Now Open: The Planet Pailly Store!!!

Hello, friends!

If you’ve ever looked at my artwork and thought it would look good on a T-shirt or a notebook cover or a tote bag, well… I have good news for you!  The Planet Pailly store is now open on!!!

You can get my artwork printed on shirts or coffee mugs or throw blankets… there’s a shockingly wide selection of stuff you can buy.  You can also get stickers in various sizes, so feel free to slap my artwork on anything and everything you want!

Now I was initially concerned about quality.  Redbubble is a print-on-demand service, and I’ve had some bad experiences with print-on-demand services in the past.  But I can assure you that Redbubble stuff is top quality.  I am really, really happy with the way this T-shirt turned out.

This spiral notebook is also really cool.

My only complaint is that Redbubble doesn’t offer free shipping.  They do, however, offer bundle discounts if you order multiple items at once.  So if you buy a T-shirt from me, and maybe a shower curtain from another artist, and a set of coasters from somebody else, your discounts should start stacking up nicely.

The Planet Pailly store currently has three “highly technical diagrams” that have previously appeared on this blog: the Sun, Jupiter, and Pluto.  More astronomical objects will be added soon (if you have requests, let me know in the comments).  Also coming soon: the cover art from Tomorrow News Network.

So if you’re looking for the perfect gift for your sciency friend, or the perfect gift for your sciency self, please check out my Redbubble store.  And be sure to check out some of the other artist stores on Redbubble too!  There’s cool stuff for everybody, and your money will help independent artists (like me) keep doing what we do.

Sciency Words: Syzygy

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:


We’ve all seen pictures like this, with all eight planets lined up in a row:

And sometimes, on extra special occasions, the planets really do line up like that, or at least they come very close to it.  When this happens, we call it a grand syzygy.

The word syzygy traces back to ancient Greek.  It originally meant “yoked together,” as in: “The farmer yoked together his oxen before plowing the field.”  According to my trusty dictionary of classical Greek, the word could also mean “pair” or “union.”

Some closely related words in Greek referred to balance, teamwork, sexy times, etc.  And our modern English words synergy and synchronized have similar etymologies.  Basically, what all these words have in common is a sense of people or things coming together, in one manner or another.

For modern astronomers, syzygy means three or more celestial bodies coming together to form a straight line.  The most commonly cited example of this is the alignment of the Sun, Earth, and Moon that occurs during either a new moon or full moon, as observed here on Earth.

But an alignment doesn’t have to be perfectly straight to be called a syzygy, especially when we’re dealing with more than three objects.  According to this article from The New York Times, a syzygy of the Sun, Venus, Earth, Mars, Jupiter, and Saturn occured between March 25 and April 7, 1981.  The Sun and five planets came “within 2 degree of arc from a perfect straight line.”  Apparently that’s close enough.

But while that 1981 syzygy was pretty grand, it was not the grandest of grand syzygies.  The planets Mercury, Uranus, and Neptune were left out.  According to another article from The News York Times, a truly grand syzygy will happen on May 19, 2161, “[…] when eight planets (excluding Pluto) will be found within 69 degrees of each other […].”

So mark your calendars, friends!  You don’t want to miss the grand syzygy of 2161!

P.S.: And if you’re a Star Trek fan, you may recall that 2161 will be an auspicious year for another reason.  That’s the year when the United Federation of Planets will be founded—a political syzygy, one might say, occurring at the same time as an astronomical syzygy.

A Rainy Day on the Sun

Hello, friends!

I was recently introduced to a new song by Jean Grae entitled “Stop Drawing Sunglasses on the Sun” (click here).  The song raises some valid points.  As an artist who frequently draws sunglasses on the Sun, I guess I have some soul-searching to do.

In the meantime, I recently saw a report on that said it was raining on the Sun.  So naturally, I drew this:

Pretty much everything associated with the Sun it extremely big, extremely hot, and relates somehow to the Sun’s extremely powerful magnetic field.  The Sun’s coronal rain (no relation to the coronavirus) is no exception.

First, let’s talk about the role of the magnetic field.  Ionized gas (a.k.a. plasma) rides up the Sun’s magnetic field lines to form solar prominences: those arch-like or loop-like structures that are often seen suspended above the Sun’s surface.

These prominences are extremely hot, at least by Earth standards, but they’re not quite as hot as the Sun’s surface.  According to this paper from Astrophysical Journal Letters, there are at least two possible explanations for how solar prominences loose their heat.  Whatever the cause of the heat loss, the result is that the cooling plasma begins to condense, much as cooling water vapor condenses in Earth’s atmosphere.  And then rain drops start to form.

But of course, these rain drops are extremely big, more like “rain blobs.”  Due to the technical limitations of Earth-based and space-based solar observatories, we can’t say for sure how big these rain blobs get, but some appear to be “on the order of 5000 km in radius,” according to that same paper from Astrophysical Journal Letters.

So in summation, it rains on the Sun.  Seriously, it rains a lot!  And like pretty much everything else relating to the Sun, this coronal rain is extremely big, extremely hot (by Earth standards), and is associated with the Sun’s extremely powerful magnetic field.  So maybe the Sun doesn’t need sunglasses, but an umbrella seems appropriate.

Next time on Planet Pailly, what is so super about a supermoon?

Sciency Words: Solar Wind

Hello, friends, and welcome to another episode of Sciency Words.  Each week, we take a closer look at some science or science-related term so we can expand our scientific vocabularies together!  Today on Sciency Words, we’re talking about:


The stars twinkle in our sky because Earth’s atmosphere scatters starlight.  The Sun has an atmosphere too, so it shouldn’t surprise you to learn that when astronomers observe stars that happen to be near the Sun (as viewed from Earth), they can see that the Sun’s atmosphere also scatters starlight.

What might surprise you—and what did surprise astronomers in the 1950’s—is that this scattering effect can extend very, very far into the space around the Sun.  The Sun’s atmosphere must be huge!  As reported in this 1959 article from Scientific American, the Sun’s atmosphere might be so big that it encompasses Earth!

Pursuing this and other lines of evidence (such as the apparent correlation between flare activity on the Sun and aurorae here on Earth, as well as apparent 11 year fluctuations in cosmic radiation levels), American astrophysicist Eugene Parker wrote this paper in 1958, introducing a concept now known as the solar wind.

As you might imagine, the Sun’s atmosphere is hot.  Absurdly hot.  Remember that temperature is really just a measure of the average velocity of atoms, and you’ll soon realize (as Parker did) that atoms in the Sun’s atmosphere must have enough velocity to escape the Sun’s gravity.  And since those atoms would also be ionized, these streams of ionized particles coming from the Sun would serve as extensions of the Sun’s magnetic field.

The term solar wind doesn’t appear in that 1958 paper.  Parker first introduces that term in this 1959 paper, in which he defends his idea and responds to critiques from other astrophysicists.  As Parker explains:

In view of the simple hydrodynamic origin of the expansion, it seems appropriate to term the stream a solar wind.

Also in 1959, the Soviet Union’s Luna 1 space probe gathered the first empirical evidence that the solar wind really does exist, leading to confirmation that Eugene Parker’s solar wind hypothesis was correct.

And today, a NASA spacecraft named in Parker’s honor is spiraling closer and closer to the Sun, gathering more data about the solar wind and other mysterious phenomena associated with the Sun.

Next time on Planet Pailly, now that we’ve talked about the solar wind in our own Solar System, we’ll check out the space weather forecast for the solar system next door.

Sciency Words: Barycenter

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about those big, complicated words scientists use.  Today’s Sciency Word is:


Excuse me, but I’m going to do that “um, actually” thing that people who think they’re really smart like to do.  Now you may think the Earth orbits around the Sun.  Um, actually… the Earth and Sun both orbit something called the barycenter.

The word barycenter comes from two Greek words meaning “heavy” and “center,” and it refers to the common center of mass for two or more celestial bodies.  Based on sources I found via Google Ngrams, the term started appearing frequently in astronomical journals during the early 20th Century, and it may have been in use as early as the 1880’s.

Let’s say you have two celestial bodies.  One is really massive, the other is much less massive.  In that case, the barycenter will probably be located somewhere inside the more massive object.  This is the case for the Earth and her Moon.  Based on numbers I got from Wikipedia, the Earth-Moon barycenter is about 1000 miles (1700 km) beneath Earth’s surface.  Or to measure that a different way, the barycenter is about 3000 miles (4600 km) away from the center of the Earth.

Now let’s say you have two celestial bodies of roughly equal mass.  In that case, the barycenter will be located somewhere between them.  Something like this has happened with Pluto and his giant moon, Charon.  Once more using numbers from Wikipedia, it looks like the Pluto-Charon barycenter is about 500 miles (960 km) ABOVE the surface of Pluto.

As for the Earth-Sun barycenter, it’s located deep inside the Sun.  So if you say Earth orbits the Sun, you’re not too far from the truth.  But of course Earth is not the only planet in the Solar System, and when you consider the Solar System as a whole, you’ll find the Sun wibbles and wobbles about in weird, loopy patterns.  As you can see in the highly technical diagram below, the Sun wibbles and wobbles so much it can wobble into a totally new position in just a few years.

Click here for an actual diagram of the Sun’s movement relative to the Solar System’s barycenter.

As explained in this paper, this is mainly due to the gravitational influences of Jupiter and Saturn. Over longer time scales (centuries rather than decades), the subtler influences of Uranus and Neptune also have a noticeable effect.

So the next time someone tells you the Earth orbits the Sun, you can do the “um, actually” thing and explain what a barycenter is.  Trust me, it’s a great way to sound smart and make lots of new friends!

Next time on Planet Pailly, what did people in 1962 think we’d find on other planets?

Sciency Words: Nominal Solar Radius

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:


Last week, I told you about the classification system in use for main sequence stars. Today we’re going to talk specifically about G-type stars.  Or rather, we’re going to talk about one G-type star in particular: the Sun.

I was recently clued in on a controversy about the Sun.  After reading up on the issue, though, I don’t think this is a real controversy.  It’s more like an Internet controversy.

If you’ve ever wondered how big the Sun is, a quick Google search will get you an answer.  But it won’t get you the correct answer.  That’s because we apparently do not know precisely how big the Sun is.  As this paper from 2018 states: “[…] measuring with high accuracy the diameter of the Sun is a challenge at the cutting edge of modern techniques.”

Part of the problem is that we’ve tried using multiple methods for either measuring the Sun’s radius by direct observation or by calculating the radius based on other kinds of measurements.  And we keep getting different answers.  I take it we’re not getting wildly different answers, but there’s enough variation there to create a problem for scientists who study the Sun.

So here’s where the alleged controversy comes in.  Our friends at the I.A.U.—the International Astronomy Union, the same organization that decided Pluto is not a planet—decided a few years ago what the Sun’s radius should be.  They said it equals 695,700 km.  No more, no less.  I mean, who are these people to decide what is or is not a planet?  Who are these people to decide now how big the Sun is?

Except that’s not actually what the I.A.U. did. Regardless of how I may feel about the whole Pluto thing, I do agree with the I.A.U. about their definition of the solar radius.  Or to speak more precisely, I agree with their definition of the nominal solar radius.  As explained in the I.A.U. resolution on this matter:

These nominal values should be understood as conversion factors only—chosen to be close to the current commonly accepted estimate […] not as the true solar properties.  Their consistent use in all relevant formulas and/or model calculations will guarantee a uniform conversion to SI units.

So I don’t think the controversy, such as it is, really exists.  If we’re going to use the nominal solar radius as a unit of measure, we all have to agree about what that unit of measure is equal to—especially because we still don’t know what the actual solar radius is.

Feel free to bash the I.A.U. about Pluto, if you want, but when it comes to their nominal solar radius definition, I think the way they handled it makes a lot of sense.

Art in the Wild: Mr. Sun

Of late, I’ve felt that I need to push myself a little harder with my art.  I’ve been doing lots and lots of drawings, so it’s not that I’ve gotten lazy; rather, I feel like I’ve gotten complacent.  I feel like I keep doing the same kind of drawing over and over again, without really challenging myself or stretching my artistic skills.

So to shake up my routine, I decided to take some of my art supplies “out into the wild,” so to speak.  Or at least I took them out of my art studio and brought them with me to my day job.  My hope was that I could draw something based on first hand observation, rather than from photo references, mannequins and maquettes, or pure imagination.

A year or two ago, a thoughtful friend left this Mr. Sun figurine on my desk.  Given the history of this blog, that seemed like a good place for me to start.

One of the challenges of drawing from first hand observation is that your mind plays tricks on you.  You have to get past what your mind thinks you should see and draw what your eyes actually see. I had a really tough time with this drawing because my mind kept insisting there should not be highlights and cast shadows on the Sun; the Sun is supposed to be a light source!

It’s been a long time since I’ve taken my art out of the studio like this.  I think it was good practice artistically speaking, and a surprisingly difficult mental challenge as well.  I plan to do a whole lot more of this.  Let me know in the comments if you’d like to see more of the results (good, bad, or ugly).

I love drawing almost as much as I love writing.  But when you love something, there’s a real danger of settling into a comfort zone, becoming complacent, and getting bored. And then you may start to fall out of love with that thing (or maybe even that person) that you loved so much.

So whatever it is you love, I hope you’ll keep pushing yourself, take some risks, and challenge yourself to do something more with it.

Sciency Words: Coatlicue

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:


You may recall the famous words of Carl Sagan: “We’re made of star stuff.”  Turns out we’re not made of just any old star stuff.  No, a great deal of our stuff came from one star in particular, a giant star named Coatlicue that went supernova about 4.5 billion years ago.

I first saw this name in a recent article from Scientific American called “The New Biography of the Sun,” which in turn referenced a paper from the journal Astronomy & Astrophysics titled “Solar System Genealogy Revealed by Extinct Short-Lived Radionuclides in Meteorites.”

In short, certain radioactive isotopes found in our Solar System can be thought of as our Solar System’s D.N.A.  The authors of that “Solar System Geneaology” paper used some of those isotopes (most notably aluminum-26) to try to reconstruct our Sun’s family tree and give us some idea about what the Sun’s “mother” must have been like.

Coatlicue would have been a giant star, approximately 30 times as massive as our Sun, ensconced within a giant molecular cloud along with other giant star siblings.  This is sort of like what we see today with the stars of the Trapezium inside the Orion Nebula.

About 4.5 billion years ago, Coatlicue went supernova.  The explosion accomplished two things: it seeded the surrounding molecular clouds with heavy elements (like aluminum-26) and, because of the force of the explosion, caused those molecular clouds to compress, triggering new star formation.

I have to confess that I feel like there’s a lot of guesswork and speculation going on here about how, specifically, Coatlicue died and how, specifically, the Sun and its planets were born.  But the general idea that the death of one star triggers the formation of others is consistent with what we already know about star formation, so it makes sense to me that something like this must have happened for our own Solar System.

As for the name Coatlicue (which I believe is pronounced Kwat-LEE-kway), that comes from Aztec mythology.  Coatlicue was the mother of the Sun.  So that makes sense.  In the myth, Coatlicue was also the mother of the stars, which actually sort of matches up with the science too.  That supernova explosion 4.5 billion years ago would have triggered the formation of other stars—perhaps several hundred of them—in addition to our own Sun.

I didn’t see this in either Scientific American or that “Solar System Genealogy” paper, but I’d like to believe Coatlicue might not have been totally destroyed in that supernova.  Perhaps some remnant is still out there, living on as a neutron star or a black hole or something.  If so, I doubt we’ll ever find it, but if I know anything about mothers, I’m sure our Sun still hears from Coatlicue every now and then.

Sciency Words: Baily’s Beads

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:


This is going to be a quick one. I sort of blew all my writing hours this week finishing the first episode of my new short story series: Omni-Science. I don’t regret that. Writing Omni-Science felt awesome, and I hope you liked reading it.

The writing prompt that inspired Omni-Science was this photograph of the “Mondretti cylinder.”

That’s a very strange and mysterious image, certainly strange and mysterious enough to get the machinery in this writer’s brain started. But being the science nerd that I am, I also recognized that this is actually a time-lapse/composite image of a solar eclipse, showing off the “Baily’s beads” effect. (Also when I downloaded the image, the file name had the words “Baily’s beads” in it, which removed any doubts I had about what I was really looking at.)

As I’m sure you know, the Moon is not a smooth, perfect sphere. It’s covered in craggy terrain, and so during an eclipse, just before the Sun disappears entirely behind the Moon, the last rays of sunlight peak out from the gaps between mountains and craters and so forth. As a result, those of us who are using proper safety gear get to see these “beads” of light around the edges of the Moon.

I’m guessing Francis Baily was not the first person to notice this, but in 1836 he became the first to explain it in a paper for the Royal Astronomical Society titled “On the remarkable phenomenon that occurs in total and annular eclipses of the sun.” Those 19th Century English astronomers certainly did have a way with words, didn’t they?

Sciency Words: Spectroscopy

Welcome to a special Saturday edition of Sciency Words, because sometimes life gets in the way of regular blogging schedules. Each week (normally on Fridays) we take a closer look at some science or science-related term so we can all expand our scientific vocabularies together! Today’s term is:


What color is it? It sounds almost like a childish question, but as we look out into space, trying to study the Sun and other stars and distant planets, we can learn a great deal just by figuring out what color things are.

The science of spectroscopy has a long history, beginning with Isaac Newton. In the late 1600’s, Newton demonstrated that pure white light can be split apart into a rainbow of color using a prism. Newton called this a spectrum, from the Latin verb specto, meaning “I observe” or “I see.” (According to my trusty Latin-English dictionary, the noun spectrum also meant “apparition” or “ghost.”)

Over the decades and centuries to come (click here for a detailed timeline), scientists used increasingly sophisticated combinations of lenses, mirrors, and prisms to study Newton’s spectrum in greater detail. They also experimented on a wide variety of light sources: sunlight, starlight, firelight, and even electrical sparks.

An especially noteworthy experiment in 1752 showed that burning a mixture of alcohol and sea salt produced an unusually bright yellow band in the middle of the spectrum (we now know this to be a emission line for sodium). And in 1802, another experiment on sunlight revealed multiple dark bands in the Sun’s spectrum (which we now know are absorption lines for hydrogen, helium, and other elements in the Sun’s photosphere and corona).

All the colors of the rainbow, except a few are missing. This is an absorption spectrum.

It wouldn’t be until the early 20th Century, with the development of quantum theory and, specifically, Niels Bohr’s model of the atom, that anyone could explain what caused all these spectral lines.

No rainbow, just a few specific colors. This is an emission spectrum.

In Bohr’s atom, the electrons orbiting an atomic nucleus can only occupy very specific energy levels. When electrons jump from one energy level to another (the true meaning of a quantum leap), they either emit or absorb very specific frequencies of light. The light frequencies are so specific that they act as a sort of atomic fingerprint.

And so today, as we look out into the universe, seeing the glow of stars and the absorption patterns of planetary atmospheres, it’s possible for us to identify the specific chemical elements we’re seeing, even across the vast distances of space, simply by asking what color is it?