system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do we know so much about the sun?

I was watching a video the other day that happened to include measurements of the sun's various layers, and I was thinking "Mhmm, right sure", when a bigger thought struck me- "Wait, what?". I don't doubt that the information is genuine, but I hear all the time that we can't even begin to approach the sun because of how hot it is. So how do we know the various depths of the sun's layers? How did we get a probe close enough? Is it done through estimation and educated guesses alone?
gpt
>How did we get a probe close enough? Is it done through estimation and educated guesses alone?

Well although we have sent satelites to study the sun, none have got particularly close. Estimation and educated guesses are certainly part of it, but it's really a case of being able to infer greater and greater information through observing it's behaviour, and coming up with testable theories that explain that behaviour.

For example we can measure the size and mass of the sun through a combination of geometry for it's size, and careful measurement of the movements of the planets let's us work out its mass. Spectroscopy tells us what it's made of, and an understsnding of how gases behave in different circumstances let's us extrapolate how hot, and how much pressure the gases must be under at the core.