Use this IGCSE Physics objective to calculate the speed at which a galaxy is moving using redshift, supported by examined Paper 4 questions and mark schemes.
The Milky Way is one of many billions of galaxies. Each galaxy contains many billions of stable stars.
On the Earth, light from a distant galaxy is observed and analysed by astronomers. This information is used to determine the speed at which the galaxy is moving away from the Earth.
State the quantity that astronomers use to determine the speed at which the galaxy is moving away.
change in wavelength (or starlight due to redshift)