Alternative conceptions in astronomy are a road block to new learning. Astronomy content is included in the Australian Curriculum (AC) from Year 3 and then intermittently in Year 5, Year 7 and Year 10. In accepting that science is socio-culturally constructed, it is important for teachers to have a clear understanding of the alternative conceptions that students bring with them to the science classroom. This article reports on the alternative conceptions elicited from 546 students ranging from Year 5 through Year 7 using a modified form of the Astronomy Diagnostic Test [Danaia, L. (2006). "Students' experiences, perceptions and performance in junior secondary school science: An intervention study involving a remote telescope" (Doctoral dissertation). Charles Sturt University, Bathurst]. Results show that some well identified alternative conceptions, such as the 'eclipse model' to explain the phases of the Moon, exist before students enter high school and prior to any formal learning on the topic. In addition, this research identified a number of alternative conceptions held by pre-adolescent students in Western Australia that were based on knowledge that should have been consolidated by students in Year 3, viz., the relative movements of the Earth, Moon and Sun. Armed with students' alternative conceptions as a part of their pedagogical content knowledge, teachers can construct active learning experiences that will challenge students' existing constructs in order to allow for new learning. This sample suggests that we need to identify the reasons behind the lack of consolidation of the foundation astronomy content of the Australian Curriculum outlined for students in Year 3.