The sun is a sphere at the heart of the solar system comprised of plasma and gas. About 91% of the gas is hydrogen followed by helium. The sun is the most significant source of energy for all living organisms. The sun accounts for 99.86% of all of the mass of the solar system and it is the brightest body seen in the sky of the Earth and the sun's temperature varies greatly.
Core Of The Sun
At the sun's core is gravitational attraction which results in immense temperature and pressure. Temperatures here can top 15 million degrees Celsius. Hydrogen atoms in this region get compressed, and they fuse together to produce helium in a process referred to as nuclear fusion. Nuclear fusion releases tremendous amounts of energy which radiate towards the surface of the sun and eventually reaches the Earth. Energy from the core makes its way towards the convective zone.
This zone stretches for 200,000 km and reaches close to the surface. The temperatures in this zone drop lower than 2 million degrees Celsius. The plasma's density is low enough in this region to enable convective currents to emerge and transport the energy towards the sun's surface. The zone's thermal columns create an imprint on the sun's surface giving it a granular appearance named supergranulation at the largest scale and solar granulation at the smallest scale.
The photosphere is the sun's outer shell and it is from where light is radiated. Most of this layer's energy escapes the sun completely, and the layer is visible. The layer's thickness is tens to hundreds of kilometers and sunspots on it are darker and cooler than the surrounding region. At the core of large sunspots, the temperatures can be 4,000 degrees Celsius. The photosphere's overall temperature is approximately 5,500 degrees Celsius. The sun's energy becomes detected as visible light in the photosphere.
The chromosphere is one of the three primary layers of the sun's atmosphere and it is about 3,000 to 5,000 km deep. It is located right above the photosphere and beneath the solar transition region. The chromosphere is not normally visible unless there is a total eclipse during which its reddish color is sighted. The layer is not usually seen without particular equipment due to the overbearing brightness of the photosphere. The chromosphere's temperature is about 4,320 degrees Celsius.
The corona stretches millions of kilometers into space and like the chromosphere, can only be sighted easily during an eclipse. The corona's temperature can reach two million Degrees Celsius, and it is these high temperatures that give it unique spectral features. As it cools off, losing both radiation and heat, matter is blown off in the form of solar wind.
Importance Of The Sun’s Energy
The sun's energy enables the plants to generate their own food which in turn is consumed by other living things. The sun's light gives vision and also warms water. It is further significant in the formation of coal and petroleum oil, and it is also an important factor in the formation of Vitamin D which is essential for the growth of bones in the human body.