Scientists have detected ammonia on Pluto’s surface, supporting the idea of an ocean hidden deep inside this distant world. A rusty red area on Pluto suggests that a mix of liquid water and ammonia periodically spews to the surface through volcanic vents. These cryovolcanoes are otherworldly versions of volcanoes that erupt water, ammonia and methane instead of ash and magma. Dr Cristina Dalle Ore, a planetary scientist at NASA’s Ames Research Centre, said: ”In recent years, ammonia has been a bit like the ‘holy grail’.