We spend a lot of time on top of our planet, but we don’t spend much time inside it. So it makes sense you might wonder what our planet is made of, deep deep down. Is it more rocks? Is it lava? Is it a gooey caramel center? And what about the other planets, like Mars and Jupiter? We asked astronomer Mark Popinchalk to help us find the answer.

Got a question that’s tearing you up on the inside? Send it to us at BrainsOn.org/contact, and we’ll help dig up the facts.

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