What Color are All the Planets?

Hello, friends!

So as you know, Earth is “the Blue Planet” and Mars is “the Red Planet.”  By my math, that leaves us with six other planets in our Solar System that don’t have color-related nicknames.  Today, I’d like to try and fix that.

Jupiter was the toughest.  He’s actually lots of different colors: red, grey, white, orange… and then the Juno mission recently showed us that Jupiter’s polar regions are blue!  Of course Jupiter is most famous for being red in that one specific spot, but even the Great Red Spot changes colors from time to time, fading from red to pink to white before turning red again.

Anyway, those are my picks for the color-related nicknames for all the planets.  Do you agree with my picks?  Disagree?  Let me know in the comments below!

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.

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?

Meet Umbriel, a Moon of Uranus

Lately, I’ve been trying to learn as much as I can about the planet Uranus and its moons.  It’s been a real challenge.  Only one spacecraft has ever visited the Uranian System, and that was back in 1986.

When I do research on most other objects in the Solar System, I usually find plenty of good, highly detailed information to work with.  Geology, chemistry, meteorology (sometimes), seismology (sometimes), astrobiology (more often than you’d think)….  But when it comes to the moons of Uranus… well, we know what color they are!

Today, I’d like to introduce you to Umbriel.  She’s sort of dark grey.  All the moons of Uranus are grey, but Umbriel is the darkest shade of grey out of them all.  In fact, that’s basically what the name Umbriel means: darkness.

According to this paper, Umbriel’s dark grey color might be caused by carbon compounds.  Imagine there’s coal or charcoal dust sprinkled all over Umbriel’s surface.  That’s basically what we think we’re looking at, except unlike coal or charcoal, Umbriel’s carbon compounds probably formed due to the photolysis and/or radiolysis of carbon dioxide, not because of biological activity.

But that dark coloration appears to be only skin-deep. Near the equator, Umbriel has a lighter, icier-looking surface feature.  It’s believed to be the result of a relatively recent asteroid or comet impact.  The color change probably means we’re seeing subsurface material that hasn’t undergone photolysis yet.  Officially, that surface feature is known as Wunda Crater.  Unofficially, it’s called the fluorescent Cheerio. Seriously, I’m not making that up.

Sending a spacecraft to Uranus is a costly and technologically challenging endeavor.  That’s why we’ve only done it once.  But if/when another Uranus mission does get off the ground, investigating that fluorescent Cheerio should be a top priority.  Anything that can tell us what lies beneath the surface of an icy moon like Umbriel is worth a closer look.

Meet Ariel, a Moon of Uranus

I have a friend who’s obsessed with The Little Mermaid.  So if I’m going to write a post about Ariel, one of the moons of Uranus, it would be a real shame if I couldn’t make some sort of Little Mermaid reference.

Unfortunately, we know precious little about Ariel, or any of Uranus’s moons, for that matter.  Only one spacecraft has ever visited: NASA’s Voyager 2, way back in 1986. And the data Voyager 2 sent back gives us a frustratingly incomplete picture.

What I can tell you is that Ariel’s surface is made of ice, specifically water ice and carbon dioxide ice.  One hemisphere appears to have more carbon dioxide than the other, according to this paper from Icarus.  And according to this profile piece from NASA, Ariel is the shiniest of Uranus’s moons–it reflects more sunlight than the others.  Oh, and Ariel’s surface appears to be younger than the surfaces of those other moons as well.  That might be important!

In fact, according to this article from Scientific American:

[The Voyagers 2] flyby revealed Ariel to be relatively smooth, as if its surface was being continually renewed by activity deep within.  It is currently believed to be the only ocean world in the Uranian system.

A word of caution: that Scientific American article says a lot of highly speculative, highly conjectural stuff. Take it with a grain of sodium chloride.

However, in the absence of better, more detailed information about Uranus and its moons, it sounds like Ariel could maybe possibly be Uranus’s version of Europa or Enceladus.  It could possibly be a moon with an icy crust floating atop an ocean of liquid water.  It might even be the kind of environment that could support life.  There might even be….

But no, I shouldn’t make a claim like that.  It would be irresponsible of me as a science blogger.  Voyager 2’s data was too limited, and subsequent observations by Hubble or other Earth-based telescopes can only tell us so much.  Until our next mission to Uranus (whenever that might be), we really can’t say what might be hiding beneath the icy crust of Ariel.

Meet Miranda, a Moon of Uranus

Miranda has been called the Frankenstein’s monster of the Solar System.  There’s just such a jumbled mismatch of landscapes.  You’d almost believe a mad scientist took pieces of several different moons and stitched them together.

Apparently this is a result of sporadic global resurfacing events.  At least that’s the conclusion of this 2014 paper entitled “Global Resurfacing of Uranus’s Moon Miranda by Convection.”  Due to a paywall, I haven’t been able to read that paper in full, but the research is summarized in articles here, here, and here.

Apparently Miranda used to have a more eccentric (non-circular) orbit than she does today.  Thus, the gravitational pull of Uranus would sometimes be stronger, sometimes weaker, causing Miranda to repeatedly compress and relax.  Imagine Uranus using Miranda like a stress ball and you’ll get a sense of what Miranda must’ve felt like.

All that squeezing and unsqueezing created friction and heat in Miranda’s interior.  Miranda’s internal ices got melty.  Convection cells formed underground, much like they do here on Earth, and some sort of tectonic and/or volcanic activity got started on the surface.

Something similar happens on Europa, a moon of Jupiter. As a result, Europa has the smoothest, youngest-looking surface in the whole Solar System.  So how did Europa turn out looking so beautifully smooth while Miranda turned into Frankenstein’s moon?

Based on what I’ve read, it sounds like Miranda’s orbit changed.  Uranus stopped squeezing Miranda like a stress ball, Miranda’s interior cooled off, and the resurfacing process came to a halt.  What we see today is a moon that is only half transformed by global resurfacing.

Personally, after studying reference photos of Miranda, learning about what happened to her, and drawing her portrait myself, I no longer feel comfortable with the whole Frankenstein’s monster thing.

I’d like to suggest a new metaphor: Miranda is the Picasso painting of the Solar System. Miranda does have a weird mishmash of surface features that don’t make a lot of sense together (much like a Picasso painting), but that doesn’t make Miranda monstrous.  It gives her her own strange, confusing beauty.

So yes, Miranda, to answer your question: I do think you’re beautiful.

#IWSG: Being a Writer is Soooo Boring!

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

I, J.S. Pailly, stand accused of being a boring person.  Or at least that’s what a few well-meaning friends and acquaintences seem to think.  You see, all I ever do is write and read and do research.  Then I do more research, which is followed up with more writing.

Most people are willing to concede that all the art I do might be fun.  But otherwise my life is soooo boring.  Boring, boring, boring.  I need to get out more, travel, go to loud parties, eat at popular restaurants… or other stuff like that, I guess.

Anyway, I’ve been accused of being boring.  So in my defense, I’m going to talk about something that I find really interesting: space.  And perhaps the story I’m about to tell will serve as a nice little allegory about what it means to be boring or interesting.

In 1986, the Voyager 2 spacecraft became the first—and thus far the only—spacecraft to visit the planet Uranus.  As I’m sure you’re already aware (you may already be giggling), Uranus is a much-maligned planet, because of its name.  Voyager 2’s visit gave us yet another reason to malign our poor seventh planet.

Uranus turned out to be a featureless cyan-blue orb.  There was nothing like Jupiter’s Great Red Spot or Saturn’s polar hexagon.  There were no atmospheric zones or belts.  There was nothing interesting to look at at all! What a boring planet, scientists said.

But of course, this was only true from our limited human perspective.  Our eyes can only see a range of approximately 400 to 700 nanometers on the electromagnetic spectrum (which we perceive as the colors violet to red).

If you observe Uranus only in this 400 to 700 nm range, there’s not much to see.  Switch to ultraviolet, however, and you’ll find a complex and dynamic atmosphere that’s every bit as interesting as Jupiter or Saturn’s.

Whether we’re talking about planets or people, what is boring versus what is interesting is all a matter of perspective.  Will this little anecdote change anybody’s mind?  I’m not sure.  I suspect if you already think I’m a boring person, me talking about sciency stuff only reinforces that belief. But I hope the rest of you get what I’m trying to say.

P.S.: Fun fact!  If you’ve ever wondered why Uranus got stuck with its giggle-inducing name, it’s because the guy who picked the name was German, and he probably didn’t realize what it would sound like in English.

Beneath the Blue-Green Clouds

It would have been the most celebrated discovery in human history: life on another world.  But the press and the late night comedians soon turned what should have been an auspicious occasion into one great big joke.

In February of 2050, NASA’s Herschel spacecraft released a small probe, one of many such probes designed to penetrate the atmospheres of gas giants.  We had learned much about the atmospheres of Jupiter and Saturn in this manner, but the Herschel mission would be a first, in more ways than one.

Among its many scientific instruments, the Herschel probe included a camera.  We expected to see a tranquil layer of blue-green clouds, with a layer of storms underneath.  If we were lucky, we thought we might even see methane ice crystals falling like snow.

But then, in a forty-three second sequence of images, we saw them.  They were giant, shadowy forms lurking in the dark, occasionally backlit by lightning.  They were enormous, easily the size of whales, and there were swarms of smaller organisms all around them, like the krill whales feed upon.

The krill-like life forms are difficult to make out in any detail, but the whales are clearly held aloft by gas bladders, filled with hydrogen, perhaps; and they have fin-like wings which they must use to maneuver. A great multitude of tentacles dangle from their underbellies, tentacles which seem to be writhing violently from one photo to the next, very much as though these animals were busily feeding.

Of all the places in the Solar System, this was the last place we expected to find alien life.  How could these creatures have evolved?  How could such a complex ecosystem sustain itself in the cold, far reaches of the Solar System?  These will have to be questions for some future mission, assuming Congress and the general public will take this seriously enough to support a future mission.

But unfortunately these mysterious and majestic creatures have become the laughing stock of the world, all because of one minor circumstance. All because of the planet where they happen to live.  All because of that planet’s name.

Although, truth be told, who wouldn’t laugh a little when the top headline on every newspaper reads: “Alien life discovered in Uranus.”

Sciency Words: Ice

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:


I have a friend who teases me whenever I use the word ice. This is because, depending on what we’re talking about, I can’t just say “ice.”  As soon as the conversation turns to space stuff (as it often does when I’m around, for some reason), I feel the need to say “water ice.” I feel the need—no, the compulsion to specify that I mean the frozen form of water, as opposed to the frozen form of something else.

In more normal, down-to-earth sorts of conversation, I don’t feel that same compulsion.  Water ice is the only kind of ice we’re likely to encounter here on Earth. On rare occasions, if you’re at a science fair, or maybe a Halloween party, you might encounter carbon dioxide ice (a.k.a. dry ice).  But that’s a very rare special case.

However, as soon as we start talking about other planets and moons, or comets and asteroids, the word ice takes on a much broader meaning. In these more cosmic conversations, you really do need to be specific about which ice you’re talking about. To quote from a recent issue of The Planetary Report:

In the strictest definition, ice is the solid form of water.  However, planetary astronomers often use “ice” to refer to the solid form of any condensable molecule.

Beyond Earth, and especially in the outer Solar System, we find all sorts of crazy ices, like ammonia ice, methane ice, or nitrogen ice.  Along with the water ice and CO2 ice we Earthlings are more familiar with, these ices make up the hard crusts of many planetary bodies, like Titan or Pluto.

We also find ice crystals (of various types) forming in the clouds of planets like Uranus and Neptune.  In fact, Uranus and Neptune are often called “ice giants” in large part because of all those weird ices found in their atmospheres.

Starting next week, I’m planning to take a much closer look at those ice giant planets.  I expect my research to turn up plenty of questions, but very few answers.  Uranus and Neptune are, at this point, the least well explored planets in the Solar System.

So stay tuned!

P.S.: I want to start referring to all forms of igneous rock as “magma ice.”  After all, what is igneous rock but frozen magma?  I can’t think of any good reason why the term “magma ice” shouldn’t apply.

Which Planet Has the Weirdest Magnetic Field?

When I did my yearlong Mission to the Solar System series back in 2015, the planet Neptune stood out as having the weirdest and wackiest magnetic field.  Here’s a totally legit photograph from 1989 taken by the Voyager 2 space probe.  As you can see, Neptune is really confused about how magnetic fields are supposed to work.

But since 2015, science has learned more about the other three gas giants in our Solar System.  Neptune’s magnetic field is still really weird, but it’s no longer clear that it is the definitive weirdest.

  • Jupiter: Based on data from the Juno mission, it looks like Jupiter has three poles instead of two.  There’s a north pole, right about where you’d expect it to be.  Then the magnetic field lines emanating from the north pole connect to two separate south poles.  The first south pole is about where you’d expect a south pole to be. The other one is near the equator. Click here for more about Jupiter’s “non-dipolar” magnetic field.
  • Saturn: As Sherlock Holmes says in one of his many adventures, “Depend upon it, there is nothing so unnatural as the commonplace.” According to data collected during the Cassini mission’s Grand Finale, Saturn’s magnetic field is almost perfectly aligned with its rotation.  At first blush, that might seem quite normal.  Commonplace, even. Except no other planet’s magnetic field is so perfectly aligned.  Not even close.  Apparently planetary scientists didn’t think such a thing was even possible.  Click here for more about the “negligible tilt” of Saturn’s magnetic field.
  • Uranus: The planet Uranus is tipped over sideways, and its magnetic field is tipped over further still.  According to recent computer simulations, these two factors combine to cause Uranus’s magnetic field to tumble over itself “like a child cartwheeling down a hill,” as one researcher put it. This leads to a “periodic open-close-open-close scenario” where the solar wind can flow in toward the planet then suddenly be blocked, then suddenly flow in again, and then suddenly be blocked.  If these simulations are correct, the Uranian aurora may flick on and off like a light switch. Click here for more about the “topsy-turvy motion” of Uranus’s magnetic field.
  • Neptune: In 1989, Voyager 2 discovered that Neptune’s magnetic field is lopsided. The magnetic field doesn’t run through the planet’s core. Instead it runs through a seemingly random point about halfway between the core and the “surface” (by which I mean the topmost layer of the atmosphere).  Also, only one of the poles ends up being near the planet’s “surface.”  The other pole is buried somewhere deep in the planet’s interior.  For more about Neptune’s “badly behaved” magnetic field, click here.

If I had to choose, I’d probably still give Neptune the award for weirdest magnetic field.  But the competition is a lot tighter than it used to be.  Maybe the real lesson here is that gas giants in general have wild and crazy magnetic fields.

So if you had to pick, based on all this new info, which planet do you think deserves the award for the weirdest magnetic field?

P.S.: Also, the Cassini mission discovered there’s an electric current flowing between Saturn and its innermost ring.