Why is Earth the only planet that has life?

The earth’s atmosphere is unique and consists of land, water, and air. These three domains interact and overlap, making the surface of the earth a complex zone. They form the Biosphere of the earth where life exists.

• The land on earth is the place where we live and many animals and plants grow. These form our Lithosphere. 
• Water covers most of the earth and constitutes 71% of its total area. It is the place where many aquatic animals and plants live. All water bodies together make the Hydrosphere of the earth. 
• The air and gasses that surround the earth are important for our survival. The air, therefore, makes up the earth’s Atmosphere.

Let’s learn more about the earth’s Biosphere.

Lithosphere:

• The solid part of the earth. 
• It includes all the land as well as the entire earth’s crust including its soil, nutrients, etc.

The earth’s surface has two components: continents and ocean basins. All oceans are connected and hence, the sea level is the same all over the earth. However, the continents look separated from each other. 

Since the sea water level is the same all over the earth, it is taken as zero when measuring the elevation of the land. The height of any land surface is mentioned in comparison to sea level. For example, the height of mountains is at least 1000 meters above sea level.

It has 7 continents:

Hydrosphere:

The earth is covered 71% by water, giving it the name “The Blue Planet”. The water in oceans, rivers, glaciers, lakes, ponds, and even the underground water and water vapour makes the hydrosphere.

More than 97% of the total water is in oceans but is unfit for human use. The remaining 3% of water includes ice and freshwater sources.

It has 5 oceans: 

Atmosphere:

The earth is surrounded by a layer of gasses that gives us the air that we breathe and protects us from the sun’s harmful rays. This layer is called the Atmosphere.

The atmosphere has several layers starting from the earth’s surface and depending on the composition and temperature, they are called: Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere. Together, the total thickness of the atmosphere is about 1600 kilometres.

There are many gases in the atmosphere. However, nitrogen (78%) and oxygen (21%) make up the major portion of the total gas composition of the atmosphere. 1% of the total gasses include carbon-dioxide, neon, argon, etc.

So, we saw that the earth has three major domains- lithosphere, hydrosphere, and atmosphere. The lithosphere is land, the hydrosphere is water and the atmosphere is air. Together, they form the part of the earth where life exists- the biosphere.
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