The Earth system :
Our Earth's position is very special in the Solar family. The Earth is placed at a distance from the sun that makes its position very conducive for the growth of living organisms. The recipe of life is unknown, but likely ingredients were methane, carbon dioxide, ammonia and water in the atmosphere and seas of the young Earth. The action of ultraviolet radiation or lightning could have combined these chemicals into amino acids, the building blocks of protein and of all living things. Plants were the first life forms to colonize the early Earth, followed by the proliferation of humans and other animals. These lifeforms are the biotic components of the Earth. Yet another special feature is the shape of the Earth. For several years, people had different views about the shape of the Earth. During the twentieth century, many satellites were launched into space. The images sent by space by space shuttles prove that the Earth has a spherical shape.
The Earth has two motions. It rotates on its axis, inclined at an angle of 23 '0 . Due to this rotation, day and night occur. The Earth also on its inclined axis revolves around the Sun and thus produce seasons. The seasons are classified based on temperature conditions. In a year, there are spring, summer, autumn and winter seasons. So, the knowledge about the 'monistic' nature of the Earth system is very much needed, rather than only knowledge about components and elements.
The systems analysis helps us to understand the Earth's structure as a whole and also the functional interactions that exist between the components. Let us understand this with an example. Assume your school is a system. The students, teachers, and other employees are important components of this system. These components have individual functional elements such as learning, teaching and administration. These functions interrelate all of you so that your school system works effectively.
Besides, the land on which your school is located is a part of the lithosphere. Similarly the water you drink and the air you breathe are part of hydrosphere and atmosphere respectively. The lithosphere, hydrosphere and atmosphere are the abiotic components of the Earth. These components interact with each other and create the fourth component of the Earth, the biosphere. Biosphere interact with the abiotic elements and a number of ecosystems are created on the surface of the Earth. Thus the Earth is considered a unique subsystem in the planetary system.