What’s Hidden Inside Planets?

Sabine Stanley with John Wenz Johns Hopkins

£14 PB

Earthquakes might be a terrifying experience for most people, but they are a very useful tool for planetary scientists. In this engrossing and lively study, Sabine Stanley draws on her professional research to set out how seismology, together with other methods of investigating what goes on beneath our feet, can explain why Earth is habitable: its iron core generates the magnetic field that protects our atmosphere from being stripped away by the solar wind.

The interdisciplinary nature of this research deepens our understanding of chemistry itself; exotic substances such as ‘helium rain’ have been hypothesised to form within the depths of gas giant planets, explaining the relative depletion of helium on Saturn’s surface. The book also discusses new discoveries of exoplanets and how they pose a challenge to the long-held assumption that only small and rocky planets could form near stars, because gas and ice giants would evaporate. Exoplanets such as the Jupiter-like 51 Pegasi b, orbiting eight times closer to its star than Mercury orbits the Sun, helped give rise to the new theory of ‘planetary migration’, in which planets can drift a long way from where they first formed.

The book finishes with an argument that we should not consider the proposed commercial mining of asteroids or allow planetary exploration to lead to colonisation, given the damage that we have already caused to our own planet. All in all, this is a great introduction to the subject, with enough up-to-date detail to ensure that even readers with some background in the subject will find something new. ★★★★★

Pippa Goldschmidt is an astronomy and science writer