The glowing surface of the sun, which we see, is called PHOTOSPHERE. Above the photosphere, is the CHROMOSPHERE, so called because of its reddish colour.
The reddish colour being due to emmision by hydrogen, is the most important component of the chomosphere. The different chemical elements making up the chomosphere are observed to different heights. The highest one (14000 kilometres) is ionized calcium, although it is heavier than hydrogen.
Beyond this layer (chomosphere) is the magnificent CORONA of the sun which is visible during eclipases only, as a remarkable silverpearly radient glow around the sun.the inner part of the corona which is the brigjest, gives a continuous spectrum on which there are superimposed bright lines.
Between the chromosphere and the corona, spectroscopic investigations have identified a distinct, very narrow boundary zone known as the transition region.
The temperature of the photosphere is about 6000°celius, that of the chromosphere about 32,400° celsius, and that of the corona, which extends far into space, about 2,700,000°celsius hot enough to emit x_rays.(the density of the gas in each layer decreases with increasing altitude, just as the earths atmosphere thins with heigh.
At the core of sun where thermonuclear reactions take place the temperature level is around 15 million degrees k. ![image]
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The density of the core is estimated at a hundred times that of water. ![image]
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Outside the core is the convection zone.here,like the bolling water in a kettle,turbulent motions of gases transport the energy that is generated in core towards the photosphere. * item 
The vislble while light of the corona is made up of a continuum of colours, such as violest, infigo, bule, green, yellow, orange and red superimposed On this continuum are hundreds of dark lines called the fraunhofer lines,. 
Each line indicates some elements present in the solar atmmospher The intensity and width of the lines.