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Full title Cosmos [permalink]
Language English
Author Carl Sagan (author)
Publisher Ballantine Books
Categories Astronomy, biology, chemistry, history, physics and science
Publication year 1985
Original publication year 1980
ISBN 978-0-345-33135-9 [Amazon, B&N, Abe, Powell's]
Pages 324

Cosmos is, as its title suggests, a book about the Cosmos. It's based upon (and can be considered a companion to) the TV series of the same name. There are thirteen chapters, each corresponding to the thirteen episodes.

The Shores of the Cosmic Ocean is setting the tone for the rest of the book. Sagan discusses the Cosmos on its largest scales, putting the Earth in perspective. He then discusses early attempts to measure the size of the Earth.

One Voice in the Cosmic Fugue is about evolution and our own species. It discusses various potential biologies that could be evolved on other worlds and muses on the implication of all this.

In the chapter Harmony of the Worlds, Sagan really shines. This chapter deals with astrology, astronomy, and the histories of both. (Sagan was an astronomer.) He explains Kepler's Laws, goes into the geocentric vs heliocentric models of the Solar System, and the history of planetary observation and theory-making.

Heaven and Hell is all about comets and asteroids. Sagan discusses the Tunguska event and the impact craters on the Moon, among other things.

Blues for a Red Planet is about Mars in fiction and fact. He goes into the canali of Giovanni Schiaparelli and Percival Lowell, H. G. Well's The War of the Worlds, and the Barsoom novels of Edgar Rice Burroughs. He then discusses the Mars probes and the potential for terraforming Mars.

Travelers' Tales is about the sailing ships and the discoveries made during the Age of Exploration, with respects to astronomy and the study of the Cosmos.

The Backbone of Night is a discussion of myths from around the world on the creation and system of the Universe, veering into a discussion of the scientific explanations (and the evidence). There's a very charming three pages of imagined inner monolog by a curious and primitive ancestor dealing with his explanation for the stars. The chapter title is a reference to the name for the Milky Way that the !Kung people of the Kalahari desert use for it.

Travels in Space and Time is about the immensity of space and time. It begins with a discussion on constellations and astrology, and has a wonderful illustration of how a constellation (in the example, The Big Dipper) would look from other angles and in other eras. It then launches into an extended explanation of the speed of light and the various paradoxes attending it (such as time dilation).

The Lives of the Stars is about atoms, chemistry, and the lives of the stars (ahem), meaning the fates and types of stars (white dwarfs, neutron stars, supernovas, etc.).

The Edge of Forever lives up to its title. Its subject matter is the beginning of time, the extent of the Cosmos, and a very entertaining discussion on higher dimensions (reminiscent of, even directly referent to, Flatland). It also discusses mythological theories on the nature of time and the Cosmos.

The Persistence of Memory is about information, in the form of DNA and brains.

Encyclopaedia Galactica is really about galactic citizenship. It goes into UFOs, SETI, the Drake equation, and contact with other intelligent beings (what it would look like and what the implications would be). This is one of the more interesting chapters.

The book ends on a somewhat morose note with Who Speaks for Earth? The chapter deals with the planet and its various challenges, most conspicuously nuclear weapons and what to do about the potentiality of our destroying ourselves. After so many chapters of uplifting speculations and explorations of immensity, this chapter is a very sobering read.


Where to start? When I watched the TV series in 2007 I was utterly blown away, and the book is even better. Being a book it's also much more detailed. If you've read anything by Sagan you know what to expect, but this work is simply breath-taking in its breadth and depth. It's personal, uplifting, educational, interesting... If you want to get a (biased, in a good sense) overview of the history of ideas and science, go read it.

Images Back of Cosmos.Spine of Cosmos.Front of Cosmos.
Structure [Toggle visibility]
  • Introduction
  • I The Shores of the Cosmic Ocean
  • II One Voice in the Cosmic Fugue
  • III The Harmony of the Worlds
  • IV Heaven and Hell
  • V Blues for a Red Planet
  • VI Travelers' Tales
  • VII The Backbone of Night
  • VIII Travels in Space and Time
  • IX The Lives of the Stars
  • X The Edge of Forever
  • XI The Persistence of Memory
  • XII Encyclopaedia Galactica
  • XIII Who Speaks for Earth?
  • Appendix 1: Reductio ad Absurdum and the Square Root of Two
  • Appendix 2: The Five Pythagorean Solids
  • Further Reading
  • Index

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