Who among us have no fantasy to know about our planet Earth. Every single nation has involved itself in expeditious research programs. These programs include the Earth, the Universe, and every location with the possibility for resources. The increasing population, and there need of ample amount of resources is forcing every country in the race of research and development. Let’s gather the information we have till date about the “Origin of Earth.”
Origin of Universe: Old Theories
- Nebular Hypothesis, by Immanuel Kant, revised by Laplace, 1896: Planet were formed out of cloud of material associated with youthful sun, which was slowly rotating, and slowly the matter condensed.
- Chamberlain and Moulton, 1900: A wandering star approach the sun, leads to separation of cigar shaped extension of material from solar surface, as the passing star moved away the separated material continued to revolve around sun and slowly condensed. When the cloud rotate faster it looses heat and radiation that slowly leads to contraction and compression of gases to solid. The solar extension slowly separated into 9 parts that is 9 planets. Later this theory was also supported by Sir James Jeans and Sir Harold Jeffrey.
- Binary theory by Otto Schmid, and Carl Weizascar, 1950: Sun was surrounded by solar nebula that contain mostly Hydrogen and Helium, along with dust particles. The friction and collision among the particles results formation of disk shaped cloud. The later times this disc leads to the formation of planet through process of accretion (or external accumulation).
Origin of Universe: Modern theories
- Big bang theory, 1920 by Edwin Hubble (expanding universe hypothesis): This theory defines the process in certain stages. At first stage, all the matter was concentrated at a single point with infinite temperature and density. At second stage, this particle exploded with a huge and rapid expansion within seconds leads to conversion of some energy into matter. At third stage, gradually the temperature drops to 4500K within 3 lakh years, and gave rise to atomic matter and the universe become transparent.
Origin of Stars
- Galaxy start to form by accumulate Hydrogen gas in the form of very large cloud, called as Nebula. Eventually the growing Nebula develops localized clumps of gases. These clumps continue to grow denser, leading to formation of stars (took 5-6 billion years ago).
Origin of Planets
- Planetesimal theory: Stars are localized lumps of gases within nebula. Gas cloud starts getting condensed around small round objects, forms smaller round bodies, called “Planetesimals.” These planetesimals by the process of Accretion, formed fewer larger bodies, called Planets.
Our Solar system
It consists of eight planets, sixty-three moons, and millions of smaller bodies called asteroids and comets with a huge quantity of dust, grains and gases.
- In 1838, George Darwin, suggested that the earth and moon formed from a single rotating body. This body was initially of dumb-bell shaped, eventually that breaks. It also suggest that the material forming the moon was separated from the Earth cause depression, called Pacific ocean.
- Giant impact or big splat theory: A larger body collide to Earth, it blast the portion into space. The separated portion continues to orbit earth, and eventually formed the present Moon.
Evolution of the Earth
The planet earth initially was barren, rocky and hot object with the thin atmosphere of hydrogen and helium. In early stages or pre-mordial stage or volatile state there was a gradual increase in density and temperature. At this stage the separation of matter on the basis of density that is ‘Iron’ will go to the core and the lighter will come at outer layers. After separation the body solidified, and formed the Earth.
Evolution of Atmosphere and hydrosphere
The earlier or primordial atmosphere was composed of nitrogen, carbon dioxide, methane, ammonia, vapor, and very little oxygen. This was lost by solar winds. The hot interior then contributed in the evolution of atmosphere, by degassing and volcanic eruptions. The continuous rain and evaporation from staring leads to develop giant oceans. The earlier rain dissolves the atmospheric carbon dioxide. In later times the composition of atmosphere was changed by the process called photosynthesis.
Origin of Life on Earth
According to scientific theories, the origin of life was a chemical reaction. It is associated with the conversion of inanimate matter to living substances. The life began on earth 3,800 million years ago from single celled, simplest organisms.