Why is Earth Called a Blue Planet

Question- Why is earth called a blue planet? 

Answer- Our planet earth has been called a blue planet due to the availability of abundant water. There is a constricted liquid water source in the solar system. Besides our planet earth, no source of liquid water has been located in the entire solar system and Interstellar space. 

The water on earth comes in many forms. Two third parts of the surface of the earth, that accounts for 71% of the planet, is covered with water. Rain water is the purest source of water on earth. Earth is also covered with fresh water from lakes and rivers. Oceans account for 71% of the planet. 

The ocean water is saline due to the presence of chemicals like chloride, sulphate, sodium, and magnesium. It also has a certain number of dissolved elements such as calcium, nitrogen and phosphorus. Nitrogen and phosphorus are elements that aid plant growth on earth. 

The oceans have been in existence for more than 90 million years. They give us an idea of the age of the earth. Earth has been in existence since approximately 3.4 billion years and the ocean bodies have had the same composition of chemicals and elements since the last 1.5 billion years. 

The chemical composition of the ocean bodies of our planet provide diversity in ecosystems and diversity in life on earth. Earth from space appears blue in colour due to the presence of these water bodies throughout the planet.  

Life can only be found on earth due to the availability of water and air. The air on earth has gases like oxygen which supports life. 

Life can only flourish where there is an abundance of water sources. Correct amount of mass, chemical composition and location determine the availability of a water source on a planet. Only earth has completed these conditions and is therefore called a blue planet.