In Memory of Cassini

September 20, 2017

Last week, NASA’s Cassini Mission came to an end when the spacecraft crashed into the planet Saturn. This was, of course, a planned event: a way for the mission to end in a blaze of glory, collect a little extra data about Saturn’s atmosphere, and also protect Saturn’s potentially habitable moons (Titan, Enceladus, and possibly also Dione) from microorganisms that may have hitched a ride from Earth aboard the spacecraft.

Cassini’s last few days were an oddly emotional time, at least for me. Somehow knowing that the end was coming, that everything was proceeding according to schedule, made it a little harder to bear. When the words “data downlink ended” started appearing in my Twitter feed, I got a little misty eyes and had to walk away from the computer for a while.

This despite the fact that I never got to know Cassini all that well. I never really followed the Cassini Mission closely (especially compared the way I follow Juno). Looking back through my old posts, it seems Cassini only ever appeared on this blog twice. Once for that time it spotted sunlight glinting off the surface of Titan’s methane lakes…

… and once more for the time it used precise measurements of Enceladus’s librations to determine that Enceladus does indeed have an ocean of water beneath its crust.

So today I thought I’d turn the floor over to several of the moons of Saturn and also Saturn herself. They’re the ones who got to know Cassini well. Not me. It’s right that they get the chance to give Cassini’s eulogy.

Molecular Monday: The Four Elements

September 18, 2017

For some reason, I’ve been thinking a lot lately about the original elements, the four elements Aristotle wrote about many millennia ago: fire, water, wind, and earth. Of course we no longer think of these as elements in the chemical sense. Instead we have the periodic table of elements, with well over a hundred elements identified so far.

But just for fun, I thought I’d try to find a way to connect the old Aristotelian elements to the first four modern chemical elements: hydrogen, helium, lithium, and beryllium. Here’s what I came up with:

  • Hydrogen: Let’s start by associating hydrogen with “water.” The word hydrogen actually means “water maker.” It got its name because in 1783, Antoine Lavoisier demonstrated that the oxidation of hydrogen gas produced water (this experiment also proved that water is not elemental).
  • Helium: Helium was first detected in the solar spectrum in 1868 and was thus named after the Greek word for “sun.” The Sun is pretty fiery, so my first instinct was to make helium represent “fire.” But I’m going to go with “air” instead, because of helium’s use in balloons and airships.
  • Lithium: As I’ve written about previously, lithium was first discovered using a method called a flame test. When a chemical substance is burned, the color of the flame can be used to determine the chemical’s identity. Lithium burns with a characteristic bright crimson flame. Therefore, I’m choosing to associate lithium with “fire.”
  • Beryllium: Beryllium was first identified in 1798 as a component of the mineral beryl, specifically a form of green beryl we all know as an emerald. So I think I can safely wrap this little game up by connecting beryllium with “earth.”

So how did I do? Do you agree with the connections I came up with? Are there other connections we could think up that might work better?

Okay, maybe this was more of an exercise in creativity than science. I’m okay with that. And besides, in the half-hour I spent researching for this post, I learned a few things about the first four elements of the periodic table that I didn’t know before. That’s always a plus.

Anyway, next time on Molecular Monday, we’ll be talking about boron. Now I wonder if I can find some way to associate boron with the girl from The Fifth Element.

Sciency Words: Retropy

September 15, 2017

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


In any serious conversation about time travel—and I mean any serious, scientific discussion of time travel, as in the kind of discussion actual real-life physicists might have—there’s a term that is virtually guaranteed to come up: entropy.

I’ve tried to define entropy before for Sciency Words, but I’ve never felt like I’ve done the term justice. It’s a big concept, and kind of a weird concept, and sometimes a depressing concept. It’s also a concept that most of us sort of grasp intuitively, even if we can’t quite put it into words.

The simplest definition is that entropy is the amount of disorder in a system, or perhaps the degree to which a system has decayed. Another good definition is that entropy is the measure of the amount of energy in a system that cannot or can no longer be used for work.

According to the second law of thermodynamics, the total entropy of any closed system will tend to increase over time. You can depend upon that! This makes entropy relevant to time travelers, because it’s one of the very few physical properties that is dependent on which direction time is flowing.

As we move forward in time, entropy will increase. And if entropy is increasing, you (as a time traveler) can be sure that you are traveling forward in time. And if you observe that the entropy of a closed system is decreasing, you can be sure you’re traveling into the past.

In the vocabulary of professional time travelers, there should probably be a special term for when entropy goes into reverse. I don’t know what that word is, but fellow blogger and poet James Ph. Kotsybar (also known as the Bard of Mars) recently proposed a pretty good option: retropy, short for retro-entropy.

He even wrote a haiku about it. It’s worth checking out, along with many of the Martian Bard’s other science-themed poems.

TRAPPIST-1: Come On, How Many Planets Are Enough?

September 12, 2017

Remember TRAPPIST-1? That ultra-cool dwarf star with a miniaturized solar system of seven planets?

Whenever we talk about TRAPPIST-1, we really should specify that it has seven planets that we know about. Astronomers are still searching for more. Specifically, they’re searching for larger, Jupiter-like bodies.

So far, astrometric observations (precise measurements of a star’s gravitational “wobble”) have ruled out some possibilities. There are no planets in the TRAPPIST-1 System with masses greater than 4.6 times the mass of Jupiter with orbital periods of one year or less, and no planets with masses greater than 1.6 times the mass of Jupiter with orbital periods of five years or less.

That still leaves the door open for a lot of other very large planets. Just imagine if we discover a couple of Saturn-mass objects, or half a dozen Neptunes. Heck, there could still be Jupiter-mass planets out there! Or maybe not. It could just be the seven Earth-sized planets we already know about.

As explained in this article from Centauri Dreams, there are currently two competing theories to explain how gas giants form. One of these theories would probably allow gas giants to form around TRAPPIST-1; the other probably would not.

  • Core Accretion: a large, rocky core forms first and then envelops itself in gases from the proto-planetary disk surrounding a newborn star. This would be a very slow formation process.
  • Disk Instability: The proto-planetary disk surrounding a young star “destabilizes,” forming whispy structures like the spiral arms of a galaxy. Knots of gas in these spiral arms would condense into planet shapes, and the rocky cores of these planets would form later (or in some cases perhaps not at all) from asteroids or other debris captured by the gas giant’s gravity. This process would happen quickly.

Given what we know so far about TRAPPIST-1, it’s unlikely gas giants could have formed there by core accretion. TRAPPIST-1’s protoplanetary disk wouldn’t have been around long enough. Therefore if we find gas giants orbiting TRAPPIST-1, that would challenge the core accretion model and give more credence to disk instability.

So now the search is on!

Will we find gas giants around TRAPPIST-1? I kind of hope we do. First off, it would make TRAPPIST-1 even more awesome than it already is. And secondly, it would mean the core accretion model—the traditionally accepted view among astrophysicists—is wrong, or at least incomplete, and when theories turn out to be wrong or incomplete, that’s when the real fun of science begins.

Sciency Words: Angstrom

September 8, 2017

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


Last week on Sciency Words, we talked about spectroscopy, a word that’s so important to the kind of space science I write about here on Planet Pailly that I’m surprised I never covered it before.

But in the interest of brevity, I had to skip a lot of the important parts of the history of spectroscopy. I mentioned Isaac Newton and Niels Bohr, but I completely skipped one of the most important “fathers of modern spectroscopy,” Swedish physicist Anders Jonas Angstrom.

Angstrom is one of those scientists who’s so important he has a unit of measure named after him: the angstrom, which equals 10-10 meters, or 0.1 nanometers, and is represented by the symbol Å (the circle over the A is a Swedish thing—Angstrom’s name is more properly spelled Ångström).

The angstrom is not officially part of the International System of Units (S.I.), but scientists use it anyway. It’s a convenient unit for measuring wavelengths of light, certain tiny crystalline structures, and other distances at the molecular and/or atomic scale.

One of the reasons Anders Angstrom features so prominently in the history of spectroscopy is that he was among the first to combine spectroscopy and photography, allowing him to not only observe a spectrum for himself but to record it for others to see.

In 1868, Angstrom published a book with the first complete map of the Sun’s spectrum in visible light, showing over 1,000 absorption lines indicating the presence of hydrogen, helium, and other elements in the Sun’s atmosphere.

This book, titled Recherches sur le Spectre Solaire (Research on the Solar Spectrum), has long since passed into the public domain, so I was able to find a copy of it available for free online. Now if only I could read French….

As one last note, in his solar spectrum book Angstrom found it convenient to quantify wavelengths of light in units equaling one ten-millionth of a meter, also known as 10-10 meters, or 0.1 nanometers. Or in other words, Anders Angstrom was the first person to measure something in angstroms.

P.S.: I really hope I got my math right for today’s cartoon.

IWSG: The Critic in the Mirror

September 6, 2017

Today’s post is part of the Insecure Writer’s Support Group, a blog hop where insecure writers like myself can share our worries and offer advice and encouragement. Click here to find out more about IWSG and to see a list of participating blogs.

First off, I want to assure you that I’m okay. Parts of this post might sound really bad, but I promise I’m okay.

At least, I am now.

Two or three weeks ago… not so much.

Back in 2012/2013, I wrote a short story series about a journalist who travels through time. Sort of like Rita Skeeter from Harry Potter becomes a Time Lord from Doctor Who. It was a pretty cool series, if I do say so myself.

But over the last few years, I’ve been struggling to figure out what to do with these all stories. I hate to admit this, but I’ve even considered letting this whole project go and starting something else instead. Something easier. Something more manageable.

Then last month, I had an idea. A brilliant idea! A crazy idea. One of my best ideas ever! I suddenly knew exactly what I needed to do with the Tomorrow News Network series; the only problem was that this idea was going to require a whole lot of work. Way more work than I’m accustomed to. I’d basically have to start the whole series over from scratch.

Do I… do I really want to do that?

Am I capable of pulling this off?

I don’t know, but when I looked in the mirror, the guy staring back at me made his thoughts on the subject plain.

I guess most writers have these kinds of thoughts from time to time. It’s just… I’ve never had this kind of self-doubt hit me so hard before, and I didn’t know how to deal with it. It made August one of the darkest and saddest months of my life.

Now regular readers of my blog know that my muse makes frequent appearances in these IWSG posts. Regular readers may also know that my muse doesn’t really understand how the “real world” works (fairy people from imagination-land typically don’t). Apparently among other things like deadlines and personal finances, she also gets confused about mirrors.

Maybe that’s not the most inspiring thing a muse can say to her writer, but I appreciate the sentiment.

We writers really are jerks to ourselves. We’re our own worst critics because we do the one thing that you’re never supposed to do when criticizing—or rather critiquing—other people’s work. We make it personal.

That guy in the mirror called me a failure. He said some other pretty nasty things about me too. But he didn’t say one word about my writing or this new idea I’m toying with. Seriously, if someone did that in a critique group, that person would be politely but sternly asked to leave.

So as I said, I’m okay. At least, I am now. I’ve recovered from my bout of self-doubt and depression, and I’ve gotten back to writing. My plan for September is to try this new idea out and see how it goes.

As for the guy in the mirror… until he learns how to give constructive feedback, I will not be listening to him.

Molecular Monday: Lithium Brine

September 4, 2017

Welcome back to another edition of Molecular Mondays, a special biweekly series here on Planet Pailly combining two of my least favorite things: chemistry and Mondays.

These past few weeks, I’ve been reading a lot and learning a lot about lithium, because I’m a science fiction writer and I need to know stuff about this particular element for worldbuilding purposes. Except so far, I seem to be doing more world-destroying than worldbuilding.

Lithium is the kind of element that tends to form really strong chemical bonds—so strong that once lithium bonds to other elements, it can be really difficult to make it let go.

In fact Johan Arfwedson, the chemist who discovered lithium, was never able to isolate the element by itself. He could only infer its existence based on the unusually bright crimson color produced when a lithium-containing compound was burned (in other words, he was only able to identify it spectroscopically).

Given how hard it is to isolate lithium, I assumed lithium mining must be an arduous task. And it probably would be if we had to extract it directly from rock; but over three quarters of the world’s commercially available lithium does not come from rock. It comes from brine.

Pockets of water beneath the Earth’s surface can, over long periods of time, leech minerals like lithium out of the surrounding rock. The lithium intermingles with other elements in the water, creating lithium salts, and gradually as the water gets saltier and saltier it turns into lithium brine.

All we have to do is dredge that briny water up out of the ground, pour it into an artificial pool, and leave it out under strong sunlight. When the water part of the brine evaporates away, we’re left with lots and lots of lithium salts (and other kinds of salt too, but for our purposes we only care about the lithium salts). Apparently this is one of the easiest mining processes around, and also one of the least harmful to the environment.

I still have more research to do on this subject, but at least now I know my fictional lithium-rich moon would not necessarily burst into flames just because there’s water.