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O: Astrophysics

Astrophysics (according to NASA) is the study of how the universe began, works and has evolved, and the search for life on planets around other stars. It's an ever-changing field as human manipulation of technology improves year on year. On 11th April 2019, for example, the first ever photograph of the event horizon of a black hole at the centre of a galaxy was captured.

The IB Physics course contains three key sections at Standard Level:

  • Stellar quantities (2 pages) - distinguishing between celestial bodies and defining units of length and brightness to cope with the vast magnitudes at play among the cosmos
  • Stellar characteristics and stellar evolution (4 pages) - categorising stars by examining the light they emit and using this information to diagnose a star's position in its lifecycle
  • Cosmology (2 pages) - using obervational evidence to make predictions about the past and future of the universe


  • Objects in the universe

    Objects in the universe, including galaxies, planetary systems and stars.

  • Stellar quantities

    The distances between objects in the universe and their brightness.

  • Spectra

    We can perform detective work on stars using their spectrum to determine temperature and chemical composition.

  • Stellar characteristics

    Stars can be displayed on a diagram and categorized in a number of ways.

  • Cepheid variable stars

    Cepheid variable stars, a pulsing star following the red giant stage, act as standard candles.

  • Stellar evolution

    The evolution of a star can be shown on the HR diagram.

  • Cosmology

    Scientists theorize that the universe commenced with a 'Hot Big Bang' of energy and matter. This theory is supported by evidence.

  • Age of the universe

     We can calculate an estimate for the age of the universe based on the velocity at which galaxies are receding from our observations.