Sputnik I was the first artificial satellite. It can be described as an aluminum【C1】______

Sputnik I was the first artificial satellite. It can be described as an aluminum【C1】______ with a diameter of 58 centimeters and weighing 83.6 kilograms,【C2】______ with instruments to measure the temperature and the【C3】______ of the atmosphere. Sputnik I was launched into【C4】______ around the Earth by the former Soviet Union on 4 October 1957. Since then, hundreds of artificial satellites have been launched,【C5】______ with a different function. Some artificial satellites are used for telecommunication, which【C6】______ us to make telephone calls to any part of the world, to see【C7】______ television transmissions and to communicate via the Internet. Other artificial satellites are used for navigation,【C8】______ people on Earth can know【C9】______ any moment the position of an object, within a few meters.【C10】______ are weather or meteorological satellites, launched to【C11】______ the state of the atmosphere and to follow the【C12】______ of the clouds as they gather. There are also military satellites, for the purpose of【C13】______ information on the armaments and the troops in countries which may be【C14】______ and also to indicate the launch of a missile. Each satellite has its own orbit which is【C15】______ according to its purpose. Communications satellites, for example, have a geostationary orbit. That is an orbit which turns at the same speed as the【C16】______ of the Earth. Satellites used for weather forecasting pass over the two poles of the Earth.【C17】______ so doing, a different part of the Earth surface is viewed on each【C18】______ orbit. All artificial satellites get the energy they need by huge solar panels which【C19】______ like wings. These are【C20】______ controlled in such a way that they are always turned toward the Sun.

【C1】

A．scope

B．sphere

C．realm

D．planet

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