Astronomical distances are measured in light-years.

1. (a)(i)State what is meant by 'a light-year'.[1]
2. (a)(ii)The Sun is one star in the Milky Way galaxy. State the approximate diameter of the Milky Way galaxy. diameter of Milky Way = ................................................. light-years[1]
3. (b)(i)There are several stages in the life cycle of a star. Complete Fig. 10.1 to show the stages that a massive star goes through after it has used up most of the hydrogen at the centre of the star. Use words from the following list: nebula neutron star protostar red giant supernova white dwarf massive star (much larger than our Sun) red supergiant and black hole or [Figure 10.1][2]
4. (b)(ii)State the stage in the life cycle of a star where heavy elements are formed.[1]
5. (c)Current scientific understanding is that the universe began 14 billion years ago in an event known as the Big Bang. Explain one observation that supports the Big Bang Theory. observation .......................................................................................................................... explanation ..........................................................................................................................[4]