The Sun is the medium sized star which was formed about 460 crore years ago by condensation of vast clouds of hydrogen gas. The Sun is the main source of energy for all the planets including our own planet earth. It is about 100 times wider than earth and its mass is about million times more than the earth. The Sun is composed of 71% hydrogen, 27% helium and 2% heavier gases like carbon, nitrogen, oxygen etc.
The temperature at the surface of Sun which appears as a bright disc is about 55000C. This bright surface of Sun is called the photosphere. Above the photosphere is a layer of extremely hot gases called corona. The temperature of corona is about 20000000C. Corona is very faint hence it is not visible to naked eye in the presence of strong light. However, this layer can be seen easily during total solar eclipse because during total solar eclipse, the light from Sun’s disc is completely cut off.
The temperature at the core of Sun is about 150000000C. The main source of Sun’s energy is the nuclear fusion reaction. In Sun, two small nuclei of heavy isotopes of hydrogen (deuterium) combine with each other to form a heavy nucleus of helium. During this reaction a tremendous amount of energy is produced in the form of heat and light.
Test Your Understanding and Answer These Questions:
- What is the composition of sun?
- What is photosphere?
- What is corona?
- What is the temperature of sun?
- Which reaction is taking place in sun?
- What is the age of sun?