The story of the Copernican revolution is usually summed up as a single moment in Western civilisation when science overturned religion, and people started to replace the Bible’s account of the world around them with theories based on physical observations.

But, as Stuart Clark shows in this skilful and fascinating fictional account of Kepler’s and Galileo’s discoveries, the reality of what happened was a lot more complex than a simple dichotomy of science vs. religion. To start with, religion itself was at war; the Reformation triggered battles for power across Europe, and the Catholic Church was only too aware that a new and better understanding of the natural world could help them gain the upper hand. The Church knew it couldn’t risk being left behind and becoming increasingly irrelevant in the modern world. And it was obvious to everyone that the old Aristotelian model of fixed spheres centred on the Earth just didn’t work. But how to dismantle that apparatus and set up a new model, while at the same time keeping hold of the power structures that the old model supported?

Furthermore, the Copernican revolution was not a single moment; it actually took nearly two hundred years to unfold fully, from the mid-sixteenth century when the model of the sun-centred Universe was first published, to the measurement of stellar parallax in the early eighteenth century, showing conclusively that the Earth moved. In this book Clark concentrates on the period of 1600 to 1633. At the start of this period, Kepler is (unsuccessfully) working as assistant to the eccentric Tycho Brahe, and the Copernican model is just an intriguing idea without any proof. By the end of it, Galileo’s apparent mockery of the position of the Catholic church in his famous publication Dialogue concerning the Two Chief World Systems has led to his recantation and house arrest.

The story moves seamlessly backwards and forwards between the two men to tell the story of their contributions to this revolution. Galileo pioneered the use of the telescope to look at the sky, discovering Jupiter’s moons, the phases of Venus, mountains on the Moon and sunspots on the Sun. Kepler did little observational work himself but used Brahe’s observations to show that the best and simplest model of planetary motion is one in which they all move around the Sun in elliptical orbits. It was his use of elliptical rather than circular orbits which showed his genius; without this the Copernican model fit the data no better than previous Earth-centred models. The book even shows him groping his way towards the idea of a force emanating from the Sun, keeping the planets in orbit around it – leading to Newton’s concept of gravity.

So what is point of a fictionalised version, when there are so many non-fiction accounts? Does the reader gain anything? It allows the author more liberty with his material, which in turn helps to make the characters more three-dimensional. We cannot know what Galileo felt when facing the Inquisition, but in this novel Clark has the freedom to guess at why Galileo recanted, and his fear and shame while doing so. We are party to the complexity of Kepler’s inner life as he makes astrological forecasts for a living, argues about theological doctrine with other Lutherans, and wonders if his wife has fallen under the spell of evil spirits. All this illustrates beautifully and concisely the mixture of medieval and modern beliefs.

And the novel has the potential to reach out to new audiences. This story is still so important to us, not just because of its historical interest, but also because the question of how scientists should speak truth to power is relevant to us in a world where Government policy is increasingly dominated by ‘evidence bases’.

There is an occasional touch of ‘historical novelitis’, in which characters are required to explain complex ideas to each other in a manner which renders them slightly too articulate to be believable. This might be a fault but it also echoes Galileo’s writing itself. Fortunately, most of the dialogue is more down to earth, some of it nicely reminiscent of Brecht’s Life of Galileo.

This book is the first of a trilogy: the next instalment tackles Halley and Newton, and the final one examines Einstein and Hubble. I’m very much looking forward to reading them.