22nd December 2020 | Daily Brief

Prepare a note on the Solar System.

The solar system is made up of the sun and everything that orbits around it, including planets, moons, asteroids, comets and meteoroids. It extends from the sun and goes past the four inner planets, through the Asteroid Belt to the four gas giants and on to the disk-shaped Kuiper Belt and far beyond to the heliopause.

The four inner four planets — Mercury, Venus, Earth and Mars — are made up mostly of iron and rock. They are known as terrestrial or earthlike planets because of their similar size and composition. The outer planets — Jupiter, Saturn, Uranus and Neptune — are giant worlds with thick outer layers of gas. Between Mars and Jupiter lies the Asteroid Belt. Asteroids are minor planets.

• Origin: A number of theories have been propounded regarding the origin of solar system which are as follows:

1. The Accretion theory: the theory states that solar system was a cloud of dust and gas known as a solar nebula. Gravity collapsed the material in on itself as it began to spin, forming the sun in the center of the nebula. With the rise of the sun, the remaining material began to clump together. Small particles drew together, bound by the force of gravity, into larger particles. The solar wind swept away lighter elements, such as hydrogen and helium, from the closer regions, leaving only heavy, rocky materials to create terrestrial worlds. But far away, the solar winds had less impact on lighter elements, allowing them to coalesce into gas giants. In this way, asteroids, comets, planets and moons were created.
2. The Protoplanet theory: The protoplanet hypothesis suggests that a great cloud of gas and dust of at least 10,000 million kilometers in diameter rotated slowly in space about 5 billion years ago. As time passed, the cloud shrank under the pull of its own gravitation or was made to collapse by the explosion of a passing star.
3. The Capture theory:  It proposed that Sun interacted with a nearby protostar, dragging a filament of material from the protostar repeatedly which formed planets.
4. The Modern Nebular theory: Sun and the planets formed in a rotating nebula which cooled and collapsed under its own gravitational force forming planets.

Though a lot of research is underway regarding the absolute origins of solar systems, none had been able to solve the mystery completely without any flaws or unanswered questions. More progress of science and teachnological capabilities will help in getting closer to answer as more and more exoplanets keep getting discovered apart from newer observations from far-off galaxies.