Several theories have been presented concerning the origin of the earth. The religious particularly the Christians, have their theory of divine creation. They believe that God created the earth and everything found around and on it including men.
According to the German philosopher Immanuel Kant, the earth, – along with the other planets in the solar system – originated from a huge gas cloud or nebula. At first, this nebula was col d and almost stationary. As time passed, particles inside the nebula began colliding with one another due to a gravitational force that caused them to spin like a top.
As it whirled at great speed, the nebula grew hotter and hotter until it became an immense sun that emitted rings of gas. In time, these rings cooled down and became the planets around the sun.
The French astronomer Pierre Simon Marquis de Laplace supported this theory. Laplaced believed that as the nebula aged, it shrank and became denser. Thus, it began to spin more rapidly. The shrinking and spinning flattened out the nebula into the shape of the disk, which spewed out rings of gas the subsequently became the planets and the asteroids.
In the 19th century, a number of American and English scientists challenged the Nebular theory. They presented the “Planetesimal Theory”, or the “Theory of the Little Planets”. It stated that, ages ago, the sun came very close to another star. As they parted at great speed, hot gasses streamed between them. These gasses gradually cooled off, turning into drops of liquid that later solidified into chunks of rock, or planetesimals. Gravitation them drew these little planets together to form bigger planets, one of which was the Earth.
Big Bang Theory
Among modern scientist, the most popular hypothesis on the origin of the universe was the “Big Bang Theory”. It stated that the Earth ad other planets in the solar system originated from a thick cloud of dust and gas that existed more than five billion years ago. This cloud floated in the atmosphere and gradually grew into a star-like object, due to gravitational force. The temperature at the center of the star became so intense that the star exploded like an atomic bomb, scattering numerous solid objects into space. There scattered bodies later became the planets.
In 1965 the discovery of a cosmic background radiation known to astronomers as 3 degree Kelvin radiation gave the Big Bang Theory greater credibility. The 3 degree Kelvin radiation was supposed to be the scientifically calculated “afterglow” of the explosive start of the universe called the “Big Bang”. Thus, its discovery greatly encouraged the supporters of the Big Bang idea. However, it is premature at this point to suggest that the question on the origin of the universe has been answered once and for all. It is unlikely that it will ever be answered with the same degree of certainty with which some other scientific questions have been resolved.