With what material are Saturn's rings made up of?               115
Does solar eclipse occur during every new moon day?             
  If so, can it be seen from some part of the earth?            116
How can scientists determine the temperature of 
  planets or stars?                                             117
How can we measure the mass of a cometary nucleus?              118
Why are asteroids not sphere shaped?                            118
What makes the earth rotate?                                    119
Why are all the planets in the universe spherical in shape?     119
Why does the colour of a star become red when it enters
  the red giant phase? Can we identify the stars which
  are going to end their life as supernova?                     120
What is the difference between a shooting star and a comet?     121