Bitesize Space Science

I'm Jon Chase. Scientist, rapper, and maybe one day, space traveller.

I'm going to be answering some big questions

about space and the universe

by exploring the science we see all around us, right here on Earth.

If you want to get your head around space,

here are some of the questions you need to ask.

Have you ever stopped to think about

where everything around us came from?

It's a question as big as the universe itself.

In order to make sense of where it came from,

we need to understand the sheer scale of the universe.

And I think I've got a wicked way to put that into perspective.

I've come to Edinburgh armed with toilet roll

and peppercorns to show you what I mean.

Do you lot know how big the solar system is?

-Big.

-It's big, innit?

-Yeah.

-Right, basically if I took that as the Sun,

Earth would be about 100 times smaller.

We'll use these to represent different planets.

I'm going show you lot how far Neptune is. That's the Sun.

I'm going to use a special measuring device, bog roll.

It's the most scientific. I got it from NASA. Nah, blatantly not.

This is the distance from the Sun to Mercury, yeah?

Closest planet to the Sun.

There's Mercury, that little bad boy there.

Does anyone know the order of the planets?

Mercury, Venus, Earth, Mars, Saturn.

-Uranus.

-Jupiter.

-Jupiter.

-Uranus.

Right. I'll give you the method that you'll never forget from now on.

My very easy method just speeds up naming planets.

If you can remember that My starts with an M, so it's Mercury.

Very starts with a V, so it's Venus.

Easy starts with an E, so it's Earth, you get my drift.

My very easy method.

Although Pluto's now been reclassified as a dwarf planet.

There's Venus,

Earth is at two-and-a-half,

Mars is at four.

So Venus is closer to Earth than Mars is. I thought Mars was closer.

No. Yeah, Mars is a bit further. See, you're surprised, innit?

We could go to Venus, but the thing about Venus,

it's a rubbish planet to go to. It smells of farts.

I'm not joking! It smells of rotten eggs,

it's 400 degrees and it rains acid. Venus is rubbish. Go to Mars.

The next planet, Jupiter, is at 13. Let's go to Saturn.

And remember, this is all if the Sun was this big.

Uranus, as you can see, it's twice as far, as far as Saturn.

This is how far Neptune is.

Right. So as you can see, at this scale, space gets really big.

If you wanted to see the nearest star,

you'd have to have it in Glasgow.

And in this model, the distance from our peppercorn Sun in Edinburgh

to the furthest point in our galaxy

would mean rolling out toilet paper

to the Moon and back.

It's hard to imagine,

but our solar system is just

a tiny part of our universe

that evolved over billions of years.

To find out where the universe came from,

it helps to know a bit about where it's going.

You can get an idea about the movements of the universe

by visiting a racetrack like this.

ENGINE REVS

When the car comes closer,

the pitch of the engine appears to get higher.

As the car travels away from me,

the pitch appears to be lower.

You can hear the same thing

when an ambulance drives past with its siren on.

SIREN WAILS

And this is called the Doppler Effect.

Sound travels in waves.

When the car is coming towards me,

the waves appear to be closer together.

As they travel away from me,

there are fewer waves arriving to me each second,

so the pitch appears to drop.

Light also travels in waves.

When a light source moves away from an object at high speed,

the light looks redder.

Waves from a receding star have further to travel

to reach the object,

so appear to have a longer wavelength...

..or are red shifted.

Because you only see red shift in objects travelling away from you,

when scientists observed distant galaxies and found that they were also red shifted,

it proved that the space between everything in the universe was expanding.

If you imagine that this balloon is the actual fabric of space

and each one of these dots is a different galaxy.

As it expands...

..the dots get further apart.

If they're getting further apart over time,

it must mean that at some time in history,

all of these dots were closer together.

And at this point, when they were all really close together,

is what we see as the beginning of our universe.

Most scientists believe that the whole universe began

in an explosion about 14 billion years ago.

This is known as the Big Bang theory

and states that originally, all the matter in the universe

was concentrated in a single point.

So we can see the effects of the Big Bang, but we can also hear them.

Scientists have discovered microwaves and radio waves

coming from every direction in space.

This is called Cosmic Microwave Background Radiation,

or CMBR.

CMBR comes from light created at the beginning of the universe,

which, as the universe has expanded,

has been stretched into microwaves and radio waves.

1% of the static I'm picking up is radio waves,

which are part of the CMBR.

So even though it's the part of the radio you never want to listen to,

the part that you're least interested in,

it's still really amazing to think that actually,

that's the sound of the beginning of the universe

almost 14 billion years ago.

It's impossible to deny the huge impact of red shift

on our understanding of where everything in the universe came from.

So if we know that galaxies are moving away from each other,

maybe the next big question is, where are we all headed?

In the 1950s, scientists first started testing a new type of bomb

1,000 times more powerful than the atomic fission bomb

dropped on Hiroshima during the Second World War.

Four...three...two...one.

BOOM!

It was called the hydrogen bomb

and it was the first time mankind had recreated

the way the Sun makes its energy.

Now, as massive as this bomb was,

the energy it released was only a tiny fraction

of the massive amounts of energy released by the Sun every second.

BOOM!

This demonstration is to help us try and show you

how energy is produced in a star like our Sun.

Obviously, we couldn't give you an exact reaction that happens on the Sun.

That would produce so much energy,

you'd probably blow up your school, if not half of this country.

So we're going to give you a representative demonstration right here.

-You lot ready for this?

-ALL: Yeah.

We're going to have to step a bit back because it will get really hot.

And we have to make sure we've got our goggles ready just in case.

Now, this looks a lot better in the dark, so let's give it ten minutes.

TICKING

This reaction of iron oxide and aluminium powder

will create loads of energy in the form of heat and light.

It can help us imagine the way the Sun gives off heat and light,

but on a slightly different scale.

THEY GASP

-Was that pretty cool?

-ALL: Yeah!

So what we just saw there was a chemical reaction.

But when you look at a star,

the reactions that go on inside isn't a chemical reaction.

It's actually a reaction called nuclear fusion.

Nuclear fusion involves light atomic nuclei fusing to form heavier ones.

The two nuclei are both hydrogen

and they join to form one helium nucleus.

In our demonstration,

the heat produced by the flame started the reaction.

In a star, the reaction is started by gravity.

The force squeezes all the hydrogen at the centre of a star so tight

that it gets hot enough for their nuclei to collide together

with enough energy and speed to start fusing into helium.

In this process, more energy is released.

So in this reaction, it soared up to temperatures in excess of...

Actually, let me see what your kind of guesses are.

What type of temperatures do you think it was?

-1,000.

-1,000?

-2,000.

-2,000?

-3,000.

-3,000?

Exactly!

You lot are on the ball, aren't you? 3,000 degrees Celsius.

But in a nuclear reaction inside a star,

temperatures are actually in excess of 15 million degrees Celsius.

That's about 5,000 times hotter than this reaction that just went off.

-Impressed?

-ALL: Yeah.

And it's so hot that it's enough to burn through the metal of this can.

I'm going to pull it off now that it's cooled down a bit.

We've had it here for a while.

So that was the top of the can and this is the bottom of the can.

When scientists tested the hydrogen bomb,

they weren't able to control the amount of heat and light released.

This made it a massive uncontrolled explosion.

If scientists were able to carry out nuclear fusion in a controlled way,

it would solve all our energy needs in one go.

the Sun produces 400 trillion trillion watts of power each second.

That means in a single second, the Sun produces enough energy

to supply the whole Earth with power for half a million years.

So stars are like massive nuclear reactors.

They're fuelled by nuclear fusion,

which releases huge amounts of energy,

keeping the reaction alive so the star shines brightly in our sky.

So inside a star, it's like a billion hydrogen bombs

going off every second.

Man, that's immense!

BOOM!

Our closest star is the Sun.

And it's one of many billions of stars

in the galaxy we know as the Milky Way.

Just like people, stars are born, they live and then they die.

-Have any of you lot played Jenga before?

-ALL: YEAH.

Yeah, you've played then? Right.

This actual stack represents a star in the main part of its life cycle.

We call it the main sequence.

And that's the part where the star's forces inside it are stable.

And that basically means that when it creates all its energy

like heat and light that you see coming from the Sun,

it pushes out with an outward pressure on the star

and it tries to blow the star apart.

But the star has got so much mass

that's trying to pull it together with gravity.

That pulling together versus the pressure pushing out

eventually gets in a balance.

You get an equilibrium.

Each one of these pieces,

each one of these blocks represents a bit of energy.

So the idea is to try and see how much energy we can release

before it becomes unstable

and everything comes falling to the floor.

And then you lose...and I win.

The energy released by the star through nuclear fusion

creates an outward pressure.

The force of gravity acting on the star's mass

creates an inward pressure.

In the main sequence, these two forces are balanced.

This is the main sequence and the star will spend about

90 percent of its life doing this,

just slowly giving off energy.

And as long as gravity's balanced, we have equilibrium.

Oh-oh-oh-oh. Wow!

So as you can see, it's taking a while, isn't it?

Different stars do this at different rates.

So big stars use up all their energy really quickly,

they just kind of throw it all out, eject it.

There we go, energy's gone. Boom!

The smaller stars can stay on the main sequence for, like, a billion years,

maybe even billions of years.

So our Sun is a few billion years old and it's in its main sequence.

EXCITED CHATTER

It's looking very precarious here.

The star's about to end its life.

It's inevitable, you can't avoid it.

All stars eventually run out of the fuel they're burning,

it's just a question of when.

Whoo!

Another gravitational collapse of the core.

Gravity wins!

That marks the end of a star.

It's released so much energy

that now, it can't balance

the gravity that's pulling it together.

And eventually, inevitably,

gravity wins.

And that happens to every single star.

The gas and dust released when stars reach the end of their life

then goes on to form new stars and solar systems.

So, in a sense, by learning about the death of a star,

we're also learning about the birth of a star.

And that's because all stars go through a life cycle.

Stars form when enough dust and gas from space

is pulled together by gravitational attraction.

As this happens, the gravitational energy

is converted into heat energy and the temperature rises.

This is called a protostar.

Once the temperature gets high enough,

hydrogen in the star undergoes nuclear fusion.

This is when it enters a long stable period,

which we saw earlier playing Jenga.

The fate of a star depends on how much matter it contains.

At the end of its main sequence,

a low-mass star, like our Sun,

will expand into a red giant,

then a planetary nebula

before contracting into a white dwarf,

and eventually a black dwarf.

A really massive star will expand into a super red giant

before exploding in a supernova.

What's left will either be a dense neutron star

or, if the star is really massive,

it will end its life as a black hole.

So, you getting it?

Maybe a rap will help.

# It starts as a big cloud of dust and gas

# But then the gravity takes over and it starts to contract

# The gases are squeezed together as the masses attract

# To make the core get hotter from the steady collapse

# The hot gases expand with an outward pressure

# That can balance the gravity that's holding the star together

# Then at a certain temperature the core will start to enter

# Into nuclear fusion of Hydrogen at the centre

# They shine like beacons entering the main sequence

# The larger the mass the more energy they're releasing

# And as the core's depleting all the energy it's keeping

# The pressure pushing outward from the core begins to weaken

# Gravity takes over now beginning to squeeze

# The core shrinks under the weight thus increasing the heat

# For nine tenths of its life the main sequence has been

# It's main home, now it's growing and it's ready to leave

# A low-mass star can become a red giant

# Then a planetary nebula is next in line

# Where you'll find a white dwarf that was left behind

# Before dimming into a black dwarf over time

# We get a red super giant from a star that's large

# A supernova marks death of these larger stars

# They leave a neutron star in their aftermath

# And if not, a black hole is thought to end their path. #

This life cycle of stars is an essential component of the universe.

At its heart is the process that produces

almost all the elements on Earth.

So every atom of carbon that makes up my body

was actually born in a dying star.

So really, we're all made of stardust.

On Earth, scientists can work out

the chemical composition of most objects.

But what do they do if the object is thousands of kilometres away?

The Sun is our nearest star

and it's a staggering 150 million kilometres away.

Now, the fastest car on planet Earth

goes at 430 kilometres per hour,

but even at that speed directly to the Sun,

it would still take us more than 40 years to get there.

Now, I haven't got a car that goes anywhere near that speed,

so, how are we going to find out what it's made of in five minutes?

I reckon I can get halfway there with this cardboard tube and an old CD.

Have you ever seen a demonstration

where white light has been split into loads of different colours?

Red, orange, yellow, green, blue?

-No.

-No.

-Like a rainbow?

Oh, yes! It is exactly a rainbow.

But you can also do it using a tube and a CD.

Don't look on the other side, you don't want to see the music that I listen to.

And if we use this special device like that,

what we can do is, if you look through that hole at the CD,

you'll be able to see, kind of, different colours.

So I'll let you all have a go.

Point it around, see if you can catch the light.

-I don't know how to do this!

-LAUGHTER

I've got another way to make it a bit brighter.

So this is an LED light

and that will give you a nice white light

that consists of all the different colours like that.

If we shine that through the end, you might be able to see it a bit better.

-I can see it now.

-Can you see all the different colours?

-Oh, my gosh, yeah. That is so cool!

-It's like making your own rainbow.

This simple, homemade spectrometer

is surprisingly similar to the equipment scientists have used

to observe the light being emitted from the Sun.

And we can learn more about the light that the Sun emits on Earth

by observing the colours produced in the flames of burning elements.

By burning compounds containing different elements,

we can see that they each have their own characteristic colour.

Potassium gives a lilac flame.

Lithium gives a red flame.

Sodium gives a yellow flame,

whereas copper gives a greenish blue flame.

Now, each element not only emits a certain type of light,

it will also absorb

the exact same colour of light.

It's because of the light given off by the elements reacting

that we are able to know what the Sun's made of.

This is an absorption spectrum of the Sun.

It's just like the spectrum we saw earlier,

but it's a lot more detailed.

These dark lines show where light of certain wavelengths

is absorbed by the elements present in the Sun.

We know elements emit and absorb the same wavelengths of light,

so this means the dark lines also correspond

to elements being emitted by the Sun.

As white light passes through

the Sun's atmosphere,

some wavelengths are absorbed

by atoms of the elements present.

This means that the light

that reaches us from the Sun

is missing some wavelengths,

which correspond to an element

in the Sun's atmosphere.

So the dark lines in the spectra of the Sun

show that it's made of hydrogen, about 70%,

helium, about 28%, and elements

such as nitrogen, oxygen and iron

in much smaller quantities.

If we look at the spectrum of any distant star,

we can work out what they're made of, too.

This has helped scientists make some amazing discoveries

about stars in our universe.

Many of which are very different from our own star, the Sun.

If you travelled to another planet,

it's not just extra terrestrials you might have to contend with,

you might also weigh twice as much as you would on earth.

Now, it might sound a bit strange,

but finding out about how our weight would change

on different planets of the solar system,

is linked to understanding how forces act.

And I've come to the fairground to find out more.

Gravity is a force.

It attracts objects with mass towards each other.

In space, it might look like there's no gravity,

but astronauts are weightless because they're in orbit,

so they're constantly falling towards the earth.

The weight of something depends on its mass

and the gravitational field strength.

Weight is measured in Newtons

and mass is measured in kilograms.

Weight is a force.

And it's caused by the pull of gravity acting on a mass.

Mass is the amount of matter in an object.

Unlike weight, it's not a force.

An object's mass has the same value anywhere in the universe.

On other planets, our mass stays the same,

but our weight would change.

That's because the gravitational force

on different planets is different.

Some of my mates have come down to help me show you what I mean.

It's not the warmest of days here on Earth,

but I'm not one to let a bit of cold get in the way of a science demo.

Guys, do you have any idea what it would be like

to be on another planet and what it would feel like, what you'd weigh?

-ALL: No.

-Right. Well, this ride will give us some idea of that.

Let's give it a go.

So we are presently, currently on planet Earth.

Let's do a visit to Jupiter.

-OK. Yeah, ready, ready.

-Oh, no, I'm scared!

OK.

YELLING

LAUGHTER

YELLING

-We are still alive.

-Whoo!

Right, so what part of that ride felt the lightest?

At the top. It made your stomach go funny, dizzy. Dizzy stomach.

Dizzy stomach! And when did you feel the heaviest?

As it, kind of, came to the bottom. A little bounce.

Wicked! You see, that ride is like actually being on other planets.

When you was at the top and at the lightest,

it's like being on a planet with less gravity, like Mercury.

But when you was at the bottom on that bouncy part where you felt a bit heavier,

well, that heavy feeling, that's like being on a bigger planet.

For example, like Jupiter.

Except you wouldn't just be feeling like that when you hit the bottom,

you'd just always feel like that.

Being on a ride like this is the closest you can really get

to actually being on another planet.

-LAUGHTER

-Yeah!

Because we know that our mass is constant,

it must be the gravitational forces

that make our weight change.

On Earth, the force of gravity on a one kilogram mass is ten Newtons.

So if my mass is 70 kilograms,

then the force of gravity on me makes my weight 700 Newtons.

As the chair and I fall,

I'm pressing less on the chair

and appear lighter.

Similar to astronauts in the space station.

This would be the same feeling on Mercury.

There, the force of gravity on a one kilogram mass is just four Newtons.

So if my mass is 70 kilograms,

then the force of gravity on me makes me weigh about 280 Newtons.

That's like me weighing as much as your family dog.

BARKING

At the bottom of the ride when it starts to slow down,

the forces were unbalanced and I felt much heavier.

This would be the same feeling on Jupiter.

There, the force of gravity on a one kilogram mass is 25 Newtons.

So if my mass is 70 kilograms,

then the force of gravity on me makes my weight about 1,750 Newtons.

This is like weighing as much as a gorilla.

So the greater the mass of the object,

the stronger the force of gravity.

That's why you'd weigh more on Jupiter.

Gravity also keeps planets and moons in orbit.

We know the gravitational pull of an object is determined by its mass.

This can also help us make sense

of the movement of the whole solar system.

All the planets and moons in the solar system

spin around a central point.

A bit like me on this roundabout.

The object with the greatest mass sits at the centre

and its gravitational pull

attracts other objects into an orbit around it.

And that's why every planet in our solar system orbits the Sun.

It's all down to gravity.

If you were to travel into space,

you might feel far away from life on Earth.

But space can actually help keep us connected.

It's all down to understanding the properties of different waves.

Now, you see when I shine this light?

That's just called visible light.

But did you know that there's other types of light that you can't see?

-No.

-There's also a type of light called infrared.

You might have heard of it on things like these, TV remotes.

To change the channel, you push a button and it changes.

There's a little red light in there.

There's a little light in there, isn't it?

-Tell me if any of you can see it.

-No.

Have you all got mobile phones?

-I do!

-Wicked!

-They've got cameras on them, yeah?

-Yeah.

You need something that's sensitive to infrared light.

-But look what your phones are capable of doing.

-Red!

-Yeah, it's red.

-Can you see the light? You can see a light off it?

-Yeah!

-And that's because your phones don't just see visible light,

your phones see infrared.

But your eyes only see visible.

The sensor on the phone's camera can detect

a wider range of wavelengths of light than our eyes can.

We can only see visible light,

but there are other light waves, all with similar properties.

We call all of these types of waves

electromagnetic waves.

And they are all arranged

on the electromagnetic spectrum.

At one end of the spectrum,

we have low-frequency radio waves and microwaves.

Infrared, visible and ultraviolet waves have a higher frequency.

While X-rays and gamma rays

have a very high frequency

and are at the opposite end of the spectrum.

All electromagnetic waves carry energy from one place to another.

And they do it at the speed of light.

They can also travel through a vacuum, such as space.

That's why they're used in communications,

because the signals can be sent rapidly across large distances.

Vans like this make sure we never have to miss any event, however far away.

They're equipped to send live video back to a TV broadcaster

from anywhere in the world.

They do this by sending microwaves

through the atmosphere to be

picked up by satellites in space

thousands of miles above the Earth's surface.

The signal is then sent via satellite

back to a TV broadcaster.

So, how does the signal actually get to my TV set at home?

The TV broadcaster can transmit it to your TV in different ways.

If you've got an aerial on your TV at home,

you receive the signals via radio waves transmitted by a TV mast.

If you've got a satellite dish on the side of your house,

you receive the signals via microwaves sent from a satellite.

Ah! Does that mean when I watch my favourite football team live on TV,

the signals have to go miles into space

and back again before getting to me?

Got it in one.

The signal isn't sent directly

because it would be absorbed by obstacles such as buildings.

Ah, that makes sense. I'm feeling your hat, by the way.

Nice one. Yours ain't too bad yourself.

Yeah!

So nearly all forms of communication,

whether emails, texting, TV or the internet,

uses some part of the electromagnetic spectrum

being sent through space.

And that's pretty amazing!

Now all it leaves for me to do is...wave goodbye.

# It starts in the radio waves

# With a lower frequency than the microwaves

# That come next as we step over the infrared

# To find Richard of York giving battle in vain

# But no threat, that's a mnemonic for the visible spectrum

# That blends into ultraviolet radiation

# Then X-rays come at increased frequencies

# With the gamma rays taking up the highest energies. #

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