Know that the light emitted from distant galaxies appears redshifted in comparison with light emitted on the Earth

Calculate the time it takes light to travel a significant distance such as between objects in the Solar System

State that: (a) galaxies are each made up of many billions of stars (b) the Sun is a star in the galaxy known as the Milky Way (c) other stars that make up the Milky Way are much further away from the Earth than the Sun is from the Earth (d) astronomical distances can be measured in light-years, where one light-year is the distance travelled in (the vacuum of) space by light in one year