About the Earth:
We all know that earth is the only planet among the eight planets where life is possible. Can you answer why life is possible on earth? The answer is simple earth possesses a balanced atmosphere and a very important element that is essential for all organisms; water. Life on earth exists due to the presence of water and the appropriate distance between the sun and the earth i.e., the earth is neither too far from the sun nor too close which avoids making it either excessively cold or hot for a life form to exist.
70% of the earth is covered with water and it appears blue from space that is why it is also called the blue planet.
Movement of the Earth:
The movement of the earth is of two types:
Rotation is the spinning of the earth on its axis. Earth completes one rotation in 23 hours 56 minutes 4.09 seconds. Earth moves in rotation from west to east. The rotation of the earth causes day and night. In the part of the earth that receives sunlight, there is day and where sunlight does not reach, there is night.
When the earth moves around the sun in an orbit is called a revolution. The earth completes one orbit in about 365 days, 48 minutes, and 45.68 seconds. Generally, a year is a total of 365 days and the remaining 48 minutes and 45.68 seconds of each year make 24 hours in four years. These extra 24 hours add up and make an extra day. Eventually, the fourth year has 366 days and is known as a leap year. Hence in the leap year, February is of 29 days.
Structure of Earth:
Earth is made up of three layers:
The crust is the outermost layer of the earth's surface. The crust is made up of metamorphic, igneous and sedimentary rocks. Earth crust is of two types i.e., continental crust and oceanic crust. The temperature of the earth increases with an increase in depth. At every 32 meters, the temperature of the earth increases by 1o.
It is the second layer of the earth's surface. The mantle consists of 2 layers i.e., the upper mantle and lower mantle. It is 2900 kilometres thick and consists of 83% of the earth's volume. The upper mantle consists of 100 to 200 kilometres below the surface and is called the asthenosphere. The lower mantle is situated just below the upper mantle. The lower mantle extends from 670 to 2700 kilometres. This layer is hotter and denser making it appropriate for the formation of minerals.
The core is the innermost layer of the earth’s interior. This layer is rich in iron and nickel. The outermost layer of the core is in the form of liquid whereas the innermost core is in the form of solid.
Domains of the Earth:
The portion of the earth where we live is known as the lithosphere. It is the solid portion of the earth's surface which consists of a thick layer of soil with nutrients and rocks.
The atmosphere is a thick blanket of air which is constituted by several gases. The various gases of the atmosphere are oxygen, nitrogen, carbon dioxide, and others.
The hydrosphere is the total amount of water which is present on the earth in solid, liquid and gas forms. The solid part of the hydrosphere is in the form of ice (iceberg, glaciers, and icecaps), the liquid part of the hydrosphere is present in the form of river, sea, ponds, lakes, groundwater, etc. and the gaseous part of the hydrosphere is present in the form of water vapours.
The biosphere is the global ecological system where we find all four zones existing together. This zone is the life support system for all the life forms from a tiny worm to the giant elephant.
This article tends to be beneficial for the following exams - REET, UPTET, CTET, Online Classroom Program TET, DSSSB, KVS etc.
|Serial No.||Book Name||Author Name|
CTET Success Master Social Science/Studies Paper-2 for Class 6 to 8 2020
|2.||12 YEAR-WISE CTET Paper 2 (Social Science/ Studies) Solved Papers (2011 - 2019) - 2nd English Edition|
CTET Social Science and Its Pedagogy
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