Grade 8 Geography : Solar System - Part 5 (Earth)

This is the planet we live in and it is the only planet where life exists. Water can exist in liquid form on the surface only on this planet and it is one reason that makes life possible on earth. Apart from the presence of water, the existence of gravitational power and a suitable atmospheric composition have led this planet to support life.  The atmosphere of the planet is composed of gases like Nitrogen (78%), Oxygen (21%) and a small amount of carbon dioxide, argon and neon. The production of oxygen though the process of photosynthesis in plants on earth contributes to the survival of living organisms to a greater extent.  For an instance, we cannot imagine life without oxygen to breathe.  Moreover, the atmosphere shields the earth surfaces from the effects of meteoroids where they burn halfway prior to landing on the earth’s surface. The Earth’s axis of rotation is tilted at angle of 230 degrees and this has led to the presence of different seasons throughout the year. It is the third planet.

 

 

from the sun and it takes almost 24 hours (one day) to complete one rotation. Earth’s revolution takes around 365 days to complete one round around the sun and we call this a year. It is also the largest planet among the inner planets; Mercury, Venus, Earth and Mars. We call this “the blue planet” as it looks quite stunning when seen from space.  Earth is also a terrestrial planet with a structure that consists of several layers namely, the inner core, the outer core, the mantle and the crust. Our home planet consists of one natural satellite and we call it “the moon”. 70% of this planet is covered by the ocean and 97% of water on earth are found in these oceans. On the other hand land makes up 30% of the earth’s surface. Earth also provides us with protection from the harmful ultra violet rays of the sun and this is done by the ozone layer that absorbs them. Several weather patterns, climatic zones, mountains, valleys and volcanoes are also present on this beautiful planet. 

 

 

 

 

 

 

 

by Mekhala Egodawele

Photo source : Internet