Geology/Core of the Earth
From what I read, the center of the planet is a solid core that is made of nickel and iron and it is surrounded by a liquid core. My question is since we haven't been able to drill that deep into the planet, how do we know what the planet's core is like? thanks
ANSWER: The makeup of the interior of the earth is derived from inference due to the fact that the Earth has a magnetic field and the prevalence of iron in the crust. Our knowledge of petrography, or the formation and occurance of rocks along with mineralogy tells us that certain conditions of pressure and temperature cause elements of behave in certain ways. Then there is use of geophysics. Geophysics tell us that the center of the earth is stratified in density. Along with the other bits and pieces it allows us to make an educated postulation of how we think the interior looks.
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QUESTION: Thanks for the answer.
I have a follow up question. I don't want to get all conspiracy theory on you but it is possible for a planet (not Earth) to be hollow? This has nothing to do with the Hollow Earth Theory. I'm just curious whether or not it is possible for that to happen or would that question be referred to an astrophysicist.
Probably not since the planet would be dead. If the interior were hollow, imagine what would happen to it should a meteor or asteroid of any size were to strike it.
Hollow would mean the planet had cooled, and contracted. If our planet completely cooled the Van Allen belt would cease and its our primary protection against cosmic radiation which would then begin to strip off our atmosphere. You can imagine what would happen next. I don't know if all life would die due to the radiation before the atmosphere got to the point that it could no longer sustain life.
So a hollow planet would have no Van Allen belt like magnetic shield.