Unit 9J Lesson 5: Satellites and Orbit Objective: to learn how objects stay in orbit and why we feel weightless when we are in orbit. Targets 1, 9, 10, 11

Satellites Satellites are objects which are in orbit around a larger body. The moon is a satellite because it orbits around the earth. Artificial satellites are launched outside of our atmosphere (the layer of air surrounding our planet) and orbit our planet in the same way the earth orbits the sun. Satellites can be used to do things such as –Cameras can see which direction the wind is blowing so we can make weather forecasts. –Search for rock features which might tell us where natural resources could be found. –To send TV and telephone signals around the world. –Seeing different life signs on Earth so we can see how healthy or unhealthy our environment is.

Orbits Observe Orbit Demonstration When a satellite is in orbit around a planet or a star there are two forces working on it. –There is the pull of gravity of the planet or star on the satellite. –There is the thrust of the satellite in a straight line forward. Forward Thrust Gravitational Pull

Orbits Continued The two forces work together to keep the satellite in orbit. –The pull of the planets gravity keeps the satellite from flying off into space. –The forward thrust of the satellite keeps it from crashing into the planet. –It is almost as if the satellite is constantly falling off of the planet but then being caught by the pull of gravity. How Things Orbit Part 1 How Things Orbit Part 2

Work to Do Read pages Complete Remember Section p.79 Homework –Complete Activity Sheet C6S3 make sure you include an explanation of how the satellite stays in orbit. –Fill in keywords orbit, artificial satellite, geostationary satellite, and atmosphere