| MadSci Network: Physics |
The sun is just a giant ball of gas held together by its own gravity; since there's no solid surface to be 'on', your question needs to be rephrased. Astronomers commonly define the 'surface' of the sun as the photosphere, the uppermost region of glowing opaque gas which is the 'surface' we see when we look at the sun. The photosphere lies 695000 km from the center of the sun, and the sun's mass is 2 * 10^30 kg.
The gravitational acceleration at a point on or above a spherical mass is
M
g = G -----
r^2
where G is the universal gravitational constant (6.67 * 10^(-11)) and r and
M are the distance and mass given above. We get
g = 275 m/s^2which is 28 times as strong as gravity on the surface of the Earth. From our experience with astronauts and pilots undergoing high acceleration, we know that humans lose consciousness with this much gravity because the heart can't pump the blood up to the head, and would probably die if exposed to loads this high for a long time.
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