Stable stars release vast amounts of energy from their cores, which is eventually radiated into space. Describe the nuclear process occurring in the core of a stable star that releases this energy.
Light from a distant galaxy is observed on Earth by astronomers.
Explain how the wavelengths of light observed from this galaxy differ from the wavelengths of light when they were originally emitted.
State the quantity related to this light that astronomers measure to determine the speed at which the galaxy is moving away from Earth.
The Hubble constant H0H_0H0 is estimated to be 2.4×10−18 s−12.4 \times 10^{-18}\text{ s}^{-1}2.4×10−18 s−1.
Calculate the distance from Earth to a galaxy that is moving away at a recessional speed of 1.8×107 m/s1.8 \times 10^7\text{ m/s}1.8×107 m/s.
Use the value of H0H_0H0 to estimate the age of the Universe. Give your answer in years (use 1 year≈3.15×107 s1\text{ year} \approx 3.15 \times 10^7\text{ s}1 year≈3.15×107 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.