Orbits

• Gravity


  Provides the force needed to maintain stable orbit
• For an object to have a steady orbit, it must travel at the right speed
• Orbits & Constant Speed

  At a constant speed, the direction of objects constantly changes
• When the Sun's core is hot enough and dense enough, nuclear fusion begins to take place: hydrogen nuclei join together to form helium nuclei
• Energy transfer in the Sun

  Energy is transferred by radiation
• The Sun is at equilibrium between gravity pulling inwards and radiation pushing outwards
• Structure of the Solar System

  • The Sun is the largest object in the solar system, with a huge gravitational field that keeps other objects in orbit around it
  • Planets orbit the Sun at different distances, with temperature decreasing as distance increases
  • Moons are natural satellites that orbit a planet
  • Dwarf objects orbit a star or planet that doesn't have a strong gravitational field
• Objects closer together have a stronger gravitational attraction


  Force is greater, leading to elliptical orbits
• Change in direction is a change in velocity, resulting in acceleration
• Object moving in a circle

  The centripetal force acts towards the middle of the circle
• Types of Orbits

  • Polar orbits
  • Geostationary orbits
• Polar orbits keep the object over Earth's poles, have slower speeds, and keep the object in orbit
• Objects in small orbits experience greater acceleration than objects in large orbits
• Objects in the Solar System

  • Comets are similar to asteroids, made of dust, rock, vaporise near the Sun, and produce distinctive tails