Course Icon
Natural Science - Year II

Unit 61: The discovery and exploration of the Planets


SO Icon

Science Weblecture for Unit 61

This Unit's Homework Page History Lecture Science Lecture Lab Parents' Notes

Science Lecture for Unit 61: Modern Planetary Exploration

For Class


The Solar System

Exploration of the Solar System

Close exploration of the solar system became possible in the 1950s with the first successful rocket launches from earth. Sputnik (USSR) and Explorer I (USA) were Earth orbiters, but Luna (USSR) and Pioneer (USA) missions both tried to explore the moon, while other Pioneer missions.

You have to be patient to be an unmanned-spacecraft explorer. Voyager 2, was launched in 1977, took two years to reach Jupiter (1979), and another two to reach Saturn (1981). Although originally scheduled only to get to Saturn, Voyager 2 was still working and responsive to directives, so NASA authorized an extended mission, and Voyager 2 reached Uranus in 1986 and Neptune in 1989. Other spacecraft have had similarly long careers: Pioneer 10 was launched in 1972 and continued to send information back until 2003.

Look at NASA's Solar System Exploration site. There is a lot of material here so concentrate on one planet (Mars) for discussion in class, then pick another planet for your homework assignment.

  • What are the limitations of observing Mars from Earth?
  • What were the first missions to Mars? The most recent missions to Mars?
  • What is the difference between an orbiter and a lander mission? What kinds of information can each gather about a planet?
  • What is the evidence for Martian
    • atmosphere turbulence (storms)?
    • geological activity (earthquakes, volcanoes)?
    • frozen water and liquid water on the surface?

For each of the other planets and moons, identify the planetary structure, atmosphere contents (if any), magnetosphere, and key surface features (eve gas giants have these!). Identify any other odd features (i.e., Uranus' tilt, Venus' slow rotation).


Planetology is the study of the common characteristics of planets. We can compare atmospheres, surface features (for terrestrial planets), rings, moons, magnetic fields, composition, amount of energy from the sun available, and so on.

Take a look at the University of Washington's Comparative Planetology lab.

  • Study the comparisons of craters, volcanoes, flood chanels, and gas giant atmospheres, and pay attention to the questions for each group of pictures.

Study/Discussion Questions:

On your own