Solar system, Stability of Orbital Motions & Satellites

• Where does the Sun lie in the Solar System?

  The Sun lies at the centre of the Solar System
• What percentage of the mass of the Solar System does the Sun make up?

  The Sun makes up over 99% of the mass of the Solar System
• How many planets are there in the Solar System?

  There are 8 planets in the Solar System
• What is the gravitational field around planets capable of doing?

  The gravitational field around planets is strong enough to pull in nearby objects
• How does the gravitational field of a dwarf planet compare to that of a planet?

  The gravitational field around a dwarf planet is not strong enough to pull in nearby objects
• Name the four rocky planets in the Solar System.

  The four rocky planets are Mercury, Venus, Earth, and Mars
• Name the four gas planets in the Solar System.

  The four gas planets are Jupiter, Saturn, Uranus, and Neptune
• What are moons an example of?

  Moons are an example of natural satellites
• What distinguishes artificial satellites from natural satellites?

  Artificial satellites are man-made and can orbit any object in space
• What is the International Space Station (ISS)?

  The ISS is an example of an artificial satellite that orbits the Earth
• What do asteroids and comets do in the Solar System?

  Asteroids and comets orbit the Sun
• What is an asteroid?

  An asteroid is a small rocky object that orbits the Sun
• Where does the asteroid belt lie?

  The asteroid belt lies between Mars and Jupiter
• What are comets made of?

  Comets are made of dust and ice
• How do comets behave as they approach the Sun?

  The ice melts when the comet approaches the Sun and forms the comet’s tail
• What mnemonic can help recall the order of the 8 planets in the Solar System?

  • My Very Excellent Mother Just Served Us Noodles
  • Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• What was the mnemonic used before Pluto was reclassified as a dwarf planet?

  My Very Excellent Mother Served Us Nine Pizzas
• What is our solar system a part of?

  Our solar system is part of the Milky Way galaxy
• How many stars are estimated to be in the Milky Way galaxy?

  There are billions of stars in the Milky Way galaxy
• What is the Universe made up of?

  The Universe is made up of many different galaxies
• How many galaxies are estimated to be in the entire universe?

  There are estimated to be more than 100 billion galaxies in the entire universe
• What allows planets and moons to be visible from Earth?

  They are visible when they reflect light from the Sun
• How far are the outer regions of the Solar System from the Sun?

  The outer regions are around $5 \times 10^9 \text{ m}$ from the Sun
• How long does it take for light from the Sun to reach Earth?

  It takes 8 minutes for light from the Sun to reach Earth
• How long does it take for light from the nearest star to reach us?

  Light from the nearest star takes 4 years to reach us
• What is the speed of light?

  The speed of light is $3 \times 10^8 \text{ m/s}$
• How can the time taken to travel a certain distance be calculated?

  The time can be calculated using the equation: $time =$$\frac{distance}{speed}$
• If the radius of Mercury's orbit is $5.8 \times 10^9 \text{ m}$, how long does it take for light from the Sun to reach Mercury?


  The time taken is $19.3 \text{ s}$
• What happens to the light we see from the Sun?

  We see the Sun as it was eight minutes ago due to the time light takes to travel
• What is the consequence if the Sun were to disappear?

  We would not notice until eight minutes later
• What is a nebula?

  A nebula is a cloud of gas and dust in space

  
• How is the Sun formed?

  The Sun is formed from massive clouds of dust and gas in space
• What happens to a nebula due to gravity?

  Gravity pulls the nebula together into a giant ball
• What occurs as the nebula collapses?

  The centre of the ball gets very dense and hot and begins to rotate
• What is formed when nuclear fusion begins in the collapsing nebula?

  A dense protostar is formed, which becomes our Sun
• What keeps stars in equilibrium?

  Stars are held together by a balance of inward and outward forces
• What are the two forces acting on a star?

  The two forces are gravity (inward) and pressure (outward)
• What happens when the temperature of a star increases?

  The outward pressure will increase, causing the star to expand
• What happens if the temperature of a star drops?

  The outward pressure will decrease, causing the star to contract
• What elements have been formed by nuclear fusion in stars?

  All naturally occurring elements, apart from hydrogen, have been formed by nuclear fusion in stars