Earth
Earth between the Venus and Mars, is the third planet in the solar system from the Sun. It is the fifth largest Planet in terms of density. It is spherical in shape with a diameter of about 12,742Km. It is the only Planet which is suitable for living .
Features
Earth rotates around the sun 365.256 days, a period called as Earth sidereal year. Earth’s gravity makes the interaction with the other objects in the solar system and space. Then the gravitational acceleration is approximately 9.8 m/s2. Earth is at a distance of 147 million Km from the Sun. surface area is about 510 million square Km.
Earth formation and History
Earth might have formed before 4.5 billion years ago, as per the radiometric dating and proof. Its age is one third of the age of the Universe. Its formation took place nearly at the time when the Universe formed.
The volcanoes and out gassing lead to the formation of the atmosphere and the oceans. From these volcanoes and out gassing, the water vapors condensed to form the ocean, which was supported by the water from the asteroids and comets. Then the greenhouse gases prevent the freezing of oceans. While the molten layer forms the crust of the Earth. At that time, the formation of solar system took place from a large rotating cloud containing the ice grains, dust and gas called solar nebula.
As per the realization from the ancient mathematicians, philosophers and astronomers, the establishment of Earth took place in the 17th century. A nebula separates a part of molecular cloud volume by gravitational collapse that starts to flatten and rotate into a circumvent disk. Then the Planets with the Sun came out of that disk.
Supercontinent formation
The process of Plate tectonics, in which the frequent heat loss inside the Earth, lead to the formation of the Continent. Over 750 million years ago, the earliest supercontinents Rodinia broken into parts. Then the recombination of the broken parts lead to Pannotia. Again some processes lead to the formation of Pangaea.
Atmospheric elements found in Earth
Earth contains 30.1% of oxygen, 32.1% of iron, 15.1% of silicon, 13.9 % of magnesium, 2.9% of sulphur, 1.8% of nickel, 1.5% of Calcium, 1.4% of aluminium and the remaining elements in 1.2%.
Rotation of the Earth
It rotates at a speed of 1600 Km per hour. The North Pole is the point in the Northern Hemisphere, where the axis of rotation of Earth touches its surface. Then the South Pole is the point where the axis of rotation of Earth meets its surface in Antarctica.
The deflection of oceans and the air currents by the Rotation. Earth’s faster rotation causes the deflection in the wind direction that leads to the rotation about the low pressure cells and high pressure cells. Earth takes 23 hours and 56 minutes to make rotation once about the axis. Then all the stars revolve about the Earth and come back to their beginning positions. This period of time is called the sidereal day by the Astronomers.
Revolution of Earth
Earth rotates the Sun at a distance of 149million Km and one full orbit consumes 365.256 days. This revolution refers to the path of Earth, through the space, due to which the seasonal changes and leap years takes place. When the Northern Hemisphere tilts towards the sun, then we see the summer. If the Northern Hemisphere tilts away from the sun, then we see the winter .
How Earth is suitable for living?
Earth and the moon have the gravitational interaction between them, which causes the tides. Then the tilted axis of rotation of the Earth with respect to the orbital plane causes seasons on Earth. It contains 71% of water and 29% of land (with continents and islands).
Lithosphere
The Lithosphere (the outer surface of the Earth) had split into many tectonic plates that move across the surface for several millions of years. Most part of the Earth’s polar part is covered with ice. The two types of Lithosphere are Oceanic Lithosphere and Continental Lithosphere.
1) Oceanic Lithosphere
This layer contains the oceanic crust, which is present on the ocean basins.
2) Continental Lithosphere
This layer comprises the continental crust with a density of about 2.7grams / cubic centimeter.
What are the five spheres of Earth?
The five main parts of the Earth as a whole form a complete system are rock, ice, air, water and life. Each of these parts is seen as a sphere. Hence there are five spheres.
1) Geosphere The Geosphere is the combination of the hydrosphere, cryosphere, hydrosphere and the atmosphere. This sphere comprises the Earth’s core, crust, mantle, rocks, continents, dust, sand, metal, asphalt and brick. The various parts of this Geosphere can exchange the masses or energy fluxes. This exchange of the fluxes causes effects on the balance of the different spheres of the geosphere. For example, the soil is the portion in the biosphere, which is also the source for flux exchange.
2) Hydrosphere
The Hydrosphere refers to the water source that exists on the surface of the earth. This sphere includes all the oceans, rivers, lakes, groundwater, snow and rain. This sphere frequently changes its shape due to the continental drift and the increase in sea level. In Hydrosphere, the saltwater is 97.5% and fresh water is 2.5%. In Earth, water plays a main role in controlling the atmosphere and ecosystem, thus Hydrosphere is more significant to the Earth.
3) Atmosphere
The Atmosphere is the layer that contains the gases which retains due to the Earth’s gravity. It comprises the oxygen, ozone, Nitrogen, wind and other gases. This part produces the pressure that allows liquid water to persist on the Earth’s surface taking in UV radiation, resulting in the greenhouse effect and lowering of the temperature between day and night. This part contains 78.09% of Nitrogen, 20.95 of oxygen, 0.93% of argon, 0.04% of carbon dioxide and less volume of other gases. Then the five major layers of the Atmosphere from higher to lower part are 1)Exosphere(700 to 10000Km), 2) Thermosphere (80 to 700Km), 3)Mesosphere(50 to 440Km), 4) Stratosphere(12 to 50 Km) and Troposphere(0 to12Km).
4) Cryosphere
The Cryosphere is a part which comprises all the water sources in the solid form on the earth. This includes the lake ice, snow, river ice, sea ice, glaciers and the frozen ground. Then the frozen water on all the parts of the Earth like ice, polar ice caps and icebergs form the Cryosphere. It is the integral portion of the global climate system with the interactions, through its effect on moisture fluxes, surface energy, hydrology, oceanic circulation and the precipitation. Cryosphere plays a major part in the global climate..
5) Biosphere
The Biosphere is the life zone on the earth, which is also called as Ecosphere. This Part comprises all the living organisms like humans, animals, plants, microbes and insects. This part is the sum of all the ecosystems with all the living organisms and their interactions. It includes the interactions with the geosphere, hydrosphere, atmosphere and Lithosphere. The Biosphere is significant, because no life will be there on the Earth like other Planets, without this Biosphere.