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Assuming it would be possible to handle the intense heat... Is the surface even? If not, would average surface elevation be an appropriate definition of "surface"?Does the sun have an atmosphere that would degrade visibility? How far apart are small solar flares that would block the horizon? What affect would the heat have on the light rays?

Assume I am 2 meters tall.

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Why did you assume yourself to be exactly 2 meters? :) –  Feynman Apr 29 '14 at 15:27
The sun doesn't have a hard surface as the rocky planets like Earth do, so this question is pretty meaningless. –  Olin Lathrop Apr 29 '14 at 23:04
@OlinLathrop That's why this question is pretty meaningless? Assume you can stand on it anyway (maybe you have a floating platform or an antigrav engine on your ultra-high-temp/pressure/gravity-resistant suit). Use a little imagination. –  iamnotmaynard Apr 29 '14 at 23:19
The question is very similar to "How far could I see if standing on the surface of Earth's atmosphere?" To answer, a definition of 'surface' is needed. It's not like a solid 'surface'. (Then, perhaps, when looking in what direction? Straight up?) –  user2338816 Apr 30 '14 at 10:56
@iamno: Imagining a platform to stand on doesn't help. Since the question is about surface roughness and resulting distance to the horizon, you need a hard surface or at least a abrupt transparent/opaque boundary for it to make any sense. Note the OP even said the observation height above the surface is 2 m. This can't be answered for something like the sun that has no sharp visual edge relative to 2 m. –  Olin Lathrop Apr 30 '14 at 15:15

3 Answers 3

According to Opacity of an Ionized Gas, "light from regions [of the sun] where the pressure is greater than 0.01 atm. is cut off completely, so that all we see comes from a spherical shell of rarefied gas".

There is no real surface of the Sun. Instead, the density and pressure of gas/plasma progressively increase from an infinitesimal value far from the Sun, to a very high value in the core of the Sun. If you flew at a level where the pressure is similar to atmospheric pressure of the Earth, you could not see anything (except light emitted from your immediate vicinity), according the the above statement.

See table 2-1 of The Photosphere for quantitative information on the opacity of the sun at different height. Only at a height in the sun's atmosphere where density is ~$1/10000$ of Earth's at sea level is a photon more likely than not to have a free path out of the sun without being scatterred or absorbed.

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but this page says the Sun has a solid surface: thesurfaceofthesun.com –  user13267 Apr 30 '14 at 4:30
@user13267 that page does not represent the mainstream view of the scientific community. See curious.astro.cornell.edu/question.php?number=673 and links therein for a discussion of that page. –  DavePhD Apr 30 '14 at 10:38

"If I were standing on the surface of the sun, how far could I see?"

Exactly the same distance as if you were standing on any other celestial body. Look up, the cosmic event horizon is about 14 billion parsecs away.

"If I were standing on the surface of the sun, how far away is the horizon?"

In theory, about 52km, assuming you survive the heat, gravity etc. and don't mind washing up and down in the surging plasma making up the surface. Any ejections or flares would be localized and transient. Also assuming it's a clear day.

"If I were standing on the surface of a sun-sized hollow sphere, how far away is the horizon?"

The horizon of the mini-Dyson's sphere would be about 52km away.

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This seems to be the (so far) only answer mindreading what the OP really wanted to know. I think it would greatly benefit from the math done to arrive at the 52km so whoever visits physics.se and wants to know the same for other stars can calculate it ;) –  PlasmaHH Apr 30 '14 at 11:10
@PlasmaHH Distance = √(height x (Diameter + height)) –  msam Apr 30 '14 at 14:03

Given that the sun regularly ejects plasma clumps kilometers long, or that "sunspots" are storms larger than the Earth's diameter, you may want to adjust your question :-).

The wikipedia page, http://en.wikipedia.org/wiki/Sun#Characteristics , gives a good description of the core, the plasma layer, the so-called atmospheric layer, and so on. If you dig into this info I suspect you'll find there is really no "surface" with any stable structure.

To answer the last question: "heat" is related to temperature, and photons are unaffected by temperature other than the chance that they'll interact with (or be emitted by) highly energetic particles.

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Heat is not a measure of temperature. –  Nathaniel Apr 29 '14 at 15:13
@Nathaniel: I am under the impression that, heat is a measure of temperature. If we have certain atoms of a particular object moving in random direction, I think their kinetic energy would generally mean heat and it would give us a measure of temperature, one could know its temperature by feeling it (not always). –  Feynman Apr 29 '14 at 16:17
"Heat" is not really a well-defined scientific term. Generally we view something as "hot" if it transfers a lot of energy to us quickly. A cast-iron frying pan feels much hotter (due to fast energy transfer) than a Space Shuttle tile at a far higher temperature (because it transfers almost no energy, thus being a great insulator) . –  Carl Witthoft Apr 29 '14 at 16:52
Thank you for the explanation. I understood what you meant to say. –  Feynman Apr 29 '14 at 17:30

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