Although the concept of sustainable development is widely used as a guiding principle, there is much less consensus on its normative foundation and ethical implications. Since the 1880s, when social tensions threatened to tear apart European societies during the Industrial Revolution, Catholic social teaching (CST) has served as a sound basis for dialogue for many political leaders regardless of national or religious affiliation. This article examines how Pope Francis’ present-day CST might foster a cross-cultural debate on the ethics of economic growth, social and ecological justice and civil participation on Planet Earth as well as in outer space.