When was the first artificial satellite launched?

           A satellite is a body that orbits around another but the term is usually applied to small bodies which orbit around the planets. Most of the planets have satellites revolving around them. For example, moon is the only satellite of earth. But apart from the natural satellites of the planets, several man-made or artificial satellites have been launched which now orbit the earth and some of the other planets in the solar system. But when did man send the first artificial satellite into the space? 

          The first artificial satellite was launched into the space by the former USSR on 4 October 1957 which was called Sputnik I. Sputnik is the Russian word for a travelling companion. It was spherical in shape with a diameter of 58 cms and weighed 83 kilograms. It orbited the earth every 96 minutes. A month later the launching of Sputnik 2, which weighed 500 kg, created another landmark in the space history as it carried the first ever space traveller, a dog named Laika. This established the fact that a warm-blooded animal could live in space thus paving the way for man’s venture into the space which finally succeeded in 1961 when Yuri Gagarin of USSR orbited the earth in his spacecraft Vostok I.

          The first American satellite was Explorer I which was launched on 31st January 1958 and weighed only 14 kilograms. The first American astronaut to be in space was John Glenn in 1962. The first woman space traveller was Valentina Tereshkova of USSR.

          But what functions do these artificial satellites perform in the space? They are used for radio and TV communications, weather forecasting, geological surveys, telecommunications, defence and spying purposes, scientific studies like space and astronomical observations, crop patterns and oceanography. Depending on their function they are called communication satellites, weather satellites, scientific satellites, earth resources satellites etc. Some satellites perform a number of functions and are called multipurpose satellites.