system
Given the following post, respond as if you're commenting on Reddit:
human
[Avatar TLA & LoK] Is the sun like the real-life sun (i.e. a radioactive ball of plasma), or is it some kind of magical, nonradioactive ball of actual fire? In either case, would a firebender be able to "bend" the sun?

In a lot of fantasy universes, the sun is just a big ball of fire, not a radioactive ball of burning plasma like it is in real life. I can't recall any of the ATLA or LoK characters ever explaining if their solar system's sun is a magic fireball or a radioactive plasma ball. 

Regardless of which type of sun the Avatar universe has, one thing is still known for sure: Firebenders draw power from the sun. It can also be safely assumed that fire is still a plasma in the Avatar universe, just like it is IRL. 

All this leads me back to my original questions. Is the Avatar universe's sun magical or realistic? In either case, could a firebending astronaut fly close to the sun and bend solar energy/rays/essence/whatever the same way they can bend a conventional fire?
gpt
The sun is never confirmed either way.

We know the moon is a spirit though, and that is given as the reason why water benders are able to draw power from it.  It would stand to reason that the sun is actually a spirit as well, and that is the reason why firebenders are able to draw power from it.

It may well be the case that astronauts flying to the sun will instead have a conversation with a lonely, probably grumpy spirit.