This article looks into notions of the sky among the Guaycurú aboriginal groups in the Argentine Chaco within the context of the socio-religious changes they have undergone since the eighteenth century. By using ethno-astronomy and anthropology of religion perspectives, and based on our own ethnographic and documentary work, we have analyzed both the continuities and the ruptures in the Guaycurú skies. In doing so, we have found that social relations between humans and non-humans shape the Guaycurú experience of celestial space. These bonds have a strongly political character as they are structured around power asymmetries. The colonial experience, including Christian missions, has imposed modernity on these groups as an overall horizon of possibilities. However, the Guaycurú have sought to redefine modernity, creating their own ‘modernity paths’.