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.


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.


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:

JUNO

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?


Sciency Words: Frost Line

December 23, 2016

Welcome to a very special holiday edition of Sciency Words! Today’s science or science-related term is:

FROST LINE

When a new star is forming, it’s typically surrounded by a swirling cloud of dust and gas called an accretion disk. Heat radiating from the baby star plus heat trapped in the disk itself vaporizes water and other volatile chemicals, which are then swept off into space by the solar wind.

But as you move farther away from the star, the temperature of the accretion disk tends to drop. Eventually, you reach a point where it’s cold enough for water to remain in its solid ice form. This is known as the frost line (or snow line, or ice line, or frost boundary).

Of course not all volatiles freeze or vaporize at the same temperature. When necessary, science writers will specify which frost line (or lines) they’re talking about. For example, a distinction might be made between the water frost line versus the nitrogen frost line versus the methane frost line, etc. But in general, if you see the term frost line by itself without any specifiers, I think you can safely assume it’s the water frost line.

Even though our Sun’s accretion disk is long gone, the frost line still loosely marks the boundary between the warmth of the inner Solar System and the coldness of the outer Solar System. The line is smack-dab in the middle of the asteroid belt, and it’s been observed that main belt asteroids tend to be rockier or icier depending on which side of the line they’re on.

It was easier for giant planets like Jupiter and Saturn to form beyond the frost line, since they had so much more solid matter to work with. And icy objects like Europa, Titan, and Pluto—places so cold that water is basically a kind of rock—only exist as they do because they formed beyond the frost line. This has led to the old saying:

dc23-outer-solar-system-christmas-party

Okay, maybe that’s not an old saying, but I really wanted this to be a holiday-themed post.


What’s Up with Juno?

December 20, 2016

It’s been awhile since we checked in with Juno, the NASA space probe currently orbiting Jupiter. So Juno, how’s the mission going?

dc20-juno-update-1

Uh-oh. That doesn’t sound good. What happened?

dc20-juno-update-2

Okay, here’s a quick timeline of events:

  • On July 4, 2016, Juno entered orbit of Jupiter. The main engine worked flawlessly at the time.
  • On August 27, 2016, Juno performed its first science pass of Jupiter. All its instruments appeared to be in working order.
  • On October 19, 2016, Juno was supposed to shorten its orbital period from 53 days to 14 days, but there was a problem with the main engine. Plan B was to just do another science pass, but then there was a problem with the main computer.

According to this article from Spaceflight 101, we now know what happened with the computer, and it sounds like it’ll be a fairly easy fix. The malfunction was caused by an instrument called JIRAM. Continuing with our timeline:

  • On December 11, 2016, Juno performed another science pass, this time with JIRAM switched off. All the other science instruments seem to be in working order, and a software patch for JIRAM will be uploaded soon.
  • Coming February 2, 2017, Juno will approach Jupiter again. This will likely be another science pass, since NASA still doesn’t know what’s wrong with the main engine.

The main engine is turning out to be the real problem. According to a press release from October, some pressure valves that should have opened in a matter of seconds took several minutes to open. Until NASA figures out why that’s happening, they’re going to leave Juno’s orbit alone.

Juno can still perform its mission in its current 53-day orbit; it’ll just take longer. We’re looking at five years rather than the original year-and-a-half. That screws up the original science observation calendar, and the prolonged exposure to Jupiter’s intense magnetic field might lead to more computer glitches in the future.

dc20-juno-update-3

Fingers crossed.


Weather Report from Jupiter

September 12, 2016

Juno has completed its second flyby of Jupiter, skimming close to the atmosphere and managing to get some interesting pictures of Jupiter’s polar regions.

sp12-juno-polar-flyby

Apparently we’ve never gotten a good look at Jupiter’s poles before. I imagine there’s a lot of frantic technical analysis going on right now at NASA, but not a whole lot of info has been released to the public so far.

We do have a press release, which I’m taking as a small preview of the real science that’s still to come. From the press release, we’ve learned that:

  • There’s a heck of a lot of storms, sort of clustered together. It’ll be interesting to find out which way they rotate. Are we looking at cyclones or anticyclones? (The Great Red Spot is an anticyclone, by the way).
  • Apparently cast-shadows are visible, suggesting clouds of varying altitudes. I’m guessing we’ll learn something about regional temperature and pressure variations from that.
  • The clouds have a bluish tint. In my inexpert opinion, that might indicate elevated concentrations of methane (the gas that makes Uranus and Neptune look so blue). That would be a change from the ammonia clouds we’re used to seeing in Jupiter’s upper atmosphere.

In short, it sounds like Jupiter’s polar regions have a whole separate ecosystem of clouds and storms. Do these storm systems function independently from the belts and zones observed at other longitudes, or could there be some complex relationship at work?

The Juno spacecraft has a little less than two years to find out. Good luck, Juno. We’re all counting on you.


Enjoy Juno While You Can

July 26, 2016

In case you haven’t guessed, I am super excited about the Juno Mission. I’m looking forward to writing (and drawing) about it a lot over the coming years.

Jy26 Jupiter and Juno 1

But for the moment, we’re sort of stuck in a holding pattern.

Juno successfully entered orbit of Jupiter on July 4, 2016; however, it will have to complete a second engine burn, scheduled for October 19, before the science mission really begins.

In the meantime, I thought I’d run through some of Juno’s equipment and some of the mission objectives I’m most excited about.

  • Juno Cam: It’s a camera. It takes pretty pictures. Nothing to get too excited about, except Juno’s orbit takes it extremely close to Jupiter. We should be getting some stunning close-ups.
  • JEDI and JADE: Juno has two instruments, named JEDI and JADE, which will detect ionized particles in Jupiter’s magnetosphere. JADE will focus on low-energy particles; JEDI will cover the high-energy stuff. As a science fiction writer, I’m looking forward to knowing precisely what sort of radiation dangers my characters will face near Jupiter specifically and gas giant planets in general.
  • UVS and JIRAM: Juno can see in ultraviolet (using its UVS instrument) and infrared (using JIRAM). So yes, Juno can “see right through” Jupiter, or at least it can see through some of the topmost layers of clouds. Also, observations in UV and IR will help us identify the chemical composition of the clouds. Maybe we’ll finally find out what makes the Great Red Spot red.
  • Gravity Science: By monitoring subtle variations in Jupiter’s gravity, Juno can determine how matter is distributed in the planet’s interior. There are a lot of hypothetical new states of matter that might exist in the interiors of gas giants (like metallic hydrogen); Juno’s gravity experiments could tell us if our hypotheses are correct.

Juno is scheduled to make a suicide dive into Jupiter’s atmosphere on February 20, 2018.

Jy26 Jupiter and Juno 2

I’d hoped there might be a possibility for a mission extension. The Cassini mission got an extra nine years to study Saturn. But NASA doesn’t want to risk contaminating any of Jupiter’s moons (especially Europa).

So over the next two years, we better make the most of Juno while we still have her.

P.S.: JEDI stands for Jovian Energetic particle Detection Instrument. The Star Wars reference is surely a coincidence; it’s not like there are any nerds working at NASA.