Pluto is less than 20% of the diameter of Earth and is on average six billion kilometres away, yet astronomers have been able to study its tenuous atmosphere since the 1980s. In this episode of the Physics World Weekly podcast the astronomers (and siblings) Leslie Young and Eliot Young talk about Pluto’s atmosphere and how it changes as the dwarf planet follows its elliptical orbit around the Sun.

The Youngs are both at the Southwest Research Institute in Boulder, Colorado and have devoted much of their careers to the study of Pluto. They chat about the joys of making new observations of Pluto’s evolving atmosphere, often by chasing its shadow here on Earth.