What are the different layers of the sun's atmosphere? Which of these layers can we see, and why?

1.The sun's atmosphere is composed of several layers, mainly the photosphere, the chromosphere and the corona. These outer layers is the sun's energy, which has bubbled up from the sun's interior layers, is detected as sunlight.

Photosphere : lowest layer of the sun's atmosphere is the photosphere. Thickness of this layer is about 300 miles (500 kilometers).In this layer is the sun's energy is released as light. Because of the distance from the sun to Earth, light reaches our planet in about eight minutes.It is marked by bright, bubbling granules of plasma and darker, cooler sunspots, which emerge when the sun's magnetic field breaks through the surface.It is is also the source of solar flares: tongues of fire that extend hundreds of thousands of miles above the sun's surface.Solar flares produce bursts of X-rays, ultraviolet radiation, electromagnetic radiation and radio waves.
Chromosphere :Next layer of the sun's atmosphere is the chromosphere.It emits a reddish glow as super-heated hydrogen burns off. But the red rim can only be seen during a total solar eclipse. At other times, light from the chromosphere is usually too weak to be seen against the brighter photosphere. It may play a role in conducting heat from the interior of the sun to its outermost layer, the corona. "We see certain kinds of solar seismic waves channeling upwards into the lower atmosphere, called the chromosphere, and from there, into the corona.
Corona : Third layer of the sun's atmosphere is the corona. It can only be seen during a total solar eclipse as well.Corona appears as white streamers or plumes of ionized gas that flow outward into space. Temperatures in the sun's corona can get as high as 3.5 million degrees Fahrenheit (2 million degrees Celsius). As the gases cool, they become the solar wind.

The photosphere is the deepest layer of the Sun's atomsphere which we can observe directly. It reaches from the surface visible at the center of the solar disk to about 250 miles (400 km) above that.