The paper reports a cross-cultural investigation conducted in 2001-2002 that seeks to reveal students' alternative ideas in two countries, Taiwan and Germany. It was carried out by means of semi-structured interviews in a story form. The targeted students were arbitrarily selected from grades 3 to 6 in both countries and amounted to 64. The questions in the interview were centered around "the heavens" (space, heavenly bodies, and familiar astronomical events) and "the earth" (the appearance, shape, movement, and, in some cases, gravity). The results indicated that, first, the students presented their ideas in a consistent manner, regardless of their cultural backgrounds, if we take into account the scope of questions and phenomena which were in their concern or of their interest. The comments from the student can be patterned into a structure-like whole, which we term "model" in the study. Second, the alternative models of "the heavens and the earth" elicited in the interviews appear to have various strengths of explaining familiar astronomical events. Interestingly, the more advanced a model is (in regard with the present-day cosmological model), the higher explanatory power it contains. As for the difference between the sample of two countries, the German students show more intention (or are more aware of the need) to explain astronomical phenomena than their Taiwanese counterparts, and thereby presented more precise models with stronger explanatory power. On the other hand, the Taiwanese students appeared to have more imagination and conceptual flexibility that should also be valued.