The photosphere is the bright surface layer of the Sun that we can see. It separates the interior of the Sun from the exterior. It is only between 300 and 400 kilometers thick.
It is the upper layer of the convection_zone, where the energy causes movements of matter. These constant eruptions give the Sun's surface a grainy texture and a spotted appearance. When the photosphere is clearly visible, it can be seen that this graininess is not uniform in all areas and also does not follow a regular cycle.
The distinct structure of the Sun's surface is called granulation. It is caused by rising masses of gas with temperatures of 6000┬░ Celsius. The brighter granules are the tops of gas columns; the somewhat darker ones are colder and fall back into the interior. Each granule is between 300 and 1800 kilometers in diameter. Their life span averages between five and ten minutes.
Some areas of the photosphere do not have adjoining granules. These pores, as they are called, can be an indication of the forming of a sunspot. As temperatures here are lower than in the rest of the photosphere, these areas appear darker. Powerful magnetic_fields exist in the sunspots and are probably the cause of this phenomenon.
Solar_flares are another interference in the photosphere that can be observed. They are bright zones, which can be observed at the edge of the photosphere with a good telescope. Zones in which solar flares occur correspond with sunspots. The temperature is at least 300┬░ Celsius higher than its immediate surroundings. Solar flares are probably hot gases that have been forced up from the interior by heat currents.
