Kepler's Dream: With the Full Text and Notes of Somnium, Sive Astronomia Lunaris, Joannis Keple

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Somnium (Latin for "The Dream") is a fantasy written between 1620 and 1630 by Johannes Kepler in which a student of Tycho Brahe is transported to the Moon by occult forces. It presents a detailed imaginative description of how the earth might look when viewed from the moon, and is considered the first serious scientific treatise on lunar astronomy. Carl Sagan and Isaac Asimov have referred to it as the first work of science fiction.

Somnium began as a student dissertation in which Kepler defended the Copernican doctrine of the motion of the Earth, suggesting that an observer on the Moon would find the planet's movements as clearly visible as the Moon's activity is to the Earth's inhabitants. Nearly 20 years later, Kepler added the dream framework, and after another decade, he drafted a series of explanatory notes reflecting upon his turbulent career and the stages of his intellectual development. The book was edited by his heirs, including Jacob Bartsch, after Kepler's death in 1630, and was published posthumously in 1634.

192 pages, Hardcover

First published January 1,1634

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About the author

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Johannes Kepler (German pronunciation: [ˈkɛplɐ]) was a German mathematician, astronomer and astrologer, and key figure in the 17th century scientific revolution. He is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy. These works also provided one of the foundations for Isaac Newton's theory of universal gravitation.

During his career, Kepler was a mathematics teacher at a seminary school in Graz, Austria, where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to astronomer Tycho Brahe, the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II. He was also a mathematics teacher in Linz, Austria, and an adviser to General Wallenstein. Additionally, he did fundamental work in the field of optics, invented an improved version of the refracting telescope (the Keplerian Telescope), and mentioned the telescopic discoveries of his contemporary Galileo Galilei.

Kepler lived in an era when there was no clear distinction between astronomy and astrology, but there was a strong division between astronomy (a branch of mathematics within the liberal arts) and physics (a branch of natural philosophy).

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Rating(4.1 / 5.0, 81 votes)
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April 16,2025
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Somnium by Johannes Kepler is considered the first Science Fiction ever written. Kepler wrote this book in 1608 in Latin and it was published in 1634 posthumously. I found an English translation for this book and after having it on my TBR for years together, I finally read it.

If you are not sure who Kepler was, he was a German astronomer who developed the laws of planetary motion. Copernicus discovered that planets revolved around sun and that Earth was not the center of the Universe. Kepler figured out that the planets revolved in elliptical orbits and that all these orbits follow some laws of Physics. Somnium in Latin means “Dream”.

This book is about a dream that Kepler saw. It’s about an Icelandic boy, Duracotus whose mother is a witch and can talk to spirits from moon. One such daemon is invoked and he tells them the story of voyage to moon, to an island called Levania. The book is pretty interesting to read as it was written at a time when they had very basic telescopes to observe moon, they had not even developed airplanes and forget about traveling to moon, people couldn’t even travel to another country by air. It must have required so much of out of the box thinking and imagination on the part of the author to have written a book about traveling to and living on the moon.

* Kepler assumes that there must be water on the moon and that the living beings there lived in “hollow caverns and continuous caves” and “deep and wide valleys” in the ground. People back in 17th century had no idea about meteroids and craters so he came up with his own explanation about the craters on the moon I guess.
* Even though he had no idea about escape velocity or rockets, he talks about gravity and this is how he describes leaving Earth which is so accurate – “he is spun upward as if by an explosion of gunpowder and he flies above mountains and seas”.
* He also talks about the difficulties that come when you leave Earth’s atmosphere, which is also correct – “Then he will face new difficulties: Intense cold and impaired respiration”.
* He even mentions air pressure from such a travel. He even talks about using some special sponges around nostrils to enable us to breathe where there is no air.
* Far side of the moon. He even talks about it. How one side of the moon always faces Earth and the other side doesn’t. He calls the two hemispheres of moon, Subvolvans and Privolvans. “Privolvans are completely deprived of the sight of their Volva”. Volva here refers to Earth. If you didn’t know, this is the reason for seeing only one side of the moon from Earth always – “One side of the moon always faces Earth because of what’s called synchronous rotation. That is, the moon rotates, or spins on its axis, in the same length of time it takes to orbit Earth” (from Link).
* He says that Earth would appear four times bigger on moon compared to the size of the moon as seen from Earth.
* I especially loved the description of day and night on moon and what it feels like to see Earth rise up in the sky on moon. Our one month will correspond to their one day – which is marked by the rising and setting of Earth in their sky, according to him. According to today’s science, Earth goes through phases similar to moon phases that we see on Earth and he even talks about that.
* He also talks about long nights and days on moon which makes sense since Moon takes a month to rotate on its axis.
* He also goes in depth about the eclipses – what a partial eclipse or a total eclipse would look like when you are standing on the moon.
* He mentions that creatures living on moon must be of monstrous sizes and that they had short life span.

It is a very short book, just around 30 pages but it was a fascinating book. There isn’t much to the story but considering this was written by a man in 17th century, I was in awe. How brilliant must he have been to have calculated and come up with so many facts about moon when not even a reflecting telescope had been invented or gravity was discovered. Reflecting telescope was invented much later by Newton in 1668 and his work was based off of Kepler’s. People who read this book when it was just released must have found it so much more interesting and magical. I am always amazed by the inventors and scientists from ancient past who advanced science by leaps and bounds when we hardly knew anything about the world we lived in.

Do read it if you are fascinated by history of science or science fiction. I gave this book 4 stars.

From what I gather, Kepler’s notes about this story is missing from this edition of the book. I am not sure where to find them. I got this book just for my collection as I am a fan of collecting older science fiction novels. But I am glad I read it. It’s amazing and just blew my mind!
April 16,2025
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Historically, a wonderful and important work. I felt compelled and obliged to read it, yet bored to tears through a major portion of it. It’s extremely short, so the boredom is short lived.
April 16,2025
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Adorei . Mais que a primeira ficção científica pra mim pareceu um tratado sobre física , oculto por causa da infâmia Inquisição católica .

Me lembrou também Uma mistura de Marco polo e Júlio verne!!
April 16,2025
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Interesting read from the point of view of when it was written. Else the writing and story won't mark too high.
April 16,2025
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I have to confess I have a serious soft spot for Kepler's fun and fanciful adventures to the moon and back. Edward Rosen's translation hits the spot, and were it not for the ponderous footnotes, this is the sort of story one could knock over in very short order. Of course, Kepler was about as didactic as they came, but his fascinating insights, theories and that ever so lyrical idea of observing the Earth from the Moon makes this an enjoyable read.
April 16,2025
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When I heard that there was a “sci-fi novel” written by Johannes Kepler in 1608, I immediately wanted to read it. You can easily find Somnium (The Dream) online - Project Gutenberg, for example - and it’s pretty short, at about 15 pages.

First, let me say, it’s not really a story. In Somnium, Kepler falls asleep and has a dream about a young man from Iceland who travels to Denmark and learns astronomy. The young man returns to his native land, where his mother, who practices magic, proposes to add to her son’s education by introducing him to the “daemons” (I.e., guiding spirits)she talks to, through whom she has travelled to distant lands. The son agrees, and discovers that the daemons can carry humans to the moon, which they refer to as Levania.

The majority of the “story” is just Kepler’s theorizing about what the moon is like, what the Earth would look like to someone on the moon, what the length of the day on a moon would be, what the climate would be, what type of creatures might live there, etc. The narrative ends abruptly with Kepler waking up.

Thus, there is no real plot, and the young man from Iceland ceases to figure in the story once Kepler starts describing Levania.

However, it is interesting as an early imagining of how one might travel to the moon (Kepler notes that the daemon-propelled trip would require the human to be carefully wrapped up to protect them from the temperature and pressure). It also shows that Kepler thought through how the universe would appear differently to someone living somewhere other than the Earth. Considering that the Earth was long thought to be the centre of the universe, this concept of living on the moon, and what it might actually be like, seems very forward-thinking.

In terms of story value, I wouldn’t give Somnium more than a 1. But in terms of historical interest, and its probable influence on initiating the sci-fi/fantasy drama, I’d give it a 5. So I’m averaging my rating out to a 3.
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