Larry FloerschWhen I was a kid, Christmas Eve almost always involved a ride in the car to search the night sky for the red light from Rudolph the Red-Nosed Reindeer’s nose. Back then we opened gifts on Christmas Eve because we were almost always at my grandparents’ farm, and any celebration had to be sandwiched between the evening and morning milkings.
So on Christmas Eve, we would all, with the mysterious exception of my Uncle Arthur, bundle up and pile into the car and motor off to a small town nearby for Christmas Eve services at the church where my grandparents were members, then we’d slowly ride home peering up at the black sky hoping to see a moving red light.
Our hopes were always dashed. Any moving red lights in the sky inevitably turned out to be airplanes heading to or from Chicago some seventy miles away. Miraculously, however, Santa had always visited and left gifts under the tree by the time we arrived back at the farmhouse.
So if you are like me, you’ve probably wondered how Santa and Rudolf always manage to escape detection. I therefore was gratified to see that science is on the case. In a recent piece in ScienceNews magazine (“Rudolph’s Nose, Glow? When Reindeer Fly”), the author, Maria Temming, explained it has nothing to do with Santa and Rudolph trying to hide their activities and everything to do with the branch of science called physics.
Temming points out it is not impossible for a reindeer to have a glowing red nose. After all, many critters show what is called “bioluminescence.” Think of fireflies flashing their lights as they try to locate each other on a warm June night. And if Rudolph and his eight other team members have already mastered the ability to fly, a glowing red nose is not out of the question. He and the other eight are obviously exceptional reindeer.
And if you needed a light to cut through the dark of a “foggy Christmas Eve,” red is the perfect color. That’s because light travels in waves, and the distance between the waves of red light is the longest in the spectrum of “visible” light, which, just like a rainbow, ranges from red to orange, green, blue, indigo, and violet (with violet having the shortest distance between waves). Because of the long distance between its waves, red light is less likely to bounce off tiny water droplets floating in the air, such as occurs with fog.
As we all know, Santa and his sleigh must move at incredible speeds to complete his task of visiting all the children in the world in one night. That speed can affect colors. Very high speeds cause what is called “red shift/blue shift” depending on where you are standing when Santa flies by. “Red shift/blue shift” is like what is called the “Doppler effect” when it comes to sound, which also moves in waves. Think of a railroad train blowing its horn as it passes by. The pitch of the horn goes down as the train is moving away from you because the sound waves from the horn are being squished closer together as it approaches and stretched out as it moves away.
The same happens with light at high speeds. If Rudolph is moving toward you at a very high speed, say, just one tenth of the speed of light (one-tenth the speed of light is still more than 67 million miles an hour!), and then passes you and begins moving away just as fast, the color of his nose would change from orange (because the red light waves are squished closer together and therefore appear orange) to a color of red so dark it would appear black (as the red light waves are stretched apart). The same is true of all the other colors. Rudolph’s brown fur would appear greenish as he approaches. Most importantly, as he and the sleigh move away, the waves for the color red would get stretched into the first color on the spectrum of “invisible” light — what is called “infrared.” Rudolf, along with his eight team mates, Santa, and the sleigh would become invisible.
That, I think, pretty much explains why everyone has such a problem seeing Santa and his team as they go flying about: We are looking for the wrong color nose (orange), or, if they are moving away from us, they are invisible.
As one of the scientists interviewed by Temming pointed out, however, all this high-speed flying requires tremendous amounts of energy. So if you are leaving treats for Santa and his team of reindeer on Christmas Eve, forget the carrots for the reindeer. They may be healthy, but they are low cal. Instead, lay out an extra large plate of really sugary cookies.
Happy Holidays!
