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?

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:


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:


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?


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


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.


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.


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.

Sciency Words: Hot Spots of Jupiter

July 22, 2016

Sciency Words MATH

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 all expand our scientific vocabularies together. Today’s term is:


This is Jupiter.

Ag05 Great Red Spot

And this is Jupiter in infrared.

Jy22 Infrared Jupiter

In 1995, the Galileo spacecraft dropped a small probe into Jupiter’s atmosphere. It was supposed to sample the chemicals in Jupiter’s clouds, but in a case of extraordinary bad luck, the probe fell into an empty gap between cloudbanks and collected virtually no data.

I like to imagine the clouds separating before the probe, like Moses parting the Red Sea, but I’m sure that’s not how it actually happened.

These gaps in the Jovian clouds are called hot spots. The thin atmospheric gases in these regions are actually quite cold, but when viewed in infrared, they appear hot due to the intense heat of Jupiter’s interior shining through.

The hot spots form—they always form—about seven degrees north of the equator. Eight to ten of them will appear at a time, evenly spaced along that seven degrees north longitude line, wrapping all the way around the planet.

This has led scientists to conclude that Jupiter’s hot spots are caused by a standing wave (more technically, a Rossby wave) in Jupiter’s atmosphere. The peaks and troughs of the wave correspond to the thickening and thinning of the surface clouds.

The Juno spacecraft’s JIRAM instrument (Jovian InfraRed Auroral Mapper) is specifically designed to study Jupiter’s aurorae (as the name implies) and also the hot spots. By staring straight down into a hot spot with an infrared spectrometer, scientists hope to identify the chemical composition of the deeper atmospheric layers. Among other things, they believe they’ll find a layer of water clouds.

Of course the Great Red Spot is a weird and mysterious phenomenon too. It deserves the high level of scrutiny it gets. But of all the spots on Jupiter, the hot spots may turn out to be the most interesting and revealing of the planet’s features.


Jupiter’s Atmosphere Has Weird Hot Flashes from

“Hot Spots” Ride a Merry-Go-Round on Jupiter from

Juno: What’s in a Name?

July 19, 2016

Why is NASA’s current mission to Jupiter called Juno? The answer might seem obvious to anyone with even a passing familiarity with Roman mythology. Jupiter was the king of the gods, and Juno was his queen. Except NASA was a bit cleverer than that.

In this press release from 2011, NASA reminds us that the legendary Jupiter (a.k.a. Zeus) would hide his mischief from his wife, Juno (a.k.a. Hera), by concealing himself and said “mischief” in a veil of clouds.

Jy19 Mythical Juno

By mischief, of course, NASA means mistress, and the veil of clouds routine didn’t work one bit. I believe NASA is specifically referring to the story where Jupiter seduces Io, one of Juno’s own high priestesses!

As for the planet Jupiter, NASA would really like to take a peek beneath the thick clouds of the upper atmosphere. That is precisely what the Juno spacecraft is designed to do, using a variety of techniques from gravity mapping to infrared spectroscopy.

Jy19 Scientific Juno

Also, Juno will not be approaching or interacting with any of Jupiter’s moons (not even Io). In fact, Juno’s mission plan was designed to avoid any close encounters with the moons (most of which are named after Jupiter’s other “mischiefs”) due to planetary protection concerns.

This too strikes me as symbolically appropriate in light of the ancient mythology.