Rockets

Artificial satellites are placed in their orbits around the earth with the help of very powerful launch vehicles or rockets. For this purpose specially designed rockets are fabricated by scientists. In rockets special kinds of fuels called rocket propellants are...

Satellites

A satellite is a small body which revolves around a planet. For example, moon is the satellite of the earth because it revolves around it. Satellites always revolve around the planets in closed elliptical paths. The closed elliptical path of a satellite around a...

Big bang theory

Various theories have been put forward by scientists to explain origin of universe. But here we will discuss only two theories related with origin of universe. These are: Big-bang theory and Steady state theory   Big-Bang Theory In 1920, an American...

Layers of earth

We have already studied in evolution of earth that the earth is made up of three layers. These are: Crust Mantle and Core   Crust Crust is the outermost solid and rocky layer of earth. The chief component of crust is silicon, which is present in the form of...

Evolution of earth

The earth was formed about 450 crore years ago from very vast clouds of gases and dust particles present in the form of disc around the sun. These particles of gases and dust collided and merged with each other to form small chunks of matter...