"Before I started searching for life in the cosmos, I just assumed scientists knew how it started on Earth. We don’t."

"…it is sobering to realize that for most of Earth’s history, humans would not have been able to survive on this planet. If we could rewind Earth’s history and start again, it seems unlikely that Earth would produce humans again. A planet with different starting conditions and paths of evolution has no obligation to support life similar to Earth’s, let alone curious humans."

The truth is out there.

"Are we alone in the cosmos? The question should have an obvious answer: yes or no. But once you try to find life somewhere else, you realize it is not so straightforward."

At least until the age of permanent haze across the planet, we have always had the stars in our consciousness. Since the second century AD we have had stories about alien worlds. Since Galileo we have been able to see other worlds in the cosmos. A 1792 novel by Voltaire tells of an alien encounter. Concern about extraterrestrial locales has been a part of human consciousness ever since. The concern is certainly fed by the history of strange human invaders helping themselves to land distant from their home soil.

The interest in things alien certainly kicked up in the twentieth century. Many of us grew up in the space age, witness to the first “Beep-Beep” from orbit, the first peopled orbiters, rapt in front of our televisions when mankind first set foot on the moon. Part of this experience is to be awash in the science fiction of our own and earlier ages, dreaming of strange other-world societies, fearful of invasion, eager to learn the lessons of advanced technology. Some were even impressed and excited enough by the technology and the optimism of the age to begin college careers with the dream of becoming aeronautical engineers, and designing some of the hardware of the future.

But so much of this was based on fantasy, (including that engineering thing) limited to imagining what might exist out there. Even the early observations of other planets in the solar system generated fantasies in addition to scientific elucidation. But in 1995 scientists discovered the first two exoplanets, and new discoveries are now a nearly daily event. Today, because of the major advances that we have made in telescope technology, we are able to see to the far ends of the universe. Enter Lisa Kaltenegger, founder and head of the Carl Sagan Institute at Cornell University

"I spend my days trying to figure out how to find life on alien worlds, working with teams of tenacious scientists who, with much creativity and enthusiasm and, often, little sleep but lots of coffee, are building the uniquely specialized toolkit for our search."

In studying what we have seen, it has become possible to detect stars that have planets around them. In fact, most stars have company. The way this is detected is to measure “wobble” in the light being observed from distant places. As if you were looking at a bright light and someone threw a ball across your field of view. The measured light would change and you could tell that something had been there. Keep looking to see if it repeats. If it does, then you probably have a planet orbiting that star. (or an annoying neighbor tossing something back and forth in front of you) Keep pointing the James Webb Space Telescope (the state of the art in telescopy today) to more and more locations in space. And discover more and more planets.

Kaltenegger has been looking into the reality of other worlds her entire career, and in doing so, has advanced our knowledge base considerably. She begins this book with a brief visit to an other planet, one that is very different from ours, a star-facing world that has portions in eternal day, night, and dusk, and local life adapted to the local venues, just to get things started on what we might expect out there, just to challenge our assumptions.

She follows with a history of Mother Earth, noting major stops along the evolution of our favorite place. She notes how life might have formed, when, and how that event altered the atmosphere and even the color of our atmosphere. The sequence is important, as her discussion of our exoplanet dreams demonstrates that we are a prisoner of time. What we see with our telescopes (and eyes) arrived here on light, and light must travel at or below the universal speed limit. (a leisurely 186,282 miles per second) So, whatever we see from even a nearby star/planet system originated tens or hundreds of years go, or even billions for our more distant neighbors. Anything residents of out there might have seen of us (really only since we started sending signals into the ether maybe a hundred years ago) is quite dated relative to who and what we are today. Absent the invention of a Warp Drive of some sort, we are doomed to be always too far away in years and miles from other intelligent species. Well, maybe.

It is possible, I suppose, for a civilization with massive resources to send a desperate one-way mission to save their species from hundreds of light years away. It is unlikely that any visitors from such distant realms would be making reports home. But this need not necessarily apply to all possible visitors. It appears that there are plenty of possible planets within a few light years of us that might present some interplanetary possibilities.

Kaltenegger delves into the nearer-earth planets, looks at their characteristics, and offers explanations as to their suitability for life. She looks at probable communication issues should we ever come across an ET, suggesting it might be the equivalent of humans attempting to communicate with a jellyfish

Kaltenegger and her team design computer simulations, based on the hard work of examining concrete materials, inert and biologic, and putting that intel into a database. Check the signature spectrum of every new world and compare it with the growing list of catalogued items.

"Today, solving the puzzle of these new worlds requires using a wide range of tools like cultivating colorful biota in my biology lab, melting and tracing the glow from tiny lava worlds in my geology lab, developing strings of codes on my computer, and reaching back into the long history of Earth’s evolution for clues on what to search for. With our own Earth as our laboratory, we can test new ideas and counter challenges with data, inspired curiosity, and vision. This interaction between radiant photons, swirling gas, clouds, and dynamic surfaces driven by the strings of code within my computer, creates a symphony of possible worlds—some vibrant with a vast diversity of life, others desolate and barren."

She notes the core need of life-sustaining planets is to be rocky. Sorry, Jupiter, no gas giants need apply (but their moons might). They also need to be within a certain range of the stars they circle, the so-called “Goldilocks Zone,” not so close as to be too hot nor so distant as to be too cold, and they need to show the presence of key life-sustaining elements.

Kaltenegger offers readers info on some topics likely to be new to most of us, Stellar Corpses, for example, warm ice, the Fermi Paradox, the Drake Equation, the Great Silence, tardigraves, and plenty more. All of these are explained clearly and simply. It is as if the author is telling us: This is what we have learned. This is what we expect. This is how we go about gathering information, fusing our fields of expertise, learning more, solving the mysteries that the data present. This is our understanding of what is possible. This is our plan for looking further and farther.

Alien Earths may not point to an actual catalog of life-sustaining exoplanets, but it does offer an accessible pop-science portrait of the current state of the art in the search. This galactic age of exploration has been ongoing for some time, getting a jolt from the discovery of other worlds. It has advanced to where we are now looking for (and expecting to find) evidence of life on other planets. It is likely that what we find will be pretty basic, single-cell critters, maybe even plant life. And it will probably take a good long time before we can move up to the final phase of the game, finding intelligent life. The time scale for any potential interaction is likely to be considerable, but who knows? The universe is full of surprises among its billions and billions of stars.

"So far, despite wild claims to the contrary, we have not found any definitive proof of life on other planets. Until we do, we will continue to improve our toolkit and look for signs of alien life the hard way: searching planet by planet and moon by moon."

Review posted – 09/27/24

Publication date – 04/16/24

I received an ARE of Alien Earths from St. Martin’s Press in return for a fair review. Thanks, folks, and thanks to NetGalley for facilitating.

What a great read! Dazzling and informative. I'm so glad I took the time to read and think about this book. More, more, more, please.

This was a great nonfiction read! This book was very introductory for the topic which I enjoyed and had a lot of really interesting information about the topic of extraterrestrial life and how they go about searching for it! Definitely recommend giving this book a read!

Final Review

"[...Although] we were relieved every time something went right, we knew that there were still hundreds of things that could go wrong." p7

As a fan of science, and especially a fan of scientists writing compelling popular science text for all of us laypeople, I knew as soon as this book was offered to me that I would love it. The science under discussions addresses one of the most pressing questions our scientific community faces today– can a second earth exist somewhere?

This is a brilliant discussion about far distant space and what makes planets able to support life. My favorite discussion questioned what it means to even ask that question. This book shares such fascinating data and ideas. It's one of my favorite popular science books.

I recommend this to anyone who likes books about outer space, astrophysics, popular science, or advancements in technology.

"Mars has taught us a profound lesson: habitability can be temporary." p127

Reading Notes:

Three (or more) things I loved:

1. I officially want to work for the Carl Sagan institute!

2. "One of the advantages of the scientific method—or disadvantages, depending on whom you ask—is that it requires you to accept what the nineteenth-century British biologist Thomas Henry Huxley called 'the great tragedy of science—the slaying of a beautiful hypothesis by an ugly fact'.” p8 And boy do hypotheses proliferate now. We need science more than ever.

3. "Not only do we need to work at the edge of knowledge, but we must ask the right questions and overcome our own biases." p7 Wow, this author speaks my language.

4. NASA uses a similar definition in its search for life in the cosmos: “Life is a self-sustaining chemical system capable of Darwinian evolution.” But a lively discussion continues as to how to best define what life is and how to find it elsewhere. Because life that doesn't evolve is as good as dead.

5. "Earth’s story did not include oxygen until the first organisms that produced it emerged." p100 Oxygen isn't required for the presence of life on earth.

6. "Science is a rich fabric of knowledge that spans time and place; an invisible net stretching above our heads like a second sky where sparkling ideas stand in for the billions of stars. When I close my eyes, I can imagine the ideas of millions of people connecting us all to those who came before us and those who will come after." p235 Science and coding makes me feel connected too!

7. "We are living in an incredible time of exploration. I am rooting for us!" p260 Since starting to study science and programming, I feel this optimism.

Three (or less) things I didn't love:

This section isn't only for criticisms. It's merely for items that I felt something for other than "love" or some interpretation thereof.

1. This science is pretty dense. Just taking my time.

2. There's a section in which Kaltenegger discusses being a woman in STEM. I'm really glad she addresses this, but I don't think she worked the subject in smoothly enough. It reads as though the passage was added as an afterthought.

<b>Rating:</b> 🌍🌏🌎🌍.5 /5 earths from space
<b[Recommend?</b> Yes!
<b>Finished:</b> Dec 9 '24
<b>Format:</b> digital, Libby
<b>Read this book if you like:</b>
🚀 space travel
🌠 stars and planets
🌋 world prehistory
🧑‍🚀 popular science

Thank you to the author Dr. Lisa Kaltenegger, publishers St. Martin's Press, and NetGalley for an advance digital copy of ALIEN EARTHS. I found an accessible digital copy on Libby. All views are mine.
---------------
Pre-Read:

I'm definitely a fan of popular science books about living creatures and the many forms that subject takes. Biology. Linguistics. Astrophysics. This was an obvious selection for me and I am absolutely loving it!

Thank you to Net Galley and the Publishing Company for this Advanced Readers Copy of Alien Earths by Dr. Lisa Kaltenegger!

Loved this book! I am an astronomy geek and geeked out at this book. I love any and all perspectives on the universe and Dr. Kalteneggers book was wonderful!

Readable and fascinating. I was mesmerized by the questions and answers this book poses about the potential for life on other planets. Very engaging.

And interesting and accessible read for non-scientists like me. Thank you #Netgalley and #StMartinsPress for the opportunity to review.

I found this book to be very interesting. I love learning about space and found this book really approachable by using comparisons that are easy to understand. The author does a great job of keeping the information understandable while keeping me, the reader curious. I even enjoyed the commentary about science fiction (books and movies).

A good read on the science of searching for proof of life on other plants. I enjoyed the science and it was written in a way that was easy to understand for someone not working in astronomy or a related field.

I really enjoyed this. It happened to pop up in my reading lineup at the same time I was watching "For All Mankind" and I felt like the information in "Alien Earths" really added to the experience of watching a show about space exploration and the possibility of building a civilization on other planets. The information presented was comprehensive but never felt dry. Definitely a welcoming and fun read.

I appreciate NetGalley and the publisher for access to a digital ARC. My honest review is my own opinion.

Alien Earths: Planet Hunting in the Cosmos by Lisa Kaltenegger
Adult Popular Science / 3 Stars / Pre-2024 Review Copy

Finally, I whizzed through my second book this year on exoplanets, can you tell they're a favourite subject of mine? This fun book didn't really cover much new ground for me, but it was bang up to date with the latest research, and I always love to read anything I can about the hunt for planets outside our solar system and the new techniques being developed to find them. This is definitely a book I'd recommend to anyone interested in the subject, as it's light-hearted and easy to read while being packed full of information.

Thanks to NetGalley for the ARC of this book. I loved this science-y exploration of if life exists on other planets, and if so, how we'd be able to identify it. As a layperson, even though the author used a lot of analogies, there were parts that went over my head. That said, it was incredibly well-written, and though the author was humble, you can tell she's an absolute superstar scientist. It felt like an honor to learn from her.

I love learning about space. It’s so fascinating: there’s so much out there. I’d be beyond thrilled if I could just go up in orbit for an hour and see our beautiful home planet from above and get a better look at the stars from a different vantage point. So I appreciate nonfiction that gives me more insight into space, and I generally enjoy fiction set in space. Given that, I couldn’t resist picking up this nonfiction book about scientists looking for other planets that could host life.

The author of Alien Earths is an astrophysicist who is the founding director of Cornell University’s Carl Sagan Institute. She shares some of her background and talks about the many things that piqued her interest in space and the search for other planets. Kaltenegger’s interests and accomplishments certainly indicate she is a brilliant and curious woman.

It’s interesting to read about the various facets of science that she researches and the types of other scientists with whom she collaborates. For instance, readers may not think about how much biology comes into play in her field. But if you think a bit longer about it, it does seem a bit obvious that it must, since if we’re looking for signs of life on other worlds, we need to define (and study) life on our own planet!

Kaltenegger explains how scientists find stars and planets circling them, even though they’re many, many light-years away. Quick hint at one way they do that: look for wobbles.

She also talks about how even if we are able to see signs of possible life on planets far, far away — or if aliens were to see signs of life here — it would be signs of life from (likely) hundreds or thousands of years ago because of the light-year distances that will (again, likely) be involved. I have to say that when Kaltenegger explored that idea a bit toward the end of the book, it took me on a fascinating train of thought. Because of those extreme distances and the speed of light, we have to think differently about time and space. Rather than thinking about “now,” we have to think about past or future. I’m simplifying these ideas quite a bit here for all kinds of reasons, but suffice it to say it is a touch mind-bending.

I appreciated much of what Kaltenegger wrote about in Alien Earths, but I wasn’t glued to it, to be honest. I felt it was dry at times, though she was trying to inject a lot of personality and personal experiences into it throughout. While I do love science and books written for the general public on scientific subjects aren’t difficult for me to follow, this book still felt a bit too textbook-ish sometimes. I had to read it in smaller bites in between some other books to get through it. I can’t say that will be the case for other scientifically minded readers, however.

This was an interesting nonfiction book that discussed the search for life in our galaxy.
I enjoyed this book as some of the information provided was new to me. The book was interesting but I would suggest that it is written for an audience that is already interested in these topics. The author wasn't afraid to dive into some basic science and assume the reader is educated on the foundations of these topics.This was a fairly small book that felt just right for the topic discussed. I would recommend this to readers who like to learn through their reading time.

Alien Earths: The New Science of Planet Hunting in the Cosmos, by Lisa Kaltenegger is at times a fascinating book, is at times an inspiring book, is often an informative book, but also, unfortunately, is often a frustrating book. Or at least it was for me. It’s a worthy read, but one that feels like it could have been much more.

Kaltenegger is director of the Carl Sagan Institute to Search for Life in the Cosmos at Cornell University and as such is one of the best candidates for writing a book on exoplanets (those planets outside our own solar system), especially as her career has spanned the entire existence of exoplanets themselves (well, our awareness of their existence, they’ve existed for billions of years, and I’m pretty sure Kaltenegger is not that old). The details of that career, or at least some of them, are interwoven throughout the book, adding a welcome personal touch amidst the more removed science.

Kaltenegger opens by setting the stage for why we need to know more about exoplanets and why some think their existence makes the case for life beyond ourselves in the universe. Basically, it’s a numbers game, as she points out that “since the first extrasolar planets was discovered in 1995, astronomers have found more than five thousand others . . . One new world discovered for ever day sine we built the first instruments sensitive enough to detect them.” She goes to note that we’ve learned that planets are shockingly common, and given that the Milky Way has about 200 billion stars, we’re talking about (in true Sagan-speak) “billions and billons of new worlds to explore in our galaxy alone. Multiply by that by the number of galaxies (and our is hardly the largest), and, well, the point is self-evident.

From the introduction, the book moves on to various sections detailing the search for both exoplanets and life, exploring topics such as the various methods of detecting exoplanets, the telescopes and probes involved in the process both in the past and (hopefully) the future, the ways in which we might try to detect signs of life (which necessitates the surprisingly difficult task of defining life) from so far away, how we might use Earth and its signs of life as a guide, the possibility of communicating with other life if it exists, and more.

The science is all explaining quite clearly with mostly a lack of technical jargon and any that is required is just as clearly explained. If anything, I’d say the book is simpler than most popular science books I’ve read on this topic or similarly difficult ones (such as physics or biology). More than once, I found myself a little surprised at the choice to stop and explain what I would consider a relatively basic concept. That’s not a complain, merely an observation, one based I’m sure more on my frequent reading of popular science books/magazines than on any “dumbing down” by the author.

Her descriptions of specific exoplanets we’ve already learned some details about, meanwhile, often border on the lyrical and are wonderfully vivid and compelling as she describes a water world (with reference to the famous/notorious Costner film), or one that rains lava or other equally exotic ones. I actually found myself wishing both she had spent more time giving us more full descriptions of those particular planets and gave us more total descriptions of other one as well.

Similarly, I felt the same way about the more personal stories she offered up, such as the nerve-wracking experience of watching one of your projects being launched (fingers crossed) into space, and then the the several hundred steps she had to wait patiently through, knowing failure at any one would doom the mission. Or, on a less positive note, the experiences she had in facing sexism, ranging from an early school person telling her girls don’t really do very well in the math/science area or a pair of colleagues discussing how she only achieved the position she held at the time because she was a woman. We get these sorts of vignettes sprinkled throughout, but I would have been happy to have had the book balanced more equally between the science and the personal (and really, it’s hard to separate the two), more of a 50-50 split. That’s one reason I felt the book didn’t reach its full potential.

The other is that overall, it felt somewhat disjointed, a bit scattered and at times a bit too much like it was skimming the surface of things. It’s not that the personal touches interrupted things—those elements actually were almost always seamlessly integrated. It was in the organization of explanations and the movement from one concept or mission to the other. In fact, by the end of the book I had started to wonder if the book was actually based on a series of columns she had written and then strung together in more narrative form. It isn’t, but the fact I wondered about that gives you a sense of how disjointed it felt to me. It’s also probably true that the book suffered somewhat from my having read two similar books, each of which was quite strong (The Sirens of Mars: Searching for Life on Another World by Sarah Stewart Johnson and The Possibility of Life: Science, Imagination, and Our Quest for Kinship in the Cosmos by Jaime Green) and both of which appeared on my Best of the Year lists for their respective publication years.

I’m certainly glad I read Alien Earths, particularly for the lively descriptions of those dozen exoplanets, but I couldn’t help feeling tantalized by what the book could have been. Recommended with caveats.

There was so much to ponder in this book. I enjoyed this exploration of space snd planets, specially the look into what could sustain life. I found the book very readable and interesting.

In Alien Earths, Dr. Lisa Kaltenegger introduces readers to a broad overview of planetary science, beginning with our own solar system and quest to explore the cosmos, branching out into our search for Exoplanets.

Dr. Kaltenegger is the director and founder of the Carl Sagan Institute for the Search for Life in the Cosmos at Cornell. It is easy to see the inspiration of Sagan in this work, for better and worse. Dr. Kaltenegger is positioning this book to be for the average reader, an introduction to modern space science with hints of her own work. As an introduction, I think this would work for any interested reader, especially those who have an (illogical) aversion to older works. This book presents the most up-to-date science in a manner that is digestible and crafted to inspire. If you are that kind of reader, with no past exposure to the subject but still an interest to learn, this book is perfect for you. For everyone else, it is harder to recommend.

I am a planetary scientist and an astrobiologist. My focus is on surface evolution of planets and moons in the solar system. I am not an expert in Exoplanets, and I picked this up hoping for a deeper dive into that field. With that said, I can look at this book through both lens: as a reader eager to learn new things versus as an expert learning and/or judging how we can discuss the science we do. I was very disappointed as the learner and still mixed as the expert.

At least half the book or more is a very broad introduction to space and planetary science. I felt like this was done well, but I also think the lay reader could have been given a bit more trust to handle a deeper dive (the book is fairly short after all). My biggest issue with the introduction is that it felt like it didn't significantly reframe the conversation. Many of the analogies and philosophical musings were things I'd heard before. They are effective, but if I was going to recommend a book (or books) on this subject, I would still urge readers to try older works (e.g., Pale Blue Dot). Sure, science evolves and changes, but its more likely that what's changed is the clarity of what we know, like putting on glasses to refine what was already there.

Unfortunately, my disappointment extends beyond the introduction. Even as we venture into the realm of Exoplanets, there remains a vaguery on the subject. I say the introduction is long, but I am not exactly sure it was all an introduction. It wasn't clear that there was a lot of new science to be introduced. It is indicative of the larger style of only dipping the readers toes in anything being discussed. This is where I had my most personal disappointment. I expected this to focus more on exoplanets. We get to hear about her work and the ongoing efforts, but we never really get to immerse ourselves within it.

I recognize I come to this with biased perspective. I am not an exoplanet scientist, but I have a professional familiarity with the science as an astrobiologist especially. Still, it is that familiarity that makes this feel so underwhelming. I felt like I learned more from Dr. Sara Seager's book from nearly 5 years ago now, The Smallest Lights in the Universe: A Memoir. That's more a memoir than a science book. If I was going to recommend a book on exoplanet science, that would easily be it. The conversation on exoplanets is secondary, so it is unlikely to overwhelm the reader. It is also a very personal story. It is Dr. Seager's personal story with grief, as a scientist, and as a woman.

Overall, I can easily recommend this to anyone curious to explore the subject for the first time. I still think it fails to really excel, and the recommendation is largely on its recency being more likely to attract new interest in the field, which I am all for. However, that relevancy will fade, and I'll be surprised if became a classic in the field of popular space science books.

3.5/5 stars

Alien Earths by Lisa Kaltenegger is an exploration to discover other planets in our atmosphere. She is a lead astronomer at the Carl Sagen Institute at Cornell.
As someone who is a lay person when it comes to astronomy, she makes it easy to understand. She gives an in depth exploration of Earths history and other planets.

She introduces us to exoplanets and bridges the gap between science fiction and reality. She makes us ponder are we truly alone in this world?

Normally I don’t read to many books like this one but Dr. Lisa Kaltenegger wrote this complex science topics in a way that made it easy to understand.
It’s interesting to learn how scientists go about researching the conditions of life on our planet and what they are looking for on their plants. If you like to learn about our plant and other you’ll find this a interesting book to read