Which Planet Has the Weirdest Magnetic Field?

October 23, 2018

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.


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.


NASA’s Next Flagship Mission

July 19, 2017

Let’s imagine you’re NASA. You have two big flagship-class missions coming up: one to search for life on Mars (launcing in 2020) and another to search for life on Europa (launching in 2022). These flagship missions are big, expensive projects, so Congress only lets you do one or two per decade.

After 2022, the next flagship mission probably won’t launch until the late 2020’s or early 2030’s, but still… now is the time for you to start thinking about it. So after Mars and Europa, where do you want to go next? Here are a few ideas currently floating around:

  • Orbiting Enceladus: If you want to keep looking for life in the Solar System, Enceladus (a moon of Saturn) is a good pick. It’s got an ocean of liquid water beneath it surface, and thanks to the geysers in the southern hemisphere, Enceladus is rather conveniently spraying samples into space for your orbiter to collect.
  • Splash Down on Titan: If there’s life on Titan (another moon of Saturn), it’ll be very different from life we’re familiar with here on Earth. But the organic chemicals are there in abundance, and it would be interesting to splash down in one of Titan’s lakes of liquid methane. If we built a submersible probe, we could even go see if anything’s swimming around in the methane-y depths.
  • Another Mars Rover: Yes, we have multiple orbiters and rovers exploring Mars already, but some of that equipment is getting pretty old and will need to be replaced soon. If we’re serious about sending humans to Mars, it’s important to keep the current Mars program going so we know what we’re getting ourselves into.
  • Landing on Venus: Given the high temperature and pressure on Venus, this is a mission that won’t last long—a few days tops—but Venus is surprisingly similar to Earth in many ways. Comparing and contrasting the two planets taught us how important Earth’s ozone layer is and just what can happen if a global greenhouse effect get’s out of control. Who knows what else Venus might teach us about our home?
  • Orbiting Uranus: This was high on NASA’s list of priorities at the beginning of the 2010’s, and it’s expected to rank highly again in the 2020’s. We know next to nothing about Uranus or Neptune, the ice giants of our Solar System. Given how many ice giants we’ve discovered orbiting other stars, it would be nice if we could learn more about the ones in our backyard.
  • Orbiting Neptune: Uranus is significantly closer to Earth than Neptune, but there’s an upcoming planetary alignment in the 2030’s that could make Neptune a less expensive, more fuel-efficient choice. As an added bonus, we’d also get to visit Triton, a Pluto-like object that Neptune sort of kidnapped and made into a moon.

If it were up to me, I know which one of these missions I’d pick. But today we’re imagining that you are NASA. Realistically Congress will only agree to pay for one or two of these planetary science missions in the coming decade. So what would be your first and second choices?


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.

Links

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.