SOLAR SYSTEM

Detailed explanation-1: -Once the temperature reaches 15, 000, 000 degrees Celsius, nuclear fusion takes place in the center, or core, of the cloud. The tremendous heat given off by the nuclear fusion process causes the gas to glow creating a protostar. This is the first step in the evolution of a star.

Detailed explanation-2: -Fusion: The energy source of stars. The energy released from the collapse of the gas into a protostar causes the center of the protostar to become extremely hot. When the core is hot enough, nuclear fusion commences. Fusion is the process where two hydrogen atoms combine to form a helium atom, releasing energy.

Detailed explanation-3: -A protostar becomes a main sequence star when its core temperature exceeds 10 million K. This is the temperature needed for hydrogen fusion to operate efficiently.

Detailed explanation-4: -The cloud contracted under its own gravity and our proto-Sun formed in the hot dense center. The remainder of the cloud formed a swirling disk called the solar nebula. Within the solar nebula, scientists believe that dust and ice particles embedded in the gas moved, occasionally colliding and clumping together.