Emma Chapman reviews Ripples on the Cosmic Ocean: How the Solar System Shaped Human History – And May Help Save Our Planet by Dagomar Degroot
We rarely think of outer space as an environment of concern for Earth, despite very real threats such as asteroid strikes and solar storms. But author and environmental historian Dagomar Degroot makes the case for its impact on us in his latest book Ripples on the Cosmic Ocean: How the Solar System Shaped Human History – And May Help Save Our Planet.
Despite the astronomical feel of the title, this is not a typical popular-science book, nor is it really a book about space. Degroot instead describes it as an “environmental history”, exploring how the evolution of our solar system has shaped human progress. It is an important distinction to make upfront – otherwise, the effect can be as jarring as expecting a day out at the Science Museum to learn about the planets, only to walk into a gallery on the Chinese Ming Dynasty. With the right expectations, however, a good day out is had by all.
Degroot – who is an associate professor of environmental history at Georgetown University in the US – has a particularly interdisciplinary and sometimes jarring perspective. His work spans climate change, space exploration and existential risk – a disconnect that he captures through his own experience of solar astronomy.
It was one thing to know, but another thing entirely to experience, that the foundation of all human existence was on some level unstable, and unpredictable
An enthusiastic amateur astronomer, he bought a solar telescope but found watching the Sun distinctly unsettling. “It was one thing to know, but another thing entirely to experience, that the foundation of all human existence was on some level unstable, and unpredictable,” he writes. Degroot eventually sold the telescope but wrote this book: an exploration of how humans have responded to that cosmic instability over the ages, individually and as societies.
The book is divided into five parts that cover the Sun, the Moon, Venus, Mars, and comets and asteroids. Each section traces how humans have responded to changes in the appearance or understanding of a celestial object. The scope is much broader than those headings might suggest. We move from food prices during the Ming dynasty to a 1972 coronal mass ejection that detonated thousands of US mines. We learn about Venus’s runaway greenhouse effect and early warnings about climate change to Martian dust storms steering the course of the Cold War.
It is all fascinating, but at times the experience is rather like following a fast-walking museum guide who throws out fascinating titbits about every object they pass, as you hurriedly glance at each one and make a mental note to come back later. Figures can resemble those from an academic review, with captions stretching to half a page, while the references alone occupy over 40 pages. There are so many facts, and such a comprehensive history, that it often feels as though an academic argument is being constructed rather than a narrative followed.
What if a solar super-storm hit?
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This might sound negative, and had I written this review the day I finished the book, that might well have been the sentiment I left you with. Instead, I missed my deadline. During August, I was sailing not on cosmic oceans but terrestrial ones, working as a cruise astronomer. It is a job that usually leaves me plenty of time to write during the day, but a bout of COVID rendered me useless for over a week. I was confined to a cabin, rolling on waves considerably rougher than a ripple.
I had plenty of time to think, and to flick back through sections of the book that I hadn’t properly digested the first time. I found myself wanting to check something, write down a reference, or note an interesting quotation I could use in my teaching. Many non-fiction books are a blast while you are reading them but once finished, they remain on the shelf, slowly gathering an undisturbed layer of dust. This one has instead migrated to my reference bookcase, whose inhabitants are pulled out again and again, never quite allowing the dust to settle.
After all, Degroot can write beautifully. Venus is “not only hotter than an oven, but hot enough to melt an oven”, while a potentially complex explanation of how oxygen isotope ratios in microscopic fossils can act as proxies for past climate change is dispatched in a single, crystal-clear paragraph that acts as a lesson in science communication.
So, would I recommend it? Perhaps not to the casual popular-science reader wanting to learn about Venus, at least not without the warning with which I began this review. My initial frustration was that Degroot’s exemplary science writing is sometimes lost in a sea of historical argument. But, as Degroot goes to great pains in the introduction to stress, this is a history book.
Viewed on those terms, Ripples on the Cosmic Ocean works extremely well as a comprehensive record of how humanity has responded to observations and changes in a handful of celestial bodies. It is ultimately a book to flick back and forth through, making liberal use of its index and references – for example, to relocate that fascinating mention of NASA’s bizarre response to potentially harmful lunar bacteria (load up the anti-bac spray). Some books make a big splash, never to return to the surface. This one produced ripples that took me a few extra weeks to appreciate, but which I suspect I will continue to feel for some time to come.
- 2026 Penguin Random House – Viking 416pp £22hb