This paper analyses the use of wonder in the TV-series Cosmos: A Personal Voyage (1980). Popular science has been studied extensively (e.g. Broks 2006; Leane 2007; Perrault 2013), and wonder has been studied moderately (e.g. Daston & Park 1998; Fuller 2006; Vasalou 2015). However, there are very few studies of wonder in popular science. This paper explores how and why wonder is used in Cosmos, with the wider aim of understanding uses of wonder in popular science. The studies that discuss wonder in popular science (Fahnestock 1986; Perrault 2013) argue that wonder is used to enthuse the audience about science, but they do not discuss why wonder has this ability, nor whether wonder has other functions. This paper argues that Fuller's (2006) psychological and evolutionary account of wonder can elucidate why wonder has the ability to enthuse; it discerns three senses of ‘wonder’ (related to objects, emotions and attitudes); and it discusses other functions of wonder (existential, aesthetic and ethical). Due to the centrality of astrobiological questions in Cosmos, this paper also highlights the relation of these questions to the senses and functions of wonder in Cosmos.