While researching the crazy cool things that light does last week, I realized I had way too much material to cover it all in one week… So here we are! Part two of how light can dazzle, entertain, and deceive us. I hope you enjoy!
Water Puddle Mirages:
As a young boy many years ago I lived in Las Vegas, Nevada with my family. I remember long drives through the barren Nevada desert in the heat of the summer. Though I was plenty hydrated, I remember seeing off in the distance water mirages in the road. Convinced my mind was playing tricks on me, I drank more and more water to see if the mirage went away. The images of water continued to appear in the distant stretch of road so I resigned to the belief that I was fit for the loony bin at such a young age.
Was this my mind playing tricks on me? Nope. It’s another example of the trickery of light! Light bends as it passes through the super heated air above the road and alters the image we see. Allow me to divulge in greater detail the secrets of light below.
The first key to this puzzle is the black asphalt road. Black absorbs all colors of visible light from the sun. As the road absorbs all the energy from incoming light, it gives off a lot of heat (if you have ever worn a black shirt on a sunny summer day you can attest to this heat production as your shirt absorbs all the colors of light). Now for key number 2. Like I talked about in Part 1 of this blog post, as light travels from one medium (like air) into another medium (like water) it bends ever so slightly and alters the image we see. As the air just above the road gets super heated, it is like the light is passing through a completely new medium. Super heated air becomes less dense than the air around it and causes light to refract (bend) as it passes through. This refraction of light just above the road causes us to see a slight shimmer, or heat wave, and we also see a slight reflection of the blue sky as the light bounces off the black road. Remember, the color of water we see on Earth is also a reflection of the sky so this should make sense. So don’t fall for light’s trap and waste valuable energy running towards that mirage!
Colors of a Sunset:
You travel home victorious. It has been a glorious day and you have had much success in basically everything you did. As you drive home you notice a beautiful sunset as if the sky were celebrating your accomplishments as well. Life is good, but as you drive off into the sunset you fail to even question how the sky is now magically red, yellow, and orange when just minutes ago it was typical blue. These beautiful phenomena occur daily, famous photos and images depict these marvels but do we even know how they occur?! Put simply, red color of light get scattered the least in our atmosphere so we see it at sunset which is the light’s longest journey to reach our eyes. Still confused? Let me attempt to break it down for you.
During the day when the sun is high in the sky but the light from the sun has a short distance to travel before it hits our eyes, we see the sky as blue because blue light is scattered the most. When I say the “light is scattered,” I mean that light from the sun collides with particles in our atmosphere and blue light is the most common color of light that is reflected by those particles in our atmosphere. But at sunrise or sunset, the sun is on the horizon and the light from the sun has a farther distance to travel before it reaches our eyes. The red and yellow colors of light are scattered the least by the particles in our atmosphere. As the light from the sun takes its long journey to our eyes at sunset, all of the blue light gets scattered out first and then by the time the light reaches our eyes, the red and yellow colors of light are all that’s left to scatter so we see those colors.
Picture this… you have a big bag full of skittles. You don’t have a lot of time to eat them so you only pick out your favorite ones, the blue ones (representing the blue scattered light). Later you have a long time to sit on the couch, watch Netflix, and eat your humongous bag of skittles. Since you have so much time, you have already eaten all of the blue ones so now you are forced to eat some of your least favorite colors like red, yellow, and orange (representing the red, yellow and blue scattered light). Just like you eating your bag of skittles, the atmosphere has already scattered all of the blue light there is to scatter before it hits your eyes and all that’s left to scatter is the red colors.
First the Lightning, then the Thunder:
Have you ever witnessed a thunder storm from a distance and noticed that you can see the lightning way before you can hear the thunder? Ok, so maybe this one is a bit more obvious and isn’t really a magic trick light plays on us… But it still plays into the unique abilities of light. Light travels significantly faster than sound.
As lightning strikes, it opens up a pocket in the air and the loud crack of thunder is created from that pocket collapsing in on itself once the light from the lightning is gone. We see the lightning before we hear the thunder because light travels way faster than sound. In fact, sound travels at a sluggish pace of 340 meters per second through air while light approaches speeds of 300 million meters per second as it travels through various mediums. To put this into perspective, a cheetah can run at a speed of about 30 meters per second once it gets up to speed. Not only is light tricky, but its “lightning fast” too!
A Word on Bioluminescence:
Some plants and animals can make their own light. They carry this light with them wherever they go. They do not get this light from the sun and they don’t need to charge their batteries by plugging in somewhere. Their light is a chemical light created from chemicals their bodies produce naturally. The ability to produce your own light is a process called bioluminescence. Most of the time, this happens from a molecule of oxygen reacting chemically with a molecule called luciferin, then an enzyme called luciferase takes over from there helping to produce the light. All of that happens inside of the organism’s body! This kind of light is arguably the most energy efficient form of light on Earth.
One of my favorite animals that uses bioluminescence is called the railroad worm. This is not really a worm at all. It is a beetle. The railroad worm produces two different colors of light. Its body can produce a greenish-yellow color of light (representing the train cars of a railroad train) which is used to warn predators of its toxicity. Its head can produce a red light (representing the headlight of the railroad train) which is thought to aid in locating and eating of prey.
Check out these awesome articles and learn more about some really cool bioluminescent organisms.
Word of the Week: “Bioluminescence”–The biochemical production of light by living organisms.
If you read this whole blog post, you are my hero! Thanks for reading. Please feel free to leave me a comment and feedback below. Also, let me know if there is any particular science topic you would like me to look at “through green tinted glasses” and I will write about it.