Wednesday Wonders: Equinox

Welcome to September 22, the date in 2021 when the Earth stands up straight and faces the Sun head on. Well, side on. The point is that on this date the Earth’s poles point at exact right angles to the Earth’s orbit around the Sun, so it marks a change of season. If you’re in the northern hemisphere, this is the first day of fall, and days will begin to grow shorter as the north pole starts to tilt away from the Sun. Meanwhile, if you’re in the southern hemisphere, today is the first day of spring, as the south pole starts to tilt toward the Sun. Oh, don’t worry, though. It’s not like the Earth is literally rolling over. The actual angle of its axis is always the same — it’s just its position relative to the Sun that changes, depending upon which quarter of its orbit it’s in. Today, though, magic happens, as the length of day and night everywhere on the planet is the same — but it’s not 12 hours, because a day is not quite 12 hours. Rather, one day is 23 hours and 56 minutes, so on this day each side of the globe receives 11 hours and 58 minutes of daylight. Close to 24, but no cigar. Each day is missing four minutes, and yes, over the year, the time on your clock technically gains because of this, but that is part of why we have leap years and all that shit in the first place. And the fact that the Earth’s axis is tilted and the apparent height of the Sun in the sky plus the length of day changing regularly is probably what led to human civilization in the first place. As soon as people noticed that the spots on the horizon where the Sun rose and set day-to-day changed, and then started to notice how high it did or did not make it into the sky by noon got folk to taking notes. Next up would have been timing the periods between its rise and set over the course of… well, it’s not defined yet. Figuring out the timing might have been tricky when there was no way to actually tell time, so maybe those first experiments just meant tracking the length of an object’s shadow right as the Sun rose and when it set, them recording the length of each one and comparing it to each subsequent day. This wouldn’t give you a length in terms of hours per se, but it could tell you, for example, how long the shadow on a particular day was. Since the Sun doesn’t cast shadows at night, this gives you length of daylight, and you can then compare that length to the length on other days. This will tell you the rate of change per day, as well as give you the relative lengths of longest and shortest days. Repeat the experiment until the pattern starts to repeat — i.e., you hit the same shadow length you started with and see the same lengths appear over the next, say, dozen measurements, and now you suddenly know how many day/night periods there are before the Sun returns to where it started. People may not have understood the concept of orbits yet and probably thought the Earth was at the center of everything, but only because that’s exactly what it does look like from down here, but it did give them a starting point from which to be able to predict the regular course of the Sun. Finally, key these measurements into the seasons, as in when is it cold, when is it time to plant, when does it flood, and when can we harvest? Eventually, over time, ta-da: You’ve created the calendar, and the basic parameters of Earth-Sun dynamics, plus axial tilt dictate the creation of four annual divisions; call them seasons. Of course, some cultures, who tended to not be agricultural, watched the Moon instead, and also divided the year into months (literally named for moons in many different languages) although not seasons. However, since the lunar month wound up much shorter than the solar month after one Earth orbit was divided appropriately, lunar calendars would always lag behind. This is why, for example, the Hebrew calendar has to add in an entire month every so often instead of just a day, and why Jewish and Islamic holidays seem to slip around the Gregorian calendar. Here’s a nice irony, though. The ultimate holiday for once-a-year Catholics, Easter, is itself set based upon a lunar calendar. The date of Easter is set as the first Sunday after the full Moon that occurs on or after the spring equinox. If that equinox is on a Sunday itself, then Easter is the next Sunday. Why this is the case, I have no idea — but events in the Islamic Calendar, as well as things like the Chinese New Year, are also set based on a particular New Moon, although they are all at different times of the year. If you’re part of the early agricultural movement, though — which led to permanent settlements and cities and irrigation, and all kinds of fancy shiz — then your city is probably going to have a nice observatory, but it wouldn’t be bristling with telescopes, which would not be invented for thousands of years. Rather, it would be a prominent building or even a temple-like structure — think Stonehenge — with very specific architectural features designed to align with the movement of the Sun, Moon, and possibly certain stars to become one giant indicator of when those significant dates passed. For example, a slit in one wall might direct sunrise light on the first day of summer onto a specific plinth or marker, or maybe even a mural or statue depicting the god or goddess of the season. Likewise, the same slit would hit a different marker for the first day of winter. Those two are easy because the sun will be at its northernmost point when summer starts and its southernmost when winter starts, which is why you can use the same slit. Spring and fall, being equinoxes, both come in at the same angle, so the light would hit the same place. However, the good news is that if you know which one was the last season, then you know what’s coming, so spring always follows winter and fall comes after summer. Somewhere around these times, these early astronomers may have even figured out the concept of the analemma and begun tracking it. This is the huge figure-8 pattern that the Sun, when recorded at the same time each day (usually noon) makes over the course of a year. Tracking the Moon would probably allow for the ability to predict solar and lunar eclipses — at the time, probably more useful as a political/religious function over anything else. “The Moon is going to die on Tuesday, and it will be your fault unless you pay us tribute and fealty, peons!” Ewww. Out front would be a huge sundial to impress and mystify the populace who, of course, would never be allowed inside such a sacred space. Same as it ever was. Except… We do have access to this knowledge now, and the short version of it is this. The Sun is the center of our Solar System, mostly by virtue of having 99% of its mass, and holding everything else in its thrall via gravity because of that. There are two planets closer to the Sun than Earth — Mercury and Venus — and both of those are barely titled. Mercury is off-axis by barely 3 hundredths of a degree, while Venus is inclined at 2.6 degrees. However, since Mercury is tidally locked with one side boiling and the other frozen, it’s not likely to benefit at all if it suddenly tilted. As for Venus — this is our solar system’s true shit-hole planet, with the hottest temperature and thickest atmosphere, a hellscape where it rains sulfuric acid constantly. If we look at the rest of the solar system, the only planets that come close to having the same axial tilt are Mars (25.19º), Saturn (26.73º) and Neptune (28.32º). Meanwhile, the planet Uranus has the most extreme tilt in the solar system, with its axle rolled over a full 97.77 º, which indicates that, at some point in the past, Uranus must have gotten rammed pretty hard by some asteroid or even a small planet. The end result is that Uranus always keeps its pole pointed at the Sun, alternating between north and south so that its seasons basically travel sideways — although those seasons aren’t much to speak of there, because the surface is pretty much a nearly featureless ball of methane with some lighter clouds in high latitudes (or is that high longitudes?) and, as recent studies have determined, there is also a big, dark spot on Uranus. Of course, we wouldn’t even know about the other planets and stars and so in if we hadn’t started looking up to figure out what was going on with our own Sun and Moon in the first place, and Uranus, Neptune, and Pluto (not a planet) were not even discovered until modern times. Uranus wasn’t even named until the late 18th Century, but the convention of naming planets over Roman gods carried on, and the place got its name at the suggestion of German astronomer Johann Elert Bode. Whether or not he knew about the comedy potential in English of that name choice is anyone’s guess, but officials agreed. And although it’s properly pronounced “OO-ra-noos,” almost no one says it that way, and so stories about the sixth planet are always unintentionally hilarious. And it all started in ancient days, when the first farmers started to pay attention to the change of seasons and tried to learn whether the gods had left them in clues in the heavens above, eventually leading to an understanding of the cosmos that required no gods at all but adhered to its own inexorable set of laws that were an intrinsic property of reality itself. Thanks, farmers! Images: (CC BY-SA 2.0)

Sunday Nibble #72: Keep it varied!

One of the big fails of modern science fiction films comes down to world-building — literally. It’s pretty much this: For whatever reason, most planets wind up with a one-world biome.

It’s a desert planet, or a snow planet, or a forest planet, or a volcano planet, and that’s it.

Now, I can see how our own solar system might have propagated this idea because, well, honestly, other than the Earth and Mars, look at Mercury, Venus, Neptune, and Uranus, and they really do seem to be mostly the same globally.

Mercury is a rock — but if you compare the temperature on the side that always faces the Sun and the side that does not, you’ll find a ridiculous extreme because it has both the hottest and coldest places in our solar system if you don’t count the atmosphere of the Sun itself.

So scratch Mercury off the list, because it has climate extremes as well. And if it had any kind of atmosphere (which it can’t), it would have incredibly violent storms along its terminator, which in this case would be a line circling its poles, with total sunshine on one side and total dark on the other.

Meanwhile… Venus is a hellhole with no variation, so it totally fits the science fiction planet stereotype. Way to go Venus!

Earth… I’ll get back to us in a minute.

Mars… it may look like it’s just a little off-orange dust-ball with easily revealed gray streaks, but that’s not really true. While it doesn’t have a lot of atmosphere to speak of, it does actually have seasons, and the climate, such as it is, in the polar zones and at the equator do vary.

Let’s jump over Jupiter and Saturn and take a look at Neptune and Uranus.

These last two are, in fact, the epitome of mono-biome worlds, as far as we can tell. They are just spinning globes of liquid methane and ammonia at really low temperatures, they lack surface features, and are pretty reminiscent of a planet like Giedi Prime from Dune, which was basically made of fossil fuels.

The only fail in those books was the idea that the planet could actually be habitable by any kind of hominid life-form. Nope. It would have been, at best, the equivalent of a distant oil field, exploited by pipeline or robot rigging crew, with the actual product shipped to a real home world to be exploited.

The real action on varied biomes this far out in our solar system probably comes among the many moons, of which Uranus and Neptune have a lot, and Saturn and Jupiter have many more — but let us get back to the king of planets, and the father of the king, by whom he was eaten.

Look it up, people.

While both places may look like they are just whirling balls of gas as well, one glance at them tells us that no, they are not. And while you have to go really far down in hopes of finding any kind of solid surface, a look at the top of their atmospheres says, “Wow. They have climates.”

And boy, do they.

Jupiter is famous for its storms, the most well-known of which is the Great Red Spot, which is pretty much a hurricane just south of the equator that has spun in roughly the same place for centuries. There are indications that it’s finally breaking up, but others are forming in a storm train that’s familiar to any Earthling who watches news of our own Atlantic hurricanes.

Jupiter’s storms are just bigger, nastier, and they last (figuratively) forever. Meanwhile, the dynamics of the rest of the atmosphere are incredible, with visible bands of clouds and gases violently interacting in a dance of fluid dynamics driven by the incredibly rapid revolution of the planet.

Jupiter’s circumference is roughly eleven times the Earth’s, but one revolution on Jupiter, aka one day, takes only 9 hours and 56 minutes. Meanwhile, one revolution on Earth takes 24 hours and 15 minutes.

The net result is that the velocity of any point on the Earth’s equator around its axis at around sea level is 1,307 mph (1,669 kph). At the top of Jupiter’s atmosphere, it’s 27,478 mph (44,222 kph), which is 26.5 times faster.

So storms are much more intense, winds are faster, and atmospheric friction makes it pretty hot along the Jovian equator.

It’s probably not that much different on Saturn, with the composition of gases in the atmosphere changing by latitude — and that’s exactly what happens on Earth, for different reasons.

Back to the biome. Earth in particular is defined by its climate zones, which were mapped and named by humans centuries ago.

The defining two lines are the equator, at 0° latitude, and the Tropic of Cancer at 23.5°N and the Tropic of Capricorn 23.44°S. What they basically define are the zones in which the Sun does its maximal and minimal height at noon thing as the seasons pass.

They’re named for the astrological signs that marked the passing of the solstice — traditionally, the Sun enters Cancer on June 21, which is more or less the Summer Solstice in the Northern Hemisphere. Meanwhile, the Sun enters Capricorn around about December 22, which is the Winter Solstice in the Northern Hemisphere.

Swap results and seasons if you swap hemispheres.

Anything north or south of these Tropics (which basically means “cut-off”) up until the corresponding polar circle is considered a temperate zone. Well, was, until climate changed started to fuck it up.

As for the polar zones, these are the areas that either receive sunlight nearly 24/7 during summer or darkness nearly 24/7 during winter.

So this is why we have ice caps (sort of still) near the poles, pleasant weather for a zone between that and hot (until recently) and then a pretty warm climate spanning the equator in a pretty equal band.

Traditionally, that would give us snow, permafrost, deciduous forest, Mediterranean climate, rainforest, desert, then repeat in the other direction. Different climates depend upon where you are on the planet. So does the atmospheric composition, with some zones having more moisture and some less.

And yes, that’s all changing, but let’s get back to the point.

Where a lot of Science Fiction world-building has fallen down is in actually forgetting the lessons of our solar system, which are these. Which planets are naturally uninhabited and which ones aren’t?

Welp, Earth comes to mind as inhabited, with Mars a good candidate as former life host, along with various moons of Jupiter and Saturn as current hosts. The common thread, though, is that we’ve only found life on the planets with varied biomes — mainly, Earth.

And yet, science fiction planet designers insist on thinking that they can create planets that are all one thing — an ice world, a rain-forest planet, a volcanic world, a total desert, a salt flat with iron oxide deposits under it, a swamp world… whatever.

Here’s the problem: None of those mono-biome worlds are ever going to naturally support life. They might manage it with a lot of heavy infrastructure dropped onto them, but otherwise not. But for the ones that do happen to have varied biomes, seasons, maybe even a big moon to create tides, the sky is the limit.

And, to science fiction writers, if you want to create an inhabited planet, make damn sure that climate and terrain do change based on latitude, axial tilt, orbital period, and other realistic things. Otherwise, nobody is going to able to live on the “one terrain, one climate” space ball you’ve created.

To take just three examples, if you have a snowball world like Hoth, an ocean planet like Kamino, or a desert world like Tatooine, you’re going to have a damn hard time providing food and water for your inhabitants.

I’ll assume that, since most of the inhabitants of the Star Wars universe we see are humanoid, that we’d need to support an Earth-like atmosphere and agriculture, and other typically human needs.

The obvious workaround, of course, is that these single biome worlds are stand-ins for similar places on Earth.

For example, Hoth is not really inhabited by any kind of advanced civilization, just the local beasties — mainly tauntuans and whatever it was that lost an arm to Luke. It’s only an outpost, and is most like an analogue of the few bases that humans have in Antarctica.

Kamino, the ocean planet, likewise doesn’t really have any civilization, just the resident Kaminoans who are cloners, and who are involved in a very secret project most likely commissioned by a Sith Lord. Think of them like oil platforms in any distant place, like the North Sea, or very remote oceanic research stations.

And then we come to Tatooine, which seems to have a thriving culture despite being a desert planet of the sandy variety. But, again, this one has an analogue on Earth and in the Star Wars universe and Tatooine itself was actually filmed not all that far from its terrestrial counterpart.

See, Tatooine is the Middle East, which provided a gateway and marketplace between Asian traders from the East and European traders from the West.

All this is well and good if you’re being symbolic, but if you want to write real science fiction, then make your civilized planets as complicated and varied as Earth.

Oh yeah — the one other thing that seems to happen a lot in science fiction films: Every inhabitant of a particular planet apparently has the same language, belief system, culture, and general appearance. There are exceptions (that are not accounted for by aliens) but they are far and few between.

You could try to write that off to the idea that a planet’s cultures cannot migrate into space until they become one, but I’d argue that we seem to be doing just fine right now while sending up astronauts and missions from multiple nations, and we even seem to have just reached the Christopher Columbus phase 52 years to the day after the first humans walked on the Moon.

That would be the “letting rich assholes go up there” phase, by the way.

Also, if it seems like I’m picking on Star Wars in particular in this piece, I’m not. It’s just that I’m slightly more into that fandom (slightly) than the other two I’ll call out now: Star Trek and Dune.

They all tell fantastic stories. And when it comes to terms of defining them as hardest to softest in terms of the science in the fiction, then the order is this: Star Trek — they at least try to come up with physical rules for shit; Dune — they at least come up with biological, genetic, and psychological rules for shit, but really, really cheat it with what mélange can do; and Star Wars —100% fantasy, but that’s okay.

Or, in other words, it shouldn’t be a surprise that Star Wars makes the mono biome mistake constantly. It should be really annoying that Star Trek and, to a certain extent, Dune both do.

That doesn’t mean that I’m not looking forward to the upcoming Dune movie, which will just be the first half of the book. I am. It looks very, very good, whether it takes place on a totally desert planet or not.

Sunday Nibble #66: Putting the Sun on pause

Happy summer solstice! This is the day of the year in the Northern Hemisphere with the longest period of continuous sunlight, which increases with latitude.

On the equator, at 0 degrees latitude, day time and nighttime are pretty much equal all year long. The farther north you go, the longer the period of sunlight. At my latitude, which is about 34 degrees north, we’ll get 14 hours and 26 minutes of sunlight on that day.

When you get to Reykjavik, Iceland, you’ll experience 21 hours and 8 minutes of sunlight plus 2 hours and 52 minutes of twilight, which adds up to 24 hours during which the sun never really sets, and if you make it to the North Pole, you’ll experience a full 24 hours of sunlight.

It’s exactly the opposite in the Southern Hemisphere, where this is the winter solstice for them, and the period of the longest nighttime, which works in a similar fashion to the north but in the opposite direction, with the night getting longer the farther south you go.

Don’t worry, though. In December, the tables are turned, and then it’s the summer solstice in the south and the winter solstice in the north.

The word “solstice” is derived from the Latin word for stopped or stationary, and this comes from what the Sun apparently does. From the time of the winter solstice, the Sun appears to climb higher and higher into the sky and it continues to do so for six months.

Then, on the summer solstice, it reaches its highest point and then appears to pause for about three days before turning around and heading back down toward the equator.

The mid points are the equinoxes, which is when the Sun’s apparent position is crossing the equator, and this is when all points on the planet have day and night time of equal length regardless of hemisphere.

We have two equinoxes, vernal and autumnal, more commonly known as the spring and fall equinox, which mark the beginning of these seasons.

Put all four together in order, and there you have humankind’s original and most basic calendar. Once the pattern had been recorded and recognized, annual events became much more predictable — the change of seasons, the likelihood of seasonal flooding, and so on.

The Moon became a secondary counter and, in fact, we landed on the idea of a lunar calendar long before the solar one. The word “month” is derived from “moon,” and one month is approximately the length of one complete cycle of the Moon’s phases, from one full Moon to another — or one new Moon to another, depending on your culture’s preference.

So why do equinoxes and solstices and seasons happen in the first place? By the very fortunate circumstance that the Earth’s axis is tilted at about 23 degrees relative to the Sun when it’s at either solstice, and the tilt remains constant relative to the Earth.

It’s probably best demonstrated with an animation to make the concept clear, so here you go, courtesy of YouTuber Brad Freese:

From the Sun’s point of view, the Earth keeps tilting back and forth as it goes around. Meanwhile, to the Earth, it looks like the Sun is bobbing up and down. The end result is the same either way: changing period of daylight that are more extreme the closer you get to the poles, seasons, and the origin of the first human calendar.

Now, a year generally has 12 full moons in it but the number of days in a lunar year, 354, is a bit short of the solar year of 365.25 days, so about every two and a half years, we get that elusive (or not so much) Blue Moon, which is just the 13th full moon of a calendar year.

But when you take 12 and divide it by 4 — the number of solstices and equinoxes — you get a nice even number, 3. So divide each solstice or equinox into three “moons,” or months, and all you have to do then is watch the phases of the Moon to know when the seasons will change.

You might have noticed that neither the lunar days nor the solar days quite add up to the number of degrees in a circle, which is 360. But add them together, rounded — 354 + 365 — and you get 719. Divide that by 2 and round it again, and you get 360.

This is actually a really interesting number, because it has so many factors, which are numbers it can be evenly divided by. If we include 1 and 360, there are 24 of them (24 being a factor of 360), and in fact every single digit number except 7 is a factor, which is very useful.

Beyond that, a lot of the numbers relate to units of time we still use now, particularly 12, 15, 24 and 60, and it’s divisible by 10, which makes it very compatible with our common base 10 system.

By the way, the Babylonians, who were big astronomers themselves, used a Base 60 system, in which the number 360 would have been expressed as their equivalent of 60.

It’s interesting to think that the larger parts of our timekeeping system are not as arbitrary as they might seem and have a strong basis in reality. As for how we chose to count weeks and the hours in a day, that’s part is totally arbitrary.

We could have just as easily divided each day into 36 hours of 40 minutes each or 18 hours of 80 minutes each, but we didn’t. Why? Who knows, but the most likely explanation is that 12 hours of “day” and 12 hours of “night” just echoed the annual pattern nicely.

Hours, by the way, were the very last thing to be measured and determined, since if you just divided amount of daylight by 12, the length of the hour itself would change throughout the year The more important markers were sunrise and sunset.

By the way, a word about the image up top. This image is what’s called an “analemma,” and it represents the position of the Sun in the sky over the course of the year, in this case, in the Northern Hemisphere. The points where they cross represent the equinoxes.

Also note that the top half forms a smaller loop than the bottom half. That’s because of a nice quirk of orbital mechanics. The Earth is at its farthest point from the Sun around the beginning of July, right after the northern summer solstice, and at its closest around the beginning of January, right after the northern winter solstice.

So… in July, the planet is actually moving at its slowest because it basically reaching the “top” of the orbit. That is, the Sun’s gravity has flung it as far away as it’s going to get, so it’s now going to slow down and come plunging back. Think of it like throwing a baseball in the air.

Once the Earth has passed through the equinox again, it’s now being pulled in by the Sun, so moves a lot faster in the same period of time.

But what I really wanted to point out was this. Although astronomers insist that “Uranus” is actually pronounced “oo-ra-NOOS” in order to avoid immature jokes, what did they name this image?

Analemma.

Anal Emma. Yeah, those mofos knew exactly what they were doing.

Image source: Giuseppe Donatiello, (CC0), via Wikimedia Commons

Whole lot of shaking goin’ on?

(Warning: Betteridge’s Law alert in effect.)

Damn. Puerto Rico has been getting pounded by quakes over the last month to the point that they have visibly changed the landscape. Why so many earthquakes? Well, as they say in real estate, it’s all about location, location, and location. The island happens to be situated on top of or next to various tectonic plates and mini-plates, and it’s the collision of these pieces of the Earth’s crust that cause quakes in the first place. Well, the ones that aren’t man-made, anyway.

Puerto Rico isn’t alone in this, either. A look at significant earthquakes over the last 30 days shows the image of a very unsettled Earth. Now, it would be easy to buy into an interesting astronomical fact being the cause. That is, the Earth reaches its closest point to the Sun, perihelion, in January. This year, it was January 4th, with the centers of the Earth and Sun being only about 91.4 million miles apart. On July 4th, they will be at their most distant, at about 94.5 million miles.

Now, true, that’s only a little over a 3% difference, but that distance is about 390 times the diameter of the Earth, and enormous masses are involved on both ends. Perihelion is also the point in the Earth’s orbit when it reaches its maximum velocity, which is what flings it to aphelion, where it slows, reaches its minimum velocity, and comes flying back into a smaller orbit, which the Sun slingshots back out. Lather, rinse, repeat.

Of course, the difference between maximum and minimum velocity is only about sixth tenths of a mile per second, but, again, we’re dealing with some pretty big objects here. And, anecdotally, I can tell you that the biggest earthquake I’ve ever experienced was in January, and so was Japan’s, a year to the day later, and now Puerto Rico is shaking apart, and it must be connected, right?

Right… except that it’s not. Earthquakes are not driven by orbital mechanics or the weather or any other factors like that, and any belief in “earthquake weather” or “earthquake season” are pure confirmation bias and nothing more nor less.

However… there’s one thing to keep in mind about this time of year. We are closer to the Sun, and so get more heat from it, right at the time when it’s winter in the Northern Hemisphere, but summer in the Southern Hemisphere. And why is that the case? Because of the way the Earth is tilted. Winter is the season when its axis is titled away from the Sun. Summer is when it’s tilted toward. Spring and Fall are the seasons where the axis is mostly straight up and down.

So… in the Northern Hemisphere, we get winter when we are closest to the Sun and summer when we’re farthest away. In the Southern Hemisphere, it’s exactly the opposite, and this is where we can see events in our solar system having an effect down here. Mainly Australia is burning.

Why? Climate change, hotter temperatures, drier forests, extreme weather (thinking thunderstorms with lightning that can start a fire), and human elements, although far from the “200 arsonists” dreamt up by the anti-climate change crowd. More like 24 actual arsonists, and then a bunch of idiots who may or may not have started fires, but at least did something that might have. And, anyway, claiming that arson and accident don’t add to the concept of anthropogenic climate change is a bit of a stretch. Humans did it? All that smoke is going to screw up the environment. And the burning would have stopped a lot sooner if the hotter climate hadn’t pre-baked the forests.

But… it’s hard to avoid confirmation bias when the earthquake alert app on my phone has been ridiculously busy since at least January 4th. The good news is that it’s easy to survive a quake with warning, and if you’re not living in buildings basically made out of mud, stone, and hope.

Just remember this: A) Do NOT get into a doorway. That’s outdated Boomer advice. Instead, squat down next to a heavy piece of incompressible furniture, like a sturdy armoire or a sofa, or barring that, right next to your bed, on your knees, rolled over, hands covering the back of your neck and head.

Once the shaking has stopped, if you can, grab your loved ones and go-bag (you have one, right?) get outside, shut off your gas if necessary, and escape to shelter, which could be your car if it wasn’t smashed flat in the collapse of a Dingbat style apartment. People, really, don’t live in them. Also try avoiding buildings that are four to eight stories tall, because they tend to sway at resonant frequencies in sync with seismic waves, and so sway harder and collapse more often.

The good news is that in a lot of places prone to earthquakes, things have been upgraded to a ridiculous and safe degree. The bad news? In a lot of places they haven’t.  Fun fact: Most of the U.S. and Canada reside on a single tectonic plate, so are not naturally susceptible to earthquakes. Not fun fact: Fracking completely fracks with that, and creates seismic events (aka earthquakes) in places that they should not be. Less fun fact: the tectonic plate with a lot of Southern California and half of the Bay Area is not the same one as the rest of North America.

Consequently, while people in other parts of the country grow up dreading tornadoes or floods, earthquakes have been my lifetime bugaboo. Good news, though. I’ve survived 100% of the ones I’ve been in… and I’ve accepted the fact that, for now, they are 100% unpredictable.