AST 401: Planets and Planetary Systems

3 credits | Prerequisites: AST 201

Course rationale

This is an elective course designed for students majoring in physics, mathematics, engineering or computer science. Students can take it as part of a minor or specialization in astronomy and astrophysics or as a free elective. The course intends to give an overview of planets and planetary systems based on current observational evidence from our Galaxy. More emphasis will be on the formation and evolution of planetary systems and origin of life on planets.

Course content

Formation of planetary systems: Laplace, protoplanetary disk, from dust to planetesimals, from planetesimals to planetary embryos, from embryos to planets, collisions and migration. Solar system: harmony of our solar system, the sun, planets, dwarf planets, satellites, asteroids, comets, Kuiper belt and Oort cloud, heliosphere and heliopause, history of our solar system. Planets in the solar system: terrestrial planets: mercury, venus, earth, mars; gas giant planets: jupiter, saturn, uranus, neptune. Dynamics of planets: laws of planetary motion, stable and unstable orbits, tidal forces. Detection of exoplanets: five ways to find a planet: radial velocity, transit, direct imaging, gravitational microlensing and astrometry. Diversity of exoplanets: exoplanet statistics, hot jupiters, cold gas giants, ocean worlds and super-earths, ice giants, lava worlds, rocky planets. Interiors of planets: interiors of mercury, venus and mars; interiors of the gas giants; interior of earth and its special position in our knowledge; evolution of planetary interiors. Surfaces of planets: rocks, geological structures, counting the craters, mercury and venus, a tourist’s guide to mars, recent research on mars. Atmospheres of planets: atmosphere of earth, atmosphere of other planets in our solar system, origin and evolution of atmospheres, atmospheres of exoplanets and possibilities of future research. Astrobiology: brief history, definition of life, origin and early evolution of life, sites for life, signs of life, astrobiology and humility. Life in the solar system: history of life on earth from dark ages to evolutionary renaissance, early mars, large habitable moons (Titan and Europa), small habitable worlds. Life on exoplanets: searches for habitable exoplanets, possibility of life on ice giants and super-earths, characterizing exoplanet atmospheres, Drake equation and extraterrestrial intelligence.

Course objectives

  1. Understand the history of the solar system in terms of the general theory of the formation and evolution of planetary systems.
  2. Appreciate the diversity of planets in the solar system.
  3. Dynamics of planets around a star and its relation to various methods of detecting exoplanets.
  4. Enumerate the current exoplanet zoo in a coherent manner with statistical tools.
  5. Understand the habitability of planets and possibility of life on planets in general.


  1. Stephen Eales, Planets and Planetary Systems, Wiley-Blackwell, 2009.
  2. Frontiers of Astrobiology, edited by C. Impey et al., Cambridge University Press, 2012.
  3. Donald Goldsmith, Exoplanets: Hidden Worlds and the Quest for Extraterrestrial Life, Harvard University Press, 2018.