Astronomy Paper on Creation of the solar system

Astronomy Paper on Creation of the solar system


The solar system also known as the Milky Way was created about 4.6 billion years ago (Williams Para. 3). The most popular theory that explains its formation is the nebular hypothesis. This hypothesis claims that the sun started off as a giant rotating cloud of gas or simply as a nebula (Lang 447). As the cloud of the gas rotated and probably some of its gaseous materials contracted, the speed of rotation increased until some of the outermost materials of the cloud could not be held by gravitational force (Spangenburg and Diane 30). The outermost materials that left the cloud of the gas formed the planets and other objects that are part of the solar system. With such a background, this essay explores the process that was followed during the formation of the solar system. The essay focuses much of its attention on the formation of the planets and the moon.

Nebular hypothesis

To begin with, the nebular hypothesis claims that the sun originated as a rotating cloud of gas and dust as shown below.

(Seeds and Dana 118)

In the process of rotating, the gas and dust contracted and because of the high speed of rotation the innermost materials of the gas and dust were held together by the gravitational force as shown below to form the sun at the center (Spangenburg and Diane 30).

(Seeds and Dana 117)

Because of the high speed of rotation some of the gas and dust materials from the sun were stripped away, and the sun was left with 99 percent of the materials. The 1 percent of the materials that left the nebula formed the planets and other objects found in the solar system. The origin of the cloud of gas and dust that formed the sun is not known, but it is believed that these materials were part of the interstellar gas that was full of particles, rocks, dust and ice together with other particles. The collapse of these materials is also not known, but it is attributed to either shock waves or a passing star (Williams Para. 3). The process of forming the solar system took many years before each of the planet and the other objects could be formed. Astronomers believe that the process took about fifty million years before it was completed. During this period, the pressure and density of the hydrogen at the center of the nebula was so intense that it caused thermonuclear fusion. The process continued until there was a hydrostatic equilibrium. Once the equilibrium was attained, the remaining gas was swept away by the heliosphere that had been formed during the process. Consequently, it is highly unlikely that there will be formation of planets and other objects in the solar system in the future.

The planets

While most of the materials were held at the center of the cloud to form the sun, some of the materials were spilled to the outer part of the solar system to form the planets. These materials did not develop into planets at once. Instead, as the process continued, the materials collected depending on their densities and masses. As the materials collected and developed into bigger objects, they were able to conserve their momentum. The process continued with some of the planets colliding and forming other objects in the solar system. Due to the planets’ high speed of rotation, the solar system flattened to form the planetary disc (Seeds and Dana 117). The following picture provides a preview of what might have happened during the process.

(Seeds and Dana 117)

As it can be seen from the picture, the sun formed at the center whereas the planets formed in the outer part of the planetary disc.

In the process of rotating, the planets attracted more particles to themselves and they were able to increase their sizes. Nonetheless, they were limited by the dust particles that were available. According to this hypothesis, there are two types of planets. The first type is the terrestrial planets that have high densities due to the types of rocks and metallic matters that form them. These types of planets are closer to the sun and they include the earth, the mars and mercury as well as the Venus (Williams Para. 5). The hypothesis claims that the metallic elements as well as high density rocks were in small quantities. Accordingly, the terrestrial planets tend to be smaller in sizes in comparison to the Jovian planets.

The second type of planet is the Jovian planet. This type of planet has high mass, but low density. The planets that fall in this group formed outside of the orbits of Jupiter and Mars where they could cool and solidify. In contrast to the materials that formed the terrestrial planets, the materials that formed this type of planet were in plenty. As a result, the planets that fall in this group are big in sizes in comparison to the planets that fall in terrestrial planets. The proponents of this hypothesis believe that the solar wind that came from the sun swept away the remaining gases and dusts to terminate the planetary formation process (Williams Para. 7). The particles that left the solar system before they formed completely are believed to have turned into comets (Sills 66).

The moon

As far as the formation of the moon is concerned, different theories relating to the nebular hypothesis have been developed. One of the theories claims that the moon was formed as a result of the collision of the earth with the asteroid objects. The collision forced the earth to melt and form the moon (Torsvik and Cocks 78). Another theory claims that in the process of forming, the earth could have attracted some materials to itself. The assumption of this theory is that the moon could have formed in another place and later on it was attracted by the earth around its orbit (Trefil 180).

Over the years, the first theory that claims that the moon could have been formed out of the collision that resulted between the earth and asteroid objects has been accepted as the accurate theory. Majority of astronomers claim that this theory is capable of explaining some contentious issues relating to the materials that form the moon (Trefil 180). As a result, it would appear that during the formation of the solar system, the earth could have collided with asteroid objects, and the moon was formed out of that collision.



Despite the criticisms that surround the nebular hypothesis, it is amazing how collision could have resulted to the formation of the solar system. Basically, the formation of the earth could have started many years before the earth was created or even it developed to what it is today. Whichever the case, the nebular hypothesis plays a critical role in explaining the formation of the solar system. As a result, it is an important hypothesis in astronomy.



Work cited

Lang, Kenneth. The Cambridge guide to the solar system. London: Cambridge university press, 2011. Print.

Seeds, Michael, and Dana Backman. Astronomy: The Solar System and Beyond. Belmont, CA: Brooks/Cole, Cengage Learning, 2010. Print.

Sills, Alan. Barron’s E-Z Earth Science. Hauppauge, N.Y: Barron’s, 2010. Print.

Spangenburg, Ray, and Diane Moser. The Rise of Reason. New York: InfoBase Pub, 2004. Print.

Torsvik, Trond, and Cocks Robin. Earth history and palaeogeography. London: Cambridge university press, 2016. Print.

Trefil, James. The Nature of Science: An A-Z Guide to the Laws and Principles Governing Our Universe. Boston: Houghton Mifflin Co, 2003. Print.

Williams, Matt. How was the solar system formed? – The nebular hypothesis. Web. 8 Dec. 2016