Why is the Sky Blue?
Credit: photo by www.tommydaspit.com


Oh, Google, how we adore you. Surely we wonder how we ever survived without you. We use you to check our spelling, for directions to the nearest Chinese restaurant, to help our kids with their homework, and to find recipes for French toast casseroles. We even use you to answer life’s great mysteries.

My favorite thing about Google is its ability to fill in the blanks of what it “thinks” I want to search for. If I type in the word “why”, it automatically supplies me the option to search for  “why is the sky blue”, this being based on Google’s data that the word “why” is more often preceded by the phrase, “is the sky blue” than any other phrase. Which tells me there are plenty of people pondering the perplexities of the universe out there. Next in ranking of “why” popularity is, “why do we yawn”, followed by “why do cats purr”. My, we are an inquisitive species, aren’t we?

In this first of a series of “Answering the Top Google Search Questions” articles, I will do as the title suggests, and attempt to answer the most often asked questions on Google in order of rank. And I promise to do my utmost to put the answers in layman’s terms that we all can understand, without the use of algebraic formulas, pie charts, or Latin expressions. You are welcome.

Thus, I will begin by answering the top 3 “why” questions according to Google. (drum rolling ensues…)


As it turns out, the sky is not actually blue. Our eyes only perceive it as being blue. It simply looks blue because of what happens to the sun’s rays as it enters our atmosphere. Were the earth's atmosphere much further away, then the sun would look just like any other star and the sky would appear black, like the dark night. (This reminds me of when I used to argue with my mother, and she would say, “If I said the sky was blue, you’d argue that it was black.” Well, Mom, as it turns out...)

Now, let’s look at what happens to cause the sky to appear blue. When the sun emits light, that light is actually a combination of many colors. If you hold a prism up to the direction of the sun, you can see that it casts a rainbow of colors that the sunlight is made up of. Now, light travels in wavelengths, and when those light waves reach the gases in the earth's atmosphere, the waves are scattered. Light waves that are more red in color are longer and have less energy. Light waves that are more blue-violet, are shorter and have more energy. The energetic blue-violet waves scatter better and more equally and thus saturate the atmosphere, causing us to perceive a blue hue across the sky. But why doesn't the sky appear violet? Or blue and violet? This is because of the limitations of our eyes. Our eyes are not able to discern more than one color per wavelength, so instead we interpret the mixture of colors as being one shade: blue. And that is why the sky looks blue.



Why Do We YAwn?
Credit: photo by Bjorn Rixman

In short, no one knows. This is fairly stunning when you consider that scientists have been able to put a roving robot on Mars but haven't been able to figure out why we yawn. One theory of the yawn is that when we are tired, we don't breathe as deeply as usual. Because our breathing is slower, we take less oxygen into our lungs. Thus our oxygen-low lungs trigger a yawn, which brings needed oxygen into the blood.

While that may be a plausible theory, it doesn't answer the question as to why we do not yawn in our sleep, when breathing is at its slowest. It also doesn't take into account that babies in the womb yawn as early as 20 weeks gestation, and they have not started breathing oxygen at all yet.

Pretty much the only thing all the scientists agree upon about yawning is that it is contagious. Yawns can be "transmitted" not just among humans, but between many other species as well. Primates, birds, rodents, and lions, tigers, and bears can all catch contagious yawns. Though for some strange reason it has been learned that turtle yawns are not contagious among other turtles. (How would you like to have been the one conducting that study?) Did you know just reading the word “yawn” can invoke a yawn? (I wonder how many of you have yawned in this paragraph alone.) And of course, no one seems to know why this occurs either. Again, we have a Mars-bot, for goodness sakes, but no one can tell me how my guinea pig just made me yawn. Amazing.



Why do Cats Purr?
Credit: Photo by Kevin Dooley

Here we go again. It seems like such a cop-out to say “nobody knows for sure” but, well, nobody knows for sure. We know that cats purr when they are happy and content, but they will also purr when they are hungry or even hurt. It is their kitty cat way of expressing emotion. But why the “purr” sound specifically? Well, unfortunately, the cats are not saying. Scientists know that the sound comes from vibration in their voice box, much like when a human hums. We also know that cats can purr while both inhaling and exhaling. And it seems to be the general consensus that cats have voluntary control over their purr-box, and they can turn it on and off at will. Also, there is evidence to support that cats are aware of the effect that their purr has on humans, and they will use it to get what they want out of us. Well played Sylvester, well played.

Stay tuned in for the next article in my series of “Answering the Top Google Search Questions” where we attempt to learn where Chuck Norris may be hiding.