Our Place in Space: The Great Red Spot

Hello, friends!  Welcome to Our Place in Space: A to Z!  For this year’s A to Z Challenge, I’ll be taking you on a partly imaginative and highly optimistic tour of humanity’s future in outer space.  If you don’t know what the A to Z Challenge is, click here to learn more.  In today’s post, G is for…

THE GREAT RED SPOT

Humanity is struggling right now.  There’s war and bigotry.  There’s disease and poverty and climate change.  Despite these problems, I still have tremendous hope for the future.  I still believe that we can work past our current problems and build a better future for ourselves and for our planet.  But when I think of this better and brighter future, there’s still one thing I worry about.  It’s a minor thing, but still… I worry: what’s going to happen to Jupiter’s Great Red Spot?  Will it still be there in the future, or will it slowly fade away and disappear?

In the late 1800’s, the Great Red Spot was observed to be approximately 50,000 kilometers wide.  For comparison, the entire Earth is only 13,000 kilometers in diameter.  But by 1979, when NASA’s Voyager space probes arrived at Jupiter, the Great Red Spot had shrunk to a mere 23,000 kilometers in width.  It was less than half the size it once was!  And today, it’s only 16,000 kilometers wide.  You see now why I’m worried.

I get a bit frustrated with news reports declaring that the Great Red Spot is certain to disappear.  I also get annoyed with news reports saying it’s certain not to disappear.  The popular press goes back and forth on this.  It’s sort of like those news reports you’ll hear about whether or not eggs are good for you.  First they’re good, then they’re bad, then they’re good if you cook them this way, then they’re still bad no matter how you cook them.  In a similar way, first the Great Red Spot is disappearing, then it isn’t, then it is again, and so on.

I think the popular press just doesn’t understand what it means when scientific research gets published.  Published research is best understood as part of an ongoing conversation.  One group of astronomers says they believe the Great Red Spot is disappearing for reasons X, Y, and Z.  Then another group of astronomers say they think it will endure for reasons A, B, and C.  Then maybe another group will contribute reasons J, K, and L to the discussion.  This back and forth discussion continues on and on in the pages of scientific journals, until some sort of scientific consensus is reached (or until the Great Red Spot actually disappears—that would also settle the debate).

But the popular press always seems to latch onto one published paper and present it to the general public as if it is the final word on the matter, as if it is a proclamation of scientifically proven fact.  That is until they latch onto the next published paper and present that as the final word.

So what’s really going to happen to the Great Red Spot?  Well, it’s undeniable that it has shrunk significantly over that last century or so.  Maybe it will keep shrinking until it’s gone, or maybe it’ll pick up steam again and start to expand once more.  Maybe the Great Red Spot goes through century-long phases of shrinking and expanding.  Maybe we just haven’t been observing it long enough to know that. Scientists are still studying this issue, comparing and contrasting their findings, and debating what it all means.  That’s often the way with science (and I hope you’ll keep that in mind the next time you see a news report that begins with the words “According to a new scientific study…”).

Even without the Great Red Spot, Jupiter would be an awe-inspiring sight.  I do hope, though, that it will still be there for all those future colonists on Callisto to see and enjoy.

Want to Learn More?

I found a few relatively recent articles that talk about the Great Red Spot and why it might or might not disappear.  These articles are, in my opinion, more responsible in how they present their information than other articles I’ve seen.

Our Place in Space: Callisto

Hello, friends!  Welcome to Our Place in Space: A to Z!  For this year’s A to Z Challenge, I’ll be taking you on a partly imaginative and highly optimistic tour of humanity’s future in outer space.  If you don’t know what the A to Z Challenge is, click here to learn more.  In today’s post, C is for…

CALLISTO

The major moons of Jupiter are Io, Europa, Ganymede, and Callisto.  In science fiction, Europa and Ganymede seem to get the most attention.  Sci-Fi writers often end up putting human colonists (or at least a handful of plucky human scientists) on the surfaces of one or both of these icy moons.  But today, I’m going to argue that Callisto would be a far more suitable home for future humans.

First off, and most importantly, there’s the issue of radiation.  The space around Jupiter is one of the most dangerous radiation environments in the entire Solar System.  As you can see in the highly technical diagram below, the radiation is most intense in the vicinity of Io.  The radiation levels get better in the vicinity of Europa and continue to taper off when you reach Ganymede.  You’re still soaking up a lot of radiation, though!  Callisto’s radiation levels, however, are fairly low.  You might even describe the radiation levels on Callisto as “survivable.”

Furthermore, planetary protection laws in the future may mean that both Europa and Ganymede are off limits to human settlers.  Scientists today are 99.99% sure that Europa has a vast ocean of liquid water beneath her surface, and (as you know) wherever there’s water, there may also be life.  There’s evidence suggesting Ganymede may have a subsurface ocean, too.  Europa is often said to be the #1 most likely place where we might find alien life here in the Solar System.  While the odds of finding life on Ganymede are considerably lower, the possibility of Ganymedean life shouldn’t be ignored.

There are already international agreements in place regarding extraterrestrial life.  Space agencies like NASA, the E.S.A., and others are legally obligated to do everything they can to protect suspected alien biospheres from our Earth germs (and also to protect Earth’s biosphere from any germs we might find in outer space).  For obvious reasons, these international agreements haven’t exactly been tested in court, and it’s a little unclear how they would be enforced.

But in a future where human civilization is spreading out across the Solar System, I’d imagine bio-contamination laws would become stronger, not weaker.  Europa would almost certainly be declared off-limits to humans, unless it is proven beyond a shadow of a doubt that no aliens currently live there.  Ganymede may end up being off-limits, too, for the same reason.

Meanwhile, we have Callisto.  Scientists who want to study possible biospheres on Europa and Ganymede could set up a research station on Callisto.  From there, they could keep a close eye on the other moons of Jupiter.  They could operate remote-controlled probes to explore Europa and Ganymede without risking contamination, or they could go on brief excursions to Europa and Ganymede themselves (taking proper safety precautions, of course).  While they’re at it, these scientist could also explore Io.  Io is the most volcanically active object in the Solar System.  There is virtually no chance that we’ll find life there, but studying Io’s volcanoes would still be interesting.

I’d be remiss if I didn’t mention this: Callisto might have liquid water beneath her surface, too.  Not as much liquid water as Ganymede, and nowhere near as much as Europa, but still… it’s possible.  Which means there’s a slim possibility that there could be life on Callisto.  But in Callisto’s case, it is a very slim possibility.  Based on what we currently know about Jupiter’s moons, Callisto still seems like the best place for humans to live.  The radiation levels are much lower, the risk of bio-contamination is negligible…  Yeah, if I were a science fiction writer, I’d put my human colonists on Callisto.

Want to Learn More?

In 2003, NASA published a plan to send astronauts to Callisto, with the intention of using Callisto as a base of operations to explore the other Jovian moons.  Click here to read that plan.  Some of the information is out of date, of course, but it’s still got some interesting ideas.  Maybe someday, something like this plan could work!

I’d also recommend this article on Planetary Protection Policy, covering some of the rules that are already in place to protect planets and moons where we might find alien life.


P.S.: If I were a science fiction writer…?  Wait a minute, I am a science fiction writer!  Click here if you want to buy my first book.  It’s not set on Callisto, unfortunately, but it’s still a fun story.

Would Europa Life Have Bioluminescence?

Hello, friends!

All month long, we’ve been talking about Europa, the sixth moon of Jupiter.  Scientists are 99% sure that there’s an ocean of liquid water beneath Europa’s icy crust, and speculation runs rampant about possible alien life swimming around in that subsurface ocean.

I’m currently reading a book called The Zoologist’s Guide to the Galaxy, by Arik Kershenbaum.  The book takes the fairly uncontroversial stance that the same evolutionary processes that shaped life on Earth would shape life on other worlds (uncontroversial among the scientific community, at least).  Specific details about biochemistry or genetics might be wildly different, but general principles like natural selection are likely universal.

Other science writers follow the same premise when imagining what we might find beneath the surface of Europa.  The environment is presumed to be very similar to the deepest, darkest reaches of Earth’s oceans.  Therefore, the same evolutionary pressures should apply, and Europa-life should have much in common with the deep ocean creatures we find here on Earth.

For example, Europa-life would probably cluster around hydrothermal vents, or similar geological hot spots, at the bottom of the ocean.  It’s nice and warm there, and there are plenty of tasty nutrients billowing up from the rocky mantle.

Another example: abyssal gigantism, which is the tendency for organisms in the deep ocean to grow to enormous sizes (compared to their shallow water cousins).  Scientists aren’t 100% sure why abyssal gigantism happens, but it may have something to do with metabolic efficiency.  If life in Earth’s deep oceans needs to be gigantic for the sake of metabolic efficiency, then Europa-life would probably be gigantic too.

A lot of science writers also predict that bioluminescence will be common on Europa.  It’s fairly common here on Earth, especially in the deepest, darkest regions of Earth’s oceans.  And as you can see in this totally legit photo from the Mariana Trench, bioluminescence is really pretty.

But while predictions about abyssal giants and hydrothermal vents make a certain logical sense to me, I’m not convinced bioluminescence makes sense on Europa.  As I understand it, life on Earth developed eyes first, and bioluminescence came later.

Having some sort of light-detecting organ makes sense on a world where there’s plentiful sunlight.  There’s an obvious evolutionary advantage to having eyes here on Earth.  And then, if some Earth-creatures decided to swim down to the bottom of the ocean, it makes sense for them to develop bioluminescence in order to help them see each other and the environment around them (or to help them lure in food).

But the ocean on Europa lies beneath a thick shell of ice.  There’s no sunlight there.  There has never been sunlight there.  So what is the evolutionary advantage of having eyes?  And if there’s no evolutionary advantage to having eyes, what would be the evolutionary advantage of bioluminescence?

Whenever Europa-life is depicted in science fiction, it’s almost always lit up in bold, bioluminescent colors.  A lot of science communicators seem to envision Europa-life that way too.  And why wouldn’t they?  To see all those strange alien creatures waving their glow-tentacles around—that would be an awe-inspiring sight!  But as awesome as it would be to see Europa-life in all its bioluminescent glory, I cannot think of a good reason why Europa-life would evolve that ability. Can you?

WANT TO LEARN MORE?

I haven’t finished reading The Zoologist’s Guide to the Galaxy yet, but what I’ve read so far is good, thought-provoking stuff.  If you’re interested in what alien life might really be like, scientifically speaking, then I’d say this book is worth a look.

The Colors of Europa: What’s That Red Stuff on Europa’s Surface?

Hello, friends!

Europa (one of the moons of Jupiter) is said to have the smoothest, youngest-looking surface of any planet or moon in the whole Solar System.  But Europa’s surface, as astonishingly smooth as it is, still isn’t perfectly smooth.  As you can see in the totally legit Hubble image below, there are dark-colored cracks and rough patches, and there are also blob-shaped discolorations that kind of look like the birthmark on Mikhail Gorbachev’s head.

I don’t want to get political on this blog, but this Gorbachev quote seems appropriate to me.

Fifteen to twenty years ago, when I started teaching myself about space, the things I read about Europa made it sound like scientists had no idea what caused the discolorations on Europa.  The blue-grey regions were frozen water, obviously; but the reddish-brown stuff… that could be anything!  Tholin?  Sulfur?  Amino acids?  Alien poo?  Anything.  Those reddish-brown areas may as well have been marked “here be dragons,” chemically speaking.

Today, though, it seems like scientists have seriously narrowed down the range of possibilities.

Sulfuric Acid: Io, one of Jupiter’s other moons, happens to be the most volcanically active object in the Solar System.  Io is so volcanically active that sulfur from Io shoots up into space and spreads to the neighboring Jovian moons.  On Europa, Io’s sulfur can react with Europa’s frozen water to create sulfuric acid (H2SO4).  This could explain some of the discoloration we see on Europa.

Epsom Salts: The discoloration could also be explained by a different sulfur compound: magnesium sulfate (MgSO4).  Also known as Epsom salts, magnesium sulfate is found in Earth’s oceans, and it’s reasonable to guess that it might be found in Europa’s subsurface ocean as well.  If so, magnesium sulfate could be spilling onto Europa’s surface through cracks and fissures in the surface ice.

Table Salt: In a previous post, I told you about the intense radiation environment on Europa’s surface.  Recent laboratory experiments have shown that sodium chloride (NaCl) can change color when exposed to that much radiation.  Just like magnesium sulfate, sodium chloride could be welling up to the surface through cracks and fissures in the ice.  And after a bit of radiation exposure, sodium chloride could cause the kind of discoloration we see on Europa.

So which of these three chemicals causes the discoloration on Europa?  Or is it some combination of all three?  From what I’ve read, I don’t think the scientific community has reached a consensus on that.  Much of the discoloration we see is in the vicinity of cracks, fissures, or other breaches in Europa’s surface.  That seems to favor sodium chloride and/or magnesium sulfate as the explanation.  However, one hemisphere of Europa is more exposed to the sulfur cloud coming from Io than the other.  And guess what!  The hemisphere that’s more exposed to Io is also more discolored!  That evidence seems to favor sulfuric acid as the explanation.

But again, I don’t think there’s a consensus about this yet.  This is still a topic of some debate among the scientific community.  However, the fact that we’ve gone from “it could be anything, here be dragons (chemically speaking)” to “it’s one or more of these three chemical substances” seems like real progress to me.

WANT TO LEARN MORE?

I relied on these three research papers for this post.  Together, I think they show the evolving conversation about Europa’s discolored regions over the last few years.

I wish I could recommend some easier and more accessible articles on this topic, but the ones I read all made claims like “scientists prove Europa’s covered in Epsom salts!”  Those sorts of articles do not reflect what the actual research papers are saying.

Radiation on Europa: How Quickly Would It Kill You?

Hello, friends!  If you happen to have any radiation protection clothing lying around—like those lead aprons they give you for X-rays at the dentist—I recommend putting it on now before you read any further.  In today’s post, we’ll be exploring the radiation environment of Europa.

Europa is often listed as one of the top four places in the Solar System where we might find alien life.  That makes exploring Europa a top priority for NASA and other space agencies.  Unfortunately, Europa is one of the moons of Jupiter, with an orbit that puts Europa deep inside Jupiter’s radiation belts.

Radiation is going to be a problem wherever you go in space, but the radiation belts around Jupiter are extra scary. If you were to spend a few days on the surface of the Moon or Mars without any sort of radiation protection gear, you’d end up with a significantly higher risk of developing cancer at some point later in life.  If you spent a similar amount of time on the surface of Europa without radiation protection, you wouldn’t live long enough to worry about cancer.  Radiation sickness would kill you in a matter of days—maybe a matter of weeks, if you’re “lucky.”

– NASA’s Juno space probe flying through radiation near Jupiter.

Even robotic spacecraft have a tough time dealing with Jupiter’s radiation belts.  The Juno mission, currently orbiting Jupiter, has all its mission critical electronics sealed up inside what NASA calls a radiation vault.  It’s basically a big, heavy box with thick walls made of titanium.  The radiation vault cannot block all of the radiation, but it blocks enough of it that Juno should survive long enough to finish its mission.

NASA’s upcoming Europa Clipper mission, which will take an even closer look at Europa, will be equipped with a similar radiation vault.

Before we end today’s post, some of you may be wondering what all this radiation means for potential alien organisms living on Europa.  Well, it probably wouldn’t affect them much, if at all.  The aliens (if they exist) would be swimming around in Europa’s subsurface ocean, beneath several kilometers worth of water ice.  And large quantities of water happen to be one of the very best radiation shields nature can provide.

WANT TO LEARN MORE?

  • “Colonization of Europa” from Wikipedia.  Yeah, it’s a Wikipedia article, but if you’re interested in what it would take to put human beings on the surface of Europa, this article is a pretty good place to start.
  • “Juno Armored Up to Go to Jupiter” from nasa.gov.  This is a press release from 2010, when the Juno spacecraft was still under construction.  It describes, in plain English, what Juno’s radiation vault is and why Juno needs it so badly.
  • “Spent Fuel Pool” from What If?  For those of you who didn’t know about water’s incredible radiation blocking powers, this is an amusing look at water’s incredible radiation blocking powers.

How Do They Know That: Europa’s Subsurface Ocean

Hello, friends!

This month is Europa month here on Planet Pailly!  For those of you who haven’t met Europa before, she’s one of the moons of Jupiter, and she’s generally counted among the top four places in the Solar System where we might find alien life.  This is in large part because Europa has a vast, global ocean of liquid water hidden beneath her surface.  By most estimates, Europa has twice as much liquid water as Earth!

But one might reasonably ask how we know, for certain, that Europa’s ocean of liquid water exists.  I mean, no space probe has ever cracked through Europa’s surface to check.  Not yet, anyway.  Which brings us to another episode of “How Do That Know That?”

HOW DO THEY KNOW THAT?
EUROPA’S SUBSURFACE OCEAN

There are three main lines of evidence pointing to the existence of Europa’s ocean: spectroscopic evidence, gravitational evidence, and magnetic evidence.

  • Spectroscopy: Every chemical substance in the universe interacts with light in its own unique way.  Very specific wavelengths of light will be absorbed and/or emitted, depending on what chemical substance you’re looking at.  So by measuring the wavelengths of light reflecting off Europa, scientists could determine what Europa’s surface is made of.  I won’t leave you in suspense.  The answer is water.  Frozen water.
  • Gravity: In the 1990’s, NASA’s Galileo spacecraft conducted several close flybys of Europa.  Each time, Europa’s gravity nudged Galileo ever so slightly off course.  By measuring exactly how much gravitational nudging Galileo experienced, scientists could calculate what Europa’s internal structure must be like.  Turned out there was a thick layer of low density material near the surface.  Water, in either a frozen or liquid phase, has a pretty low density.
  • Magnetism: Jupiter has an absurdly powerful magnetic field.  As Europa orbits Jupiter, a mysterious something inside Europa responds to Jupiter’s magnetism, creating what’s called an “induced magnetic field” around Europa.  Once again using data from the Galileo spacecraft, scientists could measure the shifting and changing intensity and orientation of Europa’s magnetic field as she orbited Jupiter.  As it so happens, a large volume of saltwater would react to Jupiter’s magnetic field in much the same way as the mysterious something inside Europa.

Taken individually, each line of evidence would have to be considered inconclusive.  Suggestive, perhaps, but ultimately inconclusive.  Sure, spectroscopy tells us there’s frozen water on Europa’s surface, but that layer of frozen water might only be skin deep.  Gravity data tells us there’s a very deep layer of low density material, but gravity data, by itself, cannot tells us what that low density material is.  And if you didn’t know anything else about Europa’s internal structure or chemical composition, then her induced magnetic field could be explained in many different ways.  Taken together, though, these three lines of evidence leave little room for doubt: there’s an ocean of liquid water (specifically saltwater) beneath the surface of Europa.

Science is, in my mind, a little like trying to solve a crossword puzzle.  Not all the answers are obvious at first, but with each word in the puzzle you find, the intersecting words become a little easier to figure out.  Maybe you thought the answer to 17 across (What’s beneath the surface of Europa?) could be three or four different things.  But then you found out the middle letter is a T, and the last letter is an R, and now you can narrow down the possibilities to one and only one solution.

By following multiple lines of evidence, scientists can now say, with a very high degree of certainty, that there’s an ocean of liquid water beneath the surface Europa.  Exactly how thick is the ice above that ocean?  And what minerals are present in the ocean?  How much hydrothermal activity occurs at the bottom of that ocean?  Those are some of the next questions that need answers.

WANT TO LEARN MORE?

There’s a lot of information out there about Europa.  A little too much, actually.  It’s hard to sort through it all.  So if you want to learn more about Europa, I highly recommend Alien Oceans: The Search for Life in the Depths of Space by Kevin Peter Hand.  It’s got all the best Europa facts you could ever want, all together in a single book.  And Hand devotes a full chapter to each of those lines of evidence that I listed above.

Oops! I Learned Something Wrong About Io

Hello, friends!

As you may remember from a previous post, Io is my favorite moon in the Solar System.  He may not be the prettiest moon, and he certainly isn’t the most habitable.  I, for one, would never, ever, ever want to live there.  You see, Io is the most volcanically active object in the Solar System.  He is constantly—and I do mean constantly!—spewing up this mixture of molten hot sulfur compounds.  It gets everywhere, and it is totally gross.

But it’s also super fascinating—fascinating enough that Io ended up becoming my #1 favorite moon in the whole Solar System.  I’ve read a lot about Io over the years.  I thought I understood Io pretty well.  But I was wrong.  One of the facts in my personal collection of Io-related facts was based on a fundamental misunderstanding of how Io’s volcanism works.  Let me explain:

Io is caught in this gravitational tug of war between his planet (Jupiter) and his fellow Galilean moons (Europa, Ganymede, and Callisto).  Jupiter’s gravity pulls one way; the moons pull another; Io is caught in the middle, feeling understandably queasy.  I always thought this gravitational tug-of-war was directly responsible for Io’s volcanic activity.  But it’s not.  Recently, while reading a book called Alien Oceans: The Search for Life in the Depths of Space, I realized that I had some unlearning to do.

The gravitational tug-of-war has forced Io into a highly elliptical (non-circular) orbit.  This means there are times when Io gets very close to Jupiter, and times when Io is much farther away.  When Io’s orbit brings him close to Jupiter, Jupiter’s gravity compresses Io’s crust.  And when Io moves father away, his crust gets a chance to relax.  This cycle of compressing and relaxing—of squeezing and unsqueezing—causes Io’s interior to get hot, which, in turn, keeps Io’s volcanoes erupting.

This squeezing and unsqueezing action wouldn’t happen if not for Io’s highly elliptical orbit, so the gravitational tug-of-war with Jupiter’s other moons is still partially responsible for Io’s volcanism.  But the tug-of-war is not the direct cause of Io’s volcanism, as I always assumed it to be.

I wanted to share all this with you today because some of you may have had the same misunderstanding about Io that I did.  Hopefully I’ve cleared that up for you!  But also, I think this is a good example of how the process of lifelong learning works.  If you’re a lifelong learner (as I am), you may have favorite topics that you think you know an awful lot about.  But there’s always more to learn, and sometimes learning more means unlearning a few things that you thought you already knew.

WANT TO LEARN MORE?

If you’re an Io fanatic like me, I highly recommend Alien Oceans: The Search for Life in the Depths of Space by Kevin Peter Hand.  The book is mainly about Europa and the other icy/watery moons of the outer Solar System, but there’s a surprising amount of information in there about Io, too.  Apparently, if it turns out that Europa really is home to alien life (as many suspect her to be), then Io may have played a crucial role in making that alien life possible.

Sciency Words: Chromophore

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we take a closer look at those weird words scientists use.  Today’s Sciency Word is:

CHROMOPHORE

Recently, just for fun, I was watching an old interview with Carl Sagan (the same interview I cited in Wednesday’s post, by the way).  Around 25 minutes into that interview, Sagan talks a little about Jupiter, and he mentions that Jupiter’s distinctive coloration is caused by something called “chromophores.”

Sagan then goes on to say, flippantly, that we call it a chromophore because “we don’t know what it is.”  But the word chromophore is not quite a meaningless placeholder term for a thing we don’t understand (like dark matter).

Definition: A chromophore is a group of atoms within a larger molecule that are responsible for giving that molecule its color.  So, for example, chlorophyll molecules have chromophores in them that soak up red and blue light, thus giving chlorophyll its characteristically green appearance.

Etymology: Chromophore comes from two Greek words meaning “color” and “bearing.”  According to the Oxford English Dictionary, the earliest recorded usage of the word is in this 1879 dictionary of chemistry.  The word appears in a section about the chemical reactions used to make dyes.

Fun fact: just like the planet Jupiter, the oil pastels I used to draw this picture of Jupiter contain “chromophores.”

To say that Jupiter’s coloration is caused by chromophores is absolutely correct, but somewhat unhelpful.  It’s like asking “what caused that sound?” and being told “vibrations of the air.”  But, at least for now, it seems we don’t have a better answer.  To the best of my knowledge, we still don’t know which chemicals, specifically, are responsible for giving Jupiter his distinctive coloring (though Jupiter researchers have a lot of plausible-sounding guesses).

But whatever those chemicals are, they must contain chromophores.  Almost by definition, that must be true.

Shameless Self Promotion Time: Looking for Jupiter T-shirts, Jupiter notebooks, or other Jupiter-themed stuff?  Click here to check out all the Jupiter-related products available in the Planet Pailly store on Redbubble!

What Color are All the Planets?

Hello, friends!

So as you know, Earth is “the Blue Planet” and Mars is “the Red Planet.”  By my math, that leaves us with six other planets in our Solar System that don’t have color-related nicknames.  Today, I’d like to try and fix that.

Jupiter was the toughest.  He’s actually lots of different colors: red, grey, white, orange… and then the Juno mission recently showed us that Jupiter’s polar regions are blue!  Of course Jupiter is most famous for being red in that one specific spot, but even the Great Red Spot changes colors from time to time, fading from red to pink to white before turning red again.

Anyway, those are my picks for the color-related nicknames for all the planets.  Do you agree with my picks?  Disagree?  Let me know in the comments below!

More Phosphine Fever with Jupiter and Saturn

Hello, friends!  When the news came out that phosphine gas had been discovered on Venus, I’m sure we were all thinking the same thing: So what?  There’s phosphine on Jupiter and Saturn too.  Everybody knows that (don’t they?), and nobody thinks that means Jupiter or Saturn have life.

Fortunately, the authors of this paper from Nature Astronomy address the obvious Jupiter/Saturn issue right away:

[Phosphine] is found elsewhere in the Solar System only in the reducing atmospheres of gas giant planets, where it is produced in deep atmospheric layers at high temperatures and pressures, and dredged upwards by convection.  Solid surfaces of rocky planets present a barrier to their interiors, and PH3 would be rapidly destroyed in their highly oxidized crusts and atmospheres.

In other words, it’s very simple for astrophysicists to explain how Jupiter and Saturn make their phosphine.  Gas giants with hydrogen-rich atmospheres can do this easily. But how does Venus do it?  That’s a much harder question.  The only other small, rocky planet with phosphine in its atmosphere is Earth, and we know where Earth’s phosphine comes from: life.

And that is why the discovery of phosphine on Venus is so exciting, while the presence of phosphine on Jupiter and Saturn is no big deal.