Sciency Words: Nice Model

May 18, 2018

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:

NICE MODEL

I recently assembled Lego’s Saturn V rocket set, and I have to say it’s a really nice model.  It even has these little orange pieces to represent the floaty things for when the Apollo capsule returns to Earth and splashes down in the ocean. That, I thought, was a really nice touch!

But as nice as that Lego model is, that’s not the model we’re talking about today.  Nope, today we’re talking about the Nice model, with a capital N.

In May of 2005, three papers were published in the journal Nature which did a nice job explaining some of the big mysteries of our Solar System.

  • First (in order of page number) was a paper on the anomalous orbital eccentricities and inclinations of the four gas giant planets.
  • Next came a paper on the Trojan asteroids which hang out around Jupiter’s Lagrange points, 60º ahead and 60º behind Jupiter in its orbital path.
  • And lastly, there was a paper on the Late Heavy Bombardment, a period of time when the Moon (and also the four inner planets) got pummeled with asteroids.

All three of these papers share a common idea: that the four gas giants of our Solar System must have started out much closer together, with a broad disk of rocky and icy debris beyond them, like a super-sized Kuiper belt.  Then, approximately 700 million years after their initial formation, three of those gas giants (Saturn, Uranus, and Neptune) started drifting farther and farther away from the Sun and away from each other.

Jupiter seems to have drifted slightly closer to the Sun, but stopped short of entering and demolishing the inner Solar System thanks to a last minute gravitational interaction with Saturn (thanks, Saturn!).

As the gas giants spread out, they threw that super Kuiper belt into chaos.  Some of that rocky and icy debris was hurled toward the inner planets, causing the Late Heavy Bombardment.  Some of the debris got stuck around Jupiter’s Lagrange points, becoming the Trojan asteroids.  And with so many complicated gravitational interactions happening at once, it’s no wonder the four gas giants ended up with some anomalies in their orbital paths.

This one idea—that the gas giants drifted apart after they formed—does a pretty nice job explaining three of the biggest mysteries about our Solar System.  But sadly, that’s not why it’s called the Nice model.  The name actually isn’t pronounced like the English word “nice” but rather like the French city of Nice (which rhymes with geese or fleece).  That’s because the model was originally formulated at an observatory in Nice, France.

Unfortunately, I didn’t find that out until I’d already sprinkled a bunch of nice puns into this post, and I don’t feel like taking them out.


The End for Juno?

May 15, 2018

We’ve always known the Juno Mission to Jupiter would be a short one.  Often times planetary science missions like Juno will get extra funding for extended missions, because it costs less to keep using a spacecraft you already have than it does to design, build, and launch a new one.  But as I wrote two years ago, this really wouldn’t be an option for Juno.

The reason is that Jupiter has at least one moon (Europa) and perhaps two others (Ganymede and Callisto) which may be home to alien life.  Based on everything I’ve read about Europa in particular, I think it would be a bigger surprise if we didn’t find life there; that’s how promising the place looks.

NASA absolutely cannot risk letting Juno crash into and contaminate any of those moons (especially Europa).  So after completing its scheduled mission, which was meant to take about two years, Juno would do a suicide run into Jupiter’s atmosphere, destroying itself to ensure there are no future accidents, and also collecting a little extra atmospheric data in the process.

Except shortly after Juno arrived in Jupiter orbit, it ran into some engine trouble, something to do with a pressure valve opening too slowly. As a result, Juno wound up stuck in a much wider and much longer orbit than originally planned.  Rather than getting a science pass every 14 days, we’re getting them every 53 days, which has dramatically slowed down Juno’s progress.

Juno’s two years are almost up, but because of that pressure valve malfunction its mission is only half complete.  So now Juno needs that mission extension that it was never supposed to get.  A planetary scientist working on the Juno Mission was recently quoted as saying: “I think for sure the continuation mission will go on.”  He then added: “I’m hopeful but nervous.”

Funding for the Juno mission (for ground operations, mission control stuff, etc) will run out in July of this year. Given the circumstances, I have to assume NASA will grant Juno an extension, but as of this writing they have not done so.  Navigating the bureaucracy here on Earth can be just as nerve-wracking as all the hazards of space.

I’m not sure how much Congress is involved in the decision making process here, so maybe that’s what’s holding things up. Or maybe Juno has run into other technical issues which NASA hasn’t made public yet.  I don’t know, but if anything else went wrong with the spacecraft during its extended mission, we might lose control of it, and we really, really do not want it crashing into those icy-on-the-outside, watery-on-the-inside moons.

So fingers crossed.  Hopefully everything works out okay and Juno can get its extended mission.


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.

Jupiter.Aurora.HST.mod.svg

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:

PLASMA TORUS

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:

DECAMETRIC RADIO EMISSIONS

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:

STOCHASTIC

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.