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Book Summary: Starry Messenger – Cosmic Perspectives on Civilization

Starry Messenger (2022) is about a way of looking at the world called the cosmic perspective. It’s the view that opens up when we think about human life in its largest possible context – that of the universe itself. This isn’t an exercise in making our worldly affairs seem small and trivial, though. It’s about unlocking insights that can help us live more happily and meaningfully on the cosmic anomaly we call Earth.

Introduction: A cosmic perspective on life.

People are fed up with experts. That was the recent verdict of the British politician Michael Gove. What people want, he implied, is more feeling. Less weighing of the evidence and more gut instinct.

Book Summary: Starry Messenger - Cosmic Perspectives on Civilization

As a recipe for politics, that statement met with lots of opposition. As a description of what’s actually happening, though, it hit the nail on the head. We live in an age of hyperpartisanship and culture wars. Reasoned debate is out; emotive shouting matches are in.

The backlash against experts has generated its own backlash: a pro-expert faction that says we ought to short-circuit all our messy disagreements and delegate decision-making to cool-headed rationalists.

Astrophysicist Neil deGrasse Tyson doesn’t quite see it that way. Science can’t stand in for politics – functioning democratic societies have to debate their fundamental values at some point or other. But he does think science has a valuable contribution to make to those debates.

That contribution isn’t about coming up with answers – it’s about helping us frame our conversations in a more nuanced way. He calls it the cosmic perspective. It’s the view of life on Earth that emerges when we place our problems in a wider context.

As we’ll see in this summary to Tyson’s Starry Messenger, this rational approach doesn’t just help us figure out what really matters – it can also stimulate a greater sense of unity.

Exploration challenges our assumptions about ourselves.

Cosmos is a big word. It encompasses every particle of matter in the universe – a vast number of galaxies in a system measuring ten billion light years in diameter. To look at life on Earth through that lens – call it the cosmic perspective – is a mind-boggling proposition. So let’s start a little smaller. We’ll come back to the stars. First, let’s rewind some 30,000 years.

Imagine a group of our distant, cave-dwelling ancestors huddled around a fire. Their “universe” is tiny. Their mental map encompasses no more than a dozen or so square miles around that cave. Beyond those frontiers lies the great unknown. Some may picture it as a vast nothingness; others see nothing but danger and death when they contemplate it.

One day, a couple of intrepid cave dwellers consult their elders. They want to see what lies beyond. The elders are wise – you don’t live long enough to become an elder without accumulating a little wisdom, after all. They weigh the matter, and ponder the risks and rewards. No, they say – there are more pressing issues. Exploration can wait. And so the group remains in its cave, working out its cave problems.

Now imagine the same scene playing out in a second cave. This time, however, the would-be pioneers win the argument. Perhaps these elders have greater foresight – or maybe they’re just less risk-averse. Either way, their go-ahead changes everything.

Sometimes, you have to leave the cave to solve your cave problems. There’s danger and death in the great unknown. But it also holds the promise of plants that cure sickness and useful materials to fashion new tools – and of new sources of food and water and shelter. Most important of all, though, there are new ways of thinking to be discovered. That’s an idea dear to many scientists, but it’s also a deeply human idea. As the American poet T. S. Eliot put it:

We shall not cease from exploration

And the end of all our exploring

Will be to arrive where we started

And know the place for the first time.

In other words, exploration is as much about the journey as it is about the destination. When we strike out, we don’t just discover new worlds – we also learn to look at the world we already know in new ways. That, Neil deGrasse Tyson argues, is the cosmic perspective. To take that perspective is to widen our frames of reference. To recontextualize familiar ideas. To see the place from which we started in striking new ways. And it changes everything.

We had to go to the Moon to truly see the Earth.

Let’s leave our cave-dwelling ancestors behind and fast-forward to 1968.

Everywhere you looked that year, new political and cultural boundaries were being opened up. In the United States, civil rights activists were redefining what it meant to be an American citizen. In Prague and Paris, Mexico City and Tokyo, students dreamed up new utopias in seminar rooms – and fought the establishment on the streets. The Beatles came back from India with a sitar-laced sound that redefined Western pop music, while hippies turned to potent psychedelics to open the doors of perception.

But it was also a year of momentous scientific exploration. On December 21, the first crewed spacecraft reached the Moon. Apollo 8 orbited the Moon ten times before returning to Earth. During one of those passes, astronaut William Anders took a famous photograph. You might not know that it’s called Earthrise, but you’ve likely seen this image of the Earth rising over the eerily empty lunar landscape a hundred times. It’s the cosmic perspective in a single snapshot.

Looking back on the Apollo 8 mission half a century later, Anders said that the crew had set out to explore the Moon but discovered something else – the Earth. Mike Massimino, an engineer whose Space Shuttle missions included a trip to service the Hubble Space Telescope, takes a similar view. In his memoir, Spaceman, he writes about looking down on Earth from space. His first thought was that this must be what our planet looks like from heaven. He quickly changed his mind, though. No – this is what heaven looks like.

In other words, we ventured into the skies, looked over our shoulders, and discovered our own planet. We arrived back where we started. As that image circulated around the globe, people began thinking about Earth in a new way. Pollution-spewing factories in Pennsylvania, acid rain in Polish forests, and oil-covered beaches in the Niger Delta no longer looked like local problems. They now appeared as the localized symptoms of problems affecting a holistic, planetary ecosystem. Put differently, it was by zooming out, literally and metaphorically, that we came to grasp the environment as a single object of concern for all humanity.

A wave of legislation reflected this shift in perspective. Between 1968 and the last Moon mission in 1973, nations around the world began passing laws regulating the emission of industrial pollutants and the use of ecologically devastating pesticides like DDT. New agencies tasked with safeguarding natural resources and preventing overfishing sprung up. The United Nations, meanwhile, began observing Earth Day – an international demonstration of support for environmental protection.

All of this could have happened earlier. In the United States, for example, a book detailing the devastating effects of industrial pesticides – Rachel Carson’s Silent Spring – topped best-seller lists for over 30 weeks between 1962 and 1963. Similarly, there were no fewer than four major government reports calling for DDT to be banned before the Apollo 8 mission.

In theory, mass environmental awareness could have taken off before William Anders took his seminal snapshot. But it didn’t. It happened in the middle of our missions to the Moon. That’s no coincidence. Concern for our planet’s ecosystem was a fruit of the cosmic perspective.

The natural world defies our common-sense assumptions.

You’ve probably heard that you have to cook things longer if you happen to be making dinner on top of a mountain. Why, though? Well, simply put, it has to do with air pressure.

The boiling temperature of a liquid isn’t a universal constant: it varies according to how much air pressure is pushing down on that liquid’s surface.

Take water. At sea level, water boils at 100 degrees centigrade. At 10,000 feet above sea level, however, there’s much less air pressure. There, water boils at just 90 degrees centigrade. Since things cook more slowly at lower temperatures, you have to extend the total cooking time to compensate. Spaghetti that’s perfectly al dente after seven minutes on the coast might take twelve minutes up in the mountains. So there’s the first part of our answer: the lower the air pressure, the lower a liquid’s boiling point.

It’s easy enough to imagine cooking penne in a mountain lodge some 10,000 feet above sea level even if you’ve never actually done it. What about boiling pasta on Mars, though? Let’s leave aside the inconvenient fact that any human who tried to do so would immediately suffocate and die, and focus instead on a technical question: At what temperature does water boil in a Martian kitchen? Here’s where things get interesting.

If you keep lowering the air pressure, water’s boiling point will eventually be lower than its freezing point. In other words, it will boil below zero degrees centigrade. This is called the triple point because water in this state is simultaneously a solid, a liquid, and a gas. Since large parts of Mars’s surface satisfy these conditions, a Martian cook has a simple answer to the question whether water is solid, liquid, or gaseous: “Yes.”

There’s that cosmic perspective again. Seen through these lenses, something as seemingly intuitive as water’s boiling point becomes confoundingly ambiguous. Scientists accept such ambiguity; they are trained, after all, to question commonsensical conceptual boundaries. It’s a different matter when it comes to politics and culture. Think of hotly contested questions around sex and gender. Can you be both male and female, or neither? Can you move fluidly between being a man and a woman? Is sexual preference fluid, too? It’s not surprising that some people struggle with these questions – we’re all embedded in cultures which for centuries saw only rigid categories where many today see points on a continuum.

For astrophysicists, though, continuums are everywhere. Take color, for instance. We usually talk about the seven colors of the rainbow – red, orange, yellow, green, blue, indigo, and violet. That, though, is a cultural convention. If we looked more closely, or took the time to develop a more sophisticated color vocabulary, we could easily identify thousands of colors. Or we could simply do away with conventional color terms and instead refer to specific wavelengths of light to describe an object’s color.

For Tyson, gender can also be seen as a form of cultural convention. Consider this experiment he conducted on the New York City subway one cold winter’s day.

His subway car was filled with a typically diverse bunch of morning commuters, all of them bundled up in the same warm, puffy, dark clothes. Everyone was seated, too. That’s significant because height differences are mainly due to the different lengths of our legs. Sitting down, our heads are all at roughly the same height – that’s why car seats adjust forward and backward, not up and down. The only thing Tyson could really see, in short, were heads and faces. Could he identify who presented as female and who presented as male using that information alone?

Sure – it was easy. On average, the women had longer hair. They were more likely to wear earrings and lipstick or have tweezed eyebrows. They didn’t have hair on their upper lips or chins. What if he tried again but left aside such social adornments and instead relied on primary features, like face shape? That was much harder. Is there a male or female face? As with color, we also have a conventional vocabulary here. Jawlines and brows and lips can be “hard” or “soft” or “thin” or “full,” and we all know which adjectives are “masculine” and which are “feminine.” When Tyson closely looked at commuters’ faces, though, he saw that those gendered traits were distributed pretty randomly. Some men had “feminine” faces; some women had “masculine” ones. Wouldn’t it be easier – and more accurate – to simply say there’s a continuum of facial traits ranging from hard to soft, and leave gender out of it?

The point is, when you strip out easy-to-read social cues, humans are remarkably androgynous. Gender, Tyson realized as he surveyed those faces, is an ongoing investment. It’s about growing a beard – or waxing your upper lip and legs. It’s about buying clothes from the men’s section of the department store – or the women’s. It’s about building certain muscles or wearing breast-accentuating bras. Or the size of your earrings or the amount of makeup you put on your face – or don’t. Take that investment out of the equation, and you’re left with a random distribution of physiological traits. In short, social coding does a lot of heavy lifting when it comes to dividing humanity into two sexes with two matching genders.

Of course, there’s a lot of history behind the social coding of gender. The Bible says that a woman shall not wear “that which pertaineth unto a man” and “neither shall a man put on a woman’s garment.” Failure to obey such commands has been severely punished down the centuries, too. When Joan of Arc was accused of heresy in 1431, it was her persistent cross-dressing that in part condemned her to being burned at the stake.

The weight of tradition often falls on the side of folly. Galileo was also tried for heresy, but he was right: the Earth does circle the sun. If the natural world defies our assumptions so regularly, why should gender be an exception?

Life is a cosmic lottery – and we all won.

We started with a big word – cosmos, the root of the cosmic perspective we’ve been exploring in this summary. Let’s end, then, with a big number.

In fact, it’s an astronomically huge number: 10 to the power of 30.

Written out, that’s a 1 followed by 30 zeros. That’s how many variations the genome which generates viable versions of us can create. In other words, there are a million-trillion-trillion possible human beings. To put that into perspective, the total number of humans ever born is around 100 billion. That means the human branch of the tree of life has produced just 0.00000000000000001 percent of all the people who could theoretically exist. If you weren’t counting, that’s 16 zeros. It’s a drop in the ocean. A needle in the haystack.

That’s how precious – and unlikely – our lives are.

We won the lottery, and we’ll likely only ever win it once. Theoretically, if you ran through all those million-trillion-trillion variations the human genome is capable of generating, you’d end up with another version of you – or your identical twin. Practically speaking, though, there’s only going to be one of each of us. It’s our luck to experience life on the cosmic anomaly we call Earth, gaze up at the starry sky, and wonder what it all means.


The human desire to know the universe is, at its essence, a desire to discover. That urge propelled our distant ancestors across oceans. In the last century, it put humans on the Moon. But we’ve always returned to where we started. The new knowledge we bring back with us allows us to see the world anew. This is the cosmic perspective: a view of life on Earth which challenges our preconceived ideas and neat conceptual boundaries. That makes our civilization seem utterly strange – and miraculous.


Science, Society, Culture, Math, Astronomy, Space Science, Astrophysics, Science Essays and Commentary, History and Philosophy of Science, Cosmology, Social Aspects, Political aspects, Social aspects, Physics

About the author

Neil deGrasse Tyson is an astrophysicist and the author of the #1 bestselling Astrophysics for People in a Hurry, among other books. He is the director of the Hayden Planetarium at the American Museum of Natural History, where he has served since 1996. Dr. Tyson is also the host and cofounder of the Emmy-nominated popular podcast StarTalk and its spinoff StarTalk Sports Edition, which combine science, humor, and pop culture. He is a recipient of 21 honorary doctorates, the Public Welfare Medal from the National Academy of Sciences, and the Distinguished Public Service Medal from NASA. Asteroid 13123 Tyson is named in his honor. He lives in New York City.

Table of Contents

Aesthetics in life and in the cosmos
The value of both when shaping civilization
Cosmic perspectives
Tribal forces within us all
Calculations we make daily with our own lives and the lives of others
We are not entirely what we cat
People are more the same than different
Once again, people are more the same than different
The foundation of civilization, whether we like it or not
Human physiology may be overrated


Bringing his cosmic perspective to civilization on Earth, Neil deGrasse Tyson, best-selling author of Astrophysics for People in a Hurry, shines new light on the crucial fault lines of our time—war, politics, religion, truth, beauty, gender, race and tribalism—in a way that stimulates a deeper sense of unity for us all.

In a time when our political and cultural perspectives feel more divisive than ever, Tyson provides a much-needed antidote to so much of what divides us, while making a passionate case for the twin engines of enlightenment—a cosmic perspective and the rationality of science.

After thinking deeply about how a scientist views the world and about what Earth looks like from space, Tyson has found that terrestrial thoughts change as our brain resets and recalibrates life’s priorities, along with the actions we might take in response. As a result, no outlook on culture, society, or civilisation remains untouched.

In Starry Messenger, Tyson reveals just how human the enterprise of science is. Far from a cold, unfeeling undertaking, scientific methods, tools and discoveries have shaped modern civilisation and created the landscape we’ve built for ourselves on which to live, work and play. Tyson shows how an infusion of science and rational thinking renders worldviews deeper and more informed than ever before—and exposes unfounded perspectives and unjustified emotions.

With crystalline prose and an abundance of evidence, Starry Messenger walks us through the scientific palette that sees and paints the world differently. From lessons on resolving global conflict to reminders of how precious it is to be alive, Tyson reveals, with warmth and eloquence, 10 surprising, brilliant and beautiful truths of human society, informed and enlightened by knowledge of our place in the universe.


“Every page is lit up by an original poetic imagination but bearing the unmistakable stamp of a rational mind, steeped in maths and science.” ―Richard Dawkins, author of The Selfish Gene and The God Delusion

“Handsome, gregarious and passionate about his subject matter, Neil deGrasse Tyson…meditates on what a life studying the majesty of the stars and the planets can teach us about how to deal with all the messy social and political conflicts bedeviling us here on Earth…Engaging as ever…He is lucidly down-to-earth and charmingly enthusiastic.” ―The Washington Post

“The way Tyson explains the significance of cosmic phenomena is just wow. His eloquence in the text and the way he reveals all the facts about black holes and supernovae (oh, and how each influenced our history) helps you get a better understanding of complex issues and…it actually proves that easy to follow writing can do a lot! For example, it can turn the most difficult concepts into something you can understand.” – Lauren Bradshaw, essay writer from CustomWritings.

“Tyson has become the most influential science communicator in the country.” ―Vox

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