Judging by the thousands of artsy-filtered pictures of leaves on Instagram, the seasons in the Northern Hemisphere have shifted into fall. But does anyone remember the elementary school science lesson that explains why?
It’s Time to Talk about the Seasons
Hey, you’re a smart person. You know things. And you don’t need to listen to some hoity-toity scientists squawking about stuff you learned in 3rd grade like the earth’s orbit, axis and seasons. I mean, who doesn’t know about that junk, right?
(In fact, a lot of people aren’t clear on that junk. If you think you may be one of them, but you’re sitting amongst a raging party full of people who get together on Saturday nights to pour over the archives of Bittel Me This on a full-wall projector screen – which I assume most of you are – then feel free to feign knowledge of the seasons and come back to this post in a more private setting.)
So yeah, let’s learn about some seasons. Like, not that I’m suggesting anybody needs this information – of course you know about the seasons! – but you know, just for fun. And totally not in an attempt to clear up a colossal misconception about the everyday world around us. Definitely not like that.
And if you absolutely positively know everything there is to know about the seasons, you might skip this one and see what the Nazis had to do with Daylight Savings Time. Also, this post comes with a soundtrack by Vivaldi – so pump it up while you geek out.
You Say You Want a Revolution
First thing’s first – seasons are not a result of the earth’s distance to the sun. Now, this isn’t an inconceivable notion. The sun is our sugar daddy of heat and light. So it would stand to reason that being farther away from said daddy would result in colder temperatures.
However, this would not account for the fact that when the United States slowly descends into fall and winter, Australia is ramping toward spring and summer. If seasons were linked to orbital distance, then the whole planet would presumably be getting their tongues stuck to flagpoles at the same time. This is not the case.
Now, the earth does have an elliptical orbit, which means its distance to the sun varies a bit throughout each yearly revolution, about 3%. This does not sound like a whole hell of a lot of variation, but consider that if the earth were just 5% closer to the sun, the oceans would have baked off and turned the world to ash just like that time you left hard-boiled eggs cooking on the stove for 14 hours during a marathon session of Madden ’06 that may have yielded multiple Super Bowls for the underdog Minnesota Vikings but ultimately imbued your college housing with the sulphurous stench of fossilized albumen.
Conversely, if earth drifted just 15% in the other direction, we’d likely be nothing but a frozen wasteland like that frigid bitch, Mars. Which is to say, while Goldilocks thought she got a good deal with that just-right porridge, we earthlings owe existence to the Hail Mary-iest of long shots.
Back to the seasons and their relation to the earth’s orbit or lack thereof. As further evidence that the seasons don’t give a hot damn about distance, earth actually reaches its closest point to the sun – called “perihelion” – around January 4th and is typically at its furthest distance from the sun – “aphelion” – around July 4th. So, goodbye to all that.
Important Distinction You Probably Totally Already Know But What The Hay Let’s Go There Anyway: One trip around the sun = a “revolution” or year; one spin on the earth’s axis = a “rotation” or day.
Fat Joe & the Four Seasons
Fat Joe, little known expert on earth’s axis.
Nicolaus Copernicus had his Heavenly Spheres, Galileo Galilei his heliocentrism, and Johannes Kepler his eponymous laws of planetary motion. These are the greats of celestial understanding. But let’s not forget another chinchilla-wearing mother-cusser of gravitation-worthy-mass. That’d be Fat Joe and his contribution to science:
Said my n***** don’t dance
We just pull up our pants
And do the Roc-away
Lean back, lean back, lean back, lean back.
In other words, to understand the wildly ranging temperatures on this fair planet, you need to picture the earth as a portly, not quite spherical, gentleman in a club. Our planet wouldn’t be caught dead standing up straight like some busta. No no. Real playas lean back about 23.45 degrees and do something called the Roc-away.
The Reason For the Season
During the red hot American summer, the Northern Hemisphere is tilted 23.45 degrees towards the sun. This is important for two reasons. First, it means we’re getting about three times more sunlight than the Southern Hemisphere. And second, the sunlight we’re getting is hitting us straight on, whereas the Southern Hemisphere’s light is hitting at an angle. (Just think about the difference between the angled sunlight of dawn or dusk and the skin-blistering rays of midday when the sun’s directly overhead.)
It’s important to note that the earth doesn’t actually tip one way or the other throughout the year. It remains half-cocked at the same 23.45-ish degrees all year, but the orientation changes as it completes an orbit.
Bittel Me More: Earthquakes & Axes
First, “axes” – pronounced ak-seez – is the plural of “axis.”
Second, last year’s earthquake in Japan was so huge, it shortened earth’s day by 1.8 microseconds and shifted our axis by about 6.5 inches. According to scientists like Richard Gross of NASA, these sorts of changes are completely normal.
Earth’s rotation changes all the time as a result of not only earthquakes, but also the much larger effects of changes in atmospheric winds and oceanic currents. Over the course of a year, the length of the day increases and decreases by about a millisecond, or about 550 times larger than the change caused by the Japanese earthquake. The position of Earth’s figure axis also changes all the time, by about 1 meter (3.3 feet) over the course of a year, or about six times more than the change that should have been caused by the Japan quake.
TRANSLATION: Richard Gross encounters so much Threat-Level-Midnight shit in his Pasadena jet propulsion lab, not even a planetary-rotation-altering-country-leveling-9-point-mother-cussing-0-earthquake can shake him. Let’s just hope the dude doesn’t have kids because noodle art doesn’t stand a chance against this man. In fact, he probably invented the Roc-away.
(Lean back, lean back, lean back, lean back.)
Images courtesy of: Helions, Earth’s Rays, Creative Commons
