The Earth is a unique planet. It is the only planet in the Solar System that supports life. Now the question is, What makes Earth suitable for life?
Reasons that make Earth suitable for life
- It is located at an optimum distance from the Sun. Thus, it is neither too hot nor too cold.
- Its average temperature is 17°C, which is suitable for life forms to exist.
- The atmosphere of the Earth consists of gases such as oxygen, nitrogen, and carbon dioxide. Ozone present in the atmosphere protects the Earth from the harmful ultraviolet rays of the Sun. The atmosphere also does not allow the heat to escape into space and hence keeps the Earth warm.
- 70% of the Earth is covered with water. The hydrological cycle helps in maintaining the life forms on the Earth.
Life on the Earth began because of the existence of the atmosphere, heat, and water.
Conditions Favouring Life on the Earth
Biosphere: It is a narrow zone between the lithosphere, hydrosphere, and atmosphere. The upper crust of the Earth is called the biosphere where all forms of plant and animal life are found. Naturally occurring communities characterized by distinctive life forms adapted to broad climatic types are called biomes. Examples: Temperate forests, hot deserts
Ecosystem: The ecosystem is a community of living and non-living organisms which are interdependent in the same area. The relationships between living organisms and their interactions with their living and non-living surroundings constitute an ecosystem. There are numerous ecosystems in the world. Examples: Pond, desert, and river ecosystems The non-living components of an ecosystem are called abiotic components. Examples: Temperature, humidity, wind, soil The living components of the ecosystem are called biotic components. Examples: Plants, animals, humans
The Gaia Theory: The Gaia theory was propounded by the British scientist James Lovelock in 1979. According to this theory, the Earth acts as a single living and self-sustaining organism which can regulate and organize itself.