In 1611, Johannes Kepler published a short treatise, On the Six-Cornered Snowflake, which was the first scientific reference to snow crystals. Kepler pondered the question of why snow crystals always exhibit a six-fold symmetry. He speculates that the hexagonal shape plays an important role in how the snowflake develops.
A drawing from Hooke’s book.
Then in 1665 Robert Hooke published a large book called Micrographia, containing sketches of practically everything Hooke could view with the latest invention of the day, the microscope. He included many snow crystal drawings, which for the first time revealed the complexity and intricate symmetry of snow crystal structure.
A snow crystal photographed by Bentley.
Wilson Bentley (1865-1931) was an American farmer and snow crystal photomicrographer, who during his lifetime captured some 5000 snow crystal images. More than 2000 were published in 1931 in his famous book, Snow Crystals. You can view many images of Bentley’s snow crystals here. There are many types of snow crystals; we explored the most common at this Smithsonian page.
Snowflakes gave us an opportunity to play with our new compasses and protractors. First we decided to learn how to fold hexagonal snowflakes, paying special attention to symmetry. We used:
- a sheet of white paper
- a drawing compass
- a protractor
8 began by plotting a circle that was 6″ in diameter for the center of the page. To find the exact center, we used a ruler to measure the length and height of the page. Then we halved both and used the ruler to plot a point at this half.
Micah works with her compass.
From the center point of the page, Max set his protractor to draw a circle with a 6″ diameter. He then used his protractor to divide the circle into six equal slices by drawing six triangles (360/6 = 60 degrees).
Next he folded the circle in half, forming a semi-circle with three 60-degree angles (180/3 = 60 degrees). Max was pretty excited by all the angles and his new toys so we took a little time to discuss symmetry as he played around with the compass.
Then we folded paper into thirds along lines between pie slices.
Now the time came to cut our snowflakes. What type of snowflake did we want to create?
Max: How about one of each?
Oh my. That would mean repeating all the steps above again at least 8 times. I was curious to see how long Max’s interest would stay with the snowflakes.
Max helped Micah a little with her cutting.