Johannes Kepler is most known for his work in the astronomy, most notably, the formulation of laws that explained the motion of planets. He was also a practising astrologer, even though he believed the practice to be nonsense. He, like many other scientists of his era, used astrology to fund their scientific research.

However, one of his achievements that he is not well known for is his essay on snowflakes, where he studied and attempted to explain their formation.

Kepler published his findings on snowflakes in the year 1611 in a 21-page booklet titled “Strena seu de Nive Sexangula“, which loosely translates into “on the six-cornered snowflake“. Below is an interesting video about how snowflakes relate to modern string theory and a deeper look at Kepler’s essay, from what inspired him to study and write on the subject, to his findings, and its importance in modern science.

Reasons for Johannes Kepler Writing the Snowflakes Essay?

In the Winter of 1610, Kepler was stressing on what to give his friend and benefactor at the Roman court, Lord Wacker von Wackenfels, as a New Years’ gift. At the time, he was employed as an imperial mathematician by the Holy Roman Emperor Rudolph II. And like many scientists and mathematicians at that time, Kepler was underpaid, thus lacking enough money to buy his friend a good gift. He thus started coming up with ideas that would be befitting to an intellectual colleague and friend. After searching and dismissing several essay topics (some he considered too light and others too heavy), he decided on the essay on snowflakes.

The idea for the essay came to him as he was walking about when he noticed snowflakes falling and landing on his coat. They instantly fascinated him as they were “something very small, smaller than any drop, yet they were falling with a pattern”. An essay on the topic of snowflakes was thus the perfect gift for a mathematician to give another colleague.

Kepler’s Fascination About Snowflakes

The falling pattern of the snowflakes – that of a six-fold shape, or rather a six-cornered crystal – is what fascinated Johannes Kepler the most. This formed the basis of his essay – “Why do snowflakes when they are falling and before they become entangled and form larger snowflakes, have six corners and are clustered like feathers.” Kepler wondered why the snowflakes did not have five-sided, seven-sided, or any other shape pattern instead. His attempt to answer this question led him to discover a treasure trove of information and would become the first recorded studying of the formation of crystals.

Aside from the pattern of the snowflakes, Kepler was also fascinated by how small they were, almost nothing, and yet exciting enough in their formation. In fact, being a poet, he played with words to show that snowflakes were next to nothing and yet something – the word snowflake translates to “nix” in Latin but sounds like “nitch” in German, which means nothing.

Kepler’s Snowflakes Investigation Findings

In attempting to answer his question as to why snowflakes have six-corners, Kepler started by considering them as being made of tiny pieces that were all identical to each other. He then considered and drew several shapes that might explain how the snowflake falls with six corners.

Some of the shapes he studied include spheres, octahedrons, and hexagons, and he, through several experiments – which included stacking and squeezing -, attempted to gain some insight into how the snowflake formed. He surmised that close-packing was the formative principle of the snowflakes. He assumed that they snowflake crystals, when falling, were made up of several small units of spheres that were closely packed together.

In his experimentation with shapes, he found that closely packing spheres could form other geometrical shapes, for example, triangle and hexagon (the pattern of a snowflake crystal). The reason for hexagonal structure, he surmised, was perhaps of it being one of the shape patterns that allow for completely filling up space without leaving any spaces.

As to how the crystals formed, Kepler surmised that they formed directly from water vapour. However, he never adequately explained why the snowflakes fell with six corners. Instead, he speculated that the interaction of heat as it retracts from the (cold) water vapour was what caused the six-cornered pattern. Nonetheless, he suggested that further studying of the snowflakes crystals using chemistry could offer a better understanding of their formation.

The Modern World’s Take on the Formation of Snowflakes

Kepler never completely satisfied his curiosity in the formation of the six-cornered snowflakes. However, his essay, though “almost nothing” at the time formed a great basis for the study and understanding of crystal structures. A few centuries later, some of his speculations would be proven and understood better thanks to the advancement of science. For example, modern science shows that macroscopic objects such as snowflakes are made of tiny identical pieces – atoms and molecules. These atoms and molecules also arrange themselves in structures similar to the close-packing suggested by Kepler.

The reason for the feather-like pattern of snowflakes can also be explained by the concept that sharper edges will form faster, as a molecule is more likely to hit and stick on them, as compared to smooth edges. The change in temperature and humidity also explains how the snowflake pattern changes after it has fallen.

Kepler’s theory of close-packing of spheres has also been proven by modern science when it comes to the formation of some complex materials, for example, opal. The opal pieces are made up of closely packed uniform hard spheres. However, this is not the only contribution his essay has had to modern science. The essay formed a strong basis for understanding crystals, which has helped in the development of integrated circuits and electronic chips – which are made using silicon and rare-earth crystals.

In the eyes of most people, a snowflake might seem like nothing, but like Johannes Kepler (and later modern science) demonstrated it is really something extraordinary. While his essay did not fully explain why the snowflake had six shapes while falling, it was an excellent work of science, given the limited research resources at the time.

On top of that, being the first attempt to study crystal structures, it provided insightful foundation knowledge, which has proven to be very useful in the modern world.