Cosmos Book Cover

Cosmos

A Personal Voyage
Book by: Carl Sagan
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What’s inside

Cosmos is a breakthrough in popular and modern science. The drama of existence can be immense at times. Due to certain incidents, or certain circumstances, we might feel like our lives will consume us, inside out. However, our universe is ever-expanding and we are just a minuscule part of it. If we compare ourselves to the universe, we will truly be aware of our existence. This, in turn, will help us evaluate and understand the problems we face in life. In this book, Carl Sagan makes the difficult subjects in the book easy to read, and relatable. In numerous ways, nothing is more colossal than the cosmos. Sagan, in this book, emphasizes that learning about the universe isn’t always math. This book talks about the journey of human interest in the universe, from the primal times to the space exploration voyages in the twentieth century.

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Lesson 1. Earth Is Small.

Humans, for the better part of history, have always been confined within the boundaries of the earth. For humans, everything is, literally our world. It is all that we consider around us. However, when we compare the earth to the universe, we realize that it is just a speck of dust. This comparison is quite overwhelming. This is because the size of the cosmos, or the universe, is beyond our measure. The universe is so big that we had to come up with a specific unit of measurement based on the speed of light. 

As we know, light is the fastest thing in the entire world. In just a second, it travels 186,000 miles, which is roughly 300,000 kilometers. If we convert it into easier terms, it is equivalent to seven times around the earth. We often look at the night sky and think about the little balls of gas. Are those kings and queens from ancient times, or are they gigantic balls of gas existing in the cosmos? When the scientists talk about the cosmos, they use a unit called ‘light-years’. A ‘light year’ is the distance light travels in an entire year. To make it relatable, it is about six trillion miles or ten trillion kilometers. It is known that the cosmos contains about a hundred billion galaxies within. To make it more remarkable, within each galaxy, there are about a hundred billion stars and a hundred billion planets. 

If we do the math, we will realize that the earth is a terribly insignificant part of the cosmos. Earth is not as unknown to humans as it was a few thousand years ago. Humans are aware of the physical structure of the earth. Two thousand years ago, scientists were already curious about the nature of the earth. They also concluded that the earth was neither flat nor indefinite. 

Eratosthenes, the director of the popular great library of Alexandria in Egypt, figured out that the earth was a sphere and not a flat surface. He experimented by placing a stick on the ground when the sun was at its highest point in the sky. He observed that there was a shadow on the ground. Through this experiment, he concluded that the earth was indeed curved and not flat. He figured if the earth was flat, the sticks would not have a shadow either way during a particular time of the day. He even used the length of the shadows to calculate the circumference of the earth. 

Lesson 2. The Human Curiosity About Stars And Planets.

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About the author

Carl Sagan Image

Sagan was Dir. of the Laboratory for Planetary Studies & David Duncan Prof. of Astronomy & Space Sciences at Cornell University. He played a leading role in the Mariner, Viking, & Voyage expeditions to the planets & was a recipient of the Pu...

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Cosmos Book Cover
Chapter List
  • Lesson 1. Earth Is Small.
  • Lesson 2. The Human Curiosity About Stars And Planets.
  • Lesson 3. The Discourse On Venus And Mars.
  • Lesson 4. Aliens And Spaceships. 
  • Lesson 5. The Development From Ancient Times To Modern Sciences. 
  • Lesson 6. Light Is An Essential Part Of The Universe.
  • Lesson 7. The Journeys Of Voyager 1 And 2. 
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FAQs

In the summary of Cosmos book, there are 7 key lessons. These lessons include:

  1. Lesson 1. Earth Is Small.
  2. Lesson 2. The Human Curiosity About Stars And Planets.
  3. Lesson 3. The Discourse On Venus And Mars.
  4. Lesson 4. Aliens And Spaceships. 
  5. Lesson 5. The Development From Ancient Times To Modern Sciences. 
  6. Lesson 6. Light Is An Essential Part Of The Universe.
  7. Lesson 7. The Journeys Of Voyager 1 And 2. 

Cosmos by Carl Sagan was published in .

Once you've completed Cosmos book, We suggest reading out The Hidden Life of Trees as a great follow-up read.

Yes, the book Cosmos is really good to read. 50 people have searched for the book summary on the Wizdom platform. The book summary has a rating of 0.0, 0 on our platform.

In the printed version of Cosmos book have over 300 pages and usually takes 8-10 days to finish. However, with the Wizdom app, including its summary and audiobook, it can be completed in just 15 minutes.

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