People’s daily lives have always relied heavily on their link with outer space. From using the constellations for navigation millennia ago to connecting with thousands of satellites that provide geopositioning, communication, and weather monitoring services, outer space has been a constant companion. But it doesn’t always appear as such in today’s world. Today, space exploration might seem distant and reserved for a select few—astronauts, billionaire tourists, astronomers, or the military. However, ethnographic work shows how deeply outer space is intertwined with people’s lives on Earth, from the daily work of space scientists to the impacts of space infrastructure on local communities around the world. Since outer space cannot often be known directly, what humans know about it and how they relate to it tends to be shaped by what they know about and how they relate to Earth. Consequently, earthly relations and political dynamics inevitably influence human activities in space. At the same time, an anthropological perspective on outer space can help defamiliarise the taken-for-granted contexts and factors specific to the earthly realm, revealing how deeply they shape human lives and people’s understanding of Earth within the cosmos. Thus, examining outer space can help us recontextualise fundamental questions about society and culture, compelling us to expand our analytical framework to encompass the cosmic realm but also encouraging us to explore alternative models for social life on Earth and beyond. This entry showcases anthropological research that has attempted to answer three fundamental questions at the human-cosmos interface: How do people interact with outer space? How does outer space impact human lives? How does outer space influence our understanding of social reality?