Category: Sciency Words

A to Z Challenge Theme Reveal

~ J.S. Pailly ~ 19 Comments

Hello, friends!

Do you have a favorite planet?  Each planet of the Solar System is beautiful in its own way, and weird in its own way, and dangerous in its own way.  It’s almost like each planet has its own distinct personality.  When you start learning about the planets, it’s hard to not pick a favorite.  My own favorite is Venus, but that’s not what I want to talk about today.  Today, I’m announcing my theme for this year’s A to Z Challenge, and that theme will be:

THE PLANET MERCURY

For those of you who don’t know, the A to Z Challenge is a month long blogging event.  Throughout the month of April, participants write twenty-six blog posts (starting with A, ending with Z) on a topic of their choice.  In previous years, I’ve used the A to Z Challenge as a platform to talk about scientific terminology, the search for alien life, and humanity’s future as a spacefaring species.  If you want to learn more about the A to Z Challenge, and if you’re interested in signing up yourself, please click here.

Now you may be wondering about the theme I picked this year.  Out of all space/science topics I could cover for an A to Z series, why the heck would I pick Mercury?  Mercury is not Mars, or Saturn, or Pluto.  Mercury is not a super exciting place.  There’s virtually no atmosphere.  There are absolutely no signs of life.  And if you’re thinking about future human habitats in space, Mercury may be the least appealing piece of real estate in the entire Solar System.

Observing Mercury with a telescope is inconvenient, due to Mercury’s proximity to the Sun.  Reaching Mercury with a spacecraft is also inconvenient, again due to the planet’s proximity to the Sun.  And what does all the inconvenience of observing Mercury or traveling to Mercury get you?  A grey rock.  There are a bunch of craters.  It gets really hot during the day, due (yet again) to the proximity of the Sun.  And there’s not a whole lot else worth saying about Mercury, right?

Wrong.  By the end of this year’s A to Z Challenge, I do not expect to change your mind about whatever your favorite planet happens to be.  My favorite planet will still be Venus.  But I do hope you’ll come to appreciate Mercury for what he truly is: a humble grey rock, with a few weird quirks, and a surprisingly big heart (by which I mean a surprisingly big planetary core–for such a small planet, Mercury has an enormous core!).

P.S.: I will be taking the rest of March off from regular blogging.  I’m still picking up the pieces after a recent family emergency, and I’ve decided that whatever free time I do have for blogging should go to preparing for this A to Z series.  So I’ll see you all on April 1st, when “A” will be for “amorphous ice.”

Sciency Words: The Gartner Hype Cycle

~ J.S. Pailly ~ 4 Comments

Hello, friends!  Welcome back to Sciency Words, a special series here on Planet Pailly where we talk about the definitions and etymologies of science or science related terms.  Today, we’re talking about:

THE GARTNER HYPE CYCLE

In my last blog post, I shared my thoughts about A.I. generated art.  It’s a new technology.  There’s a lot of hype about this new technology right now, and my suspicion is that A.I. art is getting a little more hype than it really deserves.  I feel that way, in part, because of something called the Gartner hype cycle.

Definition of the Gartner hype cycle: The Gartner hype cycle is a curvy line on a graph that purportedly models how the hype for a newly introduced technology changes over time.  First, the hype will go up—way up.  Then the hype will plummet down.  In the final phases of the cycle, hype will go slightly up again, before leveling off.

Etymology of the Gartner hype cycle: The idea that new technologies experience a “hype cycle” was first introduced in 1995 by tech analyst Jackie Fenn.  She worked for a tech consulting firm called Gartner Inc., which continues to use hype cycle charts in presentations about new and emerging technologies.

As Gartner Inc. describes it on their website, the Gartner hype cycle has five distinct phases:

Innovation Trigger: A new technology is introduced.  Hype starts to grow (and grow and grow).

Peak of Inflated Expectations: The hype surrounding this new technology gets blown way out of proportion.  Media reports make it sound like almost all the world’s problems could be solved by this new technology.  Investors on Wall Street start screaming “Buy! Buy! Buy!”

Trough of Disillusionment: The hype bubble bursts.  It becomes clear that this new technology cannot solve all the world’s problems, and those Wall Street people start screaming “Sell! Sell! Sell!” 

Slope of Enlightenment: While the new technology can’t solve all of the world’s problems, it turns out that it can solve some problems.  Interest and investment in the new technology starts to build again, based on more realistic expectations.

Plateau of Productivity: The new technology becomes normalized after finding its proper niche in society.

There are at least three major criticisms of this concept.  First, the word “cycle” is misleading.  It implies that this process is cyclical when it clearly isn’t.  Second, this concept is not good science.  How do you measure something like hype, scientifically speaking?  And third, the Gartner cycle would have you believe that every new technology will eventually find its niche.  There’s no guarantee of that.  Sometimes a new technology simply fails.  It falls into that “trough of disillusionment” and never comes back.

Despite those valid criticisms, I do think the Gartner cycle can be a helpful first approximation of what might (might!) happen with a newly introduced technology.  The cycle may not be good science.  It may not make exact predictions, and it can’t guarantee anything.  But the general idea that the hype for a new technology will go way up, then go way down, and then settle somewhere in the middle… that does seem to happen, more often than not.  There’s enough truthiness to the Gartner cycle that it’s influenced my own thinking about A.I. art, as well as my thinking on topics like cryptocurrency, commercial space flight, self-driving cars, and a bunch of other things.

And the Gartner cycle is something I’m starting to think about in my Sci-Fi writing as well.  What might happen when we invent antigravity technology?  Faster-than-light travel?  Time machines?  Would those technologies experience something like the Gartner hype cycle?  Maybe.  Or maybe not.

Again, there are no guarantees with this one. In my mind, the Gartner cycle is a useful first approximation of what might happen. Nothing more.

WANT TO LEARN MORE?

I first heard about the Gartner cycle in a video by Wendover Productions, which uses drone delivery services as an example of the Gartner hype cycle in action.  Click here to watch.

Sciency Words: Coronium

~ J.S. Pailly ~ 6 Comments

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we take a closer look at the definitions and etymologies of scientific terms.  Today on Sciency Words, we’re talking about the word:

CORONIUM

Here on Sciency Words, we usually talk about scientific terms that are relevant and useful in modern science, but sometimes I like to draw attention to scientific terms that didn’t make it.  I think it can be helpful to learn about how and why words drop out of the scientific lexicon.  So today, we’re going to talk about coronium, a chemical element that we now know does not exist.

Definition of coronium: A chemical element that scientists in the late 19th and early 20th Centuries thought existed based on a mysterious green emission line detected in the Sun’s corona.  At least one very prominent scientist (Dmitri Mendeleev) believed coronium to be an element lighter than hydrogen, with chemical properties similar to helium and argon.

Etymology of coronium: In 1869, American astronomers Charles Augustus Young and William Harkness independently detected a green emission line in the Sun’s corona during a solar eclipse.  In 1887, Professor A. Grünwald proposed the name “coronium” for whatever chemical substance caused that green emission line.  Since this unknown substance was first detected in the Sun’s corona, coronium seemed like an obvious name.

The “discovery” of coronium came right on the heels of the discovery of helium, and the story of these discoveries was eerily similar.  Scientists observe a solar eclipse.  A strange, new emission line appears in Sun’s spectrum, as measured using a spectroscope.  This emission line is (or seems to be) the first evidence of a newly discovered chemical element.

Dmitri Mendeleev was initially skeptical about both helium and coronium, because he couldn’t find places for them in his periodic table of the elements.  Toward the end of his life, however, Mendeleev tried to shoehorn these elements, along with several others, into his theories by adding a “group zero” to the periodic table.  Each group zero element is lighter than the group one element it sits next to—for example, argon is lighter than potassium, neon is lighter than sodium, helium is lighter than lithium… and coronium ended up sitting next to hydrogen, indicating that coronium is an element lighter than hydrogen.

Mendeleev was a smart man, but he was wrong about group zero.  After some reshuffling of the periodic table, most of the group zero elements were moved to group eighteen (a.k.a. “the noble gases”), and in the end, it turned out there really was no place for coronium.  No element lighter than hydrogen exists.

So what caused that anomalous green emission line in the Sun’s spectrum?  Turned out it was iron.  In the 1930’s, German and Swedish astronomers Walter Grotian and Bengt Edlén discovered that a form of super-hot, super-ionized iron gives off an emission line at 530.3 nm—an exact match with the 530.3 nm green emission line found in the solar corona.  Without the power of the Sun (or the power of modern laboratory equipment), iron doesn’t get hot enough or ionized enough to reveal that part of its spectrum.  As a result, scientists in the late 1800’s couldn’t have known what that strange, green emission line was.

Coronium is a Sciency Word of the past, from a time when the spectroscope was a relatively new scientific instrument and the periodic table was still a work in progress.  We no longer need to imagine there’s an exotic chemical element found only in the Sun’s corona, not when super-ionized iron explains that green emission line in the Sun’s spectrum just as well.

WANT TO LEARN MORE?

Here’s an interesting article about Dmitri Mendeleev and his mistakes, including his mistakes about coronium and the “group zero” elements.  For anyone involved in science education, this article makes a compelling case about why teaching the history of science is so important, with an emphasis on showing how scientists don’t always get it right on the first try.

I also want to recommend this book, simply titled The Sun.  It is full of cool and useful space facts that I had never read about before anywhere else (including the false discovery of coronium).  The Sun is part of a series called Kosmos, and I highly, highly, highly recommend this series to anyone who loves space.

And lastly, here’s a link to A. Grünwald’s 1887 paper where he first proposed the name “coronium” for a “hitherto unknown corona-substance.”

Sciency Words: Antitail

~ J.S. Pailly ~ 6 Comments

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about the definitions and etymologies of scientific terms.  In today’s Sciency Words post, we’re talking about the word:

ANTITAIL

Did you see the comet?  Pretty much everyone I know has been asking me that question lately.  Comet C/2022 E3 (ZTF) had a wild ride these last few weeks.  First, she started glowing a lot brighter and a lot greener than expected, leading to some people calling her “the green comet.”  Then, due to some intense solar activity, a gap formed in one of the green comet’s two tails.  Shortly thereafter, almost as if the comet were trying to compensate for the damage to one tail, an apparent third tail became visible to observers here on Earth.  This apparent third tail is what astronomers call an antitail.

Definition of antitail: Comets typically have two tails: a dust tail and an ion tail.  These tails are supposed to point away from the Sun.  They’re caused by the solar wind sweeping gas, dust, and other lightweight material away from the comet and off into space.  An antitail is an apparent third tail pointing toward the Sun.  At least antitails look like they’re pointing toward the Sun, but this is actually an optical illusion.

Etymology of antitail: The prefix “anti-” can mean several things.  In this context, it means “opposite,” because antitails point (or look like they point) in a direction opposite to the direction cometary tails are supposed to point.  Based on my research, I believe this term was first introduced in the late 1950’s, following the appearance of comet Arend-Roland.

Okay, I’m going out on a bit of a limb claiming that the term was introduced in the 1950’s.  I cannot find any sources explicitly stating that, but almost every source I looked at seems to agree that Comet Arend-Roland had the most famous and noteworthy antitail in the history of antitails.  In 1957, Arend-Roland developed a large and protruding “sunward spike.”  In photos (like this one or this one), the comet reminds me a little of a narwhal.

Arend-Roland cannot possibly be the first comet ever observed to have an antitail, but it does seem to be the most spectacular and most widely studied antitail in recorded history.  Crucially, I was unable to find any sources mentioning cometary antitails prior to 1957.  Ergo, I think I’m right that the term was first introduced around that time, in reference to that particular comet.  But I could be wrong, and if anyone knows more about this topic than I do, please do share in the comments below.

Regardless of how much of a first Arend-Roland’s antitail really was to the scientific community at the time, it was not much of a mystery.  Within a matter of months, scientists were able to offer explanations, like this explanation published in Nature:

No extraordinary physical theory appears necessary to account for the growth of the sunward tail […]  The sunward tail must almost certainly have resulted from the concentration of cometary debris over an area in the orbital plane.  Seen at moderate angels to the plane, the material possessed too low a surface brightness to be easily observed, but seen edge-on it presented a concentrated line of considerable intensity.

So several things have to happen in order for us Earth-based observers to see an antitail.  First, a comet needs to shed some debris that’s too big and heavy to be swept off by the solar wind.  This extra debris will accumulate along the comet’s orbital path, rather than billowing off in a direction pointing away from the Sun.  Second, Earth has to be in just the right place at just the right time to see this debris field “edge-on.”  Otherwise, the light reflecting off the debris will be too diffuse for us to see.  And third, this has to happen at a time when the comet’s tails don’t overlap with the debris field (i.e., the debris and the tails have to be pointing in opposite directions, as seen from Earth).  Otherwise, the glow of the tails will obscure the light reflecting off the debris.

Last week, I was lucky enough to see the comet, but I didn’t see her bright green color (she was a hazy grey in my telescope), and I certainly didn’t get a chance to see the antitail.  I’m pretty sure I was a few days too late for that, and besides, there’s too much light pollution where I live to see faint details like that.

Still, I consider it a great joy and privilege that I got to see as much of the comet as I did.  And for all the cool sciency stuff I couldn’t see for myself, I can always turn to my research if I want to learn more.

WANT TO LEARN MORE?

Here’s the 1957 report from Nature that I quoted above, explaining what “must almost certainly” have caused Arend-Roland’s “sunward tail.”

And here’s a more recent article about Arend-Roland, reviewing the comet’s discovery, observation history, and the appearance of his antitail.

Lastly, here’s an article from Live Science about the recent “green comet” and her antitail.

Sciency Words: P-P Chain

~ J.S. Pailly ~ 6 Comments

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we discuss the definitions and etymologies of scientific terminology.  In today’s post, we’ll be discussing the scientific term:

P-P CHAIN

I have, in the past, been accused of covering scientific terms on the basis of how silly they sound, rather than on the basis of pure scientific merit.  But I would never do such a thing.  I have far too much respect for both science and linguistics.  Now with that unambiguously established, let’s talk about the p-p chain.

Definition of the p-p chain: In the field of nuclear physics, the p-p chain refers to a series of nuclear fusion reactions, starting with the fusion of two protons and leading, ultimately, to the creation of a helium-4 nucleus.  The p-p chain is by far the most common fusion process occurring in the core of the Sun, as well as other stars of similar or smaller sizes.

Etymology of the p-p chain: The p’s in p-p chain refer to the two individual protons that fuse together in the very first step of the process.  English astronomer Sir Arthur Eddington first proposed that proton-proton fusion might be occurring inside stars, writing about it in a 1926 article titled “The Internal Constitution of the Stars.”  German-American theoretical physicist Hans Bethe worked out the step by step details of the process in a 1939 paper called “Energy Production in Stars.”  Sadly, I cannot give credit to either Eddington or Bethe for coining this term.  They came up with the idea and worked out the details, but I have not been able to determine who, exactly, first introduced the term “p-p chain” into the scientific literature.

There are at least three versions of the p-p chain, each with different intermediate steps between the individual protons at the start and the helium-4 nuclei at the end (a fourth version is possible in theory, but has yet to be verified in reality).

Recently, scientists at the National Ignition Facility (NIF) in California made significant progress in nuclear fusion research.  That recent experiment has been described as recreating the power of the Sun here on Earth, which is true enough.  But NIF did not recreate the entire p-p chain from start to finish; they did something loosely equivalent to the very last step only.  It seems that reproducing the whole chain is still beyond our current scientific abilities.

So the next time you notice the Sun, shining yellow-gold in the sky, just remember that she can still do p-p chains in ways we humans cannot.

WANT TO LEARN MORE?

If you’re looking for a more detailed and technical explanation of the p-p chain (and the three or four variations thereof), check out this article from encyclopedia.pub.  That article was my main source of information while writing this post.

You can also find Arthur Eddington’s “The Internal Constitution of the Stars” by clicking here and Hans Bethe’s “Energy Production in Stars” by clicking here.

And if you’re looking for a fun way to try nuclear fusion for yourself, check out the game Fe[26].  You slide around tiles marked with the names of different atomic nuclei, trying to combine them to make bigger and bigger elements.  Which nuclear combinations work and which ones don’t?  Play and find out for yourself!

Sciency Words: Hydrogen

~ J.S. Pailly ~ 4 Comments

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about the definitions and etymologies of scientific names and terms.  In today’s episode of Sciency Words, we’re talking about:

HYDROGEN

I want to start this with a personal story.  Imagine me, twenty years ago, fresh out of college with a degree in television and film production.  One of my first jobs was working for a company that made educational cartoons for children.  At one point, I ended up being assigned to a two minute animated music video about water.  The name of the video: “Water Can Never Be New.”

Now I’m no scientist.  I cannot call myself an expert (I’m just very enthusiastic about this subject).  And twenty years ago, I was even less of an expert than I am today.  Still, even way back then, I had a nagging suspicion that this “Water Can Never Be New” video was a lie.  Which brings me to the subject of today’s post: hydrogen.

Definition of hydrogen: Hydrogen is the very first element on the periodic table of elements.  Typically, hydrogen atoms consist of one proton orbited by one electron.  Molecular hydrogen consists of two hydrogen atoms bonded to each other.  Under Earth-like temperatures and Earth-like atmospheric pressure, hydrogen is a gas.  It’s also rather rare here on Earth; elsewhere in the universe, it’s extremely common.  In fact, hydrogen is by far the most common, most abundant chemical element in the universe.

Etymology of hydrogen: Hydrogen was first discovered in 1671 by British natural philosopher Robert Boyle.  Boyle referred to this new kind of air he discovered as “inflammable air,” because of how easily he could light it on fire.  Over a century later, French chemist Antoine Lavoisier found that burning “inflammable air” somehow produced water vapor as a byproduct.  Thus, Lavoisier changed the name of “inflammable air” to hydrogen, from two Greek words meaning “water” and “creation.”

It’s hard to imagine today just how much the discovery of hydrogen must have rocked the world of science (a.k.a. natural philosophy) back in the 17th and 18th Centuries.  Up until that point, the Aristotelian view of world had prevailed.  According to Aristotle, four elements—fire, earth, air, and water—were the fundamental building blocks of nature.  Then Robert Boyle comes along with a new kind of air (can we really call air a fundamental element if there are different kinds of it?), and Lavoisier subsequently demonstrates that you can use this new kind of air to make water (is water really a fundamental element if you can make it out of other stuff?).

Today, we know more about what happens when you light hydrogen gas on fire.  The heat energy from the flame causes hydrogen to react with oxygen, producing H2O molecules.  Water, in other words.  New water.  And, in fact, many chemical reactions involving hydrogen and oxygen-containing compounds will produce water molecules as a byproduct.  Due to the energy involved in these reactions, this new water may be too hot to form a liquid, but water vapor is still water (and it will condense into a liquid eventually, once it has time to cool off).

Of course, hydrogen does much more than help make new water molecules.  Hydrogen is the fuel that keeps the Sun shining.  It’s a necessary component in the organic compounds that make life as we know it possible, and hydrogen ions play an important role in acid-base chemistry (not counting Lewis acids and bases).  Given the wide variety of jobs that hydrogen does, you may wonder why we stick to using a name that means, simply, “water generator.”

But the discovery of hydrogen and its water generating ability helped upend some deeply entrenched and woefully inaccurate scientific ideas.  The name seems appropriate to me as a way to honor that moment in the history of science when the old Aristotelian view of nature really started to crumble.  It’s a shame more people don’t know about this story.  Maybe somebody should make an educational cartoon for children about it.

Sciency Words: Barycenter

~ J.S. Pailly ~ 13 Comments

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about those super weird (but super cool) words scientists like to use.  Today’s Sciency Word is:

BARYCENTER

Tell me if you’ve heard this one: every action has an equal and opposite reaction.  This is true even for moons orbiting planets, or planets orbiting stars.  Whenever a star exerts gravitational force on a planet, that planet exerts an equal and opposite gravitational force on the star.  As a result of this ongoing gravitational tug-of-war, we end up with a planet and a star spinning round and round their common center of mass, a point which scientists call a barycenter.

Definition of barycenter: In astronomy, a barycenter is the center of mass of two or more objects in space that are gravitationally bound together.  

Etymology of barycenter: The word barycenter traces back to a Greek word meaning “weighty” or “heavy.”  The word barometer has a related etymology (barometers measure atmospheric pressure—the “weight” of the atmosphere, in other words).

Sometimes a barycenter will be located deep inside the more massive of two celestial bodies, in which case the more massive body will appear to wobble in place.  This is the case for the Earth and the Moon.  The Earth-Moon barycenter is approximately 1700 km beneath Earth’s surface.  Other times, the barycenter will be somewhere in the empty space between objects.  For an example, look at Pluto and its largest moon, Charon.  The Pluto-Charon barycenter is more than 900 km above the surface of Pluto.

The concept of a barycenter dates back to Isaac Newton (though I can’t find any sources saying he coined the word, nor could I find any evidence that he ever used the word himself).  Newton’s Principia Mathematica, originally published in 1687, briefly discusses the Sun-Jupiter barycenter, saying, “[…] the common centre of gravity of Jupiter and the sun will fall upon a point a little without the surface of the sun.”  Newton also discusses the Sun-Saturn barycenter, which he describes as “[…] a point a little within the surface of the sun.”

And then there’s the barycenter of the Solar System as a whole: the “common centre of gravity of all the planets,” as Newton calls it.  Due to the combined gravitational forces of all the planets (most especially that of the giant planets: Jupiter, Saturn, Uranus, and Neptune), the Sun is constantly being pulled in multiple directions at once.

As a result, the Sun does not sit still in the middle of our Solar System.  It is “agitated by perpetual motion,” to quote Newton one last time.  Sometimes, as the Sun moves about, it happens to pass through the Solar System’s barycenter. Other times, it loops and spirals around the barycenter, as if performing an elaborate dance.

WANT TO LEARN MORE?

Here are a few articles that go into a little more detail about barycenters:

And here’s a link to the translation of Newton’s Principia Mathematica that I quoted in this post.  The relevant section is titled “Proposition XII.  Theorem XII.”

Sciency Words: The YORP Effect

~ J.S. Pailly ~ 12 Comments

Hello, friends!  Welcome to another episode of Sciency Words, a special series here on Planet Pailly where we talk about the definitions and etymologies of scientific terms.  In today’s episode, we’re talking about:

THE YORP EFFECT

Picture a windmill.  As the wind gets stronger or weaker, the windmill spins faster or slower, right?  Okay.  Now replace the windmill with an asteroid orbiting the Sun, and replace the wind with sunlight.  Over long periods of time, sunlight can make the asteroid spin faster or slower.  Sunlight can also change an asteroid’s axis of rotation.  This is known as the YORP Effect (not to be confused with the Yarkovsky Effect).

Definition of the YORP Effect: In astrophysics, the YORP effect is what happens when reflected and/or absorbed sunlight generates “thermal torque” on an asteroid.  Reflected sunlight exerts a very small (but non-zero) amount of force on the surface of an asteroid.  Absorbed sunlight radiates away from the surface of an asteroid as heat, exerting an additional small (but non-zero) amount of force.  Due to the irregular shapes and material consistencies of asteroids, it’s hard to predict exactly what this thermal torque will do, but over long enough periods of time it can dramatically change an asteroid’s rotation rate and axis of rotation.

Etymology of the YORP Effect: The term was coined in 1999 by American geophysicist David Rubincam.  The YORP Effect, as we currently know it, combines the previous research of Ivan Yarkovsky, John O’Keefe, Vladimir Radzievskii, and Stephen Paddack.  YORP is therefore an acronym of the names Yarkovsky, O’Keefe, Radzievskii, and Paddack.

This all started with Ivan Yarkovsky and his Yarkovsky Effect, which we talked about in last week’s Sciency Words post.  The Yarkovsky Effect has to do with the way sunlight affects the orbital trajectory of an asteroid.  The Yarkovsky Effect was lost to science for a while, then it was reintroduced in 1951.  Shortly after that reintroduction, other scientists started wondering what other effects sunlight might have on an asteroid, which ultimately led to this idea of a thermal torque effect, which we now call the YORP Effect.

To be clear, the Yarkovsky Effect and the YORP Effect are two different effects—one related to an asteroid’s orbital trajectory, the other to an asteroid’s rotation rate and axis of rotation.  They’re caused by the same thing—sunlight—but they are two different effects.

In 2007, observations of an asteroid named 2000 PH5 helped confirm that the YORP Effect is real.  The asteroid had been monitored closely over the course of about four years, and astronomers found that its rotation rate was steadily increasing.  This increase could not be explained by gravitational interactions alone, nor by collisions with other asteroids or any other known effects.  Therefore, by process of elimination, only the YORP effect was left as a possible explanation.  Asteroid 2000 PH5 was subsequently renamed 54509 YORP to honor its help in confirming the YORP Effect.

And in 2013, an asteroid named P/2013 R3 literally YORP-ed itself apart.  The YORP Effect caused the asteroid to spin so fast that it started flinging chunks of itself away.  There may have been some previous collision or other catastrophic event that made P/2013 R3 more fragile; still, in the end, it was the YORP Effect that caused the final destruction of that asteroid.

So if you’re an asteroid flying around in space, be careful.  It may be fun YORP-ing and Yarkovsky-ing around the Solar System, but you don’t want to Yarkovsky yourself into hitting a planet, and you don’t want to YORP yourself into self-disintegration either.

WANT TO LEARN MORE?

P.S.: The DART Mission is scheduled to crash itself into an asteroid tonight at 7:14 p.m. East Coast time in the U.S. (also known as 23:14 GMT).  If you’re interested, NASA TV will be live streaming the collision on their YouTube Channel.  It would not surprise me if the Yarkovsky and YORP Effects are mentioned as part of NASA TV’s science commentary.

Sciency Words: The Yarkovsky Effect

~ J.S. Pailly ~ 12 Comments

Hello, friends!  Welcome to another episode of Sciency Words, a special series here on Planet Pailly where we discuss the definitions and etymologies of scientific terms, in order to expand our scientific vocabularies together!  Today’s Sciency Word is:

THE YARKOVSKY EFFECT

Imagine an asteroid orbiting the Sun.  Every once in a while, this asteroid passes alarmingly close to Earth.  If you’re familiar with Kepler’s laws of planetary motion, you may expect that scientists could predict, with pinpoint accuracy, where that asteroid will be years, decades, or even centuries into the future.  However, there are certain physical forces acting on asteroids that are not accounted for in Kepler’s laws.  One of those physical forces is known as the Yarkovsky Effect.

Definition of the Yarkovsky Effect: In astrophysics, the Yarkovsky Effect is a thermal force that affects the orbit of asteroids.  Like most planets, asteroids rotate; therefore, you could say that asteroids have day-night cycles.  During daytime, the surface of an asteroid absorbs heat from the Sun.  At night, the asteroid’s surface cools off by radiating heat out into space.  This radiating heat generates a very, very, very small amount of thrust.  Over time, that small amount of thrust can dramatically change the orbital trajectory of an asteroid.

Etymology of the Yarkovsky Effect: The Yarkovsky Effect is named in honor of Polish/Russian civil engineer Ivan Yarkovsky, who first described a similar “heat engine” effect in 1888, and who later published a pamphlet on the topic in 1901.  Yarkovsky’s work would have been lost to history, except that Estonian physicist Ernst Öpik recalled reading Yarkovsky’s 1901 pamphlet and reintroduced the idea to the physics community in 1951.

Yarkovsky was more of a science hobbyist than a professional scientist.  He had a day job working on railroads.  In his free time, he read a lot about science, and he did a lot of thinking.  He performed his own experiments, occasionally, and he came up with some interesting ideas that sound like utter nonsense today, but which must have made sense in the context of late 19th Century science.  Even the Yarkovsky Effect, as Yarkovsky originally described it, was tied up with a now defunct scientific theory called ether theory.

Still, even if his starting assumptions were off track, Yarkovsky stumbled upon the truth at least one time.  Asteroids do have “heat engines,” as Yarkovsky described it.  Asteroids do have these naturally occurring thermal propulsion systems, powered by sunlight, which can mess with their orbits.  The challenge for astrophysicists today is that the Yarkovsky Effect is kind of random (or if it isn’t random, in the truest sense of the word, then it may as well be).

Asteroids are irregularly shaped.  Sometimes, they rotate on more than one axis (I once read a paper that called this multiple axis rotation “chaotic tumbling”).  And in terms of mineral composition, asteroids are made of all sorts of crazy stuff.  Different minerals can absorb and radiate heat in different ways.  So the Yarkovsky Effect pushes asteroids around, but because of all the variables I just mentioned, it’s hard to say which direction the Yarkovsky Effect will push at any given time.  It’s also hard to say how hard of a push the Yarkovsky Effect might give.

Which is why missions to study asteroids—missions like the recent ORISIR-REx Mission or the upcoming DART Mission—are so important.  We may never understand asteroids perfectly, but we do need to understand them better.  There are so many asteroids that fly alarmingly close to Earth.  It would be nice if astrophysicists could predict, with pinpoint accuracy or something near to it, where those asteroids will be years, decades or centuries into the future.

WANT TO LEARN MORE?

I used the following sources to write this blog post.  The one at the bottom is kind of a long read, but it tells the fascinating story of Ivan Yarkovsky, a man who was nearly forgotten by history.  For those of you who are interested in the history of science, it is well worth a read.

Sciency Words: Stochastic

~ J.S. Pailly ~ 11 Comments

Hello, friends!  Welcome to another episode of Sciency Words, an ongoing series here on Planet Pailly where we take a closer look at the definitions and etymologies of science or science-related terms.  Today on Sciency Words, we’re talking about:

STOCHASTIC

There are no true synonyms, according to American writer Roy Peter Clark.  Sure, two words may mean basically the same thing.  Two words may be so similar in meaning that you could use them interchangeably.  But there will still be some subtle difference between them, some slight shade of connotation that separates them.  The word “stochastic” is almost a synonym for “random.”  Almost.

Definition of stochastic: In statistics, a stochastic process is a process that is best modeled using a random probability distribution.  The process being modeled may, in fact, be random, or it may not.  The important thing is that a stochastic process is a process that scientists have modeled as if it were random.

Etymology of stochastic: The word comes from an ancient Greek word meaning “to aim in the right direction” or “to guess.”

Lots of things in the world are not truly random, but they may as well be.  The weather.  The economy.  Chemical reactions.  Changes in animal populations.  The orbital drifting of asteroids and comets.  Modeling these things in a strictly deterministic way would be mindbogglingly complicated and utterly impractical.  So scientists create stochastic models instead—models that include some random element to represent the super complicated parts that are impractical to model any other way.

These stochastic models are not perfect, but (as the etymology suggests) they aim us in the right direction, and they allow scientists to make pretty good guesses about what might happen with the weather, or the economy, et cetera, et cetera.

WANT TO LEARN MORE?

I try to avoid telling you to just go read Wikipedia, but the article about this on Wikipedia is actually pretty good.  Most of the other sources I looked at (or tried to look at) were super math heavy.  And you know how I feel about math.