Sciency Words: Bunny Hopping

Sciency Words: (proper noun) a special series here on Planet Pailly focusing on the definitions and etymologies of science or science-related terms.  Today’s Sciency Word is:


So yesterday I was reading up on the latest spacesuit design from NASA, and I came across a term that I don’t remember ever seeing or hearing before.  In this article from Space Daily, NASA Administrator Jim Bridenstine is quoted as saying: “If we remember the Apollo generation, we remember Neil Armstrong and Buzz Aldrin, they bunny hopped on the surface of the Moon.”

This left me wondering: do people really use the term “bunny hopping” to describe how Apollo astronauts moved about on the Moon?  I tried really hard to trace the etymology of this term.  I didn’t find much, but honestly, when you see clips like this one, it’s easy to figure out where the term came from.

In my previous research on this topic, I’ve seen this method of locomotion referred to as “loping-mode” or “skipping-mode.”  But sure, we can call it “bunny hopping” too.  So why did astronauts do this?

Well, there’s something about walking that most of us, in our daily lives, don’t realize: Earth’s gravity does some of the work for us.  When you take a step, first you lift your foot off the ground, then you extend your leg, and then… well, try to stop yourself at this point.  With your leg extended forward like that, you’ll find that your center of gravity has shifted, and you can feel the force of gravity trying to pull you through the remainder of your walk cycle.

So walking feels like a natural and efficient way for us humans to get around because Earth’s gravity helps us.  Take Earth’s gravity away, and walking suddenly feels awkward and cumbersome.  In lunar gravity, which is approximately ⅙ of Earth’s gravity, the Apollo astronauts found other methods of locomotion to be more comfortable, more natural.  In this clip, we hear audio chatter of astronauts disagreeing about whether “hopping” or “loping” is a better way to get around.

Personal preference seems to be important here, both in how astronauts “walked” on the Moon and in how they described the experience of this new kind of “walking.”

Getting back to the new spacesuits from NASA, the new design features a dramatically improved range of motion.  The next astronauts on the Moon will have a much easier time getting around, and according to Administrator Bridenstine there will be no need for bunny hopping.  “Now we’re going to be able to walk on the surface of the Moon, which is very different from the suits of the past.”

And that’s got me confused.  I’m really not sure what Bridenstine means by that statement because, as I just explained, it was the Moon’s gravity—more so than the spacesuits—that made Apollo era astronauts feel the need to “bunny hop” on the Moon.  The new spacesuits, with their improved range of motion, should help astronauts in the new Artemis program avoid gaffs like these…

But without altering the Moon’s gravity, I don’t see any way to avoid “bunny hopping.”

New Pens for My Coffee Mug Full of Pens

A few weeks back, I told you all about my writing zone—that magical place where writing happens.  One of the main fixtures of my writing zone is a coffee mug full of pens, the purpose of which is self-explanatory.

Following that blog post, an anonymous somebody decided to “buy me a coffee” through the website Buy Me a Coffee.  In fact, this unknown benefactor bought me three coffees, equaling a total donation of $9, to help me buy more pens to put in my coffee mug full of pens.

Now I’m rather picky about the pens I use for writing.  I only buy Pilot Precise V5 pens.  They’re self-described as “the ultimate writing machine,” which is marketing hyperbole, of course.  But still, they’re really nice pens.

However, given that that $9 seems so extra special to me, it didn’t feel right to just buy the same old pens I always buy.  So I got these pens instead.

They’re still Pilot Precise V5 pens, but instead of boring old black ink, these pens have an art deco style and come in pretty colors.  My muse (also known as my Best Imaginary Friend Forever or B.I.F.F.) seems to approve.

And the first draft of this blog post was written in a very lovely turquoise ink.

So today I just wanted to say thank you to whoever donated this money.  I really appreciate this, and you’ve helped make the magic of writing just a bit more magical for me!

And if anyone else would like to “buy me a coffee,” please click here.  I don’t actually drink coffee, so the money will be used for writing and art supplies to help keep this blog going, and I promise to keep you all updated on how that coffee money is spent!

Sciency Words: Plasma Torus

Sciency Words: (proper noun) a special series here on Planet Pailly focusing on the definitions and etymologies of science or science-related terms.  Today’s Sciency Word is:


Astronomers have discovered thousands of planets out there.  Exoplanet hunting techniques have gotten so good that astronmers are now moving on to the next great challenge: finding exomoons.  And one possible method for detecting exomoons involves something called a plasma torus.

Ever since the 1960’s, we’ve known something weird was happening with Io, one of the moons of Jupiter.  In 1964, an astronomer by the name of E.K. Bigg determined that Io had some strange power over Jupiter’s magnetosphere.  Subsequent research identified clouds of ionized sulfur and sodium in the vicinity of Io’s orbit.  Then in 1979, NASA’s Voyager 1 space probe photographed Io up close, catching Io in the act of spewing a mix of sulfur compounds and other noxious chemicals into space.

We now know that Io is the most volcanically active object in the Solar System and that Io’s volcanic activity directly affects Jupiter’s magnetic field.  As you can see in this totally legit Hubble image, Io has created a nasty mess around Jupiter.

All those nasty chemicals get swept up in Jupiter’s powerful magnetic field, which acts like a supersized particle accelerator, turning those chemicals into a high-energy plasma.

I can’t be sure who coined the term plasma torus, but a multitude of papers from the 1960’s and 70’s (like this one, or this one, or this one) attempt to model the plasma clouds surrounding Jupiter as a torus—torus being the fancy mathematical term for “donut-shape.”

The nifty thing about Io’s plasma torus is that you can detect it even from a great distance.  Even if you’re too far away to observe Io directly, you can still infer that she’s there based on all those ionized chemicals swirling around Jupiter and the effect those chemicals have on Jupiter’s magnetic field.

So could we find volcanically active exomoons by looking for plasma tori?  According to this paper from The Astrophysical Journal, we sure can—and maybe we already have!  The paper identifies the signatures of possible plasma tori encircling several large exoplanets.

One thing I’m not sure about: when we find a plasma torus, can we be 100% certain it’s caused by an exomoon?  Are there any other natural (or unnatural) phenomena that might cause a plasma torus to form?  I don’t know.

P.S.: Safety warning to any space adventurers who might be reading this.  A plasma torus is a high radiation environment.  Keep your distance!

Origin Stories: Who Invented Time Travel?

Welcome to Origin Stories, a monthly series here on Planet Pailly where we take a look at the origins of popular Sci-Fi concepts.  Today on Origin Stories, we’re looking at the origins of:


If I ever have a time machine—a real, working time machine—the first thing I’d do is go back in time and meet the person who invented time travel.  We do know who that person was.  His name was H.G. Wells, and he was the author of the classic science fiction novella The Time Machine.

Wells got the inspiration for The Time Machine from an unlikely source.  As science historian James Gleick explains in his book Time Travel: A History:

At some point [Wells] sees a printed advertisement for a contraption called Hacker’s Home Bicycle: a stationary stand with rubber wheels to let a person pedal for exercise without going anywhere.  Anywhere through space, that is.  The wheels go round and time goes by.

Of course there had been time travel-like stories before.  Remember the ghosts of Christmas Past, Present, and Future.  Remember the story of Rip Van Winkle, who found himself suddenly in the future after a really long nap.  Or remember Mark Twain’s A Connecticut Yankee in King Authur’s Court, in which a man from Connecticut gets bonked on the head and wakes up to find himself in the distant past.

But H.G. Wells was the first to take the idea of time travel semi-seriously.  He was the first to try to dress up the idea with scientific and technological jargon.  And in my opinion, no other author has handled time travel so clearly and concisely as Wells did.

The protagonist of The Time Machine, a man of science referred to only as “the Time Traveler,” first explains to a group of friends that we exist in a world of not three dimensions but four.  Everything that exists in this universe has the qualities of “Length, Breadth, Thickness, and—Duration.”  The Time Traveler’s friends then raise all the objections Wells’ readers might have had, and the Time Traveler explains all those objections away in exchanges like this:

“But,” said the Medical Man, staring hard at a coal in the fire, “if Time is really only a fourth dimension of Space, why is it, and why has it always been, regarded as something different?  And why cannot we move in Time as we move about in the other dimensions of Space?”

The Time Traveler smiled.  “Are you sure we can move freely in Space?  Right and left we can go, backward and forward freely enough, and men always have done so.  I admit we move freely in two dimensions.  But how about up and down?  Gravitation limits us there.”

“Not exactly,” said the Medical Man.  “There are balloons.”

“But before the balloons, save for spasmodic jumping and the inequalities of the surface, man had no freedom of vertical movement.”

In other words, we can only move freely in the third dimension thanks to technology—hot air balloons, airplanes, rockets….  Therefore technology may also give us the power to move freely through the fourth dimension of time.

Of course H.G. Wells didn’t actually believe in time travel.  As James Gleick goes on to say, all Wells was trying to do was “gin up a plausible-sounding plot device for a piece of fantastic storytelling.”  But as it would turn out a decade or so later, Wells was not too far off from the truth.  Physicists like Albert Einstein and Hermann Minkowski were soon treating time as variable, rather than a constant.  No, Einstein and Minkowski didn’t build any bicycle-like contraptions in their basements, but the notion of time as the fourth dimension—that soon became serious science.

Time travel has always been my favorite subgenre of science fiction.  It has been ever since my Dad first introduced me to Doctor Who.  I realize time travel isn’t everyone’s cup of tea, but personally I enjoy the kinds of brain-twisting puzzles that a good time travel adventure presents.  It’s the reason I still love Doctor Who, and it’s the reason time travel features so prominently in my own writing.

So if I ever have my own time machine, the first thing I’d do is go back in time to meet H.G. Wells.  I think I owe Mr. Wells a thank you.  

LIGO: The Next Generation

As everyone knows, I’m a total surfer dude.  So after all my recent blog posts about the LIGO project (click here, here, or here), I’ve been wondering: could I “hang ten” on a gravitational wave?

There’s still a lot we don’t know about gravitational waves.  LIGO—the Laser Interferometer Gravitational-wave Observatory—is one of the most delicately sensitive scientific instruments ever built.  But as sensitive as LIGO is, it’s still not sensitive enough.  The next generation of gravitational wave detectors promises to do better.

  • Cosmic Explorer: The United States wants to build a bigger LIGO.  Cosmic Explorer will use the same L-shaped interferometer design as LIGO, only ten times bigger.  This will increase the signal amplitude without adding to the amount of background noise the detector picks up, according to the Cosmic Explorer website.  Click here to learn more.
  • Einstein Telescope: Meanwhile the Europeans are planning to build a gravitational wave detector underground.  The Einstein Telescope, as the project is named, will incorporate not one but two laser interferometers, arranged in a triangular pattern.  One of these interferometers will pick up low frequency gravitational waves; the other will pick up waves of higher frequencies.  Click here to learn more.
  • LISA: And lastly, NASA wants to put a gravitational wave detector in space.  The project is called LISA, which stands for Laser Interferometer Space Antenna.  LISA will consist of three small spacecraft beaming lasers at each other, forming a giant equilateral triangle.  Size really does matter when it comes to gravitational wave detectors, and this space laser triangle will be far, far larger than anything we could have built here on the ground.  Click here to learn more.

Some of the questions these next generation gravitational wave detectors could help us answer: How many black holes are there in the universe?  What’s going on inside neutron stars?  What about pulsars or magnetars?  Are there gravitational waves associated with the cosmic microwave background?  Are there gravitational waves associated with dark matter?  Are any gravitational waves coming from unexpected or unknown sources?

So much science will be gained from these projects!  However, I’m not sure if Cosmic Explorer, the Einstein Telescope, or LISA will be able to answer the question I asked at the beginning of this post.  Total bummer!

Disclaimer: I’m not really a surfer dude.  Actually, I’m terrified of the ocean and I’ve never even learned how to swim.

Sciency Words: Kilonova

Sciency Words: (proper noun) a special series here on Planet Pailly focusing on the definitions and etymologies of science or science-related terms.  Today’s Sciency Word is:


In a recent presentation at Princeton University, Dr. Beverly Berger—an astrophysicist from LIGO—used a very interesting term.  Imagine a pair of neutron stars orbiting each other, spiraling closer and closer together, until suddenly “they go splat!” as Dr. Berger enthusiastically described it.

The more official-sounding term for this is kilonova, Dr. Berger then explained.  The term kilonova originates from this 2010 paper, which predicted that the merger of either two neutron stars or a neutron star and a black hole would produce a very bright flash of light.

The authors of that paper calculated that, at peek luminosity, this flash of light would be approximately a thousand times brighter than a nova explosion—hence “kilonova.”  (In case you’re wondering, a kilonova is still not as bright as a supernova—a supernova is “as much as 100 times brighter than a kilonova” according to this article from NASA.)

Of course the LIGO project is designed to detect gravitational waves, not bright flashes of light.  But as you can see in the highly technical diagram below, a kilonova is accompanied by subtle ripples in the fabric of space-time—gravitational waves, in other words.

In August of 2017, the LIGO project detected exactly the kinds of ripples that would indicate two neutron stars had “gone splat.”  As this article from the LIGO website explains, alerts were “sent out to the astronomical community, sparking a follow-up campaign that resulted in many detections of the fading light from the event, located near the galaxy NGC 4993.”

One thing I’m still not clear about: what happens after a kilonova?  It seems the scientists at LIGO are wondering about that too.  According to that same article from the LIGO website, the 2017 kilonova produced either the largest neutron star that we’ve ever observed OR the smallest black hole.  “Both possibilities are tantalizing and fascinating,” the article says, “but our data simply isn’t good enough to tell us one way or the other.”

Fortunately there are a few projects in development that might help us understand kilonovae—and similar cosmic cataclysms—a little bit better.  We’ll take a look at some of those upcoming projects in Monday’s post.

#IWSG: Stop Acting Like a Little Kid

Welcome to the Insecure Writer’s Support Group!  If you’re a writer, and if you feel in anyway insecure about your writing life, click here to learn more about this awesome group!

All in all, last month was a good month for me.  I had a meeting with my editor that I thought went well.  I attended a physics seminar in Princeton, an experience which really fueled my creativity as a science fiction writer.  Oh, and I wrote an article that I’m really proud of for Fiction Can Be Fun (click here to read it!)

But no matter how well things are going for me, there’s always somebody who wants to drag me down.  This time, I’ve been told that I need to stop acting like a little kid.  I’m too old to keep chasing these childish writing dreams.

Except I didn’t find this particular insult to be particularly insulting.  Rather, my thought was: Little kid?  Oh, you have no idea how right you are!  Allow me to give you a tour of my personal “writing zone.”

A few years back, I moved to a new house.  In that process, I ended up getting rid of my writing desk.  I don’t like desks.  Sitting at a desk is such a grownup thing to do, and I didn’t want to do it anymore.  Instead, I bought a thick, heavy blanket, laid it out on the floor, and called that my new writing zone.  It’s a comfy and cozy environment for writing.

As you can see in the highly technical diagram above, I keep several things in my writing zone:

  • A dictionary, specifically the New American Heritage Dictionary, which happens to be my favorite dictionary.
  • Two thesauruses, because if I can’t find the right word in one of them, there’s still a chance I might find it in the other.
  • Two notebooks, one for first drafts and another for rewrites.
  • My computer, so I can stream music.
  • Coffee mug full of pens.  Why?  I think that’s self-explanatory.

So whenever I write, I don’t sit at a desk.  I don’t even own a desk.  Not anymore!  Instead, I lie down on my belly, feet kicked up in the air—just like a little kid.

Oh, and you may have noticed in that highly technical diagram one other thing I keep in my writing zone: a picture of my B.I.F.F.  That’s a picture of my muse.  She’s not just my imaginary friend—she’s my best imaginary friend forever, or my B.I.F.F.

So if you want to insult me, don’t tell me my writing dreams are childish.  Don’t tell me I’m acting like a little kid.  That’s not an insult to me.  That’s a point of pride.

P.S.: Shoot, I always forget to promo this….  If you’d like to help support what I’m doing here on Planet Pailly, click here to “buy me a coffee.”  I don’t actually drink coffee, but your money will help me keep my coffee mug full of pens.

That Time the Galaxy Ripped Itself Apart

Do you remember that time back in 1969 when the entire galaxy ripped itself apart?  No?  Me neither.

Last week, I had the opportunity to attend a physics seminar at Princeton University.  The presenter was Dr. Beverly Berger of LIGO.  She was there to tell us all about the discovery of gravitational waves.

Part of Dr. Berger’s presentation was historical.  There were attempts to detect gravitational waves before the LIGO experiment.  The first such attempt was conducted by Joseph Weber of the University of Maryland.  Weber’s idea was that gravitational waves would cause solid objects to expand and contract ever so slightly.  This expansion and contraction would produce friction and thus heat.

In principle, this change in temperature could be measured.  So Weber constructed a giant metal cylinder to serve as a gravitational wave detector (click here to see a picture of it).  And in 1969, Weber detected his first gravitational wave!  Or at least he thought he did. There was a tiny pulse in his data which, as Dr. Berger described it in her presentation, indicated that gravitational waves were emanating from the center of our galaxy!

Except no one was able to confirm Weber’s findings, and the discovery was widely discredited as a result.  But of course we now know, thanks to LIGO, that gravitational waves do exist.  We also know (or at least we strongly suspect) that there is a supermassive black hole in the center of our galaxy, right where Weber’s gravitational waves supposedly came from.

Given all that we now know, I think it’s fair to ask if Joseph Weber might have detected gravitational waves after all.  Someone in the auditorium did, in fact, ask that question.  But no, it’s absolutely impossible.  Weber’s instruments simply weren’t sensitive enough.

According to Dr. Berger, the only way Weber’s gravitational wave detector would have detected gravitational waves is if the entire galaxy had suddenly ripped itself apart.  Obviously that didn’t happen. The galaxy is still here. [citation needed]

P.S.: I’ve had the pleasure of meeting Dr. Beverly Berger several times now.  It’s sort of a friend of a friend situation.  Anyway, Dr. Berger has very kindly introduced me to a new scientific term.  I’ll have that for you in Friday’s episode of Sciency Words!

Your Life: Now with More Sci-Fi

The nice people over at Fiction Can Be Fun invited me to write a special blog post for them.
Has life got you down? Try turning your problems into science fiction! It won’t make your problems go away. Trust me, it won’t. But you might get a really cool Sci-Fi story out of it!

Fiction Can Be Fun

As it says on the front page, whilst Debs and I write the majority of the content on this blog ourselves, we’re also delighted to post contributions from others.  The periodic fifth Sunday in the month frequently causes consternation as we try and figure out what we’re going to be putting in that slot.  This time around, that fifth Sunday has coincided with our third birthday (time flies…), and we wanted something extra special.  This month we kicked off with a prompt we came up with in honour of James Pailly.  James runs the Planet Pailly blog, which is completely awesome, and well worth your time (once you’ve finished up here of course).  James has been a great friend to this blog, and he has very kindly written this article for us. I feel very privileged that we get to post it here.

–    David

They say we’re all…

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Sciency Words: Gravity Waves vs. Gravitational Waves

A few years back, I made a bit of a fool of myself in front of a professional physicist from LIGO.  You see, I kind of have a reputation, both online and in real life.  I’m the Sciency Words guy.  I’m the guy who knows stuff about scientific terminology.

So it’s pretty embarrassing when I get my scientific terms mixed up!  For today’s episode of Sciency Words, I’d like to share with you the two terms I got confused about so that the next time you meet a physicist from LIGO, you won’t make my mistake.


Gravity waves have to do with fluid dynamics: the movement of liquids and gases.  As an example, imagine an air mass being blown up and over a mountain range. Once over the mountains, that air mass will start to fall downwards again due to the force of gravity.

But of course air masses don’t sink straight down like lead weights.  Air has a lot of buoyancy, so that air mass will bob up and down for a while until it settles into a stable equilibrium.  This bobbing up and down motion will produce ripples in the atmosphere, and those ripples are called gravity waves.

Gravity waves have been observed both in Earth’s atmosphere and Earth’s oceans.  They’ve been observed on other planets as well.  Basically any time part of a liquid or gaseous medium is forced upwards, you can expect gravity to pull it back down again, producing gravity waves.


Gravitational waves have to do with Einstein’s theory of general relativity.  As an example, imagine two black holes spinning rapidly around each other. Even if you’re watching this from a safe distance, you might notice the combined gravitational attraction of those black holes grows stronger and weaker in a regular, oscillating pattern.

Well, actually you probably won’t notice that.  Even in the most extreme circumstances, those oscillations in gravity are barely detectable.  But they do happen.  The LIGO Project confirmed that in 2015 (the news wasn’t announced until 2016).

French theoretical physicist Henri Poincaré gets credit for coining the term gravitational waves (ondes gravifiques in French).  He first wrote about them in 1905, around the same time Einstein was formulating his theory of special relativity.  I’m not sure who coined the term gravity wave, but English mathematician George Biddle Airy was the first to mathematically describe gravity waves in 1841.

My mistake was asking a physicist who studies gravitational waves for LIGO a question about gravity waves in the atmosphere of Titan.  I mean, it’s an understandable mistake, getting these two terms confused—unless you’ve been introduced as an expert on scientific terminology!!!  Then it’s super embarrassing!!!

P.S.: As it so happens, I got the chance to meet up with that same LIGO physicist once again this week.  She was giving a presentation at Princeton University.  Don’t worry.  I didn’t embarrass myself too much this time.  I’ll tell you more in Monday’s post!