One night in the year 1577, a German herb doctor named Katharina Kepler took her 6-year-old son up a hill to look at the sky. Together they observed a comet as it blazed across the sky. This comet – the Great Comet of 1577 - was a one-off and would not be seen from Earth again. But it left a remarkable impression on the little boy and would start him on a path that would see him change the world.
The lad would go on to become one of the most important figures in the history of science. His name was Johannes Kepler and his work laid the foundation for the science that enabled humanity to head out into space.
Kepler was many things – an astronomer, an astrologer, a mathematician, and a philosopher. He was also a writer of fiction. 361 years before humans set foot on the Moon, Kepler wrote Somnium (Latin for The Dream), a novel about travelling to the Moon with the aid of demons! It has been called one of the first works of science fiction, but it brought tragedy to the lives of both Kepler and his mother.
Reproduction of 1634 title page of Somnium by Johannes Kepler - Translatorː Francisco Socas. Editorialː University of Huelva Publications. Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=20055891
Who was Johannes Kepler?
Kepler began his career as a maths teacher, before going on to work as an assistant to the astronomer Tycho Brahe. Brahe is himself an important figure in the history of astronomy and is remembered for his prosthetic brass nose!
Eventually Kepler became the imperial mathematician to the Holy Roman Emperor. He was a friend of another famous astronomer - Galileo Galilei - and the pair exchanged letters about their work.
The work of Nicolaus Copernicus had a tremendous impact on Kepler. Less than 100 years earlier Copernicus had presented the revolutionary idea that the Sun was the centre of everything rather than the Earth. Most people at the time - including Brahe - rejected this idea, but Kepler was drawn to it. He said that he felt God’s work in the ideas of Copernicus.
Portrait of Brahe by Eduard Ender (1822-1883). Credit: Public domain, via Wikimedia Commons
Using observations of the planets that Brahe had made during his lifetime, Kepler discovered that the orbits of the planets followed three laws:
1. The planets in our Solar System move around the Sun in an elliptical shape, not a circular shape as everyone believed at the time.
2. The planets are all moving at different speeds depending on how close they are to the Sun.
3. There is an exact mathematical link between a planet’s distance from the Sun and the amount of time it takes to revolve around the Sun.
Years later Isaac Newton would go on to use these three laws to put together his own law of gravity!
In the early 1600s however, Kepler still had to convince people that the Earth was going around the Sun. One of the ways Kepler hoped to do this was through Somnium. His book wasn’t just an early work of science-fiction, it was an early piece of science communication!
Model of the Universe from Nicolaus Copernicus' De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres. Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=12353176
Somnium – the first science fiction story?
The novel begins from the point of view of Kepler himself, who falls asleep while reading about a mythical Czech sorceress. Within the dream Kepler is reading a different book – the story of an Icelandic boy called Duracotus, who gets sold to a sailor and ends up working for Tycho Brahe, just as Kepler had done in real life. While working under Brahe the boy develops a love of astronomy.
Eventually the boy travels home to his mother - a herb doctor with an interest in astronomy. Here was another detail from real life – Katharina Kepler was a herb doctor. The mother is delighted that her son now shares her interest, and she tells him the secret of summoning “daemons”! These daemons can travel to the “Island of Levania” – otherwise known as the Moon - and they can even take people with them!
Duracotus meets his mother’s favourite daemon, who explains that Levania (AKA the Moon) is “fifty thousand German miles high up in the sky” and travelling there is not for wimps!
“We do not admit desk-bound humans into these ranks, nor the fat, nor the foppish. But we choose those who regularly spend their time hunting with swift horses, or those who voyage in ships to the Indies, and are accustomed to living on hard bread, garlic, dried fish and other abhorrent foods.”
An illustration from the History of Witches and Wizards (1720). Credit: Public Domain Mark. https://wellcomecollection.org/works/abkab8tq/items?canvas=1
The daemons can take human companions to the Moon by pushing them there with great force “not unlike an explosion of gunpowder, as he is hurled above the mountains and the seas.”
During the journey the daemons must shield themselves from the light of the Sun with the shadow of the Earth. The daemons can protect their human companions from the cold of space, but the humans must push damp sponges up their noses in order to breathe.
There are alien creatures on the Moon. Their name for the Earth is Volva. The Moon is divided into two sides. The aliens on the side of the Moon facing us are called Subvolvans. They are “forever blessed by the light from Volva which for them takes the place of our Moon”. The Privolvans who live on the far side of the Moon aren’t so lucky – they are “eternally deprived any sight of the Earth.”
These Moon-aliens are very different from humans. “Whatever springs from the land or walks upon the land is of a monstrous size. Increases in size are very rapid. Life is of short duration because all living things grow to such an enormous bodily mass. The Privolvans have no fixed dwelling place. In the space of a single day, they traverse the whole of their world in hordes, following the receding waters either on legs that are longer than those of our camels, on wings, or in boats.”
To the occupants of the Moon, “Levania appears to stand unmoving, among the moving stars, no less than our Earth appears to we humans.” The view of the stars and planets is so different to the view from Earth that the aliens “have entirely their own system of astronomy.”
These Moon-aliens have a completely different perspective on the Universe to us.
The daemon goes on to describe further details about the Moon, but suddenly Kepler is awoken by a storm outside. It was all a dream!
An illustration from the History of Witches and Wizards (1720). Credit: Public Domain Mark. https://wellcomecollection.org/works/abkab8tq/items?canvas=1
Kepler and the future of space travel
It’s incredible to think that Somnium was written in a time when so little was known about our place in space, or even about the Moon. Kepler wrote the book a year before his friend Galileo turned his telescope towards the Moon and recorded what he saw.
Somnium is full of amazing predictions. Modern astronauts do indeed have to be physically fit, just as Kepler describes. Astronauts do indeed need protection from the Sun’s rays, as well as a method of breathing in space and controlling their temperature.
Kepler got the distance from Earth to the Moon wrong – it’s an average of 238,855 miles away rather than 50,000 miles. But Kepler’s basic point - that the Moon was an incredibly long distance away - was spot on.
Several decades before Newton discussed gravity, or laws of motion, Kepler suggested that a tremendous force would be necessary to launch travellers into space. He was correct, however that force would eventually be provided not by “daemons” but by powerful rockets.
Perhaps the most striking thing about Somnium is the incredible display of imagination and empathy on Kepler’s part. He not only created alien beings, he put himself into their shoes and showed his readers a completely new perspective on the Universe.
The Apollo 11 Saturn V rocket launch. Credit: NASA - Public Domain, https://commons.wikimedia.org/w/index.php?curid=6448924
Kepler and the witch trial
Kepler didn’t publish Somnium but he did pass it around his friends. Unfortunately, at some point in 1611 the manuscript got away from him and began to be passed around Europe. Distorted accounts of the book’s contents were spread through gossip and eventually reached the hometown of Kepler’s mother, Katharina.
Katharina had gotten into an argument with a neighbour. As a result, she had been accused of witchcraft! For an elderly woman in 1615 the accusation itself was as good as a death sentence. Between 1580 and 1630 it’s estimated that around 50,000 people were burned at the stake after being prosecuted for the crime of witchcraft. Many of those accused were over 40 and most of them were women.
Kepler believed that Somnium had provided his mother’s accusers with damning evidence. He believed that his mother’s accusers had used the fact that the mother in the book had summoned “daemons” as proof that his own mother was doing the same thing in real life.
Rather than enlighten people, Kepler’s book had fuelled deadly ignorance, and now his own mother – the woman who had first inspired him to look up at the stars – would pay the price!
Katharina’s trial began in 1620. She was imprisoned and threatened with torture, but she confessed nothing. Her son devoted himself to her defence. He even gave up his job and moved his whole family from Austria back to his hometown in Germany.
At that time the Thirty Years War – one of the most destructive wars in European history – was raging across Europe. Kepler and his family packed up everything and journeyed through the chaos so he could be by his mother’s side.
Kepler devoted all his scientific genius to freeing his mother. He provided the court with logical and medical explanations for every single magical act of which she was accused.
As a result, Kepler secured his mother’s release from prison in 1621. But by that point Katharina - who was in her early 70s – had spent 14 months sleeping on a floor in a stone cell. She died in 1622, only a few months after being set free.
A statue of Katharina Kepler was erected in 1937 in Eltingen, Germany – the village where she was born. Credit: Harke, CC BY-SA 3.0, via Wikimedia Commons
Kepler’s legacy
This was just one of many tragedies that Kepler faced in his life. Many of his loved ones were taken from him over the years. In 1630, he contracted a fever and passed away aged 58. His son Ludwig published Somnium four years later.
Despite all the hardship he faced, Kepler’s contribution to science was incredible.
In a letter to Galileo in 1610 Kepler wrote of “ships or sails adapted to the breezes of heaven” and imagined future explorers who would no longer “shrink from” the “vast expanse” of space.
Over 300 years later NASA’s Apollo program enabled human beings to travel to the Moon for the first time. Kepler’s laws of Planetary Motion laid the foundations for the science that got them there.
In 1968, as his spacecraft orbited the Moon, the Apollo 8 astronaut William Anders took a famous photograph. It was of the Earth rising behind the lunar horizon. The “light of Volva” taking the place of the Moon in the sky – just as Kepler imagined.
Kepler himself had set humanity on the path to making his dream a reality.
