The news anyway connected with space appear in media every day. But about what represents space and at what distance from Earth it begins very few people think.
Instruction
1. Initially Greek word κόσμος meant all Universe. It is considered that the first this term as designation of the world, or the Universe was entered by Pythagoras, meaning proportionality and harmony of its parts. Philosophers and sometimes call today space the Universe. Only at the beginning of the twentieth century began to determine by this term only that space which is located outside the atmospheres of planets.
2. But where the atmosphere comes to an end? Its density falls with increase in height not in steps, and smoothly. Therefore the border of space is chosen conditionally. On one classification it is equal to height in 70 kilometers, and on another - in hundred. For comparison, the regular passenger plane flies at height which is not exceeding ten kilometers.
3. Through many centuries the mankind investigated space only theoretically - at first with the naked eye, and then with use of optical devices. The first space flights were made only in the twentieth century. In the beginning so-called subspace flights during which the device though crossed conditional border of space, but at the same time did not remain in it in an orbit, and immediately returned to the earth were arranged. Similar flights are sometimes carried out and today. In 1957 the Soviet Union launched the First artificial satellite of the earth which flight was orbital. On its board the transmitter which is specially constructed so that it was rather easy to accept its signals was placed. It worked at two frequencies, and, at the moments when the signal was present at one frequency, it was absent on another and vice versa. Solar batteries on its board were not and therefore after the category of chemical sources of current the transmitter became silent. In 1961 the orbit for the first time the world was visited by the person - our compatriot Yury Gagarin. The USA calls astronauts astronauts, that is participants of flight to stars. It is wrong as any flight to stars it is made was not anybody yet.
4. Today the European Union and China prepare to visit to start in operation.
5. The satellite television and the Internet also became today habitual for many. Even if you use these services in a different way (air, a cable, ADSL, GPRS, etc.), probability is very high that a certain site of a way of a signal from a source to you passes through space.