Earth facts

Earth is one of the planets of our solar system and it belongs to Milky Way galaxy. It has only one natural satellite
called the moon. It is the third planet from the sun.

  • Its weight is roughly 5,974,000,000,000,000,000,000,000 kilograms.
  • According to our knowledge, it is the only planet that has life.
  • It has 70% water.
  • Once upon a time, people believed that earth is flat in shape.
  • The earth rotates west to east on its axis.
  • Its orbital period is 23 hours, 56 minutes, and 4 seconds. It takes 365.24 days to rotate around the sun.
  • It is the largest of the terrestrial planets.
  • It is the only planet in our solar system not to be named after a Greek or Roman deity.
  • The Ozone layer is found in the stratosphere. Ozone layer saves us from the ultraviolet radiation coming from the sun.
  • In ancient times people believed that earth is the center of the universe.
  • Polish astronomer Nicolaus Copernicus put forth that sun is the center of the universe and all planets are revolving around the sun.

Earth’s Atmosphere is divided into five main layers. They are Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere.


Atmosphere of Earth

Troposphere          :     0 km to 12 km. (0 to 7 miles)

Stratosphere          :    12 km to 50 km. (7 to 31 miles)

Mesosphere           :     50 km to 80 km. (31 to 50 miles)

Thermosphere       :     80 km to 700 km. (50 to 440 miles)

Exosphere               :     700 km to 10,000 km. (440 to 6,200 miles)


Composition of air

Nitrogen                        78 percent

oxygen                             21 percent

Argon                              0.6. percent

Carbon dioxide            0.04 percent

There are some other gases in trace amount. They are helium, neon, methane, krypton, hydrogen

and water vapour.

Earth’s inside

Earth inside

The inner parts of the earth divided into four layers. They are crust, mantle, outer core and inner core.

The outermost solid part is crust. It is divided into oceanic crust and continental crust. The Crust

thickness averages about 30 kilometers (18 miles) under the continents, but only about 5

kilometers (3 miles) under the oceans. The thickness of  mantle is 2,900 km thick and composed of

molten/solid rock. The thickness of the outer core is 2,300 km (1400 miles). It is composed of nickel-iron alloy.

The inner core is earth’s innermost part. The Inner Core is about 1250 km thick and is the second smallest layer.

At the very center of the earth, the gravitational force is zero.