We have dust storms on Earth and of course the famous dust storms on Mars. There are even dust storms on Titan. What causes these storms and how do they work differently on the worlds in the solar system. But what about the exoplanets?
The bane of solar panels, humans, and robots, dust storms have a way of picking up steam (or at least dust) all over the solar system.
Show Notes
- Earth’s Dust Storms
- Mars’ Global Dust Storms
- Dust Storms on Titan
- Potential Dust Storms on Exoplanets
Transcript
Fraser Cain: Welcome to Astronomy Cast, your weekly facts-based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. I’m Fraser Cain. I’m the publisher of Universe Today.
With me, as always, is Dr. Pamela Gay, a senior scientist for the Planetary Science Institute and the director of CosmoQuest. Hey, Pamela, how are you doing?
Dr. Pamela Gay: I am doing well enough. I’m still fighting a cough, so I apologize in advance if there’s any coughing in this episode. It’s just from allergies, so no real worries, just frustrations.
Fraser Cain: I’m sure there will be this beautiful edited version that no one hears the coughs, but for you, I know this is sort of like a response to smelling tomatoes or something ridiculous like that.
Dr. Pamela Gay: Yeah, it was the most ridiculous allergic reaction ever.
Fraser Cain: Yeah. Yeah. And for me, it is, we’re entering spring, and the thing that I always have to remind myself is this feeling that I have where my eyes are red and my head feels woolly and my nose, it’s allergies.
Fraser, you have allergies. Don’t fight it. Take your Claritin and move on.
So I’m ready. I’m ready for when, you know, here we are, the flowers are going to start to bloom shortly, and I’m ready to battle the allergies. So just keep that in mind, that there are these cycles and we are all a part of it.
It is true. We have dust storms on Earth and of course the famous dust storms on Mars. There are even dust storms on Titan.
What causes these storms and how do they work differently on the worlds in the solar system? But what about the exoplanets? We’ll talk about it in a second, but it’s time for a break.
And we’re back. Have you ever been in a dust storm?
Dr. Pamela Gay: Yes. Yes.
Fraser Cain: I haven’t. What happened?
Dr. Pamela Gay: That it’s just one of these things of I need to be inside right now as the air suddenly becomes thick and loud and it’s just not normal. You can actually see the storm coming. Wow.
Where were you? Tucson. I’ve seen them in Tucson and it’s just creepy.
That’s the best word I’ve got for it is you shouldn’t be able to see eddies in the air and you can with dust storms.
Fraser Cain: Wow. I guess, I mean, the closest I’ve ever seen is I saw dust devils when I was driving across the US and we were in a deserty part of Eastern Washington and I saw a bunch of dust devils and that’s a very tiny version, but you can get these, as you say, these giant ones that are horizon to horizon and approaching you like a wall. That’s crazy.
Before we get off of planet, what’s going on? There’s winds all the time. How do you get this very specific kind of event that creates this giant dust storm?
Dr. Pamela Gay: It’s a combination of having air that is the correct humidity. You need it to be dry of having a storm front coming through over the dustiness. Once you get some particles levitated, they will start interacting with the surface, which levitates more and actually ends up being a lot of an electrostatic effect, which is why you need to have the dry air, right?
Sand is, is conductive at enough of a level that you end up with charge in the atmosphere, a deficit in the ground and suspended particles that are just gross, right?
Fraser Cain: And whipped up by the wind. And it’s kind of amazing the impact that these dust storms have here on earth. I mean, there’s some really incredible pictures from earth observing satellites where you can see these giant trails of dust leading off of Africa, making its way across to South America and probably depositing itself down in, in the forests there and delivering nutrients in some cases to places that are actually surprisingly nutrient starved or dropping it in oceans and leading to plankton blooms. So there’s, there’s a that, that dust actually has a pretty big impact on planet earth.
Dr. Pamela Gay:Yeah. It can get suspended to higher altitudes than I, I had generally been thinking about until a few years ago, there was the massive dust plumes that coded Europe in layers of dust where people in Spain were going outside and just like you could take it off of the windshield of your car and see it on your hand.
Fraser Cain:Right. That feels like what happened after Mount St. Helens blue, we were in Vancouver. We weren’t like super close, but it rained dust.
And so there was this dust flaring on top of everything that you could, yeah, you could absolutely like snow, but it was made of rock.
Dr. Pamela Gay:And with, with volcanoes, it kind of makes sense because you literally have an explosive force sending the material high up into the atmosphere. The fact that wind can take dust from the surface and manage to keep lofting it higher and higher. The physics of that is, is just super cool because it requires so many different things to be going on in terms of, you have to have this turbulence, you have to have the electro static forces as well.
And it’s that combination that allows it to loft higher and higher. And even just the collisions between the grains can make the grain smaller, which makes it easier for them to loft because it requires less force to loft small things.
Fraser Cain:Right, right, right. Okay. Well, I think we’re going to shift gears and talk about Mars in a second, but it is time for another break.
And we’re back. So while the dust storms on earth can be incredible, they are still limited in scope and size, but something very different happens on Mars.
Dr. Pamela Gay:And this all comes down to the energy balance of our two worlds here on earth. We have a mostly, but not quite, but mostly circular orbit that has the point in the year when we’re closest to the sun is usually around January 5th. So it’s not too different from the winter solstice.
So we have the Northern winter is made less drastic than the Southern winter by this closest approach. The tilts of our planet are slightly different. The weather factors are slightly different, but it all adds up that we end up with some excess heat at the tropics.
We end up with a better regulation of cold. Generally that’s changing with climate change at the poles. No big deal.
We have a slight energy imbalance across the seasons. We’re fine. Now with Mars, it’s more than slight.
Mars has a more elliptical orbit than we do. They’re tilted more than we are. And it turns out that they are closest to the sun in their Southern spring time.
Now this alignment of the seasons and the fact that it’s the Southern hemisphere, which is geologically radically different. It’s the Southern highlands. Mars, two hemispheres are radically different.
There’s lots of different explanations. It’s fun to watch them compete. We’re not going to worry about why.
Fraser Cain:Yeah. I can think of like five times I’ve reported on different explanations for why the Mars highlands are high compared to the other parts of the planet.
Dr. Pamela Gay: Whatever the reason is, this confluence of topography, where it’s the highlands of springtime and closest to the sun, leads to an energy imbalance where they end up with a whole lot of excess energy in the Southern hemisphere in the spring. And this imbalance in where the energy is can drive massive storms. And what’s wild is here on earth, you have to be at a distance to see these storms coming up.
The poor satellites going round and round Mars can only see a fraction of the disk at any given moment. Here on earth, we can see the entirety of the disk. And there are amazing amateur images every time these storms come up that will show the storms coming away from the edge of Mars and see sections of Mars blurred out.
Usually once some amateurs alert that this is going on, they’ll get the Hubble Space Telescope pointed at Mars. And we can see these storms slowly erasing the entire face of the world as they start out sweeping across the Southern hemisphere and will often go to engulf the entire atmosphere of the world.
Fraser Cain: And I know that one of the spacecraft that has been helpful for this is the HOPE mission from United Arab Emirates. And they were able to take these whole disk images of Mars and have been charting changes in seasonal changes on the planet. And it has been able to sort of watch some of these processes coming together as well.
But as you say, it’s sort of like one of those fields where amateurs are able to make a significant role because they’ve got the time to watch Mars all the time while Hubble’s got work to do. So, but I guess like sometimes you get these regional dust storms and then things settle down and the dust storm goes away. But other times the conditions are perfect and you get this full global dust storm where no part of the surface of Mars is visible.
Do we know why one situation happens in the other?
Dr. Pamela Gay: It’s looking more and more like it’s when do the storms start. So it’s just like we have a hurricane season here on earth where the difference between how hot the tropical weather is, the excess energy in the oceans allows these hurricanes to develop. Well, on Mars, it’s that excess energy in the springtime is allowing these storms.
So when you have storms occurring, when you don’t have this energy imbalance, when you don’t have the extremely hot land that is radiating, heating up the atmosphere at the junction between surface and atmosphere, without that excess heating, you don’t have the energy necessary to generate the storms. So it all comes down to where is the energy here on earth? They say for the economy, follow the money.
When it comes to meteorology, follow the energy. Right.
Fraser Cain: So my story on this, or the story that we did on Universe Today, but this was my title, was that when the weather is nice on Mars, you should panic.
Dr. Pamela Gay: Oh, yeah. The clear air has a real part to do with it.
Fraser Cain: Yeah. Yeah. Like you get warm weather, clear air, drier conditions, that heating effect is starting to take over.
And it really feels like it’s those periods of nice weather on Mars that actually drive more severe dust storms within a few months of when that nice weather started. And so I love this idea that if there are people living on Mars at some point in the future, they’ll be like, wow, the weather’s been really nice. Oh, no.
Here comes the dust storm.
Dr. Pamela Gay: And it’s one of those things where here in winter, when the weather is perfectly clear, we know it’s going to be a super cold day because the earth is able to more effectively radiate away its heat. Cold days, you stay warm. Summer is the exact opposite.
A crystal clear day in the summer means it’s going to be super hot. Mars is the same thing going with those crystal clear days are the days that more energy is able to heat the surface. The more you heat the surface, the more energy imbalance you get, the more these storms can occur.
So yeah, watch out clear skies in combination with the excess heating and spring will lead to global dust storms.
Fraser Cain: The Lionel posted in the chat, clear sky morning, Martian take warning, which I love. So I mean, and the effect of these dust storms. I mean, like, I think we all remember watching the Martian where he is out and caught out in this dust storm and the wind is howling and and the hardware is being thrown around.
Dr. Pamela Gay: It was exaggerated. So so the storms, they have winds that are 60 miles per hour, which is. As a Midwesterner, it’s like, oh, that’s challenging, but not that bad in one percent atmospheric density.
And that’s the thing on Mars, they don’t have nearly the atmospheric density we have. So while the extremely fine grained dust is able to get lofted up and then it also spends due to it has the same static issues going on that we have here on Earth, even more so there. It’s it’s not that thick an atmosphere.
So 60 miles per hour is just kind of cute.
Fraser Cain: Yeah. Yeah. You barely feel it.
You can fly a kite in it.
Dr. Pamela Gay: Exactly.
Fraser Cain: But that dust gets everywhere. And that’s the challenge.
Dr. Pamela Gay: And it settles out of the atmosphere eventually. And it’s the settling out of the atmosphere when the wind isn’t gusting. That’s the problem we found with the rovers, that the wind gives and the wind takes.
There are gusts that do good by clearing off the solar panels when the wind stops and the dust just settles out of the atmosphere is when you have to really worry about how much energy you no longer going to be able to get through your solar panels.
Fraser Cain: But we lost opportunity to a dust storm.
Dr. Pamela Gay: We did. So opportunity was stuck in the sand. It wasn’t at an opportune angle, but it was still functioning.
They were still doing science with it. Then there was a global dust storm and it it shut down as far as it could, but it just didn’t wake up on the other side.
Fraser Cain: Yeah. Yeah. And I think that’s the is that, you know, the temperature is still cold and this storm was cutting off almost all of its illumination.
And so it was very, very dark. There’s some great images that they show you, the perspective, the opportunity had as the dust was, was causing its landscape to fade darker and darker and darker until, you know, it would have been just a useless environment for trying to draw power from solar panels. And also it was cold and it no longer had enough power to keep itself warm and it couldn’t recover when the dust storm had ended, which was, was very sad, but I mean, yeah, you know, more than a decade of operation, which was fine.
All right. We’re going to talk about Titan in a second, but it’s time for another break and we’re back. So I think most people would be surprised to hear that there are dust storms on Titan.
Dr. Pamela Gay: This is one that surprised me. We, we know from the images that, that there are dunes on Titan. So I guess it shouldn’t be surprising that there are dust storms, but it just hadn’t occurred to me, I guess.
And this is the thing about science is the universe is far more creative than a lot of us are as human beings. And, and so here we have a world, it has a environment that’s methane and ethane liquid instead of water liquid. It has clouds, it has rains and snow.
We think these are all the kinds of meteorology that can break down landscapes, create sands, transport them through. It has this super thick methane atmosphere. It has temperature variations and where you have temperature variations in an atmosphere, you have wind.
And there are these amazing images that show shininess that isn’t on the surface. It’s only somewhat up in the atmosphere. It’s not all the way up in the atmosphere.
And they’re able to figure this out based on how it moves in the images as the spacecraft and the, the moon both move. And so by figuring out how high up it was and how long it lasted, they were able to figure out that what they were looking at was actually a dust storm. So it appears that the, the grains that form those sand dunes, and this was occurring in the same region of Titan where they have the sand dunes, it appears that Titan with its winds can also loft sand into its atmosphere and have these dust storms.
Fraser Cain: But I think it’s really important to make the distinction about what these, the terrain on Titan is like compared to the terrain on, on a place like Earth or Mars. On Titan, the ground is made of ice. The mountains are made of ice.
The sand is made of ice. The sand dunes are made of ice. And so I guess the dust is made of ice with various hydrocarbon deposits mixed in with that, that are being lofted up into the, into the atmosphere.
So it’s, I just did an interview with somebody about, about Titan and how this world is like, everything’s shifted over. And then you can go to Pluto and you take it to the next level where now the, the atmosphere falls to the surface and becomes glaciers. But you know, that’s a, that’s a future episode.
But, but, and so to think that this, even though you’ve got, you know, ice, not rock, you still have very similar processes that are happening on the surface of this world, a place that seems so alien and yet so familiar.
Dr. Pamela Gay: And what’s, what’s interesting is since it’s all cold, you end up with different physics. You don’t have the same electrostatic forces building up between ice grains that are interacting, but you still have now, I guess it’s more like thinking about snow getting lofted into the atmosphere. So imagine where the snow is getting lofted upwards and the interactions between grains allow it to go higher and higher up until you end up with these clouds.
It’s white out conditions in a way without having it falling out of the sky. It’s literally falling up into the sky.
Fraser Cain: Right. Yeah. I guess falling is the wrong word.
Yeah. And then while with Mars, we talked about how the atmospheric pressure on Mars is, is 1% of what it is on, on earth. On Titan, it’s the atmospheric pressure is more than it is on earth.
And so high winds will have a completely different effect on, on you and on the, you know, on, on the sand and the dust around you.
Dr. Pamela Gay: And things didn’t make it as high up into the atmosphere comparatively. One of the crazy things about Martian dust storms is they can actually get dust a hundred kilometers into the atmosphere. So we’re talking insane altitude of dust grains, and that’s why it gets so dark, even though there’s not that thick of an atmosphere as you have kilometers upon kilometers of dust getting lofted up.
So Titan, you have a thicker atmosphere. Things aren’t getting lofted as high.
Fraser Cain: Hmm. That’s really interesting. So I want to talk about exoplanets then.
Do we have any evidence that there are dust storms on exoplanets?
Dr. Pamela Gay: So I wouldn’t phrase it as dust storms, but if we talk about dust generally being either hydrocarbons, which is what we’re seeing on Titan or silicates, which is what we’re seeing on earth and Mars, we do see silicate clouds on hot Jupiters. So in these worlds, you have basically vaporized glass atmospheres is one way to think about it. And at the, the junction between, for tidally locked worlds at that junction between the night side and the day side along that terminus, you can get the formation of essentially nanoparticles of glass.
So nanosilicate particles lofted through the atmosphere. We’ve seen this in JWST data of WASP-17. So there are sand particles forming in the atmosphere and snowing out and quartz particles forming in the atmosphere and snowing out.
And that’s just wild to think about. And they’re getting whipped around at extremely high velocities. These are not safe places to be, but they are amazing to imagine.
Fraser Cain: Yeah. And, and that, that is a mild hot Jupiter that the, that the really extreme ones are the ones where titanium and iron become ionized and become the atmosphere of this, of these atmosphere, you know, of these worlds where it’s so hot, the temperatures are thousands of degrees. The winds are, I think in one case was at 30,000 kilometers per hour, like just ludicrous wind speeds.
And so, you know, the closer you get to the star, the more you have this energy input and no way to get rid of it. Easily the planet goes berserk.
Dr. Pamela Gay: And, and these are worlds that are not going to have the same life expectancy as Jupiter. They, they are streaming particles out behind them. They are getting destroyed by these stars.
Fraser Cain: But, but theoretically we should eventually probably find similar conditions. We have three places here in the solar system that gives us good odds that we should find these out there around the universe.
Dr. Pamela Gay: Find what out there in the universe?
Fraser Cain: More dust storms.
Dr. Pamela Gay: Yes. We will continue to find more dust storms. We just haven’t discovered them yet.
We’re still figuring out what to observe the atmospheres of. So far it’s easy to see the big things with lots of starlight passing through atmospheres. We’ll eventually see the atmospheres of smaller worlds.
We’re just not there yet.
Fraser Cain: It feels like a thing that’s possible that, that, that dust gives off a certain signature, spectroscopic signature. And James Webb is perfect for that kind of thing.
Dr. Pamela Gay: It has IR. Yeah. Yeah.
It, it re-emits extra light in the IR and has absorption bands. So that is detectable.
Fraser Cain: Yeah. And so you would think that eventually if, if it turns out that M dwarf planets can support atmospheres, we, these may be the kinds of observations that we can make. You think about places like you know, there are these exoplanets that have, that are thought to have lava plumes that are filling the, you know, creating a cloud like, like IR.
Dr. Pamela Gay: Yeah. Yeah. There, there was that discovery, I want to say a few months ago where they believed that they detected, uh, the atmospheric signature of volcanic eruptions.
Fraser Cain: Right. And I think it was, it was, it was in the, the orbital disc of the orbital plane of the planet that was leaving a trail kind of in the same way that, that Mars is thought to be respond, that Mars dust is leaving a trail behind Mars as it goes. And it’s thought to be actually responsible for the zodiacal dust here in the, in the solar system.
Um, so, uh, Zephan, Zephan mentioned that. And so I thought I would bring that back into the conversation. Um, but yeah, it’s amazing.
I can’t, I can’t wait to the time when we can get more data points beyond just the three that we have here in the solar system. We actually can, yeah, I’m ready. I’m ready to write that article, you know, dust storm found on the, on an exoplanet.
Dr. Pamela Gay: Our, our life is, is going to be defined from coming of age as, as exoplanets were first discovered to hopefully being able to see either biosignatures or technosignatures at some point. It’s, it’s really an amazing time to be alive.
Fraser Cain: Very cool. Thanks, Pamela.
Dr. Pamela Gay: Thank you, Fraser. And thank you so much to all the patrons out there that allow us to pay our editors to make us sound good. Um, this week we would like to thank Alex Raine, Andrew Palestra, Antesor, Astra Bob, Astra Sets, Benjamin Carrier, Benjamin Davies, Bill Smith, Bob Crail, Boogie Nett, Brenda, Brian Kilby, uh, Bruce Amazine, Samansky, Claudia Mastroianni, Cody Rose, David, David Russ, Resetter, uh, Diane Philippon, Don Mundus, Frodo Tenenba, uh, Jeff McDonald, Gold, Hal McKinney, Janelle, Jeremy Kerwin, Jim McGeehan, Jimmy Drake, Jordan Turner, Justin Proctor, Katie and Ulyssa, uh, Christian Magaholt, uh, Mark Schneider, Michael Purcell, Michael Reagan, Nate Detweiler, Papa Hot Dog, Rando, uh, Robert Hundell, Robert Plasma, Ryan Emery, The Air Major, Thomas Gazetta, Time Lord Iroh, Will Hamilton, William Andrews. Thank you all so very much.
Fraser Cain:Thanks, everyone. And we will see you next week.
Dr. Pamela Gay:Bye-bye. AstronomyCast is a joint product of Universe Today and the Planetary Science Institute. AstronomyCast is released under a Creative Commons attribution license.
So love it, share it, and remix it. But please credit it to our hosts, Fraser Cain and Dr. Pamela Gay. You can get more information on today’s show topic on our website, astronomycast.com.
This episode was brought to you thanks to our generous patrons on Patreon. If you want to help keep this show going, please consider joining our community at patreon.com slash astronomycast. Not only do you help us pay our producers a fair wage, you will also get special access to content right in your inbox and invites to online events.
We are so grateful to all of you who have joined our Patreon community already. Anyways, keep looking up. This has been AstronomyCast.