How the Planets Formed

Over the past centuries, astronomers have aspired to find the perfect explanation for the formation of our solar system. There are religious views and beliefs on how the world was created and there are numerous scientific explanations which explain this phenomenon. Various hypotheses and theories have been introduced and tested to verify how the sun, stars and planets were formed. The formation of the planets is a mystical and mysterious inquiry. One of the theories that explain how our solar system was formed is the nebular theory. The hypothesis was first formed in the 18th century by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace. The nebula hypothesis argued that the stars and planets were formed from slowly rotating gaseous clouds, or nebulae, which eventually collapse and flatten due to gravity. The nebula hypothesis claims that the solar system began as a nebula (area in Milky Way that was concentrated with cold gas and dust) that began to condense, due to some perturbation, or pull together under the force of the nebula’s own gravity. As gravity became stronger and more material was attracted to the center, concentration became faster. Gravity caused the center of the nebula to contract, causing pressure and temperature in the mass to reach so high that nuclear fusion began. As a result, the central mass became our Sun. At the same time, condensation was occurring in the disk. Gas and dust combined to create tiny particles, which gradually combined with other particles, creating bigger and larger objects. These objects grew into protoplanets. The protoplanets had much stronger gravity than the tiny particles of gas and dust surrounding them. They began to act like a vacuum, attracting the tiny particles around them and they began colliding at various times. Therefore, the collisions and the vacuum-like behavior made the planets of our solar system. The theory claims that these bodies were pulled into their sphere-like shape by the influence of gravity.

However, this model was challenged in the ’70s by astronomer Victor Safronov that introduced the widely accepted Solar Nebular Disk Model (SNDM). This model explains that 4.568 billion years ago, our star system was created when a tiny piece of a huge molecular cloud had the occurrence of a gravitational collapse. Much of the collapsing mass came together in the center and formed the Sun while the rest of the mass turned into a flattened protoplanetary disk from which many small solar system bodies and the moon, asteroids, and planets were created. In other words, planets are simultaneous by-products of star formation. In reality, Safronov’s model and the nebula hypothesis are not so different. They both explain the formation of the planets using many similar concepts such as gravity, gas and dust, and mass in their explanations. Furthermore, there are other theories that explain the formation of our solar system. The well-known big bang theory claims that at one point in time, all of the matter in the universe was contained in a small area. The heat and pressure that grew in this confined space became so massive and strong that it resulted in a huge explosion, causing everything in the universe to expand rapidly. Scientists supporting this theory claim that in about 2 minutes, 90% of the universe that is known to us today was created. They also use this theory to explain why the universe is continuously expanding.





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