The present study used exploratory, open-response format questionnaires to explore student misconceptions
about gravity, which allowed themes to emerge naturally in students’ typical language. This is the first comprehensive
study tailored specifically to introductory college astronomy students’ understanding of gravity. A variety
of contexts were explored, including the strength of gravity in and around Earth, in terms of the solar system,
and in hypothetical situations. Fifteen student interviews supplemented student responses as a deeper probe of
misconceptions. In addition to the typical documented misconceptions about gravity, previously undocumented
misconceptions were observed. In fact, the breadth of questions allowed a description of possible student mental
models. We defined three possible alternative mental models about gravity—the boundary model, the orbital indicator
model, and the “mixing of forces model.” These alternative models are the first to rigorously generalize
student ideas about gravity. Additionally, we explored certain surprising disparate misconceptions and common
misapplications of the scientific model in terms of mass, distance, and the cause of gravity. Taken as a whole, our
proposed alternative models and description of misapplications of the scientific model offer a new language for
astronomy researchers and educators to use in understanding their students’ ideas about gravity. These models
give educators a vantage point from which to understand their students’ background knowledge and to navigate
potential pitfalls in learning the scientific model. The results can lead to immediate formative assessment in the
classroom and instructional development.