look like the Earth, the moon and the sun,

and I've got to figure out the rest of it. Come on!

Whilst the kids are getting ready,

I'm going to mark out a bit of the solar system.

This circular path is the one that the Earth's going to have to take

as it goes round the sun.

The moon's got a slightly trickier job.

That's got to orbit the Earth as the Earth orbits the sun.

That's my orbit. Now all I need are the Earth, the sun and the moon.

That was the fastest-looking solar system I've seen.

That's what you guys are going to be - an element of the solar system.

So, you two in blue,

Dzhem, Tiani, you're the Earth.

Now, are you two OK holding hands?

-Yes.

-Yeah? Go on. For the sake of television,

for the sake of the solar system.

You have to hold hands and rotate around.

You both have to spin around.

How long do you think it takes the Earth to do one rotation -

-spin on its axis?

-One day.

-One day! Spot-on.

That's why it looks as though the sun rises and sets once a day.

So, come together and start spinning round.

Oh, beautiful! Round you go.

No, don't disappear into space. Just come rotating here.

It can't be that difficult.

The Earth does it every day and never complains.

Fantastic! I'm loving that. That's like a day, right.

Nice spinning. Now we need your satellite, your moon.

The moon's smaller than the Earth, it's actually quite a lot smaller.

We'll just have one body as the moon.

Now, how long do you think it takes you, as the moon,

to go all the way round the earth?

-A week?

-A week's not bad. A quarter of the way there.

The other thing is, the moon always keeps its same face to the earth.

We only ever see one side of the moon.

While these guys are turning, you go round with them.

Perfect. Keep looking at them.

You can go nice and slowly. Don't worry, Castor.

They have to go round about 29 times faster than you.

You just sort of keep with them.

Now, for the most important, in many ways, body in the solar system.

The thing that holds the solar system together, the sun.

You go right at the centre of the solar system.

It's your gravity that stops the planets

flinging off into outer space.

You've got an important job. You have to be highly energetic.

If the Earth and the moon are straying off,

it's your job to hold them together. So feel free to shout instructions.

So, you're here, providing energy and encouragement.

OK. You are simply astonishing, apart from we're going the wrong way.

Keep spinning round, keep spinning.

I think you guys are spinning that way.

Then this is your orbit now.

You have exactly one year to make it all the way round.

# Dizzy... #

Don't crash into the Earth!

# I'm so dizzy My head is spinning... #

You see these guys drifting in towards you, it's a disaster.

The Earth's going to burn up.

So shout, "No, you're coming to close to the sun!"

# You're making me dizzy My head is spinning... #

-Don't come too close to the sun.

-You'll burn up.

You're going to burn up planet Earth.

# And it's you, girl making it spin... #

This is brilliant. Keep going, keep going.

In real life you're supposed to be going 67,000 miles an hour.

You're coming to close to the sun!

That was good gravity. You kept them in such a good orbit.

# Like a whirlpool It's spinning... #

We finally managed it.

We've managed to simulate the movement of the planets

using just six people.

What we've got going on here is the sun's in the centre

and its enormous gravity is holding the solar system together -

stopping the Earth drifting out into space.

The Earth goes round the sun once a year.

The Earth rotates on its own axis once a day.

And the moon goes round the Earth once a month.

It all goes off in our solar system all the time.

I think these fellas have done an amazing job.

It's not easy, but I recommend trying it.

So, school field, playground, wherever. Best of luck.

I'm here at the Godlee Observatory in Manchester.

With me is Luke, who's going to help me with our next challenge.

Let's have a look what it is.

Sometimes when you look at the moon it's round,

but at other times it can be shaped like a banana. Why's that?

-I think we can solve that, don't you?

-Yep.

What do you know about the moon? Why does it light up?

Is the sun reflecting on it?

That's right. Just like us, the moon doesn't generate its own light,

it gets it all from somewhere else.

Do you know how old the moon is?

-No.

-It's really, really old.

Almost as old as the Earth. Its 4.5 billion years old.

It's not just the moon's age that's amazing.

There are craters and plains on its surface.

Just like here on Earth, there are mountains and valleys.

Because there's no weather to wear down these features,

you can see them really clearly.

Even the footprints of astronauts

who landed on the moon 40 years ago can still be seen.

That's what's on the moon. Our challenge is to discover

why it looks as if it has these different shapes

when seen from Earth.

I think we can do this with just a few things. I think we need

a revolving chair and something to be the moon

-and a bright light and a stick. Shall we go and find them?

-Yep.

Helen, I've got it.

Right, I think we've got everything.

I think you should be the Earth because you've got a blue top.

What have you got there?

I've got a polystyrene ball as our moon and a stick.

So the moon can orbit you because you're holding it on a stick.

Fabulous! And we've got a bright light in here

to set up as our sun.

Our universe has a bit too much light.

Let's turn the lights off.

Now the sun's lit, we're all ready to go.

So that you can see the moon all the way around you,

you need to be sitting on this spinning chair here.

That's right. Hold the moon out in front of you.

I'm going to spin you around

so you can see what the moon looks like as it goes around you.

What can you see?

I can see one minute it's white and the next it's black

and, in some shapes, it's like a banana.

So, it's changing gradually as you go round

and those are the phases of the moon.

You have to make sure you're holding it high enough.

If you don't you'll see that as you come round the back here,

your shadow will cover the face of the moon,

and that is what a lunar eclipse is.

So, holding it down low there, can you see the lunar eclipse?

-Yes.

-The shadow of your head crossed over the moon.

This lunar cycle starts with the new moon,

when you can't see the moon at all.

As the moon travels around the Earth,

it takes 29.5 days to get back to where it started.

On the way you can see all the phases of the moon.

So, what do you think?

We've cracked it, Helen, yes.

We have. If you have a simple desk lamp,

you can try this for yourself at home or at school.

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