The Little Book of Exoplanets

"Yes, it’s a good primer. It’s not that short a book, actually, but it’s written in a very nice, concise way. Joshua Winn, who I’ve met a few times at Princeton, is a top-tier exoplanet researcher. He’s on the TESS science team. TESS is the space telescope in orbit that succeeded the Kepler mission. Kepler was the workhorse for finding exoplanets for seven or eight years, but it’s finished now and TESS has taken over the mantle, especially of looking for nearby, Earth-like planets. Joshua Winn is part of the TESS team and it’s always interesting to hear about a subject from someone in the field who is at the top of their game. “Everyone’s just waiting for the next step, which is to find biology” The book is also organized extremely well. He just leads you through the subject in what seems like a logical, sensible way. He’s not always historical. A purely historical approach doesn’t always work, because science progresses in chaotic ways sometimes. He just steps back from the subject and says, ‘Okay, what would someone need to know first, and then second, and then third, to understand what’s going on?’ I liked it for that reason as well. It’s a rival book, of course, but that’s not a problem. The field is big enough that there can be multiple books on exoplanets! My book is aimed at a broad audience where you don’t need to know anything about astronomy or exoplanets. The Little Book of Exoplanets is for a general audience as well, but I would say it’s at a slightly higher level. I enjoyed it for that reason—because I learned some things too. In my book, I was also trying to make a connection to the state of the Earth because, otherwise, exoplanets are just out there, far away. Who cares? If you’re excited by exoplanets fine, but what’s that got to do with anything that’s happening on Earth? It may have been a stretch when I was conceiving it, but I tried to make the connection between how we define habitable planets far away in the universe, and how we think of the Earth—because the habitability of the Earth is, of course, in jeopardy. Yes, and when we talk about Earth, we get these warm, soft fuzzy feelings. It’s our planet, the pale blue dot and so on. But the exoplanet game has told us that it’s not that special, even as a water world. There are planets that have 100 times as much water as the Earth does in its oceans, these incredible water worlds. Then there are planets that are more habitable. Earth is not the “best of all possible worlds” as Leibniz might have said. It’s a good planet, there’s nothing wrong with it, but it’s on the edge of chaos. There was at least one snowball episode, and possibly a second one, where the planet might have tilted into a deep freeze that it would never have escaped from, and life would have been extinguished. There was also heavy bombardment early on that possibly obliterated life on Earth. We’ve seen historical climate change back in the geological record that dwarfs anything we’re doing to the planet ourselves. Planets can have crazy histories. We’ve found planets out there that are more tranquil than Earth and probably a little calmer for long-lived life. That matters because we care about biology elsewhere. There could be Earth clones, or better, more-habitable-than-Earth planets, that got a head start on the Earth by eight billion years, because the Earth formed four-and-a-half billion years ago, and the universe is 14 billion years old. There was plenty of carbon and water within half a billion years of the Big Bang . There are potential biological worlds out there that have had an awfully long time for evolution to produce interesting things. That’s a thought experiment at the moment, because we haven’t found them, but it’s a possibility."