Sun with sunspots and limb darkening as seen in visible light with solar filter.
The Sun exhibits limb darkening in a photograph taken from Earths surface. Being a black body, the Sun should show limb darkening, but as we have no photographs of the Sun from outside of Earths atmosphere, we can not say that it is not an effect of the atmosphere that is producing the darkening. Radio astronomy, going back to WW2 era, could not confirm the limb darkening due to the complexity of the experiments, some believe the darkening was detected, others said it may be diffraction in the Suns outer region, and that only the advent of instruments in space could answer the question with certainty. Well, there are no radio telescopes in space because they, like the optical telescopes, do not work outside of the atmosphere, so the question remains. If the limb darkening can not be shown from space, then the Sun is not a black body, and can not be assumed to be hot, or even warm.
In looking into the origin of water in the Universe I find that it is believed to be formed during the time when the young Sun was forming, when the hydrogen created in the re-ionisation phase of the Big Bang reacted with the oxygen which was produced in the early stars.
Scientists Just Discovered the Origins of Oxygen in the Universe
http://gizmodo.com/scientists-just-disc ... 1782092592These oxygen atoms we found are a kind of the first oxygen ever produced in the Universe, because oxygen did not exist at the Big Bang. In fact, all elements heavier than lithium are produced inside stars and are spread out the Universe when they die,” Inoue told us. “And oxygen and other elements make up dust particles which eventually make up planets and possibly life on them. Therefore, our finding shows the origin of oxygen, one of the most important elements for humans, in this Universe.
So oxygen is "cooked up" by fusion in the stars, and if a star is large enough, it will spew it out into the Universe when it finishes its life in a supernova event, and that oxygen, along with all the other stuff, then is gravitationally drawn together again to create our solar system.
Well, I don't buy any of it. I have a hunch, by no means certain yet, that in the late 1960s and 70s, that the Naval Research boys, most appropriately, were actually looking for signs of water creation in the Sun, by looking for the IR emission signature of the exothermic event that produces water, or rather a nano-ice with a temperature of around 170K. It is possible that with this idea I may be even more "out to lunch" than believing that the Sun is not visible from clear space, but until I see solid scientific proof that the Sun emits any heat whatsoever, I'll believe the Sun is most likely creating water.