Why couldn't you stand on the sun's surface?

Answer 1

The sun is comprised of more that 98% gas. The density of this gas near the surface is roughly 500 times less dense than the surface of the ocean while at its core it's more than a thousand times as dense as the ocean. So, assuming you are in a space suit that can withstand the temperature, you would find yourself falling right through the sun surface and travelling deep into the bowels of the star before the density of the gas nearer the core was great enough to offset the gravitational force and create buoyancy.

Also consider that the sun is likely around 1% solid matter. May not seem like much but that 1% is equivalent to several thousand earth masses. You would expect to impact something solid as you near the core. If you do some squats and eat your Wheaties, you could stand there.

Answer 2

It is impossible to walk on the Sun as it has no surface to walk on.

Apart from that "small" detail, you would be incinerated well before you got anywhere near it's extremities.

Answer 3

The sun is composed mostly of gas. Where it converts hydrogen to helium.