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).
59 exam-style questions on CIE IGCSE Physics 6.2.3a Galaxies and the scale of the Universe. Each one has a worked solution and a mark scheme showing where the marks go.