Orbit

• Orbit


  The curved path of one celestial object or spacecraft around another celestial object
• Objects orbit rather than just flying off in a straight line or being pulled in towards the object they're spinning around
• Newton's first law


  An object traveling at a certain velocity will continue to travel at that velocity unless acted upon by a resultant force
• The moon is traveling at 1023 m/s


  It should continue to travel in this direction and at this speed forever
• The earth is so massive and relatively close to the moon

  It exerts a strong gravitational pull which is felt as an attractive force towards the earth
• The moon has a lot of momentum in its forward direction


  The gravitational force isn't strong enough to completely pull it in towards the earth, it can only change its direction very slightly
• The moon is basically always orbiting around the earth
• The moon's speed is always the same


  Its velocity is constantly changing because its direction is constantly changing
• Every time the moon changes direction as it orbits, it's actually accelerating even though it's not getting any faster or slower
• Steady orbit


  • Instantaneous velocity of orbiting object
  • Gravitational pull of larger object
• If the moon's orbit is pulled inwards so it's closer to the earth


  The size of the gravitational force will be much greater
• To avoid being pulled in towards the earth

  The moon would have to start traveling much faster so its instantaneous velocity increased
• Stable orbit


  The smaller an object's orbit, the faster that object must be traveling in order to maintain a stable orbit