The nature of students’ ideas about the scientific practices used by astronomers when studying objects in our Solar System is of widespread interest to discipline-based astronomy education researchers. A sample of middle-school, high-school, and college students (N=42) in the U.S. were interviewed about how astronomers were able to learn about properties of the Solar System as a follow-up question after specific questions about the nature of the Solar System and its objects. These students often held naive ideas about the practices of astronomy, and 19% of them proposed that humans or robots have returned samples of the planets to Earth for analysis. While the college students provided more sophisticated responses to the questions than the ...