The interior of Jupiter is a tough problem for us.
To get deep inside, we have to use indirect methods. We can't go there.
We think that Jupiter has a core but we don't know for sure.
It is nonetheless likely to be perhaps ten times the mass of the earth.
It may not be solid, it's very hot.
The pressure is too great, the temperature is too high, it's just too far in. We can't get there.
So what we have to do is to use radiation that's coming to us from those lower depths to tell us what's going on down there.
And this is where Juno comes in.
Juno is exciting because we will learn such a wide range of things.
For indeed Jupiter is the most massive planet in the solar system.
It is the body you want to understand in order to understand the architecture of everything else, including Earth.
What is the proportion of water on Jupiter compared to the amount of hydrogen on Jupiter?
And how does that compare with the proportion of hydrogen to water in interstellar space and in the sun?
That's a very important question and that's one of the things that Juno is going to address directly.
I would expect Juno to tell us more about how planets work.
Meaning how the heat gets out, what kinds of flows exist inside the body,
how magnetic fields get generated.
Learning what Jupiter is made of and learning about how it works
Those to me are what make the Juno mission exciting.