Astronomy

Introduction

The human knowledge in regards to the origin of the Universe stems from two primary sources: the study of the formation of stars in the molecular clouds nearby and the solar system itself. The both are completely different from one another. In the first scenario even when studying the star formation closest to Earth (approx. 140 pc from the Sun) there are unclear details and resolutions. Additionally, snapshots are taken like stop-motion animation during their formation stages to figure out the sequences in orders of time and the variety of processes and stage it undergoes. Also a few of the events or processes are not even applicable to the human Solar System (Woolfson, 2011, Pp. 170- 172).

The next source, solar system study has a lot of intricate data on the small heavenly bodies, satellites and the planets. However, the modern System has had billions of years to evolve in its current shape meaning that it has differed greatly from the initial condensed interstellar cloud.

Discussion

According to the modern theory, stars are born in molecular clouds. These clouds are formed containing 105-106 M? mass of hydrogen (Firefly, 2011, Pp. 200-205). There are cores or denser areas in the clouds where the formation of stars occur. A process, like maybe a shockwave originating from a close supernova, activates the cloud cores' gravitational collapse. Matter free falls towards the core's center by the influence of its own gravity and the huge body starts growing in the clouds' centre. The infalling matter is heated by the gravitational potential energy making it luminous. It is then called a protostar. Even though the temperatures and central pressures are that high that they might trigger a nuclear fusion, it still starts heating the thriving nebula which encircles the protostar. 106 years the cloud material's infall time in a solar-mass cloud. The said material of the infalling cloud is comprised of both dust and gas. The gases are majorly helium (22% by mass) and hydrogen (75%). (2%) is dust, which is mostly a mixture of interstellar grains for instance organics, condensed ices and silicates. Studies state that these grains of silicate are covered with mantles which are icyorganic (credoreference.com, 2007). As these grains of dust free fall inside, they go through huge pressures because of the rising gas density in the direction of the nebula's center. That breaks the speeds of the grains and also stops the motion of the inward radial component. Still, these grains of dust are able to move on a vertical scale in regards to the nebula's central plane, dictated by the original cloud core's vector of rotational angular momentum.

Once these dust grains start settling, they start colliding with each other. They start clumping and growing fast from their micro size to macroscopic objects that might be even a few meters. The whole process goes on and also accelerates when the grains start reaching the denser environment located on the nebula's central plane (Seeds, 2007, Pp. 105).

. They start growing from meter to kilometer ...