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Physical Principles of Astronomy


  • Credit value: 15 credits at Level 6
  • Tutor: Professor Ian Crawford
  • Prerequisite: Foundations of Astronomy
  • Assessment: a 2.5-hour examination (75%) and two problem sheets set during the module to assess your understanding of the module content (25%)

Module description

This module is designed to give you a quantitative understanding of key physical processes and concepts that underpin the disciplines of astronomy and astrophysics.

Indicative module content

Celestial Mechanics (two lectures)

  • Newtonian mechanics
  • Angular momentum and moment of inertia
  • Gravity (Newtonian gravity, potential energy, escape velocity, Roche limit, rotational stability)
  • Orbits (Kepler’s laws)

Time (one lecture)

  • Solar time (GMT)
  • Sidereal time (including relation to right ascension and hour angle)
  • Atomic time
  • Universal Coordinated Time (UT, UTC)
  • Variations in length of day

Electromagnetic Radiation (one lecture)

  • Wave and quantum theories of light (wave/particle duality)
  • Blackbody radiation (Wein’s Law; Stefan-Boltzmann law)
  • Doppler effect
  • Atomic and molecular basis of spectroscopy

Analysis of Starlight (three lectures)

  • Stellar luminosity and effective temperature
  • Calculation of planetary effective temperatures
  • Quantification of stellar magnitudes and colours (colour indices)
  • Bolometric magnitudes and corrections
  • Quantitative spectroscopy (equivalent widths, line saturation, deriving abundances from line strengths)

Interstellar Processes (two lectures)

  • Interstellar reddening and colour excess [E(B-V)]
  • Properties of interstellar dust
  • Quantitative information from interstellar absorption and emission lines
  • Interstellar chemical processes

High Energy Astrophysics (two lectures)

  • Introduction to special relativity
  • Brehmsstrahlung and synchrotron radiation
  • Gravitational redshift
  • Physics of neutron stars and black holes
  • Cosmic rays

    Learning objectives

    By the end of this module, you will be able to:

    • demonstrate knowledge of the specific aspects of astronomy and astrophysics outlined in the syllabus
    • demonstrate an understanding of how this knowledge has been arrived at and the relationship between theories, hypotheses and observations in the planetary sciences
    • demonstrate skills such as writing, numerical reasoning and the comprehension of scientific concepts.