A galaxy is approximately 9.5×1025 m9.5 \times 10^{25}\text{ m}9.5×1025 m from the Earth.
Astronomers observe that the light from this distant galaxy is shifted towards the longer end of the electromagnetic spectrum. State the name of this phenomenon.
State the current estimate for the Hubble constant H0H_0H0 in s−1\text{s}^{-1}s−1.
Calculate the speed at which this galaxy is moving away from the Earth.
Scientists have measured the speeds at which distant galaxies are moving away from the Earth and their distances from the Earth. These measurements suggest that all the Universe was once at a single point. Explain why.
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.