P5- Space for Reflection

P5- Space for Reflection

1. Satellites and their orbits

   • A Satellite = any object that orbits around a larger object in space.
     • two types of satellites
       • Natural
         • things that naturally orbit e.g. moon orbiting planets, planets orbiting the sun
       • Artificial
         • Something manmade e.g weather satellites, communication satellites, spy satellites
           • communication satellites put in to high orbit over the equator. They orbit once every 24 hours
             • Means that they stay above the same point on the earth's surface as they're moving the same speed as the Earth
               • Satellites that move that same speed as the Earth called Geostationary satellites
               • ideal for telephones, TV and radio- cause always over the same part of the earth so you know where they are and signals can be transferr
           • weather and spy satellites need to be in low orbit
             • geostationary too high and too stationary to take good weather or spy photos-need low polar orbits
               • low polar orbits pass over both poles and are nice and low
                 • closer to earth than Earth than geostationary- pull of gravity is stronger, meaning they move much faster
                   • orbit very quickly, often within period of less than 2 hours
                 • each time satellite comes around it can scan the next bit of the globe
                   • allows whole surface of planet to be monitored each day

2. Gravity and Orbits

   • GRAVITY =the universal force of attraction between masses
     • Gravity provides the Centripetal force that causes orbits
       • An object travelling in a circle is constantly changing direction
         • An orbit is a balance between the forward force of the object and a force pulling it inward. The force pulling an object towards the centre is called the CENTRIPETAL FORCE
           • if the force is removed or the object moves too fast the object goes off in a tangent
           • planets orbit around the sun- centripetal forces that make this happen provided by the gravitational force between each planet and the sun
             • moon orbits the Earth- because of the centripetal force produced by gravitational force between the moon and the Earth
         • The object keeps accelerating towards the thing its orbiting, but it's tangential motion keeps then in an almost circular orbit
     • GRAVITY
       • Gravity is caused by objects having mass
         • mass causes the gravitational pull to vary