Cosmos Summary

1-Sentence-Summary: Cosmos will make you smarter by teaching you the basics of how the universe works, including our own solar system and its history.

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Cosmos Summary

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When I was young I saw a movie that would forever change the way I saw outer space. It was about a woman who was researching messages from outer space in an effort to communicate with extraterrestrial life. At one point, after a lot of waiting, something finally comes through on their giant radio telescopes. 

The signal gives a blueprint for a machine that can allow humanity to teleport and meet aliens across space. Contact was the name of the movie and Carl Sagan wrote the book it was based on. 

It was with the same wonder I had for space when I saw this movie that made me pick up Sagan’s Cosmos. Although this one isn’t science fiction, it’s got some incredible facts that will fill you with curiosity about outer space.

Here are the 3 most mind-expanding lessons I got out of this book:

  1. The cosmos is constantly calling us to explore and teaches us about our place in the universe.
  2. It’s possible that aliens exist, but the odds aren’t great that they would come here by spaceship.
  3. Voyager 1 and 2 are on an interstellar journey carrying humanities history with them.

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Lesson 1: We learn our place in the universe from the heavens, which make us constantly curious.

Are those little dots we see in the sky at night the kings of the past, or burning balls of gas millions of miles away? Today we know more about the universe than we ever have. But it wasn’t always this way. 

From the beginning, we’ve been fascinated with the heavens, trying to figure them out. Even early nomadic peoples used the stars to set the time for annual gatherings. They could also determine when to pick fruits or know migration times of buffalo by where the stars were.

We can predict the movements and places of almost all celestial bodies with increasing accuracy. Even the planets move in a cool figure-eight shape called an analemma. Ptolemy used this fact to theorize that the Earth was the center and everything revolved around it.

This way of thinking persisted for centuries until Copernicus posited that planets revolve around the sun instead. Later, scientists like Kepler and Brahe would further develop our understanding of the heavens. 

Kepler, for example, was the first to suggest that planets orbits around the sun were elliptical and not circular. Turns out he was right about this. He also stumbled upon Newton’s theory of gravity half a century early, even if he did first call it magnetism.

Lesson 2: UFO’s are probably not how aliens would make first contact with us.

The movie Contact might only be really good science fiction. After all, we all wonder if we are really alone in the universe, don’t we?

The reality is radio waves are the most likely way that extraterrestrial life will first connect with us. The reason for this is because this technology is quick, low-cost, and simple. The likely message they would send is something like a set of prime numbers because it would succinctly and clearly communicate intention and intelligence.

What would these lifeforms even look like though? Chances are they’d be quite different from us. Just take our own earth for example. How many different types of living creatures can you think of? There are a lot, and this is all the result of a slow and random process that is a result of the earth’s unique conditions. 

It’s only logical, then, that extraterrestrials will look pretty strange to us. Life on Jupiter, for example, might end up being some balloon-shaped organisms that make food with some sort of photosynthesis. 

Although, is it even possible for us to make physical contact with these aliens? Theoretically, it might be a possibility. But our planet’s political system makes it a fat chance. Project Orion is one example of why. It proposed an interstellar ship that could use atomic energy from explosions to get through space. 

But the treaty between the US and the Soviet Union that prohibited nuclear weapons being detonated in space forever sealed its terrible fate.

Lesson 3: In the late 70s humankind sent two space probes on what would become an interstellar journey.

So what is the most distant object that we’ve sent out into space? The answer is the Voyagers 1 and 2 spacecraft that are taking our species story through the universe. As of this writing, they’ve just passed our solar system. You can check on their current location here.

Their mission began in the late summer of 1977. Each has millions of redundant systems to keep them traveling for a long time. Both have duplicate versions of three different kinds of computers and run on a piece of plutonium for propulsion.

Data from the probes has contributed to a lot of amazing discoveries. Through pictures from the missions, for example, one scientist learned of an active volcano on one fo Jupiter’s moons!

It’s not just what they’ve sent us that makes their journey amazing. They also contain records of many things that represent humanity. Each has a phonograph with instructions on how to play them. The recordings have all sorts of things that NASA thought would represent us well. 

This includes information about our brains, greetings in dozens of different languages, and even favorite songs from all around the world. The scientists that created these records also put sounds of our technologies and natural world.

But what really makes these two so special is that they represent our sense of wonder at the universe. May we never cease discovering more about the grand cosmos that we are a part of!

Cosmos Review

My love for the stars is almost as vast as the cosmos itself. Okay, maybe that was a little cheesy but really, Cosmos is a great book. Carl Sagan was a brilliant man and it’s amazing that we get to learn from his intelligence!

Who would I recommend the Cosmos summary to?

The 17-year-old who can’t help but look up at the sky and think about the vastness of space each night, the 37-year-old that loves a good science fiction book, and anyone who wants to know just a few of the reasons why science is so cool.

Last Updated on September 1, 2022

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Luke Rowley

With over 450 summaries that he contributed to Four Minute Books, first as a part-time writer, then as our full-time Managing Editor until late 2021, Luke is our second-most prolific writer. He's also a professional, licensed engineer, working in the solar industry. Next to his day job, he also runs Goal Engineering, a website dedicated to achieving your goals with a unique, 4-4-4 system. Luke is also a husband, father, 75 Hard finisher, and lover of the outdoors. He lives in Utah with his wife and 3 kids.