What would happen if we stepped on the Sun?
I mean in intrinsic detail. What would happen to our bodies besides "burst into flames"?
Wouldn't one be dead ,long before even reaching the Sun, from heat and radiation ?
Well first thing's first: You would disintegrate. At the temperature of the Sun, most of the molecules that make up our bodies could not even survive, that is why we would not only fry and die, we would really disintegrate (all the molecules breaking apart, leaving only loose atoms).
Let's now pretend heat doesn't exist. This is what would happen. First, we must remember that there is no solid surface to the Sun just like there is no surface to Uranus.
As soon as you reached the Sun itself, you would sink. The sun's density is less than 1 — and 1 is the density of water. So you would be sucked inside kind of. Except that there are convection currents. If we happen to be just above one, we might be kept close to the surface.
But, eventually, the eddies would entrain us sideways until we came to a "downdraft" that would take us downwards.
Anyway, let's talk about gamma rays now. Gamma rays are a form of light.
So even though heat is out of the way, all of these light rays are now trying to tear up whatever remaining molecules we have. This could trigger nuclear reactions.
Eventually, you (not me, I'm out of there) would cycle between two layers, in a convection cell moving you up and down, above and below the depth where the density of the gas is the same as the density of your body.
So I guess there's one sure thing about all of this.
You're going to need some sunscreen.
Assuming you have some kind of space suit made of unobtainable and you could survive the heat and gamma rays, the gravity on the surface of the sun is 28 times that of earth. If one of those up-drafts held you reasonably aloft, the gravity would crush you even in an indestructible suit. Humans can't survive 28 Gs for long. This would feel like more wind than you could ever experience on Earth, it would be quite the wild ride, for the half second you'd survive that is. :-)
If no updraft, you'd fall faster than you can imagine falling on earth. In 1 second on earth, you fall 16 feet. 1 second into the sun you'd fall nearly 450 feet, minus plasma resistance, of-course. As the plasma resistance slowed you down, you'd begin to feel the suns g forces again and get crushed again. The only way to really survive it would be a space ship (sun ship?) that flies through the sun very very fast at near orbital velocity, as this would counteract the gravity problem. We don't have that technology yet. (love your answer by the way Pies).
Looks like we'd fall about halfway to the core before reaching neutral bouyancy: http://th.physik.uni-frankfurt.de/~scherer/Blogging/StandardSolarModel/solar_density.png Of course, the graph gives no indication of what figure they're using for the suns's diameter.