Book review: "The Planet Factory", by Elizabeth Tasker

It is unusual for a popular science book to start by saying that what you are reading will probably be proved wrong in a very short period. Yet that is exactly what astrophysicist Elizabeth Tasker states in this excellent book about how planets and moons form.

There is a good reason for this: twenty-five years ago we did not know of any planets outside our solar system, and some people claimed that our planetary system might be unique. All our models on how planets formed had to be based on what we could see in our own system. Yet by mid-2018 we knew of 3,700 planetary systems, and virtually every one has posed more questions than it has answered. Together, they have caused us to question our assumptions on how all planets - including the Earth - formed.

Ms Tasker details how primordial clouds of dust and gas collapses to form full solar systems with stars and planets, and how much we still have to learn about this most fundamental of processes.

She examines the weird planets that may exist: such as ones that orbit within their star, ones with seas of tar, or ones made of lava or others where it rains diamonds. Truly alien worlds that belong in science fiction - and indeed, science fiction worlds may not be as fictional as we once thought. Want a planet with two suns, such as Star Wars' Tatoooine? They exist. Want an ice world? Take your pick.

The reason many people are interested in planets is the possibility they may harbour life. In reality this is the only time when the media pays attention to the discovery of a new planet, usually with headlines such as "Most Earth-like planet could harbour life." Ms Tasker dives behind the headlines and looks at why they are often misleading, and how life might occur on planets that might be very different from the Earth. Finally, she examines how in the future we might be able to detect life on a distant planet, if not the form of the life, even from tremendous distances.

Planetary formation can be a very dry subject, and Ms Tasker does a good job in explaining the terminology in a light and accessible manner. Even so, this is not a children's book, and in places will require a little perseverance to understand the concepts, and some thumbing back through the pages to find definitions. But the perseverance certainly pays off.

The biggest issue I found with this book is how the uncertainty of how things happen and the resultant speculation can make things confusing as temporary theories conflict. An enhancement of the glossary at the end of the book for commonly-used terms would also be helpful.

If you have any interest in how the Earth formed, or in whether there is life elsewhere in the universe, then this book in an invaluable primer.

4 out of 5.