What is the visible surface of the Sun called?
The photosphere is a layer below which the Sun becomes opaque to visible light. It is tens to hundreds of kilometers thick, and is slightly less opaque than air on Earth. Because the upper part of the photosphere is cooler than the lower part, an image of the Sun appears brighter in the center than on the edge or limb of the solar disk, in a phenomenon known as limb darkening.
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What is the source of the most powerful release of energy in the universe, second in scale only to the Big Bang?
What was the most beautiful comet of the second half of the twentieth century, with two tails visible to the naked eye?
There was no such comet