Question

Due to the nuclear reactions in the Sun, the temperature of the surface of the Sun is a million degrees centigrade

Answer 1

  MORENASA's Solar Dynamics Observatory saw sunspot AR 1520 before the solar flare erupted from it on July 12, 2012.Credit: NASA/SDO (via Twitter @NASA_SDO)

The sun is a big ball of gas and plasma. Most of the gas — 91 percent — is hydrogen. It is converted into energy in the sun's core. The energy moves outward through the interior layers, into the sun's atmosphere, and is released into the solar system as heat and light.

Nuclear fusion

In the sun's core, gravitational forces create tremendous pressure and temperatures. The temperature of the sun in this layer is about 27 million degrees Fahrenheit (15 million degrees Celsius). Hydrogen atoms are compressed and fuse together, creating helium. This process is called nuclear fusion. As the gases heat up, atoms break apart into charged particles, turning the gas into plasma.

The energy, mostly in the form of gamma-ray photons and neutrinos, is carried into the radiative zone. Photons can bounce around at random in this zone from somewhere between a few thousand to for about a million yearsbefore traveling to the surface, according to Sten Odenwald

Answer 2

It is because of Nuclear fusion