What is a snowflake?
Snowflakes are intricate, beautiful, mysterious,
and totally captivating.
But for all their complexity – and endless variety –
the structure of a snowflake can be explained
by a few universal laws of nature.
Laws that explain everything from snowflakes to galaxies.
Let’s start at the beginning.
What is a snowflake?
Or, to use its more technical name, a snow crystal?
A snow crystal forms up in the clouds
How snowflakes are made – and why no two snowflakes are the same
when water vapour meets little specks of dust or pollen.
This forms its tiny hexagonal heart.
The tips stick out and are rough.
This attracts water molecules.
And then more water molecules.
And then more.
These form the branches of our snowflake.
The size and shape of these branches
depends on the exact temperature and humidity
that the snowflake meets on its journey through the clouds,
pulled down by the force of gravity.
Each one takes a very slightly different route –
meaning no two snowflakes are quite the same.
When a snowflake lands on your sleeve,
it has been on its own, totally unique, journey to reach you.
Before melting away in a moment.
Johannes Kepler asks: Why do snowflakes always have six sides?
Way back in 1611, on a bitterly cold January morning in Prague,
a snowflake landed on the sleeve of mathematician Johannes Kepler.
And it got him thinking:
“Why do snowflakes have six sides?”
Kepler’s breakthrough was his theory that this hexagonal pattern
is the most efficient use of space.
Whether it’s a honeycomb within a beehive.
Or piles of stacked cannonballs.
Or a delicate, transient snowflake.
It took 400 years –
400 years! – for his theory to be proven.
What Kepler didn’t know at the time is that each molecule of water,
or H2O, is made up of two hydrogen atoms and one oxygen atom.
As the water molecules cluster together when they freeze,
the angle between the hydrogen atoms is always,
approximately, 105 degrees.
And that gives us the six sides.
At its heart, a snowflake is always a hexagon.
Different snowflake shapes
But it can grow into all sorts of weird and wonderful shapes.
Long and thin, like a pencil.
Sharp like a needle.
Cylindrical like a bullet.
Round like a cup.
Or, just occasionally, triangular.
The truth is though, most snowflakes are kind of…well, blob-like.
Snowflake photography and how to take the perfect shot
If you speak to a snowflake photographer –
there are just a handful in the world –
they’ll tell you it takes days and days out in the cold
to get that “money shot”.
And the conditions have to be just right –
between minus 15 and minus 13 degrees.
But ever since Wilson Bentley,
a farmer from the US state of Vermont,
painstakingly took the first photos of stunning snowflakes in 1885,
we’ve been hooked.
Snowflakes and symmetry
Scientists have shown that symmetry
is incredibly pleasing to the human brain.
Snowflakes are all radially symmetrical,
which means you can cut them into identical slices, like a cake.
Shells, flowers, starfish,
even spiral galaxies,
like the Milky Way, share this type of symmetry.
And nature has one last trick up its sleeve.
Snowflakes aren’t actually white!
Snowflakes aren’t actually white.
They’re clear, but they have lots of edges,
and this scatters the light, making them appear white.
Each snowflake is a microcosm of the laws of physics.
Snowflakes and the Universe
Gravity makes it fall.
Electromagnetism dictates its shape.
And you’ve got symmetry.
It’s the same with the stars, and solar systems, and planets.
And with us.
When you look at a snowflake, you can read its history.
Its own unique story.
The experiences it encounters shape it into what it is.
Just like us, really.
