Recent studies have shown that not only primary school students but also their future teachers reach science courses with pre-constructed and consistent models of the world surrounding them. These ideas include many misconceptions which turn out to be robust and hence make difficult an appropriate teaching-learning process. We have designed some tools that proved helpful in putting in evidence some of the most frequently used alternative models on a few basic astronomical notions. We have tested these tools with preservice elementary teachers from various normal schools in Buenos Aires and made a first analysis of the results. The collection of data recovered so far shows that some non-scientific conceptions are indeed part of the prospective teachers' (scientific) background and that, therefore, the issue deserves special attention during their formal training.