The temperature of the surface was estimated in the late 1700's by William Herschel - and he got it right to within 10% of so! It is a fascinating experiment. He simply timed a sheet of ice melting in the noon-day sun, imagined the sheet as part of a huge sphere the same thickness surrounding the sun, shrunk the sphere without changing its mass to sit on the sun's surface - so it was now a lot thicker, and used known physics to determine how hot the surface must be to melt that much ice that quickly!
The surface erupts in huge flares, like these ones...
http://sohowww.nascom.nasa.gov/hotshots/2003_11_04/which throw material far into space - indeed way beyond the Earth's orbit...
The Earth is, of course, quite a long way from the Sun - how far?
/Bevin