unit 14 satellites

课件22张PPT。1 Unit 14 SatellitesSenior English Book 2B2 Lesson 54 Satellites Teaching content of this lessonLook and listenText understandingText explanationExercises3Look and listen The moon travels round the earth once every month. It is a natural satellite of the earth.The earthThe moonThe sunText4Tapes of SatellitesA satellite is an object, either natural or man-made, which travels in an orbit round another object in space5How are man－made satellites carried up into space？ Man-made satellites are carried up into space by rockets. To escape the pull of the earth, a rocket must reach a speed of 28.440km/h. If the rocket does not reach this speed, it will fall back to the earth. A rocket must reach a speed of 28,440 km/h to escape the pull of the earth . The heroic bearing of the rocket with satellite 6A satellite is one of the most expensive pieces of scientific equipment in the world. Expensive pieces of science equipmentSun panelsExpensive camera7Why is a satellite so expensive?First it must be very light, the lighter the better, because it has to be sent up into space by a rocket.Second, it usually contain very expensive camerasIt has equipment for making electricity from sunshine, using very broad sun panels. There is a rocket motor on the satellite by which the direction of the satellite can be changes if necessary.8 Satellites for broadcasting are used to send radio and TV programmers from one part of the world to another. Most of these satellites do not change their positions. They remain above the same place on the earth and travel round it in a very high circle.Sun panelsThe earthBroadcasting satellitetransmitterBroadcasting satellites9 In this way, they are able to connect broadcasting stations which are a long distance from each other. Signals travel at the speed of light. They reach the satellite and return to the earth in less than a second. Broadcasting stationsatelliteThe earthreceiving antennatransmitterstudiosatellitecitycountrysignalsBroadcasting satellites10Weather satellites send information and photos of weather conditions to weather stations on the earth. It is therefore possible to say not only what the weather is like at present, but also what is likely to happen in the next day or two.Weather satelliteearth11 This is useful when there is a hurricane in an area, as it is possible to see the path of the hurricane in the satellite pictures. Ships and planes can be warned so that they can keep out of the path of the hurricane.hurricaneSatellite cloud atlas12The main idea of the passageThere are two types of satellites-natural and man-made satellites. Man-made satellites are carried up into space by rockets and they are very expensive. There are different kinds of man-made satellites，such as broadcasting satellites，weather satellites，communication satellites and space satellites. They are of great use.13What can satellites do? 14Read the following statements and say true or false1）When we talk about the satellite，we ... ...