To explain how this works, let me tell you more about tourists in the Alps. After the school ended on Friday I stayed for the weekend in Les Houches and, following Alain Leger’s advice, I used Saturday to go up to one of the highest peaks – Aiguille du Midi (3,842m), which offered incredible views of the Chamonix valley. I took a thrilling cable car ride up to the top – a whopping 2,807-meter ascent in just about forty minutes!
Just got back from majestic Sedona, Arizona, where my family and I spent Thanksgiving. Sedona is a charming and crazy amalgam of spectacular geology, amazing Fall foliage, exciting restaurants, and an eclectic mix of new age shops and centers. Believers of aura photos, energy vortices, and natural healing flock from all over the country to the countless psychic and supernatural shops in this beautiful town. Sedona may be infamous for its fortunetellers but deservedly famous for its amazing rock formations, which provided the backdrop for many Western movies, with stars from John Wayne to Clark Gable filming there.
Sedona’s rocks are also exciting for anyone interested in Earth’s past as they provide spectacular and rare insights into the Permian period (299 to 251 million years ago) when the Pangea supercontinent converged. At the time of Pangea, all continents on Earth joined together: one could have walked from the Northern American plate to the Australian, African, or even to the Antarctic plates.
Today, the rock formations cut across about 2,000 feet of Permian deposits: they consist of beautifully exposed wind-deposited (eolian) and coastal deposits. The amazing dark red rock layers that surround Sedona are part of the Supai Group: these interbedded layers have been deposited in the early Permian, when the Colorado plateau has been partly covered by an inland sea and a large desert. The inland sea has extended and receded many times during the early Permian; every time it receded the desert expanded and giant sand dunes covered the region that once was occupied by the sea. The shallow sea and the dunes left deposits that are different in color and deposit grain size; these layers of alternating colors make up the Supai group (seen as the mostly reddish, layered rocks in the photos). On top of the Supai group is the whitish/grayish Coconino Formation – a younger, thick sandstone layer, deposited in the mid-Permian, in giant wind-blown dune fields (such locations are also known as erg, Arabic for sea of sand).
The soft red sandstone Supai group is easily sculpted by wind and rain erosion; harder sections of the Coconino formation on top of the red sandstone can protect somewhat the underlying the softer rocks, leading to the characteristic columns and spires typical to Sedona.
Although I have been to Sedona many times in the past, I somehow missed the Slide Rock State Park. This is a great location where flash floods have cut across the soft Supai sandstone and the creek now hosts a fast stream with beautiful pools — in the summer crowded with bathing families, but pleasantly serene in the Fall.
I may have missed the opportunity to have my aura photograph taken or to learn about my future from a Sedona fortuneteller, I can certainly understand the sense of magic this spectacular and serene scenery invokes in visitor – although for me, the true magic is not the mist in the crystal ball but knowing a bit about the incredible and distant past these majestic rock formation witnessed.
I always found whales fascinating and after a recent workshop in Seattle, WA, I jumped on a whale-watching boat. It was great fun – we have seen a pair of humpback whales and a fin whale, all set in an amazing landscape.
After two hours of hike up on a rocky trail in the Italian Alps, finally I stand at an elevation just above 2,500 meters, staring at a breathtaking and unique mountain range, the Dolomites, that holds an exciting clue to the habitability of our planet.
With gigantic sharp white-gray peaks emerging from the lush green of Alpine meadows, these mountains rise where the African continental plate has been slamming violently into the European plate for millions of years, forcing rocks up thousands of meters — and giving birth to the geologically young Alps.
In a trip zig-zagging Europe — visiting observatories, universities, and workshops — I stopped briefly in South Tirol for a few hikes. The most picturesque of them took me up to the Three Peaks of Lavaredo (or Tre Cime di Lavaredo), three 3,000m-high peaks, one of the gems of the Alps. Dotted by rifugi (mostly little huts, but at the easier trails often with nice cafes) the trails are popular among both tourists and locals. They offer an incredible view ascending towards the peaks, before joining an old network of high-altitude Alpine hiking trails, many of which take a week to complete.
The Dolomites are a unique mountain range within the Alps: their composition and history is different from any other in the Alps. They also hold an exciting clue to the process that keeps our planet habitable. Named after a relatively rare form and unusually stable form of carbonate rocks, dolomite, the mountain range’s unique color and composition was noted long ago and, for some time, posed one of the mysteries of geology. Now we know that the majestic dolomite layers in the Dolomite mountains are — amazingly — the work of tiny organisms: it is a very thick layer of ancient coral reefs. During part of the Triassic period (about 255-199 million years ago) the region was part of a shallow sea, which was slowly pulled deeper and deeper. But corals, only capable of living in the upper photic zone of the sea (where enough light is present for photosynthesis), kept on building their reefs higher and higher, managing to always keep the top layer of the coral reef close to the sea surface. With the sea floor sinking and the coral reef growing higher, these tiny animals constructed one of the giant carbonate deposits of the Triassic period.
As most geological periods, the Triassic also did not end well: in fact, it ended with the Triassic-Jurassic mass extinction, one of the greatest extinctions known, which eradicated about 50% of the known marine species. This extinction — occuring just before the Pangea super-continent began to break apart — paved the way for dinosaurs to become the dominant land animals in the Jurassic period that followed. The giant coral reefs of the Dolomites sank further and were covered by sedimentary layers and laid in depth for the next two hundred million years.
Only recently, when the African continental plate collided again with the European plate, were the ancient coral reefs forced to resurface again. Together with other Triassic layers these rocks — once a seafloor — were now pushed up thousands of meters to become the dramatic high peaks of the new-born Alps. Once exposed to snow, ice, rain, and wind, the layers began to rapidly erode, creating the picturesque formations I was able to see today.
But the Dolomites’s story also holds a clue to why we are here: amazingly, the process that formed them and destroys part of a grander process them keeps Earth habitable. The mean temperature of Earth and its local and seasonal variations — its climate — is relatively stable: although major global changes occurred in the past and will probably occur in the future, Earth’s mean temperature mostly remained close to the current temperature and has seen much smaller changes than Mars and Venus have.
The key long-term stabilizing mechanism that keeps Earth’s climate in the habitable range (allowing liquid water on its surface) is the carbon cycle: it is the journey of carbon through the atmosphere, the ocean, the rocks, and the volcanoes of our planet. It is a journey that may take hundreds of million of years for a given carbon atom to complete, providing a slow connection between key reservoirs of carbon in Earth: CO2 in the atmosphere and carbonate rocks in the lithosphere. What makes this journey a feedback cycle is that it is both sensitive to the temperature and able to regulate it: The amount of CO2 — a powerful greenhouse gas — in the atmosphere directly impacts Earth’s temperature: the more CO2 is in the air, the more of Earth’s own emission is captured by it and re-radiated back to Earth, just like a blanket would provide additional heating to our planet (by slowing its cooling) — just as glass windows do in a greenhouse. However, the higher the temperature, the higher the humidity in the air and the more condensation occurs — and the more it rains, the more CO2 is washed out from the atmosphere forming acidic rain. The rain then interacts with silicate-rocks and forms carbonate rocks in the silicate weathering process — or, in a planet that is so filled with life as ours, tiny organisms can grab the carbon-dioxide dissolved in the ocean to build shells or coral reefs. As the Dolomites also show, vast amounts of carbon dioxide can be captured (over long periods of time) in rocks. Slowly, the carbonate rocks will be eroded and carried by rivers to the oceans, deposited to the ocean floor and, eventually, subducted along the oceanic/continental plate boundaries. There, many kilometers deep, the carbonate rocks will be exposed to very high pressures and temperatures, converting the carbonate rocks back to the silicates and expelling CO2 and water — these gases will then find their ways to the surface through explosive volcanoes near the plate subduction boundaries.
Because the loss of CO2 from the atmosphere is temperature sensitive (higher temperature leads to more rain and more carbonate formation) but the source of the CO2 is temperature insensitive (volcanoes do not care about the surface temperatures), the whole cycle forms a net negative feedback cycle: higher temperatures will result in cooling and lower temperatures will result in warming. The negative cycle means that it is stabilizing the temperature of Earth: because the carbonate reservoirs are vast, the effect is powerful; but because it takes hundreds of millions of years to transport carbonate rocks to subduction zones via plate tectonics, the cycle is also very small. While it has kept Earth habitable on long timescales (~100 Myr), the cycle can’t work well on short timescales (<10-30 Myr).
How would this apply to other Earth-like planets? While on present-day Earth the carbonate formation is dominantly through organic processes (various shell-forming marine organisms are happy to make use of the CO2 dissolved in the ocean), in the early Earth and, presumably, in other Earth-like planets with little or no life the same process can occur inorganically, but somewhat slower, in silicate rock weathering.
Therefore, as long as the overall composition of other Earth-like planets are the similar to ours, we would expect them to sport a carbon cycle (either organic or inorganic), also providing a stable climate for them — as long as the planets remain within the temperature range where the carbon cycle can work.
This means that carbonate deposits should be common even beyond the Solar System — and, just perhaps, a few in the Galaxy will also match the majestic beauty of the Dolomites.
Mikayla Mace is a UA journalism graduate student who is writing a nice series of article on our Earths in Other Solar Systems work. She has just posted a piece on our Genesis Database, the mother of all planet formation simulations, featuring Gijs Mulders and Fred Ciesla. The Genesis Database will help us understand how habitable earth-like planets can form and around which stars are they more likely to exist:
By Daniel Apai
Includes interview with Nick Siegler and Shawn Domagal-Goldman
Over the weekend, at the Hilton on the San Diego Bay, a small group met to speak about the present and future of NASA’s Exoplanet Exploration program. To someone not in the field of exoplanets the talks and debates may have resembled science fiction: giant space telescopes, rockets and spacewalks, hyper-precise measurements of stellar motion, search for alien life, exploration of volcanism on exoplanets, laser-combs, starshades, and other Earths across the Galaxy were just a few of the topics that were debated. The memorable images included cows illuminated by lasers in a Nevada desert. It was a fun meeting and a timely one, too.
The field of exoplanets is hotter than ever: we learned that planets are literally everywhere and that planets with sizes similar to Earth are the most common among the known planets. Many of the stars (probably 1 in 4) harbor about-earth-sized planets with stellar heating similar to Earth. Not only did we learn about the frequency of the planets, but also about their properties. New missions and instruments are being built and planned, conferences and school galore, and amazing discoveries are made almost weakly. The enthusiasm is palpable in the field; yet. we know that reaching our grand goal of finding extraterrestrial life is going to be anything but easy.
We can only find life if it produces a signature that is detectable from vast – literally astronomical – distances. Seen from space humans, trees, elephants, or even whales are undetectable and unremarkable, yet Earth would reveal its secret to an outside observer through the surprising abundance of a highly reactive gas, molecular oxygen. Oxygen is and has been produced by advanced photosynthetic organisms, first in the ocean and then on land. About 2.3 billion years ago oxygen has saturated the planet’s surface and rapidly accumulated in vast amounts in our atmosphere, From that point on Earth’s atmosphere became a glowing indicator of life for the entire Galaxy – at least, for civilizations that are slightly better in building telescopes than we are.
So, starting from the only example we have, NASA’s Exoplanet Exploration program is aiming to build a telescope that will look for oxygen or other similarly odd gases in other earth-like planets atmospheres as possible signatures of life.
In a perhaps unusual consensus, the exoplanet community is united behind the most important goal, surveying nearby exo-earths for biosignatures. Few other approaches to detecting extraterrestrial life seem feasible. Although the goal is clear, possible approaches and ideas are plenty: the abundance of proposed approaches stems from the fact that no telescope that exists today (or at least, accessible to astronomers) is capable enough to directly search for biosignatures in known exo-earths. Building one that will be up for the job is not going to be easy: in fact, right now, we do not know how good exactly that telescope would need to be, what capabilities it would have to have — and we don’t know how we would build it.
Guided by the vision of finding extraterrestrial life, astronomers, astrobiologists, technologists, engineers, project managers are all working together to come up with concrete plans for such telescopes. Our goal is to create at least two different designs for life-finding telescopes by 2019. The year is important, because in 2020 the astronomical community will issue a major report, the Decadal Survey. This study will set the strategy for NASA for 2020s and beyond and will determine whether planning and construction of such a telescope can begin in a few years or we need to wait another decade.
What the best telescope design is will depend on what questions we want to answer and on the properties of planets, too: our meeting in San Diego explored these issues as well as the technology development needed to build a telescope more ambitious than anything very built. For example, one possible telescope design would use a “starshade” – a giant (think fifty meters or hundred and fifty feet) flower-petal-shaped mask. The strange mask would fly tens of thousands of miles in front of the telescope and could, if positioned precisely, cancel out the light of the host star completely, revealing the faint planets. However, nothing like this has ever been flown in space or used in ground – so a Northrop-Grumman team of engineers is testing this idea in the night in a dark Nevada desert, shining bright a light to a telescope from miles away and covering the light with a small starshade mask in between. One night however, a cow, perhaps intrigued by the strange glowing flower in the desert, wandered into the light beam and photo-bombed the experiment, thus becoming part of the history of space exploration.
The San Diego meeting was exciting and fun: a lot of progress has been made recently, but much more needs to be done in the next three years to finalize plans for a space telescope that can look for life on other Earths
At the meeting I also grabbed the opportunity to interview two experts who approach this question from different angles: Dr. Nick Siegler, who is the Chief Technology of NASA’s Exoplanet Exploration Program; and Dr. Shawn Domagal-Goldman, astrobiologist and biosignature-expert at the NASA Goddard Space Flight Center.
Several important studies of space telescope design and science questions will be carried out over the next year or two, pushing our technology and understanding toward the long-term goal. It will be exciting to see how this group of smart people figures out solutions to problems that were thought to be impossible to solve, and how it will overcome unexpected barriers, such as curious cows.
News and updates on NASA’s Earths in Other Systems Project from PI Daniel Apai. May 10, 2015.
Sunday early morning with a coffee in my hand, sitting next to giant blooming Saguaro cacti and citrus trees in Tucson with the spectacular Catalina mountains in the background. Two tiny hummingbirds angrily hover around each other in the air, in a surreal, high-speed aerial fight over the nectar drops in our bottlebrush flowers. A rare, quiet moment to reflect on the launch of our Earths in Other Systems project and the five years ahead of us in this exciting endeavor.
After almost two years in planning and preparation, our Project EOS has finally began: an exciting meeting at NASA HQ has launched NASA’s new Nexus for Exoplanet System Science program (which is funding EOS), we published the first paper with EOS results and investigators, the first postdoctoral researchers and a program coordinator are joining our project in May, our website is also online, and we began preparations for transforming a group of offices at the Steward Observatory of The University of Arizona into the EOS “Headquarters”.
Project EOS is an ambitious, exceptionally large-scale research project that combines different disciplines and research techniques to understand how Earth-like planets form. While we now know that Earth-sized planets that receive similar amount of energy from their host stars as Earth does are common in the Galaxy, we do not know how similar these worlds are to Earths: do they only have the same size, but very different compositions, or are many of these worlds truly Earth-like, each carrying in it a potential for rich and complex living systems to emerge? Consider Venus, Earth’s “evil twin”: 81% as massive as Earth and orbiting at 72% of the Earth-Sun distance, it is a world that — seen from hundreds of lightyears — could appear misleading similar to Earth. Yet, through differences in its formation and evolution Venus has become a world with a surface and atmosphere astonishingly different from Earth: entirely devoid of water, lacking plate tectonics and its ability to bury CO2 and stabilize its, Venus’s thick CO2 atmosphere traps the incoming solar radiation and heats up to about 740 K (464 C). Or consider the opposite extreme: NASA’s Kepler mission has found a new type of planets, super-Earths, to be very common in the Galaxy. Many of these super-earths may have very low densities, an evidence that they must have lot of water and light, extended atmospheres. And a “lot of water” here means hundreds or thousands of Earth oceans’s worth of water, completely covering the silicate mantle of the planets, most likely in hundreds of km-thick high-pressure water ice layers, below thick liquid oceans or high-pressure steam atmospheres. These “water worlds” may be just inhospitable to life as the hot, acidic, bone-dry desert Venus has evolved into.
How many of the planets in the solar neighborhood are truly Earth-like — moderately rich in volatiles and organics — is an essential question to answer if we want to carry out a meaningful search for extraterrestrial life: for surveying nearby Earths for signatures of life is going to be one of the most complex and challenging endeavors in science yet.
In Project EOS twenty-five of the best experts from five disciplines will work together over the next five years to understand how the composition and volatile and organics budget of newly formed Earth-sized planets is set. In a fascinating set of projects we will look at the smallest scales and back in time, probing the mineralogy and composition of micron-sized grains in ancient meteorites using the most sophisticated microscopic techniques, to explore the history of volatiles and organics in planetary building blocks at the time when the Solar System was young. We will also use optical, radio, and infrared telescopes to study young stars and, around them, planetary systems in formation to piece together the incredible story of a dusty disk rapidly transforming itself into a planetary system that may support life. In search of new knowledge our team will travel to most continents on Earth and will use telescopes in the Sonoran Desert, the Chilean Atacama Desert and on Hawaii’s Mauna Kea; the Hubble and Spitzer Space Telescopes. We will also build powerful computer models for the planet formation process and use these to inspect the details and fill out the gaps; we will compare the predictions of these models to the properties of exoplanetary systems: planetary orbits, masses, densities, atmospheric compositions. If we succeed, what we learn here will guide our and NASA’s search for life beyond Earth.
I am fortunate enough to work with a team of truly outstanding scientists from the diverse fields, all working toward a shared goal. Over the next five years, our team will also be joined by a dynamic group of young students and postdoctoral researchers: the team at its largest will include over forty researchers. But we will reach an and involve much larger groups: Our results will find their way to the courses we teach and we will also build up a team of Other Earths Ambassadors – citizen scientists excited by the search for life on other planets and eager to contribute.
We will share the excitement and news from the EOS project through blog updates, public talks, Twitter and Facebook posts; join us and follow the blog and twitter feeds and you will learn about our science results, discoveries, travels, and about exploring other worlds, directly from the front line.
Twitter: @EOSNExSS, @danielapai
Two weeks ago NASA has announced its new Nexus for Exoplanet System Science, which may prove to be a major change in the way NASA will fund exoplanet science in the future. Our UA-led team was part of the first selection and I, the principal investigator of our project, joined the program’s two-day kick-off meeting at NASA HQ. The meeting was exciting, inspiring, and challenging at the same time. There have been several press releases and articles about the program in various online and printed media; what follows is my own personal perspective on the meeting.
NASA has invited the principal investigators and key members of 16 NASA-funded teams working on topics related to exoplanet habitability, as well as the directors of the new initiative to discuss and debate the best format and goals for the new program. The teams were selected from regular proposal submissions to different NASA programs through the usual peer-review process, but invited to NExSS in addition to their selection to carry out the research they proposed.
The motivation for launching NExSS, as I understand, comes from the rapidly growing importance of extrasolar planet habitability research within many different NASA programs. The recent restructuring of NASA research grant programs (XRP, Habitable Worlds, etc.) further emphasized planetary habitability studies across many programs, which led to different aspects of habitability funded through different channels, without a good way to coordinate research between the programs. In addition, planetary habitability-related proposals accounted for a very large fraction of the major proposals that responded to the latest opportunity to join the NASA Astrobiology Institute.
NExSS is a new approach to study extrasolar planets: the program’s idea is to combine various studies of planetary habitability funded through existing NASA programs into a new framework – one in which the teams collaborate and have influence over the broader, longer-term research directions.
Although many people at NASA have been involved in and contributed to launching NExSS, Mary Voytek, senior scientist for astrobiology, is the chief architect of the new program and program officers Christina Richey and Doug Hudgins, among others, also played important roles. Shawn Domagal-Goldman has also provided important input and advice for the new program.
Our meeting began with short talks at a NASA HQ auditorium, which included welcomes by Jim Green and Paul Hertz, the directors of the NASA Planetary Sciences and Astrophysics divisions. They expressed excitement about exoplanet research, emphasized the need for studying planets as “systems” and they strongly endorsed connecting research projects in different disciplines that address exoplanet habitability. Their enthusiastic support of NExSS was a clear demonstration of how strongly NASA is supporting the new interdisciplinary research coordination network.
Next, lightning talks by the leads of each of the 16 teams introduced the scope of the teams; the single-slide presentations gave the first insights into the surprising breadth of NExSS. The NExSS teams have been selected from a set of projects submitted and selected for regular NASA programs (e.g., XRP, Habitable Worlds, Astrobiology, Heliophysics), so the sixteen teams brought very different expertise and perspectives to the table.
The projects also covered a broad spectrum in size, ranging from a few 1-2 investigator grants through a number of medium-sized teams to a few really large teams with multi-million dollar grants. These latter programs are our University of Arizona-led Earths in Other Solar Systems team (PI: Apai), the Arizona State University-led team (PI: Desch), a team led by NASA Goddard Institute for Space Sciences (PI: Del Genio), a team led by Berkeley (PI: Graham), and the one at Hammond University (PI: Moore). NASA’s press release and the team websites provide more information about the teams; I will instead focus on the kick-off meeting.
In contrast to the more usual top-down approach, our group’s first task is to brainstorm on its own purpose and definition. This has been an unusual responsibility; most committees are tasked to chart a course to reach a specific goal on a well-defined timescale. Defining our own goals and purpose is much more challenging; however, it also gave us the valuable opportunity to brainstorm and debate on the importance and achievability of different science goals over various timescales.
NASA has contracted a small company, KnowInnovate, to facilitate the creative process; this small team — two brothers — helped us move forward in the complex debate. Indeed, it has proven challenging for our team to converge on a set of well-defined goals in its first meeting; but by the end of the meeting we did identify our next steps and, I believe, made progress forward in surveying the questions, problems, and goals for the field.
The 2-day discussion resulted in covering most vertical surfaces of the meeting room with neon-colored sticky post-it notes, each with a question, problem, goal, or idea relevant for exoplanet studies. Arranged thematically, by importance, or by timescale, these stickies captured well the complexity and the heavily connected nature of next decade’s exoplanet research.
There discussion was productive and interesting; the number of questions and problems identified, and their complexity, is daunting, to say the least. Questions ranged from the impact of stellar hosts on the habitable planets through the importance of the formation and evolution of planetary systems to the unknowns of planetary interiors and life’s impact on the planet.
Nevertheless, in a process that built on large quantities of coffee, snacks, and post-it notes, we identified some short-term steps and topics of immediate interests. These included establishing working groups on topics relevant for many questions (missing experimental data, cloud physics and chemistry), plans for workshops/conferences to connect to the community, blog-type snippets on new exoplanet research papers, just to name a few.
It has been exciting to see a launch of a new program and one the exoplanet community can so actively shape. From my perspective, the NExSS group’s most important goal is interfacing and connecting: both within the group – in which we had a great start – and also with the broader community. The NExSS Executive Council will gradually change as PIs rotate in and out of the group over the next years, but I am very hopeful that the group will maintain its collaborative spirit as we put together the pieces of this exciting, but complex extrasolar puzzle.
You can follow our team’s work and results on Twitter (@EOSNExSS) or by subscribing to email announcements on our website ( http://otherearths.org ).
My Extrasolar Storms talk, given at the Hubble 25 Symposium, is now available online – check it out if you like a mix of the Hubble Space Telescope, iron raindrops, gigantic storms, and methods to map extrasolar planets: http://tinyurl.com/pjjbyv4
I am often asked to recommend books on astrobiology, habitable exoplanets, and extraterrestrial life.
There are many great books in these exciting fields, but there are a number of stand-outs that I highly recommend. Below is a gradually growing list of my favorite ones.
Is your favorite book missing? Add other book suggestions in the comments below!
A classic 1980 book by Carl Sagan. Although missing some of the new developments, this book remains an excellent treatise on life in the universe (and Earth).
Peter Ward and Don Brownlee
This is a classic book which provides an interesting overview of many key factors and problems that have made it difficult for complex life to evolve on Earth. Many of these factors apply to all habitable planets making, in the view of the authors, complex life extremely rare.
The “Rare Earth” hypothesis splits astrobiologists and it will take decades — if not centuries — until we will be able to decide if Ward and Brownlee are right. Nevertheless, the book provides a highly readable and interesting narrative of many exciting problems related to the development of simple and complex life.
Peter Ward is a Professor of Geosciences at the University of Washington, has led one of the NASA Astrobiology Institute nodes and an author of 16 popular science books.
Don Brownlee is a Professor of Astronomy at the University of Washington and the Principal Investigator of NASA’s Stardust mission.
How to Find a Habitable Planet
Princeton University Press, 2010
James Kasting is one of the pioneers of planetary habitability studies and in this book he provides an insider’s view on what makes a planet habitable and how can we find planets suitable for life.
The 5th Miracle: The Search for the Origin and Meaning of Life
Paul Davies’s book provides an exciting exploration of the possible origins of life, including the principles of biological systems.
Basic Books, 2009
Alan Boss’s book offers an enjoyable insider’s view on the birth of the exoplanet field: from the first radial velocity discoveries until the launch of the Kepler mission, Alan gives a diary-like summary of the major new exoplanet discoveries and results, including the controversies, debates, and the impact of politics and space policies on the science of exoplanets.
Alan P. Boss is an astrophysicist at the Carnegie Institution for Science’s Department of Terrestrial magnetism and an expert on extrasolar planets and the formation of planetary systems.
Biology / Paleontology
Life on a young planet
Princeton University Press, 2003
The book provides an interesting, in-depth, but very readable discussion of research on the earliest life on Earth and especially on microfossils. While the book does not focus on extraterrestrial life, the history of life on Earth is an absolutely fundamental part of astrobiology and this is a great introduction to it.
Copernicus Books, 2002
A somewhat older, but excellent book on the beginning of the era of exoplanet discovery and characterization. The book includes great interviews with many of the prominent scientists in the field and provides a great introduction to the initial discoveries of extrasolar planets.
Strange New Worlds
This book provides an exciting narrative of exoplanet exploration and discoveries, with clear explanation oft he techniques and peppered with anecdotes from the field.
Life in The Universe
J. Benneth, S. Shostak
A best-selling introduction to astrobiology, mainly aimed at non-science majors. This richly illustrated and entertaining textbook provides a well-balanced overview of how concepts from astronomy, planetary sciences, geosciences, and biology can be combined to search for life in and beyond the Solar System.
How to Build a Habitable Planet: The Story of Earth from the Big Bang to Humankind
Charles Langmuir and Wally Broecker
Princeton University Press, 2012
This well-written book follows Earth’s formation and evolution, including the overview of biological evolution. The book provides an interesting, geoscience perspective on these topics, which complements well most other books that approach the topic more from an astrophysics/planetary sciences perspective. Well suited for undergraduate courses.
Earth: Evolution of a Habitable World
Cambridge University Press, 2013
An excellent undergraduate introduction to the formation and evolution of Earth and to the processes that made and keep our planet habitable.
See my review of the this book in Meteoritics & Planetary Sciences.