Define what is meant by a galaxy.
A nearby dwarf galaxy is located at a distance of approximately 180 000 light-years180\,000\text{ light-years}180000 light-years from Earth. Determine this distance in kilometres (km\text{km}km).
Astronomers study the movement of distant galaxies relative to Earth.
State one observation of light from a galaxy that shows it is moving away from Earth.
State one cosmic object of known luminosity (brightness) used to determine the distance to a far galaxy.
State the mathematical relationship between the recession speed of a galaxy and its distance from Earth.
If the Hubble constant H0H_0H0 is estimated to be 2.3×10−18 s−12.3 \times 10^{-18}\text{ s}^{-1}2.3×10−18 s−1, calculate an estimate for the age of the Universe in seconds (s\text{s}s).
104 exam-style questions on CIE IGCSE Physics 6.2 Stars and the Universe, covering 6.2.1 The Sun as a star, 6.2.2a Galaxies and astronomical distances, 6.2.2b The life cycle of a star, 6.2.3a Galaxies and the scale of the Universe, 6.2.3b Redshift, 6.2.3c The Big Bang Theory and cosmic microwave background radiation, and 6.2.3d The Hubble constant and the age of the Universe. Each one has a worked solution and a mark scheme showing where the marks go.