Going Up: Jupiter’s Auroras Get Weirder Than Ever

July 17, 2017

Last week, the Juno mission flew over Jupiter’s Great Red Spot and sent back some spectacular close-ups. But I’m not ready to talk about that. Not yet. I’m still catching up on the Juno news from two months ago.

Toward the end of May, NASA released a ton of fresh data from Juno, including new information about Jupiter’s auroras. Astro-scientists had previously known about two sources contributing to these auroras: the solar wind and the Io plasma torus. Now Juno may have discovered a third.

As Juno flew over Jupiter’s poles, it detected electrically charged particles flying up.

I can’t emphasize enough how weird this is. I wanted to write about it right away, but I held off doing this post because I was sure I must have misunderstood what I was reading.

Auroras are caused by electrically charged particles accelerated down toward a planet’s magnetic poles. These particles ram into the atmosphere at high speed, causing atmospheric gases to luminesce. At least that’s how it’s supposed to work. I guess nobody told Jupiter that.

In addition to the “normal” downward flow of particles from the Sun and Io, Jupiter’s magnetic field apparently dredges charged particles up from the planet’s interior and hurls them out into space. So Jupiter’s auroras are triggered by a mix of incoming and outgoing particles.

This definitely falls under the category of “further research is required.” Even now, I still feel like I must have misunderstood something. This is just too weird and too awesome to be true.

P.S.: As for the Great Red Spot, I’m waiting to hear something about the microwave data. We’re going to find out—finally!—just how far down that storm goes.

Io: Jupiter’s Ugliest Moon

July 11, 2017

For today’s post, I hopped in my imaginary spaceship and flew all the way out to Io, one of Jupiter’s moons. Without a doubt, Io is the ugliest object in the Solar System.

I know, that’s mean. I shouldn’t say things like that. But come on, just look at it. Seriously, look at it. It’s like some moldy horror you might find in the back of the fridge.

So yeah, Io’s hideous. Let’s go look at something else instead. Something pretty, like Jupiter’s auroras.

We have auroras back on Earth, of course, but Jupiter’s are a whole lot bigger, a whole lot more powerful, and when viewed in ultraviolet, a whole lot brighter. Also, unlike Earth’s auroral lights which come and go, Jupiter’s are always there. They may vary in intensity, but they never stop, never go away.

Auroras are caused by charged particles getting caught in a planet’s magnetic field, directed toward the magnetic poles, and colliding at high speed with molecules in the planet’s atmosphere.

On Earth, those charged particles come mostly from the Sun in the form of solar wind. No doubt the solar wind contributes to Jupiter’s auroras as well, but the greater contributing factor is actually—believe it or not—Io. That’s right: ugly, little Io causes Jupiter’s auroras. I guess spreading ionized sulfur all over the place is good for something after all!

In fact if you ever get to see a Jovian aurora, you’ll notice little knots in the dancing ribbons of light. These knots correspond to the positions of several of Jupiter’s moons. And the largest, brightest, most impressive of these knots… that one belongs to Io.


Image courtesy of Wikipedia.

So I guess today’s lesson is that even the ugliest object in the Solar System can still help make the universe a more beautiful place.

Sciency Words: Plasma Torus

July 7, 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:


Saturn may have the most beautiful rings in the Solar System, but Jupiter’s got the most impressive plasma torus. Torus is the proper mathematical term for a donut shape, and plasma refers to ionized gas. Put the two words together and you get a giant, donut-shaped radiation death zone wrapped around a planet’s equator.

Jupiter’s plasma torus is faint, almost invisible; but if we take the totally legit Hubble image below and enhance the sulfur emission spectra, you’ll see what we’re talking about.

Ever since the discovery of Jupiter’s decametric radio emissions, astronomers have known there must be a relationship between Jupiter’s magnetic field and its moons. Well, I say moons plural, but it’s really only one moon we’re talking about: Io.

It wasn’t until the Voyager mission that we figured out why Io has so much influence over Jupiter’s magnetic field. In 1979, the Voyager space probes discovered active sulfur volcanoes on Io. They also detected ionized sulfur and oxygen swirling through space conspicuously near Io’s orbital path.

It seems that due to Io’s low surface gravity, Io’s volcanoes can easily spew a noxious mix of sulfur dioxide and other sulfur compounds up into space. Jupiter’s intense and rapidly rotating magnetic field acts as a sort of naturally occurring cyclotron, bombarding these sulfur compounds with radiation, breaking them apart into ionized (electrically charged) particles and accelerating those particles round and round the planet.

The result is a giant, spinning, donut-shaped cloud of ionized gas. We’re talking about a lot of radiation here—seriously, keep your distance from the Io plasma torus! We’re also talking about a lot of electrically charged, magnetically accelerated particles moving through a planetary magnetic field.

One source I read for today’s post described Io as “the insignificant-looking tail that wags the biggest dog in the neighborhood.” Jupiter has by far the largest, strongest magnetic field of any planet in the Solar System, but thanks to this plasma torus, it’s Io—tiny, little Io—that has the real power in the Jovian system.

Next week, we’ll go take a look at Jupiter’s auroras. They’re rather different from the auroras we have here on Earth, and SPOILER ALERT: Io has a lot of control over them.

Sciency Words: Decametric Radio Emissions

June 30, 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:


The decameter doesn’t get as much love as the meter or the kilometer, but it’s still a perfectly legitimate S.I. unit of measure. It equals ten meters.

In 1955, astronomers Bernard Burke and Kenneth Franklin detected radio emissions coming from the planet Jupiter, radio emissions with wavelengths long enough to be measured in decameters. Thus these emissions came to be known as the decametric radio emissions.

Surprisingly, the decametric radio emissions don’t radiate out into space in all directions. Instead, they shoot out like laser beams. Or perhaps I should compare them to searchlights. As a result, we can only detect them here on Earth if they happen to be aimed right at us.

Now here’s the part that I find really interesting. There are currently seven known sources for the decametric radio emissions, and they’re classified into two groups: Io-dependent and Io-independent.

The Io-independent sources require Jupiter’s magnetic field to align with Earth just so in order for us to hear them. And the Io-dependent sources? Well, they depend on Io, one of Jupiter’s moons. Jupiter’s magnetic field has to align with Earth, and Io has to be in the proper phase of its orbit.

I’m not sure why I think the decametric radio emissions would sound like dubstep. Click here, here, or here to find out what they actually sound like.

In next week’s edition of Sciency Words, we’ll take a closer look—a much closer look—at Io. It seems this humble little moon does more than adjust Jupiter’s radio emissions. Io wields enormous power and influence over the entire radiation environment surrounding Jupiter.

P.S.: Okay, on second thought, maybe we shouldn’t get too close to Io.

Sciency Words: Stochastic

June 23, 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:


At first glance, stochastic appears to have a pretty easy definition. Basically, it means random. A stochastic event can be defined, quite simply, as a random event. So why do scientists need this weird term? Why can’t they just say random if they mean random?

I’ve seen this word now in a surprisingly wide range of scientific fields, most recently in relation to the population dynamics of endangered species and then in relation to the magnetic field of Jupiter. The thing is that in actual usage, stochastic and random aren’t quite synonyms. A better definition for stochastic might be “seemingly random.”

The word originates from a Greek word meaning “to aim at” or “to shoot at.” So it’s an archery term, but the Greeks also used it to mean “to guess at.” I like this linguistic metaphor because a guess really is like aiming for the truth; whether or not you hit the mark is another matter.

Anyway, the word seems to have migrated from Greek to German to English, and in its modern scientific sense it refers to something that might be predictable in theory but appears to be random in practice. As an example, you may have heard that the flapping of a butterfly’s wings could set in motion a chain of events ultimately leading to a devastating hurricane.

In theory, these butterfly-initiated hurricanes could be predicted, if only we knew the exact locations and flapping behaviors of every single butterfly on Earth (along with a million and one other factors). But in practice, since we can’t gather all the necessary data, we can only make educated guesses about when and where the next hurricane will hit.

In other words, hurricanes are stochastic events. They seem random, even though they’re not.

Jupiter’s All Warm and Fuzzy Inside

May 30, 2017

Don’t let Jupiter’s stormy personality fool you. He’s all warm and fuzzy on the inside.

I have a couple more “Alien Eyes on Earth” posts on the way, but last week one of my favorite space missions was in the news: the Juno mission to Jupiter.

Now I have to confess I haven’t done a whole lot of research on what Juno’s found. I take it some of the highlights are:

  • We got a cool picture of Jupiter’s rings with the constellation Orion in the background.
  • Those cyclones clustered around Jupiter’s poles—those are still weird.
  • It sounds like something freaky is happening with Jupiter’s auroras. I’m planning to do a separate post on that in the near future.

But the thing that really grabbed my attention was this: Jupiter’s core is being described as “fuzzy.” I’m not sure how to visualize that, but it’s also being described as “partially dissolved,” which makes a little more sense to me.

We know about this because Juno is gravity mapping the planet—using highly precise measurements of Jupiter’s gravitational field to determine how mass is distributed in the planet’s interior.

We also know about it thanks to Juno’s magnetometer. Planetary magnetic fields are generated by an internal dynamo effect, the result of all that pressurized liquid metal swirling and churning around a planet’s core. But according to Juno’s magnetometer, it seems Jupiter’s magnetic field is not what we expected, which suggests… what? Multiple dynamo effects? A big dynamo in the middle with smaller dynamos surrounding it?

Again, I haven’t done any proper research about this. Not yet. But I had a thought that I wanted to throw out there: we never figured out why Neptune’s magnetic field is so out of whack.

So now I’m wondering if there could be a connection there. Could weird, confusing, complicated magnetic fields just be a common feature of gas giants?

Also, the Sun has a wildly complex tangle of magnetic field lines around it. Might there be a relationship between the weird magnetic fields of gas giant and the weirder magnetic fields of stars?

I don’t have any answers. I’m just speculating after all the Juno news last week. It’ll be interesting to see what Juno tells us next.

On Thursday, we’ll get back to those aliens studying Earth from a distance.


Jupiter Surprises in Its Closeup from Science Friday.

Jupiter Data from Juno Probe Surprises Scientists from Solar System Digest.

Jupiter Surprises in First Treasure Trove of Data from NASA’s Juno Mission from Spaceflight Now.

Sciency Words: Juno (An A to Z Challenge Post)

April 12, 2017

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, J is for:


The current NASA mission exploring Jupiter is named Juno. That stands for Jupiter Near-polar Orbiter. Except not really. I’m pretty sure someone came up with that acronym long after the Juno mission was already named.

According to a press release from 2011, NASA named its Jupiter mission after the Roman goddess Juno (a.k.a. Hera), the wife of Jupiter (a.k.a. Zeus). Now if you’re at all familiar with Greek and Roman mythology, you know Jupiter and Juno didn’t exactly have an ideal marriage.

In that 2011 press release, NASA reminds us of one specific story in which Jupiter tried to hide his “mischief” behind a veil of clouds. Of course the whole veil of clouds routine didn’t work, and Juno saw right through her husband’s trickery.

NASA was kind of brilliant with this specific mythological reference. It’s a lot cleverer than some silly acronym.

The Juno space probe is equipped with ultraviolet and infrared cameras, which can see through the top most layers of Jupiter’s atmosphere. Even better, Juno is carrying instruments for studying Jupiter’s magnetic field, which will indirectly tell us more about the planet’s core. And Juno will be mapping the planet’s gravitational field, which will reveal how mass is distributed in the planet’s interior.

In other words…

Next time on Sciency Words: A to Z, what’s the total mass of a kilogram?