Have you looked up at the sky on
a cloudless clear night? What do you see there high up in the sky? There are
millions of stars hiding the secrets of the universe. Among them, if you look
at the sky very carefully for some time, you can see blinking stars moving from
north to south or south to north and you will understand that their movement is
very fast. What are they? Why are they moving so fast? They are man made stars;
they are called artificial satellites.
An
artificial satellite is a space craft. It orbits the Earth at a fixed distance.
Artificial satellites are sent to space on various purposes such as
communication, remote sensing, military purposes, space astronomy. However, the
main purpose of satellite is communication. They bring the world together. It
is with the help of communication satellites we enjoy the thrill of Olympic
Games, World Cup Football, Asian Games or the World cup Cricket Finals being
played anywhere in the World. How does CNN or BBC news come to us? How does the
weather forecast come to us? They all
are communicated with the help of satellites orbiting the Earth.
The first Artificial satellite, Sputnik I was
launched by Soviet Russia (USSR) on 4th October 1957. It was a
competition between the USSR and the United State of America (USA) at the
beginning. Later, other countries like France, China, India & Japan too
started launching their own satellites for various purpose, mainly for
communication. In 1945 the honoured Sri Lankan citizen Arthur C. Clarke made a
very famous statement about making communication possible with countries all
over the world with the help of a space craft orbiting the Earth. The world
became a single village as a result of satellite communication. There are
commercial communication satellites like TELSTAR, INTELSAT ect. Providing
communication facilities for the whole world.
Geostationary
satellites orbit the Earth at a distance of 35900 Km and take 24 hours to
orbit. That’s why they appear almost at the same time of the day in the sky. If
you observe the sky for a few days you will be able to see these artificial
stars orbiting the Earth everyday at the same time. At the moment there are
more than 3000 satellites orbiting the Earth.
