The photosphere.
During an eclipse, the outer layer of the sun that you can see like a halo, is called the corona.
The visible light emitted by the Sun originates from the photosphere, which is the outermost layer of the Sun's atmosphere. This is the layer that we see when we observe the Sun from Earth.
See "What does the ozone layer do?"
Hottest Layer of the Suns Atmospere.The core is the hottest layer of the sun. Its temperature is nearly 15 million degrees F.The reason that the core is the hottest is due to the gravitational pressure.This being said, there are individual spots in the corona of the sun which from time to time is known to be hotter than the core. The corona is an outer atmosphere of the sun (if you see a picture of a solar eclipse, the corona is typically the edge of the sun not covered by the earth).
The corona is the visible part of the Sun that we can see.
The portion of the sun normally visible from Earth is the photosphere. This is the outermost layer of the sun's atmosphere that emits light and heat, allowing us to see the sun's surface.
The sun's atmosphere, or the chromosphere and the corona, can be seen with the unaided eye only during a total solar eclips.
See "In what layer of the atmosphere do you find the ozone layer?"
The layer of the Sun that releases visible light is the photosphere. It is the outer layer of the Sun's atmosphere, located above the convective zone and below the chromosphere. The photosphere emits light due to the temperature of about 5,500 degrees Celsius (around 9,932 degrees Fahrenheit), making it the layer we perceive as the Sun's surface. This emitted light is what we see as sunlight.
See "Where is the ozone layer found?" in the "Related questions" section below.
The ozone layer's home is the stratosphere. It is embedded in that layer. The stratosphere is the 2nd layer of the atmosphere.
See the related questions section below.