Science explains how Rudolph navigates with his baby blue eyes

23 Dec 2015

We all know about Rudolph’s ‘nose so bright’, but did you know there’s actual science behind why he has such a bright nose, and why his eyes are a dazzling blue at night?

The eyes of Rudolph, and every other reindeer for that matter, have a unique property that Dartmouth College professor Nathaniel Dominy felt was worth investigating following a tough line of questioning from his four-year-old daughter.

According to AP, Dominy has been extensively studying the unique way a reindeer’s eyes are able to see not only on the visible light spectrum, but also on the ultraviolet spectrum, which helps them spot predators like bears and wolves against the depths of snow.

But if reindeer had the same red nose that Rudolph had, well, then they would be some of the best navigating animals on the planet, if they needed to fly through fog.

What to feed Rudolph

As Dominy explains, the blue seen in a reindeer’s eyes is due to the reflective tissue that lights up when hit with light, but only occurs during winter as, during the summer months, it turns a more golden colour.

“What happens is that, at night, the animals are trying to dilate their pupils to allow as much light into the eye as possible and, because those muscles are so active, it actually blocks little valves in the eye,” he says. “The pressure in the eye builds up and compresses that tissue in the back of the eye, which causes the refractive properties to change.”

So if Rudolph was to navigate the foggy skies, the addition of a glowing red nose would be perfect, as its colour allows it to pierce the fog, only helped by reindeers’ UV-spotting eyes.

There is a downside to having such a bright nose, though, as Dominy says that reindeer have a complex blood vessel system in their noses, which keeps their noses from freezing, but leaves their body susceptible to intense loss of body heat.

“One way to heat your body is to burn fuel. You do that by burning fat and calories,” Dominy advises. “Children should be aware of Rudolph’s condition and leave high-calorie foods for him.”

Colm Gorey was a senior journalist with Silicon Republic