What do you think?
Rate this book
Exoplanets: Diamond Worlds, Super Earths, Pulsar Planets, and the New Search for Life Beyond Our Solar System
The past few years have seen an incredible explosion in our knowledge of the universe. Since its 2009 launch, the Kepler satellite has discovered more than two thousand exoplanets, or planets outside of our solar system. More and more exoplanets are being discovered all the time, and even more remarkable than the sheer number of exoplanets is their variety. In Exoplanets, astronomer Michael Summers and physicist James Trefil explore the unbelievable recent discoveries: planets revolving around pulsars, planets made out of diamond, planets that are mostly water, and numerous rogue planets wandering through the emptiness of space. This captivating book reveals the latest, greatest discoveries and argues that the incredible richness and complexity we are finding necessitates a change in the questions we ask and the mental paradigms we use. In short, we have to change how we think about the universe and our place in it, because it is stranger and more interesting than we can even begin to imagine.
224 pages, Hardcover
First published March 14, 2017
Ratings & Reviews
Friends & Following
Create a free account to discover what your friends think of this book!
Community Reviews
Displaying 1 - 30 of 103 reviews
March 24, 2021
Q:
The world is not only stranger than you imagine, it’s stranger than you can imagine.Attributed to J. B. S. Haldane, Daedalus, or, Science and the Future, 1923 (c)
A lot on chauvinism, be in planeraty, surface, carbon or chemical. :)
Where's everybody? Enrico Fermi (c)
Q:
...the new assortment of planets includes:
•Super Earths—rocky planets several times the size of the Earth. There seem to be a lot of these out there.
•Styrofoam worlds—planets so light that we cannot figure out why they don’t collapse under their own gravity.
•Diamond planets—planets made of pure carbon, with diamond mantles and cores of liquid diamond, a material unknown on Earth.
•Multistar worlds—planets that circle up to four stars, systems that were supposed to be dynamically impossible.
•Hot Earths—worlds so close to their stars that their surface rocks are vaporized. When such a planet rotates, “snowflakes” made of solid rock fall from the sky.
•Rogue planets—planets wandering around unattached to stars. It is possible that the majority of planets in the galaxy are of this type. (c)
KEPLER 186F!
Q:
... life is like pornography—we can’t define it, but we know it when we see it. (c)
Q:
In fact, this so-called tidal heating is enough to keep Europa’s subsurface ocean above the freezing point of water. (c)
Q:
The Kepler spacecraft detects planets by a method that is easy to describe, if not necessarily easy to carry out in practice. It’s called the transit method, and it works because of a simple fact: when a planet passes between an observer and a star, the observer sees the light from the star dim slightly, then return to normal as the planet moves on. A repeated pattern of such dimmings is a fingerprint suggesting the presence of the planet. As simple as this technique sounds, however, it encounters problems when actually implemented. (c)
Q:
So now it is clear why we called our imaginary rogue planet Haven. Despite the absence of a star, its moons could have liquid oceans, perhaps even surface oceans. In the cold depths of interstellar space, its moons could indeed be havens for life, possibly even life on the surface. (c)
Q:
In fact, just as these ice planets might hold most of the liquid water in the galaxy, they might also be the home of most of its life.
This conjecture is supported by the red organic dust we see on Pluto’s surface (although the term organic, when applied to molecules, simply means that there are carbon atoms present in their structure—it does not mean that the molecules came from living systems). (c)
Q:
Near the horizon, a small sun sinks, casting a reddish glow over the landscape. The land is low and flat, its lagoons and pools interspersed with muddy banks. Behind us flattened plants stand, their black leaves capturing what energy they can from the faint sun. The breeze seems to move the heavy atmosphere past us, and we seem heavy, too. Welcome to Archipelago World. (c)
Q:
However, as data from the Kepler spacecraft continue to be analyzed, a new kind of planet—called a super Earth—seems to be emerging as a common type. Super Earths are planets, probably rocky, most with two to three times the mass of Earth, but some with up to 10 times Earth’s mass. You can think of them as being somewhere between a large Earth and a mini-Neptune in size. We don’t have any planets like this in our own solar system, so in this respect at least, our system may be somewhat atypical. (c)
Q:
The world is not only stranger than you imagine, it’s stranger than you can imagine.Attributed to J. B. S. Haldane, Daedalus, or, Science and the Future, 1923 (c)
A lot on chauvinism, be in planeraty, surface, carbon or chemical. :)
Where's everybody? Enrico Fermi (c)
Q:
...the new assortment of planets includes:
•Super Earths—rocky planets several times the size of the Earth. There seem to be a lot of these out there.
•Styrofoam worlds—planets so light that we cannot figure out why they don’t collapse under their own gravity.
•Diamond planets—planets made of pure carbon, with diamond mantles and cores of liquid diamond, a material unknown on Earth.
•Multistar worlds—planets that circle up to four stars, systems that were supposed to be dynamically impossible.
•Hot Earths—worlds so close to their stars that their surface rocks are vaporized. When such a planet rotates, “snowflakes” made of solid rock fall from the sky.
•Rogue planets—planets wandering around unattached to stars. It is possible that the majority of planets in the galaxy are of this type. (c)
KEPLER 186F!
Q:
... life is like pornography—we can’t define it, but we know it when we see it. (c)
Q:
In fact, this so-called tidal heating is enough to keep Europa’s subsurface ocean above the freezing point of water. (c)
Q:
The Kepler spacecraft detects planets by a method that is easy to describe, if not necessarily easy to carry out in practice. It’s called the transit method, and it works because of a simple fact: when a planet passes between an observer and a star, the observer sees the light from the star dim slightly, then return to normal as the planet moves on. A repeated pattern of such dimmings is a fingerprint suggesting the presence of the planet. As simple as this technique sounds, however, it encounters problems when actually implemented. (c)
Q:
So now it is clear why we called our imaginary rogue planet Haven. Despite the absence of a star, its moons could have liquid oceans, perhaps even surface oceans. In the cold depths of interstellar space, its moons could indeed be havens for life, possibly even life on the surface. (c)
Q:
In fact, just as these ice planets might hold most of the liquid water in the galaxy, they might also be the home of most of its life.
This conjecture is supported by the red organic dust we see on Pluto’s surface (although the term organic, when applied to molecules, simply means that there are carbon atoms present in their structure—it does not mean that the molecules came from living systems). (c)
Q:
Near the horizon, a small sun sinks, casting a reddish glow over the landscape. The land is low and flat, its lagoons and pools interspersed with muddy banks. Behind us flattened plants stand, their black leaves capturing what energy they can from the faint sun. The breeze seems to move the heavy atmosphere past us, and we seem heavy, too. Welcome to Archipelago World. (c)
Q:
However, as data from the Kepler spacecraft continue to be analyzed, a new kind of planet—called a super Earth—seems to be emerging as a common type. Super Earths are planets, probably rocky, most with two to three times the mass of Earth, but some with up to 10 times Earth’s mass. You can think of them as being somewhere between a large Earth and a mini-Neptune in size. We don’t have any planets like this in our own solar system, so in this respect at least, our system may be somewhat atypical. (c)
Q:
March 22, 2021
Science always underdetermines. That’s a feature not a bug. There will always be more than one theory to explain the facts. I can always add auxiliary observational assumptions, a new paradigmatic ontology (a new way of thinking about the world) or my imagination and create a potentially better theory for explaining the world. New tools give new observations leading to new facts about the world and the Kepler telescope is giving us new ways of explaining the world one new exoplanet at a time that was not apparent previously. Each fact we acquire about the world helps us focus on the best theory about the world and let us discard the less likely theories about the world.
Science has multiple values. One of those values is the narrative that explains the story being told must be understandable and kept simple (Occam’s razor). This book provides narratives as explanations tying the new observed facts about the newly discovered exoplanets. The author connected some dots that I wasn’t aware of. Rogue planets, planets far from their sun, moons of large planets are all possible candidates for life because they all can have possible energy sources that aren’t necessarily dependent on a sun and can last for eons. The authors will step you through the logic for reaching that conclusion.
I thought the book was better than the ordinary popular science book for the first two thirds of the book, but the last third of the book really knocked it out of the ball park for me. As he started talking about the Drake equation I thought ‘oh no, here we go again somebody that’s going to underwhelm me and reach the wrong headed conclusion’. I was wrong. He saw the Drake equation for what it is and what it lacks and focused on the ‘great filters’ and how the Drake equation can just as easily show that we (you and me!) might be the only complex life in the universe, or using Proust’s criterion for what makes humans special from all other known creatures we may be the only creatures in the observable universe ‘[that] can doubt are own reason’.
Of all the Gods I know about so far, Jupiter is the only one deserving of the status of being worshipped. He (It?) first cleared out the inner solar system making Earth possible and then was dragged back by Saturn to act as the solar collector and protector of the Earth from potentially lethal comets and asteroids and other unwanted objects that would have certainly rammed into the Earth; for me, a God deserving of worship. Potentially habitable earths might require such a shield, and perhaps there is only one deserving God in the universe. The moon, the prokaryote with eukaryote transmogrification, the multi cell from single cell, the magnetic shield of the earth, DNA from RNA from homeostasis (or RNA world), the Alvarez comet destroying the dinosaurs, the Enlightenment giving primacy of science over religious faith, Trump or his ilk potentially destroying the earth (the great filter can lie in the future) because they do believe ‘climate change is a Chinese hoax’ and that statement is that of a psychotic and anyone who supports that absurdity is crazy and can lead to the destruction of the earth. All of these kinds of items can refute those who believe that our solar system and Earth is ‘mediocre’ and typical of what we could find out in the galaxy or the observable universe. Just maybe we are the only rock in the observable universe with complex life or maybe we aren’t, but I really get annoyed with shallow arguments from shallow people who have never read a book on the topic thinking it means I’m arrogant to think we could be alone in the observable universe (except for the one God I know of so far deserving of worship, Jupiter).
The Fermi paradox has never been resolved (at least not for me). It would only take a civilization 30 to 300 million years to completely colonize a galaxy with Dyson Spheres or orbiting space stations and their signatures should be visible, but don’t seem to be. Can you imagine if we Earthlings last another 1000 years or maybe just 100 years how advanced our Super AIs would be and how we would almost for sure create self replicating Van Neumann probes to explore and colonize? Where are the signatures?
The book did a decent job on the science of exoplanets, biology and the chauvinism we possess by our way of self centered thinking (a Bayesian fallacy if there ever was one). This book knocks it out of the park with why we (earthlings) very well might be alone within our galaxy or even the observable universe as a whole. Most of the above thoughts are in this book (I don’t think he speaks of AI or Thomas Bayes, but I think he covered most of everything else I said above).
Science has multiple values. One of those values is the narrative that explains the story being told must be understandable and kept simple (Occam’s razor). This book provides narratives as explanations tying the new observed facts about the newly discovered exoplanets. The author connected some dots that I wasn’t aware of. Rogue planets, planets far from their sun, moons of large planets are all possible candidates for life because they all can have possible energy sources that aren’t necessarily dependent on a sun and can last for eons. The authors will step you through the logic for reaching that conclusion.
I thought the book was better than the ordinary popular science book for the first two thirds of the book, but the last third of the book really knocked it out of the ball park for me. As he started talking about the Drake equation I thought ‘oh no, here we go again somebody that’s going to underwhelm me and reach the wrong headed conclusion’. I was wrong. He saw the Drake equation for what it is and what it lacks and focused on the ‘great filters’ and how the Drake equation can just as easily show that we (you and me!) might be the only complex life in the universe, or using Proust’s criterion for what makes humans special from all other known creatures we may be the only creatures in the observable universe ‘[that] can doubt are own reason’.
Of all the Gods I know about so far, Jupiter is the only one deserving of the status of being worshipped. He (It?) first cleared out the inner solar system making Earth possible and then was dragged back by Saturn to act as the solar collector and protector of the Earth from potentially lethal comets and asteroids and other unwanted objects that would have certainly rammed into the Earth; for me, a God deserving of worship. Potentially habitable earths might require such a shield, and perhaps there is only one deserving God in the universe. The moon, the prokaryote with eukaryote transmogrification, the multi cell from single cell, the magnetic shield of the earth, DNA from RNA from homeostasis (or RNA world), the Alvarez comet destroying the dinosaurs, the Enlightenment giving primacy of science over religious faith, Trump or his ilk potentially destroying the earth (the great filter can lie in the future) because they do believe ‘climate change is a Chinese hoax’ and that statement is that of a psychotic and anyone who supports that absurdity is crazy and can lead to the destruction of the earth. All of these kinds of items can refute those who believe that our solar system and Earth is ‘mediocre’ and typical of what we could find out in the galaxy or the observable universe. Just maybe we are the only rock in the observable universe with complex life or maybe we aren’t, but I really get annoyed with shallow arguments from shallow people who have never read a book on the topic thinking it means I’m arrogant to think we could be alone in the observable universe (except for the one God I know of so far deserving of worship, Jupiter).
The Fermi paradox has never been resolved (at least not for me). It would only take a civilization 30 to 300 million years to completely colonize a galaxy with Dyson Spheres or orbiting space stations and their signatures should be visible, but don’t seem to be. Can you imagine if we Earthlings last another 1000 years or maybe just 100 years how advanced our Super AIs would be and how we would almost for sure create self replicating Van Neumann probes to explore and colonize? Where are the signatures?
The book did a decent job on the science of exoplanets, biology and the chauvinism we possess by our way of self centered thinking (a Bayesian fallacy if there ever was one). This book knocks it out of the park with why we (earthlings) very well might be alone within our galaxy or even the observable universe as a whole. Most of the above thoughts are in this book (I don’t think he speaks of AI or Thomas Bayes, but I think he covered most of everything else I said above).
March 22, 2017
I have mixed feelings about this book. It had some great ideas and a few great chapters, but everything kind of felt forced together and rushed, probably to capitalize on the recent earth-like exoplanets spied by TRAPPIST (there is no mention of these newly discovered worlds in this first edition).
I found at least 4 grievous errors in the first few chapters alone, e.g., Venus is our nearest planetary neighbor, not Mars. However, I found the chapters on rogue exoplanets and of ice and water very interesting, and the final chapters regarding extraterrestrial life were extremely thought-provoking.
I found at least 4 grievous errors in the first few chapters alone, e.g., Venus is our nearest planetary neighbor, not Mars. However, I found the chapters on rogue exoplanets and of ice and water very interesting, and the final chapters regarding extraterrestrial life were extremely thought-provoking.
March 21, 2021
Another Astronomy book ticked off from my never-ending reading list. The discovery of Exoplanets (planets outside our solar system) paved the way to debunk or abandon at least some of our old, chauvinistic thinking of the universe, such as Stellar Chauvinism which states that planets, at least capable of supporting life, have to be in orbit around stars, and Surface Chauvinism which provides that in so far as water is necessary for the development of life, it need be found on the surface of a planet. But the most fascinating take away from this book is the discovery of Rogue Planets - those planets roaming in our galaxy independent of or not orbiting a star. How cool is that! One day, there will be more explorations about these planets to answer those seemingly elusive questions: Are we alone in the universe? Are there any life forms outside our own physical and chemical understanding? The universe is a lot more complex and diverse than we imagined.
July 7, 2024
Well presented, but there are no surprises. The sad fact is that although we are finding large numbers of exoplanets, there are still none that we know much about. Colour, temperature, radius, and mass are the only things we can actually measure. Mind you, there are parts of our own solar system that are not properly mapped yet.
March 24, 2022
At five years old, it is already dated. NASA ha recently announced the discovery of the 5,000th exoplanet. It still is valuable for those who are not science minded and wants a layman’s lesson on the subject.
March 22, 2018
Do you think all solar systems and planets formed like ours did, with small rocky planets close to the sun and large gaseous planets farther out? Well you are in good company. Many leading scientists believed the standard theory of solar and planetary formation too... that is until all the evidence began to filter in once humans built sophisticated telescopes that helped us discover just how strange our universe really is. Recently our depiction came to include:
- Moons of Jupiter and Saturn that have liquid oceans covered in ice that might harbor life
- The Kuiper Belt that houses Pluto (which might also have a liquid ocean teaming with life) and other planets/ mini planets with their own moons
- Planets like Pluto that might have tectonic plates
- Planets circling pulsars (They think they must have formed after supernovae explosions)
- Large, huge, hot Jupiters orbiting extremely close to their stars
- Rouge planets that have no start around which to orbit
- More than 4,000 exoplanet systems
- Super earths, rocky planets larger than earth
- Styrofoam planets, so light scientists wonder how they don’t collapse under gravity
- Diamond planets made of pure carbon, with charcoal crust, a liquid carbon diamond core that erupts to the surface and turns into crystalized diamonds. (This planet is called 55 Cancri e and I bet it will be your favorite planet after reading this book.)
- Multi star worlds, in which planets circle up to 4 stars
- Hot earths, planets so close to their stars, their surface rocks are vaporized (when such a planet rotates, snowflakes made of solid rock fall from the sky)
We have now gone far beyond the model of solar system formation outline by Laplace in which the solar system disc flattened out, concentrating most of the material in a sphere in the center-- our sun, and flinging out the other material such that heavy elements remained close, making the small, dense, rocky planets and flinging the lighter elements out even farther, making the large gaseous planets. We have gone beyond our understanding of our own system and now know that the initial solar cloud kept contracting and flung whole planets out of the solar system while pulling other planets into the sun. We know that in each orbit, the planet in that orbit kept sweeping up the bits of matter to make one whole planet in each orbit. We now know the Kuiper Belt is an entirely new world of ice planets small and large that might change everything we thought we knew about our own solar system. For example, life might exist far from the sun on an ice planet like Pluto (the authors provide an argument about definition of planet-- you can call Pluto a planet or not).
We know that planets look different based on what generation star is the center of the system that created them (including rogue planets). For example, our sun is a 3rd generation sun. That means 3 generations of stars exploded before it, creating heavy elements like carbon, oxygen, lead, uranium, etc. Because of the chemicals in our original solar cloud, we have planets like Venus and Mars that are rocky, Earth that is not only rocky but can support living organisms, and huge planets like Jupiter. Unlike Earth, 55 Cancri e was made from a solar system that was 4th generation and had even heavier elements to construct its planets. As a result, 55 Cancri e is burning fire of diamond, charcoal, and liquid diamond that is far too hot to support life.
The discussion of 55 Cancri e segued perfectly into the competing forces of magnetic fields and wind. So beautifully written, the authors brought to life the struggle between the winds that push the magnetic field down and blew away the atmosphere and the magnetic fields that try to keep building and rebuilding an atmosphere.
The authors also included a thoughtful discussion on the origins of life, RNA world v Metabolism First. RNA world asserts that in order for life to originate on Earth or any planet, a miracle (or happy accident if you would rather) must occur to randomly assemble RNA. Once RNA is made (by magic) it can then act as DNA that carries the code and the enzyme which can build the molecules of life. Importantly, this miracle would have to occur on every planet that could harbor life. That is a lot of miracles and lot of magical thinking coming from scientists who spend most of their time arguing against creationists. Unlike the Gene first (RNA) camp, Metabolism first suggests that life got it start where there was a rich source of energy, like ocean vents, that have the power to rip apart molecules and put them back together to create DNA, proteins, and fatty acids. No magic needed, just the energy provided at the vents by tectonic plates that rip up the plates to free the elements of life and the H+ that bubbles up out of the vents and acts like the battery that powers the assembly of those elements.
They finished with a discussion about the Drake equation and how likely it might be to find life in other parts of the universe.
- Moons of Jupiter and Saturn that have liquid oceans covered in ice that might harbor life
- The Kuiper Belt that houses Pluto (which might also have a liquid ocean teaming with life) and other planets/ mini planets with their own moons
- Planets like Pluto that might have tectonic plates
- Planets circling pulsars (They think they must have formed after supernovae explosions)
- Large, huge, hot Jupiters orbiting extremely close to their stars
- Rouge planets that have no start around which to orbit
- More than 4,000 exoplanet systems
- Super earths, rocky planets larger than earth
- Styrofoam planets, so light scientists wonder how they don’t collapse under gravity
- Diamond planets made of pure carbon, with charcoal crust, a liquid carbon diamond core that erupts to the surface and turns into crystalized diamonds. (This planet is called 55 Cancri e and I bet it will be your favorite planet after reading this book.)
- Multi star worlds, in which planets circle up to 4 stars
- Hot earths, planets so close to their stars, their surface rocks are vaporized (when such a planet rotates, snowflakes made of solid rock fall from the sky)
We have now gone far beyond the model of solar system formation outline by Laplace in which the solar system disc flattened out, concentrating most of the material in a sphere in the center-- our sun, and flinging out the other material such that heavy elements remained close, making the small, dense, rocky planets and flinging the lighter elements out even farther, making the large gaseous planets. We have gone beyond our understanding of our own system and now know that the initial solar cloud kept contracting and flung whole planets out of the solar system while pulling other planets into the sun. We know that in each orbit, the planet in that orbit kept sweeping up the bits of matter to make one whole planet in each orbit. We now know the Kuiper Belt is an entirely new world of ice planets small and large that might change everything we thought we knew about our own solar system. For example, life might exist far from the sun on an ice planet like Pluto (the authors provide an argument about definition of planet-- you can call Pluto a planet or not).
We know that planets look different based on what generation star is the center of the system that created them (including rogue planets). For example, our sun is a 3rd generation sun. That means 3 generations of stars exploded before it, creating heavy elements like carbon, oxygen, lead, uranium, etc. Because of the chemicals in our original solar cloud, we have planets like Venus and Mars that are rocky, Earth that is not only rocky but can support living organisms, and huge planets like Jupiter. Unlike Earth, 55 Cancri e was made from a solar system that was 4th generation and had even heavier elements to construct its planets. As a result, 55 Cancri e is burning fire of diamond, charcoal, and liquid diamond that is far too hot to support life.
The discussion of 55 Cancri e segued perfectly into the competing forces of magnetic fields and wind. So beautifully written, the authors brought to life the struggle between the winds that push the magnetic field down and blew away the atmosphere and the magnetic fields that try to keep building and rebuilding an atmosphere.
The authors also included a thoughtful discussion on the origins of life, RNA world v Metabolism First. RNA world asserts that in order for life to originate on Earth or any planet, a miracle (or happy accident if you would rather) must occur to randomly assemble RNA. Once RNA is made (by magic) it can then act as DNA that carries the code and the enzyme which can build the molecules of life. Importantly, this miracle would have to occur on every planet that could harbor life. That is a lot of miracles and lot of magical thinking coming from scientists who spend most of their time arguing against creationists. Unlike the Gene first (RNA) camp, Metabolism first suggests that life got it start where there was a rich source of energy, like ocean vents, that have the power to rip apart molecules and put them back together to create DNA, proteins, and fatty acids. No magic needed, just the energy provided at the vents by tectonic plates that rip up the plates to free the elements of life and the H+ that bubbles up out of the vents and acts like the battery that powers the assembly of those elements.
They finished with a discussion about the Drake equation and how likely it might be to find life in other parts of the universe.
July 20, 2019
With a title this sexy, one would expect this to get pretty great pretty quick. So it's a bit disappointing that it takes a full 75 pages of background and history before we get to see our first serious exoplanet.
It's kind of like if you rented a porno (assuming anyone still "rents" porn?), only to have the first half hour not only focus entirely on the delivery of a pizza to some conveniently cash-strapped young lady, but to also go back and show the making of the pizza; the drive from the pizza shop to the "you-think-they'd-have-$20-here-somewhere" McMansion in L.A.; and then finally a mini-documentary on the history of Italian cuisine...
But then finally in Chapter Five we get to the good stuff, and Stormy finally starts paying for her pie.
And was it worth the wait! Diamond volcanoes; ice worlds; water worlds; dinosaur and "pond scum" planets; rogue infrared planets cruising through the interstellar blackness; "Super Earths" and styrofoam planets - mind-blowing stuff, but in these authors' hands all surprisingly believable. I just wish they'd found a bigger publisher who would have blown for some of the awesome artwork that these stories cry out for, (and that you probably get cheap from any wallpaper website):
Also surprising, despite these way-cool if hypothetical alternate worlds, I personally found the last third of the book - the "search for life" part - the most interesting. Summers and Trefil, (both professors at our "local" George Mason University), present a nice summary of the famous Drake equation, but then update it to reflect our more recent understanding of the number of planets out there and what it might take for intelligent life to arise - all of which results in an unexpectedly lower chance of an impending alien invasion.
(The original Drake equation - any questions?)
They also neatly tie in Occam's razor (so that I now understand the "razor" part of that phrase - it "shaves off" unnecessary complexity); the "Great Silence" as summed up in Fermi's famous "then where are they?" question; and a really nifty concept introduced by another GMU professor called "the Great Filter," which further throws the whole thing up for grabs.*
Alternately exhilarating, depressing, inspiring and unsettling, Exoplanets: DWSEPPATNSFLBOSS" is near-consistently fascinating. I would highly recommend to any of my nerdier friends who are even vaguely into this sort of thing.
* Since you asked, "The Great Filter" posits an additional variable in Drake, that would more-or-less change everything. Examples: if the development of intelligent life required a planet to be far from the galactic center - and thus farther away from other exploding stars - or to have a Jupiter-sized planet running "interference" to prevent frequent meteor strikes, that filter would impact the very beginning of the formula, so that life on other planets might be very rare indeed. However, if the filter came later in the equation, such as a requirement for environment-altering geography resulting in plate tectonics or the occasional ice age, then the galaxy would more likely be full of dinosaur-level planets that never developed more intelligent or technological life forms. And finally, there's the theory arguing that "the Great Filter" remains in our future - i.e., the depressing explanation that we haven't detected any advanced civilizations because when they reach our level [or slightly beyond], they invariably use their technology - or alien equivalent of the Electoral College - to wipe themselves out.
It's kind of like if you rented a porno (assuming anyone still "rents" porn?), only to have the first half hour not only focus entirely on the delivery of a pizza to some conveniently cash-strapped young lady, but to also go back and show the making of the pizza; the drive from the pizza shop to the "you-think-they'd-have-$20-here-somewhere" McMansion in L.A.; and then finally a mini-documentary on the history of Italian cuisine...
But then finally in Chapter Five we get to the good stuff, and Stormy finally starts paying for her pie.
And was it worth the wait! Diamond volcanoes; ice worlds; water worlds; dinosaur and "pond scum" planets; rogue infrared planets cruising through the interstellar blackness; "Super Earths" and styrofoam planets - mind-blowing stuff, but in these authors' hands all surprisingly believable. I just wish they'd found a bigger publisher who would have blown for some of the awesome artwork that these stories cry out for, (and that you probably get cheap from any wallpaper website):
Also surprising, despite these way-cool if hypothetical alternate worlds, I personally found the last third of the book - the "search for life" part - the most interesting. Summers and Trefil, (both professors at our "local" George Mason University), present a nice summary of the famous Drake equation, but then update it to reflect our more recent understanding of the number of planets out there and what it might take for intelligent life to arise - all of which results in an unexpectedly lower chance of an impending alien invasion.
(The original Drake equation - any questions?)
They also neatly tie in Occam's razor (so that I now understand the "razor" part of that phrase - it "shaves off" unnecessary complexity); the "Great Silence" as summed up in Fermi's famous "then where are they?" question; and a really nifty concept introduced by another GMU professor called "the Great Filter," which further throws the whole thing up for grabs.*
Alternately exhilarating, depressing, inspiring and unsettling, Exoplanets: DWSEPPATNSFLBOSS" is near-consistently fascinating. I would highly recommend to any of my nerdier friends who are even vaguely into this sort of thing.
* Since you asked, "The Great Filter" posits an additional variable in Drake, that would more-or-less change everything. Examples: if the development of intelligent life required a planet to be far from the galactic center - and thus farther away from other exploding stars - or to have a Jupiter-sized planet running "interference" to prevent frequent meteor strikes, that filter would impact the very beginning of the formula, so that life on other planets might be very rare indeed. However, if the filter came later in the equation, such as a requirement for environment-altering geography resulting in plate tectonics or the occasional ice age, then the galaxy would more likely be full of dinosaur-level planets that never developed more intelligent or technological life forms. And finally, there's the theory arguing that "the Great Filter" remains in our future - i.e., the depressing explanation that we haven't detected any advanced civilizations because when they reach our level [or slightly beyond], they invariably use their technology - or alien equivalent of the Electoral College - to wipe themselves out.
September 26, 2017
This should have been much better, but the authors spend a chapter belittling and ridiculing peers that they don't agree with. Very petty and unprofessional.
July 15, 2017
Exoplanets: Diamond Worlds, Super Earths, Pulsar Planets and the New Search for Life beyond our Solar System, by Michael Summers and James Trefil, is a look at the expanding science of exoplanet research. The authors look at a variety of planets that are posited to exist in our galaxy, and further elaborate on the innovations in telescopic technology allowing us to discover planets in orbit around distant stars. This is a difficult process, as currently planets in orbit around their stars are difficult to spot due to interference from the intense light coming off of their star. They can be spotted by viewing a dimming of the stars light, signifying a planet has passed by and eclipsed some of the light. Scientists have discovered many new planets, which has opened up the debate about life-supporting planets in solar systems outside our own. The authors explain the Circumstellar Habitable Zone (CHZ) of a star, which scientists posit is the Goldilocks zone for life to develop on an Earth like planet.
The authors also talk about various bias' in this analysis. Currently humans only have one single life bearing example of a planet; our own. On top of that, we still do not understand how life developed on Earth fully, in terms of the many complex factors involved in the creation of our solar system and our planet. Scientists argue whether water and organic materials were brought to Earth by comets, or were created due to our tectonic activity or a combination of these and other factors. Is this same process possible on other planets? Looking at our own solar system, there is a slim possibility that life like Earth's (carbon based, reliant on water etc.) has developed on other worlds. The most promising are Europa - one of Jupiter's moons. It is thought that Europa has a salty ocean underneath its frozen crust, and the planet also has tectonic forces due to the gravitational effects of Jupiter on the moon. Enceladus, a moon of Saturn, is another promising candidate, as a flyby by a NASA probe detected water and organic materials within plumes being shot out of the moons immense geysers. Enceladus features an underground ocean much like Europa. Mars also has the potential for life due to increasing evidence that liquid water exists in some form under the surface. Clearly, if life in the galaxy needs to develop like it did on Earth, these planetary-bodies in or own solar system, and other planets in the Goldilocks zone (or potentially other moons of gas giants) offer ideal conditions for the development of some of the building blocks of life.
The authors talk about other interesting topics; purely carbon worlds with intense heat and tectonic activity that have produced large amounts of diamonds. Earth-like planets much larger than our own that may support liquid surface oceans as archipelago planets. Planets entirely covered on the surface by liquid oceans. Planets that rotate around Pulsar's and around multiple stars. Rogue planets that have been flung out into space and are not attached to any solar system. Their are also discussions on the likelihood of life existing outside of Earth. The authors discuss the Drake equation and SETTI, the Fermi paradox (if life is out there, where is it and why haven't we seen any evidence so far?). The authors discuss carbon-bias, and how life might theoretically develop under different conditions. If it had, could we recognize it?
Clearly there are some interesting ideas in this book. So why the 3-star rating? A review of this book by user Ra7thsign points out a number of errors in this book that are noticeable and a bit annoying. I will leave that user's review to explain it, but suffice to say it does make the book a bit more difficult to believe. Secondly, the complete lack of a source list in this book (there literally is not one) makes it difficult to fact check. It also does not add outside perspective past the authors' own, and does not help a reader looking for more information on these very interesting topics. The authors are basically saying to the reader "believe me, or Google it yourself". This is unfortunate for such interesting topics as those covered in this book. Other than that, the fascinating 'science fiction'-like aspects of the book, as well as the timely update on where we are at in terms of exoplanet discovery, makes this a book worth reading, despite its setbacks. I can easily recommend this book to a laymen on the subject (like myself) as well as those interested in a light read on Space that moves on the side of speculative science.
The authors also talk about various bias' in this analysis. Currently humans only have one single life bearing example of a planet; our own. On top of that, we still do not understand how life developed on Earth fully, in terms of the many complex factors involved in the creation of our solar system and our planet. Scientists argue whether water and organic materials were brought to Earth by comets, or were created due to our tectonic activity or a combination of these and other factors. Is this same process possible on other planets? Looking at our own solar system, there is a slim possibility that life like Earth's (carbon based, reliant on water etc.) has developed on other worlds. The most promising are Europa - one of Jupiter's moons. It is thought that Europa has a salty ocean underneath its frozen crust, and the planet also has tectonic forces due to the gravitational effects of Jupiter on the moon. Enceladus, a moon of Saturn, is another promising candidate, as a flyby by a NASA probe detected water and organic materials within plumes being shot out of the moons immense geysers. Enceladus features an underground ocean much like Europa. Mars also has the potential for life due to increasing evidence that liquid water exists in some form under the surface. Clearly, if life in the galaxy needs to develop like it did on Earth, these planetary-bodies in or own solar system, and other planets in the Goldilocks zone (or potentially other moons of gas giants) offer ideal conditions for the development of some of the building blocks of life.
The authors talk about other interesting topics; purely carbon worlds with intense heat and tectonic activity that have produced large amounts of diamonds. Earth-like planets much larger than our own that may support liquid surface oceans as archipelago planets. Planets entirely covered on the surface by liquid oceans. Planets that rotate around Pulsar's and around multiple stars. Rogue planets that have been flung out into space and are not attached to any solar system. Their are also discussions on the likelihood of life existing outside of Earth. The authors discuss the Drake equation and SETTI, the Fermi paradox (if life is out there, where is it and why haven't we seen any evidence so far?). The authors discuss carbon-bias, and how life might theoretically develop under different conditions. If it had, could we recognize it?
Clearly there are some interesting ideas in this book. So why the 3-star rating? A review of this book by user Ra7thsign points out a number of errors in this book that are noticeable and a bit annoying. I will leave that user's review to explain it, but suffice to say it does make the book a bit more difficult to believe. Secondly, the complete lack of a source list in this book (there literally is not one) makes it difficult to fact check. It also does not add outside perspective past the authors' own, and does not help a reader looking for more information on these very interesting topics. The authors are basically saying to the reader "believe me, or Google it yourself". This is unfortunate for such interesting topics as those covered in this book. Other than that, the fascinating 'science fiction'-like aspects of the book, as well as the timely update on where we are at in terms of exoplanet discovery, makes this a book worth reading, despite its setbacks. I can easily recommend this book to a laymen on the subject (like myself) as well as those interested in a light read on Space that moves on the side of speculative science.
June 2, 2017
I am filled with genuine feelings about outer space and planets. There is so much I never considered about the universe and I am delighted that I decided to pick up this book. Definite recommendation!
March 29, 2017
Easy to read and understand. A good book for mid graders on up.
July 10, 2018
This short science book really tells a story about the planets that exist, or theoretically exist, in the universe, and describes the science behind the descriptions and the history of the discovery of these planets. Two signs of a good pop-science book are vivid descriptions and analogies that simplify the story for lay readers. Both happen in this book. I will remember “hot Jupiters” and how they came to be the first kinds of distant planets discovered. And I will remember the description of diamond worlds, with diamonds thrown from volcanoes. This is a great read about planetary science advances over the past ten years or so.
June 22, 2018
A succinct introduction to exoplanets, rogue planets, and the arguments behind SETI. It's written in a layman manner and the authors inject just the right amount of scientific information without making it too boring, although it's inevitable in some segments.
May 18, 2017
A fun, brief overview of current scientific understandings of what kinds of worlds and life might exist out there.
March 1, 2018
This is a non-technical survey of exoplanet research. The authors write in an almost breezy, accessible style, telling us, first the basics of exoplanets, how they are detected, what the current state is, and then they go into a kind of tour guide to some example types of exoplanets. The book concludes with short chapters on the Drake Equation, the search for intelligence, and the Fermi Paradox.
That’s a lot to cover in a little over 200 pages, so don’t expect too much depth on any one thing. I’ve been following exoplanet research for some time, but I always find revisiting the facts and reasoning behind it a good use of time. It’s chance to climb out of the middle of debates and issues and get a fresh perspective.
The first five chapters lay out basics, including a discussion of the definition of a planet, detection methods, and a chapter on the Kepler mission. Chapters six through ten are speculative sketches of what five sample exoplanets are really like, imagining a close-up visit to them. The five include:
- 55 Cancri E (“Diamond World”)
- "Haven", an imagined rogue planet (a planet no longer orbiting a star)
- A Pluto-like “Ice World”
- Kepler 186f (“Archipelago World,” with a watery but not fully submerged surface and orbiting an M Dwarf star)
- Gliese 1214b (“Water World”)
These chapters are entertaining, speculative, and tempered by explicit caveats about how much we can really know and how much is educated guessing
Those are followed by a discussion of life on earth and how it may have originated, as a guide to think about how the same (or something very different) might happen elsewhere. Then come short chapters on the search for life, the search for intelligent life, and a concluding discussion of the Fermi Paradox. All of these topics, of course, are treated in much more depth in other books. What you’re getting here is strictly overview.
The one theme that the authors really want to drive home is to caution our reasoning in light of “the curse of the single example”. We have only one known example of a planet that supports life, one example of the origin and evolution of life, one example of a technological species (capable of interstellar communication), one example of a planetary system whose history and structure we have detailed knowledge of, . . . and so on.
It’s not just that we have little data to base our reasoning and speculation on, it’s that that one example may implicitly limit our imaginations. The authors cite some good examples. One in which our limited imaginations have been busted — the recognition that rogue planets, cruising independently through interstellar space far from any star, could provide environments rich enough in energy and heat to potentially support life. Others are drawn from science fiction — Isaac Asimov’s vision of a composite life form, made of rocks or grains of sand connected in some non-apparent way, or a life form on Titan, with a metabolism so slow in its frigid environment, that it takes 1,000 years to draw a single breath. Are we sure we would really even recognize an alien life form as alive, much less intelligent?
Time and again, as they point out, we are surprised. We were surprised by Pluto, that a planet so far from its star could generate enough internal heat to apparently host a subsurface ocean. We were surprised by the prevalence of subsurface oceans in moons of planets well outside of the sun’s “habitable zone”. It sounds like a cliche, but, as a warning against making premature conclusions about anything to do with exoplanets, the possibilities for life, and all the rest, we must always recognize that surprise is a constant in this field.
Books in this field are guaranteed to be born out of date. You won’t find anything here about Proxima B or the Trappist system of exoplanets. Those currently hot topics arrived too late for the authors to include. They do discuss Tabby’s Star (the “alien megastructure” star). But there is just no way to keep up, given the time it takes to get a book to print. Readers who want the latest news and conjectures on those topics, and the latest on Kepler detections, are better off with online sources.
That’s a lot to cover in a little over 200 pages, so don’t expect too much depth on any one thing. I’ve been following exoplanet research for some time, but I always find revisiting the facts and reasoning behind it a good use of time. It’s chance to climb out of the middle of debates and issues and get a fresh perspective.
The first five chapters lay out basics, including a discussion of the definition of a planet, detection methods, and a chapter on the Kepler mission. Chapters six through ten are speculative sketches of what five sample exoplanets are really like, imagining a close-up visit to them. The five include:
- 55 Cancri E (“Diamond World”)
- "Haven", an imagined rogue planet (a planet no longer orbiting a star)
- A Pluto-like “Ice World”
- Kepler 186f (“Archipelago World,” with a watery but not fully submerged surface and orbiting an M Dwarf star)
- Gliese 1214b (“Water World”)
These chapters are entertaining, speculative, and tempered by explicit caveats about how much we can really know and how much is educated guessing
Those are followed by a discussion of life on earth and how it may have originated, as a guide to think about how the same (or something very different) might happen elsewhere. Then come short chapters on the search for life, the search for intelligent life, and a concluding discussion of the Fermi Paradox. All of these topics, of course, are treated in much more depth in other books. What you’re getting here is strictly overview.
The one theme that the authors really want to drive home is to caution our reasoning in light of “the curse of the single example”. We have only one known example of a planet that supports life, one example of the origin and evolution of life, one example of a technological species (capable of interstellar communication), one example of a planetary system whose history and structure we have detailed knowledge of, . . . and so on.
It’s not just that we have little data to base our reasoning and speculation on, it’s that that one example may implicitly limit our imaginations. The authors cite some good examples. One in which our limited imaginations have been busted — the recognition that rogue planets, cruising independently through interstellar space far from any star, could provide environments rich enough in energy and heat to potentially support life. Others are drawn from science fiction — Isaac Asimov’s vision of a composite life form, made of rocks or grains of sand connected in some non-apparent way, or a life form on Titan, with a metabolism so slow in its frigid environment, that it takes 1,000 years to draw a single breath. Are we sure we would really even recognize an alien life form as alive, much less intelligent?
Time and again, as they point out, we are surprised. We were surprised by Pluto, that a planet so far from its star could generate enough internal heat to apparently host a subsurface ocean. We were surprised by the prevalence of subsurface oceans in moons of planets well outside of the sun’s “habitable zone”. It sounds like a cliche, but, as a warning against making premature conclusions about anything to do with exoplanets, the possibilities for life, and all the rest, we must always recognize that surprise is a constant in this field.
Books in this field are guaranteed to be born out of date. You won’t find anything here about Proxima B or the Trappist system of exoplanets. Those currently hot topics arrived too late for the authors to include. They do discuss Tabby’s Star (the “alien megastructure” star). But there is just no way to keep up, given the time it takes to get a book to print. Readers who want the latest news and conjectures on those topics, and the latest on Kepler detections, are better off with online sources.
January 23, 2019
Sometimes really interesting, but mostly not much new for me here, and I felt like they spent more time than I wanted talking about themselves and their colleagues in annoying ways and making dumb mistakes. It's a super interesting topic, but the authors get in their own way far too often here. :/
August 31, 2017
This book is very readable and pretty up to date (for a few minutes at least). The authors are scientists trying to write rather than writers talking about science. I think this shows primarily in the way they weight and shade their claims. They focus on mainstream headline sort of topics, but they put in disclaimers to keep themselves honest, sometimes even about relatively subtle distinctions.
However, the book is more interested in entertainment than education. There is a lot of emphasis on the mind-boggling variety and strangeness of what's out there than on how we know it. They briefly describe the principle of doppler shift and transit methods of planet detection, and they describe that we can get spectra from the atmospheres of certain planets. However, they never really connect the dots between specific observations and specific conclusions. This feels like looking at the "artist's conception" drawing in a press release and forgetting that most of what's actually shown is made up. The authors defend this to some extent by repeatedly saying "even if the specific details we filled in the gaps with aren't true here, they're almost certainly true on another planet because there are so dang many planets!" Since they are focusing on scientific conjectures, that's probably fairly defensible, but it is still a little unsatisfying. I'd rather have a clearer distinction on what we actually know and then have them describe how we can reasonably extrapolate that to a mental picture of what it would look like to orbit that planet.
However, the book is more interested in entertainment than education. There is a lot of emphasis on the mind-boggling variety and strangeness of what's out there than on how we know it. They briefly describe the principle of doppler shift and transit methods of planet detection, and they describe that we can get spectra from the atmospheres of certain planets. However, they never really connect the dots between specific observations and specific conclusions. This feels like looking at the "artist's conception" drawing in a press release and forgetting that most of what's actually shown is made up. The authors defend this to some extent by repeatedly saying "even if the specific details we filled in the gaps with aren't true here, they're almost certainly true on another planet because there are so dang many planets!" Since they are focusing on scientific conjectures, that's probably fairly defensible, but it is still a little unsatisfying. I'd rather have a clearer distinction on what we actually know and then have them describe how we can reasonably extrapolate that to a mental picture of what it would look like to orbit that planet.
September 29, 2018
The authors do seem to go out of their way to hedge on many of the claims in the book (at least some of which have already been thrown into doubt), but I felt like a lot of this book was a little bit of science filled up with a lot of popular speculation. I think you can safely discount most things they say about extra-terrestrial life, since it is way too early to speculate about that.
I find it hard to put my finger on any one thing that wasn't properly hedged or touched upon, but the overall impression was that this is the same kind of puffery engaged in by scientists everywhere, and NASA in particular is notorious for this sort of thing. Of course it's hard to write a book that is both firmly grounded in reality and entertaining, but alas no one ever said it was easy.
2.5 of 5 stars
I find it hard to put my finger on any one thing that wasn't properly hedged or touched upon, but the overall impression was that this is the same kind of puffery engaged in by scientists everywhere, and NASA in particular is notorious for this sort of thing. Of course it's hard to write a book that is both firmly grounded in reality and entertaining, but alas no one ever said it was easy.
2.5 of 5 stars
April 27, 2017
Brings together quite a few concepts I already knew, so nothing Earth-shattering (hehe). The discussions of how little we actually know and our "chauvinisms" that have blinded us was very interesting -- essentially that for a long time we've been looking for things like ourselves and our planet, but have suddenly woken up to the fact that there are so many more options available that we literally can't imagine all of them.
The tone of this book drove my rating down. I felt like it was speaking to a younger or less-knowledgeable audience, with quite a bit of repetition for such a slim book, and I would have preferred (and was expecting) something a little denser. Despite that - a good introduction and overview of where things stand today with the investigation of exoplanets.
The tone of this book drove my rating down. I felt like it was speaking to a younger or less-knowledgeable audience, with quite a bit of repetition for such a slim book, and I would have preferred (and was expecting) something a little denser. Despite that - a good introduction and overview of where things stand today with the investigation of exoplanets.
December 31, 2019
3,2 stars. I liked this one , especially the narration. Also , I really appreciated how the authors explored the possibility of life developing on rogue planets and/or their moons. Overall, pretty good -would definitely recommend.
June 24, 2017
I really wanted this to better than it was. It was less science and more opinion.
April 29, 2019
Interesting enjoyed it
July 2, 2022
Very disappointing when it digresses from the titular subject. Monarch butterflies winter in California? No, they winter in Mexico. But this is just the tip of the iceberg. Chapter 11 is just a repetition of the typical Darwinian theology. Where evolution is the deus ex machina of creationism. The author cites "massive evidence" from the "fossil record" (fossils don't contain any record because, by definition, they no longer contain any DNA) and from "modern DNA studies" (DNA has a sine qua non relationship with its organisms and since fossils contain no DNA, wherefore studies?). Massive evidence, maybe, but no proof whatsoever, certainly no proof that would stand up in any court of law. Note: there is no DNA evidence linking one species* to another i.e. a common unique DNA sequence. Where common unique DNA sequences have been found, the organisms in question are always found to be intraspecific. Thus proving the Book of Genesis correct. . . . Just kidding.
*A species is a unique type of organism which can only produce infertile hybrids, if any, when crossed with any other species (introgression notwithstanding).
Supplemental note: Leaves are green, not black, because they are translucent, not opaque.
*A species is a unique type of organism which can only produce infertile hybrids, if any, when crossed with any other species (introgression notwithstanding).
Supplemental note: Leaves are green, not black, because they are translucent, not opaque.
October 27, 2021
Check out that subtitle! This one was so cool and remarkably broad for being pretty short. One of the best things is that the authors combine science with some imagination - they say okay, we know these a few things about what this exoplanet might be like, what would that actually look like if you were standing on the surface? Really fun and accessible.
Main takeaways:
- Rogue planets! Planets not orbiting anything but just traipsing along through space. The image the authors use is a house with the lights off but the furnace running.
- The discussions on what is necessary for life and the curse of the "single example." We'd assume life would be on the surface of a planet, near a star, with water and carbon - and yet why should that be the case?
Main takeaways:
- Rogue planets! Planets not orbiting anything but just traipsing along through space. The image the authors use is a house with the lights off but the furnace running.
- The discussions on what is necessary for life and the curse of the "single example." We'd assume life would be on the surface of a planet, near a star, with water and carbon - and yet why should that be the case?
Shelved as 'didn-t-finish'
March 18, 2024I really enjoyed the speculation about different planets, but I found that I lost interest in the chapters that went a little broader, such as the idea of life on other plants or the structure of the solar system. I'm really just hear to learn about the diamond volcanoes. Sorry....
Otherwise, not a bad book.
Otherwise, not a bad book.
December 7, 2022
Great book for those interested in current research on exoplanets! Easy read with plenty of things to research on your own time if you enjoy it.
March 28, 2023
A great refresher! Amazing to think how many more expo planets have been discovered since this book was published.
December 16, 2018
Pretty good overview of the state of planet hunting from physicist James Trefil and astronomer Michael Summers. Describes how exoplanets are found, how the Kepler probe works and what's in store for the future. Speculation about some kinds of possible planets (and moons) different to Earth and a science-lite description of their characteristics and potential for organic evolution.
I wished it could have been longer and more detailed - plate tectonics and geodynamos got only a brief look-in - but since neither of the authors are geoscientists, it's understandable that they would concentrate on the physics side of things. A nice treatment on rogue planets and why they could harbor life (even if briefly) that I hadn't read about much before. Would have like to learn more about archipelago planets and their differences to ocean planets (water worlds). Seems like there could be a lot of in-between scenarios (depending on the type of plate tectonics in operation) and would have enjoyed a discussion about that.
I liked the 'why isn't Pluto a planet' rant - dwarf planet indeed - even though Brown's book which explains why the international astronomers demoted Pluto was also very good. It's good to hear both sides.
The authors admit that they are carbon-based-life chauvinists, so I can't fault them for that, even if I wanted to hear more about other possibilities. We just don't know.
I wished it could have been longer and more detailed - plate tectonics and geodynamos got only a brief look-in - but since neither of the authors are geoscientists, it's understandable that they would concentrate on the physics side of things. A nice treatment on rogue planets and why they could harbor life (even if briefly) that I hadn't read about much before. Would have like to learn more about archipelago planets and their differences to ocean planets (water worlds). Seems like there could be a lot of in-between scenarios (depending on the type of plate tectonics in operation) and would have enjoyed a discussion about that.
I liked the 'why isn't Pluto a planet' rant - dwarf planet indeed - even though Brown's book which explains why the international astronomers demoted Pluto was also very good. It's good to hear both sides.
The authors admit that they are carbon-based-life chauvinists, so I can't fault them for that, even if I wanted to hear more about other possibilities. We just don't know.
August 23, 2022
Summers and Trefil describe the recent discoveries that show that planets and moons are very different than what had been expected. The main findings are a greater distribution of water and the effects of heating. Heat can be supplied to a planet through:
- direct radiation from a star
- outflow from an interior still hot from the formation of the planet
- radioactive decay of elements in the interior
- tidal heating
- phase change from the condensation / solidification of elements
Studies of Jupiter's moon Europa has produced many surprises. It has an ocean of liquid water under an icy crust. Hubble captured images of a water plume 200 km high. As the water is salty, it creates a magnetic field. It is likely that meteorites crack the ice allowing water to flow over the surface, smoothing it out. The heat required to keep the ocean liquid comes from the gravitational effects of Jupiter. A subsurface ocean has also been detected on Enceladus, the sixth moon of Saturn. These discoveries have shown that there is much more water in the outer solar system than had been expected, thus changing the paradigm that all outer planets and moons were cold, rocky and dead.
The authors describe the issues in defining a planet, the decision to remove planet status from Pluto and the fact that Pluto is one of many Kuiper Belt Objects (KBO's). They would have preferred to just categorize all objects moving around the sun as terrestrial (small and rocky), Jovian (gas giants) and Plutonic (Pluto and the KBO's).
The Kepler spacecraft was launched in 2009 to look for exoplanets. It looks for solar variation that could be caused by the passage of a planet past a star. Objects of interest are verified to become exoplanet candidates, then go through a confirmation process. Physical calculations allow calculation of the radius and mass of an exoplanet, while spectroscopy allows the composition of the atmosphere.
Diamond World: 55 Cancrie (40 light years from Earth) is tilted 80 degrees from the equatorial plane, is half the diameter of Earth but nine times the mass. Half the material is carbon so it does not reflect much light. The interior is very hot with higher elements in liquid form, probably resulting in a magnetic field several times stronger than Earth's. The action of the stellar wind on this field likely causes intense displays like Earth's aurora. The hot interior is expected to result in tectonic plate movement, with volcanoes in the subduction zones spewing liquid carbon which may crystallize into diamonds.
Rogue planets: Solar system formation processes cause some large bodies to be ejected which wander the galaxy. There may be more of these rogue planets than planets circling stars. So far, only a handful of rogue planets have been detected through observation of gravitational lensing. Many are expected to be rocky bodies larger than the Earth, but having moons that accumulate substantial water ice. Heat from formation and radioactive decay would result in liquid oceans on the moons. While many would have thick ice crusts, some may release gases from the interior and develop an atmosphere.
Ice worlds: The 2015 flyby of Pluto by the "New Horizons" spacecraft showed that it had mountains of solid water, glaciers of nitrogen and mantle activity. It is possible that the interior is hot giving Pluto has a subsurface ocean. The source of heating is unknown - possibly radioactivity or phase change. It is possible that life could form around vents in a subsurface ocean. Kuiper belts with large amounts of water may be common in other solar systems, with the prospects of subsurface oceans and the possibility of life.
Super Earths: Earth orbits the sun in the continuously habitable zone (CHZ) where water is liquid over long periods of time - a Goldilocks situation. Kepler 186f orbits a type M dwarf in its CHZ. Statistically, it is expected that their are some 25 million planets in the Milky Way galaxy circling dwarfs in their CHZ. Kepler 186f's size suggests that it would retain an atmosphere and it may be that it accumulated water during formation as did Earth. Its larger size suggests higher winds and faster erosion which may result in much low lying land covered with swamps - excellent for the formation of life.
Water Worlds: On Earth, the heavier basalt has sunk below the granite forming ocean basins while the accumulation of water has resulted in the basins being filled while leaving significant land mass. It is expected that many planets would not have the differentiation of materials and would accumulate more water, leaving no free land. However, tectonic activity may well result in vents around which life could form.
The authors describe the idea "metabolism first" where life started as simple chemical reactions, with the development of more complex structures evolving later. Supporting this argument is that life appeared on life shortly after conditions made it possible. It follows that life will develop whenever the geochemical situation is appropriate. However while life on Earth started early, the evolution of multi-cellular organisms took a long time and may well have been a low probability chance event. It is most likely that any life found on exoplanets would be micro-organisms.
Looking for life on an exoplanet would be best be done by looking for oxygen in the spectrum. "At the moment, scientists cannot think of a way that significant oxygen can get into an atmosphere without the presence of life...". Checks for imbalances of methane and ammonia may also be indicative.
Updated calculations using Drake equation for the likelihood of extraterrestrial intelligence, put the numbers in the range of a few hundred worlds with intelligent beings to less than one. SETI searches for extraterrestrial signals have turned up nothing - the "Great Silence". The authors explore various ideas as to why that may be.
Displaying 1 - 30 of 103 reviews