it's another beautiful day in Sydney
I'm out enjoying the Sun and looking to find out if anyone knows
Why the Sun shines?
So the sun gives us a lot of ... ? - Heat? Sunshine?
Provides energy (yes) heat energy
Where is the sun get that energy from?
Some kind of chemical reaction...
yeah gas explosions
Does it burn gas?
- It burns gases? - It's burning air - Fire
The fire that's on the sun
But is the Sun really a giant ball of fire
I mean wouldn't go out after five billion years?
This is one of the things that you just assume you know, but you don't actually know
So in this bucket I have the components of the Sun
Well, I have protons and neutrons
There's some electrons but I didn't bring them
Most of the Sun is actually protons - OK
So what the protons does in the Sun - It's dance together
Okay okay Like this
When they come close, you know what they do?
They just ... - Colide Actually they bounce off each other
I'm coming in... - UOOOOOOH
Why the protons bounce off each other? - Something about the electrons ....
Positive and negative eletrons?
Cause they don't like each other - They don't like each other
That's because a proton needs a neutron, right?
You know why they... they repel like that?
The repelling magnetic type thing?
Magnetic field, uh?
Positives and negatives.
Positive and Negative
It's to do with the positive negative, right?
We got protons, protons are?
-They're positively charged
-Yeah so the positives repel each other, ok?
This is why its so important that the sun's hot
Cause if the sun is hot enough it gets these things moving so fast, that sometimes they can't avoid a collision
-And when they get too close they actually go *Pshh*
-Smash the protons -Positive?
-Yeah, yeah, yeah, yeah No, no, no, sma... ahhh
and now they're stuck together and you saw what happened when they smashed together
*Pshh* is that energy?
Well the water poured out, but
I guess energy would have poured out then.
-The energy came out -The energy came out! what was the energy before it was energy?
-Kinetic energy? -Stored energy.
So what's happening there?
-It's releasing some mass... like lighting? -Yeah, yeah, and that mass is, uh?
-It's converted as energy, yeah
It was the mass of the proton -(Ahhh!)
When the protons smashed together they got lighter!
-Yeah, yeah, yeah
And they lost that mass and the mass was converted energy
-Yeah, yeah -You know the famous equation about that?
-(E = mc^2) -Yeah!
E = mc^2?
-which? process proton makes energy?
Ha ha ha ha
E = mc^2 squared? Yes?
So what's E?
The Sun, I don't know, ha ha ha
-E, E is energy, um
m is *mass*
C is.. -Cassidy
I don't remembers what C means...
So c is...
The speed of light
-Speed of light?
no, right? really -Yeah
-Oh, I thought it was something different -Isn't that weird?
The speed of light.
(Wow, no wonder we jumped science)
it seems most people have a tough time remembering that C is for the speed of light
maybe that's because C is a bit of a strange letter to represent a speed
in fact in Einstein's original paper he used the letter V
for velocity of light but nowadays everyone uses the letter C
for constant it's a constant of the universe the speed of light
though some people claim the letter C stands for celeritas
the Latin word for swiftness
What is that equation telling us about energy and mass?
Energy equals constant mass?
The mass and the energy...
combine together, create
Ha ha ha ha
it's basically saying like this mass that comes out -yeah
gets converted to a lot of energy
And the speed of light is a huge number
-Yeah -If you think about that, a tiny bit of mass is a huge amount of energy
so every second the Sun is actually losing 4.3 billion kilograms
every second -every second?
-That amount of mass is being converted into
In the Sun hydrogen fuses together to form helium
but, that's a little confusing because
how out of only protons do we create a helium nucleus which has
two protons and two neutrons well the thing is
when the first two smash together
one up the protons actually emits a positron and a neutrino
and quickly becomes a neutron
next thing that happens
is another proton smashes in *Pshh*
and again we get more energy released
now if two particles like this collide
*Pshh* they emit two protons
and what we're left with is a helium 4 nucleus
there you have hydrogen fused into helium
and a lot of mass lost, a lot of energy hehehe
if you wanna know more about fusion in the Sun check out this video by minute physics
it explains how the protons can fuse even though they're not really going fast enough
to overcome their repulsion
(...for fusion will fuse together anyway)
(and the Sun is so big it has so much hydrogen that these small chances happen all the time)