These aspects of gravity were further narrowed for the questionnaires to focus on those shown in the concept
map in Figure 1. While the topic of tides is prevalent in most astronomy courses, it was eliminated because a
thorough understanding requires higher levels of physics, such as gradients and multipole expansion of the
gravitational field. It should be emphasized that this concept map is merely a guide; adhering too strictly to it
could limit exploration of student conceptions. While it is convenient to separate different aspects of gravity, it is
important to keep in mind that all are inherently related. Testing one will inevitably test another.