How do scientists know (with some certainty) the composition of planets’ (w/in our solar system) interior and core make up? How do they guesstimate the radius of the core? Thanks.

Question

An example of this is Mars. Here is a quote from Mars’ Wikipedia Page:

“Current models of its interior imply a core with a radius of about 1,794 ± 65 kilometres (1,115 ± 40 mi), consisting primarily of iron and nickel with about 16–17% sulfur.”

How the heck can this be estimated?

In: Geology

Answer 1

Well I just looked it up and it looks like it’s a combination of calculating using the force of gravity on the surface of the planet and making educated guesses as to what the core is made of based on the surroundings of the planet. The article I read explained that scientists know earth’s core is probably mostly iron because it’s extremely common in our solar system and I know from my high school physics class that there are a wealth of equations that could give you the size of one sphere within another based on their materials their masses and their gravitational pulls etc. I’m not professionally educated in this regard though…

http://www.bbc.com/earth/story/20150814-what-is-at-the-centre-of-earth