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The energy released by sun is called solar energy. A
massive amount of hydrogen gas keeps on converting Factual Study

into helium at the core of the sun. Therefore, very The sun is approximately
large amount of heat and light energy is released in 93 million miles away from the
this process. Sun’s temperature on the surface is about earth. A car travelling at 96 km/hr
60,000˚C. Hence, all the living things are dependent would take about 1777 years to

on the solar energy for survival. reach the sun from the earth.

E arth

Earth is the third planet from the sun and the only planet which supports life. It protects
us from the harmful radiations of the sun.

About 30% of the earth’s surface is covered with land, while about 70% is covered by oceans
and other water bodies. Currently, about 7 billion people live on the earth.

The air that envelopes around earth is called atmosphere. There are three layers of earth

– Crust, Mantle and Core.

1. Core: Centre or the innermost layer of the
earth is called the core. The temperature
here is as high as 7000˚C, hotter than the Crust

surface of the sun. It is mainly composed Mantle
of iron and nickel. The outer core, in a
molten liquid state, extends up to 3,400 Inner
km. The inner core is situated about 1,220 Core Outer

km from the outer core. Core

2. Mantle: The layer between crust and the
core is called mantle. The thickness of
mantle extends upto 2,900 km. It is made

up of a thick, solid, rocky substance that
represents about 85% of the total weight and
mass of the Earth. Its outer region consists of
solid rocks whereas its inner region consists

of molten rocks. During volcanic eruptions, Factual Study
Mercury, Venus, Earth and
molten magma comes out from this layer to Mars are called the terrestrial
the surface of the earth.
planets. Terrestrial planets
3. Crust: The earth’s outermost layer is called crust. The are the innermost four
range of its thickness is about 5 km below the ocean planets of our solar system.

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