Our five senses are all we have to allow our brains to interact with the world outside our bodies. Space exploration relies almost entirely on one, the sense of sight. Space probes send us images of planets, moons and other objects which we then have to decipher as best we can. Richard Greenberg in his book Europa, The Ocean Moon uses recent images of Europa, together with our understanding of celestial mechanics and plate tectonics, to unravel this little moon’s mysteries. For Europa’s biggest mystery is whether it harbours life who may be looking right back at us from their own little world.