Stars and the Universe

Learning objectives

Know that the Sun is a medium-sized star made mostly of hydrogen and helium that radiates mainly infrared, visible and ultraviolet, and at Extended that stars are powered by the nuclear fusion of hydrogen into helium

Know that galaxies contain many billions of stars, that the Sun is one star in the Milky Way, that astronomical distances are measured in light-years and, at Extended, that one light-year is about 9.5 × 10¹⁵ m

Describe the life cycle of a star from an interstellar cloud and protostar to a stable star, then a red giant or red supergiant, ending as a white dwarf in a planetary nebula or as a supernova leaving a neutron star or black hole (Extended)

Know that the Milky Way is one of many billions of galaxies and is about 100 000 light-years across, describe redshift as an increase in the observed wavelength of light from receding galaxies, and use it as evidence that the Universe is expanding

Describe the Big Bang theory and, at Extended, the cosmic microwave background radiation as evidence for it and the use of the Hubble constant H₀ = v/d (about 2.2 × 10⁻¹⁸ per second) to estimate the age of the Universe as 1/H₀