Question

ESSAY ON
FORMATION OF SOLAR SYTEM (600 WORDS)

Answer 1

Approximately 4.6 billion years ago, gravity pulled a cloud of dust and gas together (called nebula) to form our solar system. Although scientists aren't definite of the exact nature of the process, observations of young stellar systems combined with computer simulations have allowed them to develop three models of what could have happened so many years ago.

A shock wave from a nearby supernova explosion (when a high mass star uses up its fuel) probably initiated the collapse of the solar nebula. A massive concentration of nebula created a molecular cloud that would form the sun's birthplace. Cold temperatures caused the gas to clump together, growing steadily denser. The densest parts of the cloud began to collapse under its own gravity, forming a wealth of young stellar objects known as proto-stars. Gravity continued to collapse the material onto the infant object, creating a star and a disk of material from which the planets would form. When fusion kicked in, the star began to blast a stellar wind that helped clear out the debris and stopped it from falling inward. After the Sun formation in the center, a massive disk of material orbiting around it , from which planets are formed. In a similar manner, moons formed orbiting the gas giant planets. Comets (balls of ice and dust) condensed in the outer solar system, and many of them were thrown out to great distances by close gravitational encounters with the giant planets. After the Sun ignited, a strong solar wind cleared the system of gas and dust. The asteroids (small rocky or metallic bodies) represent the rocky debris that remained.

Processes in Solar System formation

Collapse and Rotation
The slowly rotating solar nebula collapsed under its own gravity to form a rapidly rotating disk, with the Sun at the center. Collisions of gas and dust within the disk concentrated the material into a thin plane.

Condensation
The inner region of the solar nebula was hot, allowing only rocky material to condense. The rocky terrestrial planets formed there. Gases and ice could condense in the cooler outer regions, where the gas giant planets and their icy moons formed.

Accretion
Small bodies collided and stuck together to slowly build up the terrestrial planets. Such accretion also built the cores of the gas giants until they were massive enough for their gravity to capture the abundant gases.

Differentiation
The terrestrial planets, as well as the larger moons and asteroids, have spherical layers that were created by melting and differentiation. Heavier elements sank to the center, forming iron-rich cores. Lighter materials were buoyed upward to form the outer rocky layers.