This is strange behaviour usually you think of if I have a ball of material and
I add more to it it gets bigger, in this case it's the exact opposite and the exact
opposite is because of that quantum mechanical effect that equation of state.
Which is that the additional pressure is so high as you add more mass in through
here that the density increase more than compensates for
the extra material that you have adding on.
And so your objects actually shrink, some think the mass of Jupiter,
made out of hydrogen and helium,
is bigger than something 20 times the mass of Jupiter made out of Hydrogen-Helium.
This is a cool plot seeing how, how hy, Hydrogen-Helium planet would go
as function of mass and it shows once again that Jupiter doesn't fit.
What is going on with Jupiter?
We'll talk also, when we talk about Saturn we'll.
Also, that Saturn doesn't fit either.
What is going on with Saturn?
One or
more of the assumptions that we made in trying to construct Jupiter was wrong.
There was really only one way to make Jupiter smaller for the mass that it is.
And, that's by adding heavier material to it than just Hydrogen and Helium.
Well, that's not a big surprise.
We know that the universe is more than just hydrogen and helium.
But even if we added these small amounts of additional materials that are in, say,
the sun, you would get very little difference.
You might drop it down by a little bit.
Jupiter has to have more material than just Hydrogen and Helium, and
it has to have more of that material than the sun does.
And there are two ways to have that material [INAUDIBLE] there are probably
more then two ways but there are two end members of ways you could have
that material you could imagine that Jupiter just had Hydrogen and
Helium and everything nicely mixed throughout.
Or, you can imagine, that, Jupiter has Hydrogen and Helium and
then a core of solid material that's a different composition.
We'll talk a lot about these two different ideas but I'm going to show you first that
this calculation, this a line that you see right here goes like this,
comes up like that, goes through Jupiter and keeps going.
That a line is for the composition of a planet that's mostly
Hydrogen-Helium except the inside has a core
that is 15 times the mass of the Earth, that's how I'll write Earth mass.
That's a little circle with a plus in it is the Earth symbol.
15 Earth masses.
Of material on the inside.
If I add this 15 Earth-mass core, I can make Jupiter.
Do I have to have a truth 15 Earth-mass core?
No. I can distribute that
material throughout there like this, and
we will use additional observations to try to determine whether or not this 15
Earth-masses that we need, extra, is down here like this or spread throughout.
Now, to be fair, one of the big problems that we have
in constructing our model of Jupiter is that equation of state.
The equation of state, particularly at the highest pressures, is pretty uncertain.
It's uncertain by a factor of a couple, and it's enough uncertain that
you could probably get away with using a slightly different equation of state.
You could probably get away with just Hydrogen and
Helium making it through Jupiter.
Most people think that the equation of state requires that there is this
additional material inside Jupiter, but it's not 100% certain.
What is certain, and again, we'll talk about when we get to Saturn,
this is the symbol for Saturn,.
When we get to Saturn is that even with a modified equation of state,
you can't make Saturn out of just Hydrogen and Helium.
There must be additional ma, material inside of Saturn.
if there's di, additional material inside of Saturn, and we think there probably is
additional material inside of Jupiter, we're going to go on the assumption that
it's, that it's probably really there, in one of these two forms.
And see if we can figure out what might be going on, on the inside.
