Light pollution has emerged with the industrial development in recent decades. It is becoming a significant environmental issue for cities today and it will probably become more important in the near future. However, very little research has been carried out on this issue in the field of science teaching, despite there being a general agreement that education has an important contribution to make in the protection of the environment. This research analyses this problem in secondary education, through the official curriculum and textbooks published for the Valencian Region (Spain). We have based the research on the "Content analysis" method. Light pollution, despite being included in the Spanish compulsory secondary education curriculum, is an issue that is barely touched on in the majority of the first and second year Natural Science textbooks analysed.