Ep. 691: Jupiter’s Changing Red Spot

Podcast: Play in new window | Download

Subscribe: RSS

Transcript

(This is an automatically generated transcript)

Fraser Cain [00:01:50] Astronomy Cast. Episode 691 Jupiter’s Changing Red spot. Welcome to Astronomy Cast, your weekly fact based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain. I’m the publisher of Universe Today, and with me, as always, is Doctor Pamela Gay, a senior scientist for the Planetary Science Institute and the director of Cosmic Quest. Hey, how are you doing? 

Pamela Gay [00:02:12] I’m doing well. How are you doing? Well, sad. 

Fraser Cain [00:02:16] We. You know, we had to say goodbye to our dog this week. 

Pamela Gay [00:02:20] So that’s just hard on the heart. 

Fraser Cain [00:02:23] Yeah. It is. You know, you sort of spend all the time, have all this love, but then you sort of know it’s time. 

Pamela Gay [00:02:32] Yeah. So the best things in light of life are fleeting. 

Fraser Cain [00:02:37] Yeah, yeah, yeah. And I think, you know, it’s it’s. So for those of you who do have your fur babies, give them a hug and a kiss. From us. Jupiter’s Great Red spot is one of its most iconic features, first seen hundreds of years ago. Although it’s certainly long lasting, it’s been changing in size over the last few decades shrinking, changing in color. Is it fading away? And what can the changes tell us about storms on giant planets? All right, so those of you listening this might not know, but this is the second time that we tried to record this episode. And so I’m going to remember what I asked you last time, which was when was the first time that you saw Jupiter’s Great Red spot? 

Pamela Gay [00:03:25] So. So for me, I think it was probably at some random point when I was in elementary school, my parents got me the exact type of telescope we tell people never to get. Do not get one of these. I had like a Sears Thanksgiving Day sale four inch Newtonian telescope that I did my best to look at absolutely everything with, and I have no memory of seeing Jupiter, but I know I must have because I pretty much looked at everything out there to be seen except for Andromeda, because I could never find Andromeda as a kid. That that would have to wait till I moved somewhere other than Boston. 

Fraser Cain [00:04:06] You’re waiting for me to tell you how easy it was for me to find a job? Yeah, because that’s what we talking about last time. Yeah. Yeah. It’s funny how this works. Yeah. So, you know, I live in dark skies and grew up in, like, whatever the called. The darkest mortal skies you could get. And, you know, it’s not quite as good now, but it was definitely very, very dark skies. And so you could just see Andromeda with the unaided eye. And so you would sort of unfocused your eyes look in the sky and you would see this blurry blob and you’re like, oh, there’s Andromeda. And then you would point your telescope at that thing, and for you, you had to start off your way there. 

Pamela Gay [00:04:41] And the problem was that I could, like, see Cassiopeia. I could see the square of of Pegasus, but not really the legs. And the square was kind of iffy. And there’s just this vast swath of nothing between the square and the W, and that was not quite enough to stir up. So. Yeah. 

Fraser Cain [00:05:04] So for me, I bought my first telescope when I was 14 and and I did it right. I got a proper 4.5in Newtonian reflector, paid a couple hundred dollars of my, you know, hard saved money. And, it didn’t have an equatorial mount. It had an old as mount, but it was still a pretty good telescope. And I had a bunch of eyepieces with it. And so I was able to see Jupiter right away, and the rings of Saturn and the bands across the planet on Jupiter, and the moons of Saturn, or the moons of Jupiter and, and, you know, look at the moon and so on. And then I bought a Barlow lens, and the Barlow lens gives you a three times magnification, which you think is going to be great, but it’s actually not that useful for seeing deep sky objects because it doesn’t improve the light gathering of your telescopes. It just sort of magnifies the image, but then makes it fainter. And so often things look best when they’re actually with a very fast eyepiece. But Jupiter, because it’s so bright, you know, all the planetary stuff look great in, what you see. And so you see, you could see I could see the, the great red spot on, on the surface of Jupiter and and to watch it and kind of come back and be like, oh, red spot. Oh no. Red spot. You know. Well, yeah, the sky because it rotates so quickly. And so you sort of, you know, you got about it, I would say like a 30% chance of seeing it because, you know, you’re sort of it’s hard to know when it’s sort of at extreme angles on the sides of the planet. But once face on, yeah, you can definitely see it. And then, you know, I could share that with my friends and family. So, it’s great to sort of. See these things that you’ve had sort of seen pictures of, and you had had context. 

Pamela Gay [00:06:43] Yeah. And while I’d seen Jupiter plenty the first time, I actually remember seeing the great Red spot was the summer of Shoemaker-Levy nine, when I was an intern out at Kitt Peak, and all the amateurs were there with their amazing systems and their eyepieces and their barlows. And so it was someone like you, except much older and gray haired, because it seemed like all of them were older and gray haired. That was like, hey, do you want to see the dark spots from the impact? And then of course, I could see the red spot as well. It was kind of awesome. Spots upon spots next to spots. 

Fraser Cain [00:07:22] So then, you know, that’s us. When did humanity first notice Jupiter’s Great Red spot? 

Pamela Gay [00:07:29] This this is of debate, and one of the things that I find amusing is, like most NASA websites will be like, we have been looking at Jupiter’s Great Red spot for 400 years because the telescope’s 400 years old, and there is questionable evidence whether or not Galileo was able to see the red spot. He was a good enough scientist that he wasn’t going to claim to see things he couldn’t repeatedly see. Right. Clearly, yes. So while looking at some of his sketches, folks are like, maybe and maybe not. When folks look at Jupiter with similar telescopes to what he was using as a really just a cute little fuzzy blob, and his primary goal was to watch the moons orbiting Jupiter. And so that’s really what he was recording. So we can’t really know for sure. Did he didn’t he? But, Robert Hooke clearly saw and documented it in 1664. Giovanni Cassini clearly saw it and documented it in 1665. Or at least they saw and documented a red spot. Continuous observations of the red spot didn’t really start until about 1711, when it started appearing in artwork and being continuously observed on a yearly to multiple times per year basis. 

Fraser Cain [00:08:59] Now, do we have any sense about how long the Red spot has lasted? Like if people tried to calculate how long this thing has been around based on how it changes in size? 

Pamela Gay [00:09:10] So the problem is we didn’t really have great measurements of it prior to the age of photography. People did sketches. The sketches were pretty accurate, we think. But in the grand scheme of things, this this is something that has varied in in human lifetimes with high quality measurements from a little over three Earth diameters to a little over one Earth diameter. And while a 60%, difference in size is dramatic when you’re hand sketching things. Yes, it’s it’s hard to say with certainty. Yes, it varied by 20% according to this pencil drawing done by someone using the Earth’s atmosphere. 

Fraser Cain [00:09:55] Right? Right. Yeah. Using their eyes to sketch a thing. In the end, you know, the Jupiter is getting closer and farther, right? Right. And so scale is, is really hard to to. 

Pamela Gay [00:10:08] And everything’s fuzzy until you get above the atmosphere. And the first really clear images that told us this is a spinning anti cyclonic storm we didn’t get until 1979 when we sent Voyagers. 

Fraser Cain [00:10:30] Right to expect the spacecraft to go there. I mean, it is kind of amazing how many of the things that we take for granted today. As you said, the great Red spot, the, the the atmosphere of Venus, the landscape of Mars, these things were all, you know, the big volcanoes on Mars, like, these are things that we only found out about when we sent a spacecraft to these destinations, you know? Yeah, all the, the, the Soviet Venera spacecraft that had to make their way down through the atmosphere and failed. And only then did you find out how bad that atmosphere was. And and. Yeah. And so you think about it like, it’s only like we were both children when the Voyagers arrived. When launched. 

Pamela Gay [00:11:20] Yeah. Betty White predated sliced bread and knowledge that Venus and Mars didn’t have life on them. 

Fraser Cain [00:11:27] Right. So so then it’s like, what is our modern understanding of what the great Red spot is? 

Pamela Gay [00:11:36] We know. That it is a counter-rotating storm. These are maintained by high pressure fronts. We get the same thing usually in the winter here in North America when, high, pressure front drops down from the north and things start turning in the direction opposite of what we expect from watching hurricanes, for instance. We also know that it varies in color slightly. Over time, it has gone from browner to redder, and we know that its shape has gone from more cigar shaped to more circular, while at the same time we’re pretty sure it’s its thickness has has gone so that it now reaches up to higher altitudes than it did in the past. 

Fraser Cain [00:12:28] And this is one of those things that people don’t understand. Like even when you saw old renderings of the great Red spot from castles and things like that, you kind of imagine this, this swirling whirlpool that if you could sort of fly above it, you would sort of see the, the walls of the cloud tops descending down below. But it’s the opposite of that. It’s actually raised up. It’s a, it’s a bump on the surface of Jupiter. Now, there are other storms on Jupiter. 

Pamela Gay [00:12:58] Oh yeah. 

Fraser Cain [00:12:58] And they’re like a smaller they’re generally white. So what do we think is the cause of Jupiter’s color compared to the other objects on the surface? 

Pamela Gay [00:13:10] There’s a variety of different ideas that all come down to large molecules. Hayes. That I just is really good at reflecting redder shades of light. Now the question becomes, is the storm haze all the way down, or is this an effect of the chemicals getting lofted up, interacting with the ultraviolet light from the sun, and essentially the storms? I saw one article that explained it as being sunburned. Where the the storms? Essentially are interacting with ultraviolet light and they’re red at the top. But if we could go further down, they’d be white. And this idea is carried forward by the reality that in 2000, we saw three different white ovals, white storms merged together over time and become a new. We call it Red Spot Junior because we’re not very creative. But Red Spot Junior really only came into existence about the year 2000, and Red Spot Junior is hanging out about the same color. It’s also an anti cyclonic storm and it is almost the size of Earth. So you have two storms, one shrinking, the other growing that are the same color. And so we have to ask the question is this other storm what caused the great Red spot to form? And the fact that we know that it formed as part of the reason that we’re always cautious to say, we think that what Hooke and Cassini saw in the 1600s was the same red spot, but we can’t say it definitively. 

Fraser Cain [00:15:04] So they’re like the great red spot that we know today. Could have. Yeah, could have been like we know definitely from the 1800s have been like continuous observations of this. So we know it’s been around for over 100 years, but we don’t know if it’s the same thing was there. 

Pamela Gay [00:15:19] 40. 

Fraser Cain [00:15:20] Years ago. 

Pamela Gay [00:15:21] And really since 1731 we’ve had pretty good observations going that show. It’s been at the same latitude, which is easy to see because other spots pick other bands. And this is actually a key point. One of the things they think that keeps the storm going is it’s wedged between the these, convective bands, and it’s the energy from those bands they think that keeps it spinning. 

Fraser Cain [00:15:49] And, I mean, this is something that’s always so fascinating to me. When you look at the bands across the surface of Jupiter, they are moving in alternating directions. And so the one, you know, you see one band and the end and all those clouds are like, like a jet stream that’s going in one direction. And then the next band down, everything’s going in the opposite direction and expand down. It’s going in the opposite, you know, it’s going back and forth all the way down. And so you get as these, you know, you have the two bands and then the band in between going the other direction. And that sets up these swirling forces. And we have something very similar on Earth. It’s just that we have land that breaks up these, these counter-rotating bands. And so we don’t get the same kind of structure that is beautifully described, you know, around a sphere in the way that is a Jupiter. So back to that idea that you mentioned earlier about. So you’re saying that, you know, one possibility is that we are that that the great red spot, because it’s so large, is dredging up material deeper down into the planet. And so we’re seeing that material exposed to the surface. And then the other possibility is because that storm is so big, it is holding material aloft higher and longer than other material. And so it’s. 

Pamela Gay [00:17:00] Allowing hazes. 

Fraser Cain [00:17:01] Yeah, to turn that red color. 

Pamela Gay [00:17:04] Yes. And and that latter idea, makes our new ability to observe with more and more missions all that more important. Because if we can see that cloud altitude is related to color, that will help us start to understand this. But right now, we just don’t have the missions capable of this specific kind of understanding, and we’d love to get right. 

Fraser Cain [00:17:34] So I think, you know, the whole point of this episode, you know, we talked about the great Red spot in the past. But I think what’s really interesting is that it is changing in size. Yes, it is shrinking quickly. 

Pamela Gay [00:17:45] Yes. 

Fraser Cain [00:17:46] And people are really noticing this. So yes, give us a sense of of how much the great Red spot has shrunk and and how long has this been going on? 

Pamela Gay [00:17:56] Since 1979, when Voyager two was there, it has shrunk roughly 60%. 

Fraser Cain [00:18:03] And now. 

Pamela Gay [00:18:04] As we got better and better, telescopes were able to start seeing in the 2000s, essentially red chunks flaking off as the storm got smaller, which has led people to wonder, is the storm dissipating? And then we’re also seeing the overall temperature of Jupiter seems to be increasing. And there’s lots of reasons for this. Don’t go like getting confused with Earth’s climate change, right? Totally different world, totally different situation, totally different scenarios. But it’s thought that as Jupiter undergoes this long term transport of thermal energy down to its southern hemisphere, those increasing temperatures are affecting the storms in ways that we don’t fully understand. And here on Earth, we struggle enough. And part of our struggle is, admittedly, we have land. Jupiter doesn’t have land. It doesn’t have any of these frictional forces like we have that can pull energy out of the storm from below. But at the same time, we don’t have the same mass of thermal conveyance. We don’t have heat getting generated in our core because we’re that well, we do, but it’s a different scale. Everything at Jupiter is a different scale and works just enough differently that we see the thermal changes going on. We see the warming going on, we see the red spot changing color and getting smaller. We don’t know if this is transitory, permanent. We don’t know if the red spot is going to go away. There is a whole lot we don’t know. And that’s actually really awesome. We keep doing science, we keep launching spacecraft, and we keep struggling because we don’t know everything and we want to. 

Fraser Cain [00:19:58] So I mean, there must be multiple camps then, right? One can says it is disappearing. Do they give a sense of if it is disappearing, how long it has left. 

Pamela Gay [00:20:08] So so this is one of those things where I have to admit, I look at a number of papers and all of them contradict each other. And so I’m like, okay, so it may end and we don’t actually know when I have not picked sides. I have simply decided to be an observer and to step back and watch the argument as a sport. 

Fraser Cain [00:20:26] But we’ve seen smaller storms dissipate. 

Pamela Gay [00:20:29] Oh yeah, the ovals occasionally will lose an oval here and there. Jupiter has it’s it’s named ovals, numbered ovals that are the white storms that last. Some of them have been there as long as we’ve had the resolution to see them. One of the three storms that formed Red spot Jr. We actually watched it pop into existence in 1938, but we already knew about the other two. They’d been around as long as we had the capacity to see them. So the fact that we can occasionally see these bright white storms pop in and out of existence, merge and change tells us this is a dynamic system. Change is possible. 

Fraser Cain [00:21:12] And so what typically happens, like when a storm dies, what do we see? 

Pamela Gay [00:21:19] Well. We haven’t had the resolution in papers I’ve read. You may jump in and say that you’ve seen something I haven’t. That often happens here. So far we haven’t had the detailed resolution while a storm was going away to see in detail what was happening, except in cases where things merged. And we were able to say with certainly those two things merged. Otherwise it was much more of a That’s but didn’t come back around again. That spot that we saw three months ago isn’t there anymore. And this is where it would be glorious if we could somehow stick a spacecraft far away from each of these gas giants, but closer than anything we have now, so that we could see the full desk and see the change in weather. And this is something I think a lot of people don’t understand. We had the capacity to see so much with Voyager, because it started out far enough away to capture the entirety of the disk, and then zoomed past Galileo, snuggled right up to the world and wasn’t catching the same full disk images Juno has off and on, had the capacity to see full disk, but most of the time it’s not seeing the full disk either. And for whether you need to see the full disk. 

Fraser Cain [00:22:49] So we need like some kind of, like spacecraft that’s orbiting at, you know, at Jupiter’s. 

Pamela Gay [00:22:57] Level one or L2. 

Fraser Cain [00:22:59] Level one of the L2 or, you know, like at the equatorial orbit. Right. And so you’ve got this perfect position where it can just like it can turn at the same rate that the that the storm is turning. And just like storm watch nonstop. That would be. 

Pamela Gay [00:23:16] I wonder if it doesn’t that doesn’t work because Jupiter orbits I think in like nine ish hours, and you’d have to be in a really low orbit to go around every nine hours. 

Fraser Cain [00:23:30] So is there not a geostationary orbit for Jupiter? That you then modify to the speed that the that the storm is. 

Pamela Gay [00:23:40] There are geostationary orbits, but the geostationary orbit doesn’t give you the full disk view. 

Fraser Cain [00:23:50] Oh, I mean it just so. So I’m getting a 160,000km. Yeah, it seems okay. 

Pamela Gay [00:23:59] It’s it’s okay ish, but it’s a really big world. Yeah. I’ll stand back and enjoy it. 

Fraser Cain [00:24:07] Yeah, but I one. But but if all you want to do is just stare at that one storm. I feel like you could do that. You could put a spaceship. That’s true. In geostationary orbit. Yeah. And then just have it constantly track the storm nonstop and have all the right instruments on board. This is exciting. Let’s do this. Let’s let’s crowdfund this mission. Let’s send it to Jupiter. 

Pamela Gay [00:24:29] And also do a fisheye lens so that you can catch, albeit distorted, the rest of the world. 

Fraser Cain [00:24:33] Right? So what? What do you think this tells us? You know, we only have still the one because we have four examples of giant worlds here in the solar system. Saturn is nothing like Jupiter. 

Pamela Gay [00:24:44] No, it does have a great white storm, right? That seems to be fairly persistent. 

Fraser Cain [00:24:48] And Neptune has a storm. Yeah. 

Pamela Gay [00:24:52] Which it’s weather is variable. It has storms that come and go. 

Fraser Cain [00:24:55] But we required Webb to be able to actually see the storm again because it had been seen by the Voyagers. Then we didn’t have the technology to see it, and now we can see it again. It’s true. That’s true. So we need to go back, I think. But what do you think about exoplanets? Do we see any kind of evidence of storms on exoplanets as they’re transiting? Or. 

Pamela Gay [00:25:18] So we’re getting there. What we can see is variations in light that cannot be explained purely through change in sun planet angle. So, so essentially, as you have a I don’t have I’m going to use we’re going to pretend this is a planet real fast. So as we have our planet going around, it’s going to be getting hit by different differing amounts of sunlight that it reflects back towards us until it’s essentially, only showing its dark side. And, it’s mostly illuminated right before it passes behind the star. So there should be a nice, smooth variation in the amount of light received from these planets. But sometimes the variations in light can’t be purely explained by the variations in, reflected light. And so this starts to tell us that there either land masses that vary, there are clouds. And as we look at different kinds of worlds with the gas giants, so it can be like, okay, there are variable clouds. Yeah. And that’s. 

Fraser Cain [00:26:34] Cool. I mean, I know we’re already at the point where you can detect changes in temperature between the hemispheres of the planet. For the ones that are tidally locked. And you can see like they’re they’re somewhere facing side is extremely hotter than the than the far side. But it would be amazing to get to this point where we are resolving temperature changes due to have a spherical weather, landmasses, oceans. 

Pamela Gay [00:26:57] It’s exciting. So we can see the temperature variations. We can see the brightness variations. We just don’t have the detail. To know exactly what’s causing everything. And more telescopes, please. That is the moral of the show. 

Fraser Cain [00:27:14] Telescopes, please. Yeah. All right. Now place your bets. Do you think we’re going to lose Jupiter’s Great Red spot in our lifetime? 

Pamela Gay [00:27:22] No. 

Fraser Cain [00:27:23] Okay. Thank you Pamela. 

Pamela Gay [00:27:28] Thank you Fraser. And thank you so much to all of the people out there who support the show. As a reminder to all of you if you would like to get this completely ad free. Join our Patreon at Patreon.com Slash Astronomy Cast. We do have a staff that we sometimes torture with our with our retakes and multiple takes and everything else, and we pay them, to do all of the miraculous editing work that they do. So this week I would like to thank our Patreon, Jim Schooler, Kimberly Reich, Alex Cohen, Matthias Hayden, the Big Squish Squash, Tim McCormack and Claudia mastroianni, Scott Cohn, Justin Proctor, Tim Garrett, conception Filippenko, guru Gregory Singleton, Kenneth Ryan, Jeff Wilson. Cooper, Don Mundus, Michael Regan, Paul de Disney era aileron Z Grove. I just totally mangled your name. I’m sorry. Benjamin Mueller, Michelle Cullen, Veronica cure, Scott briggs, Matt rucker, J. Alex Anderson, Frodo, tan Bo, Ninja neck and Esau. MH w 1961 soup. Bruce. Amazon. Jim McGinn. Father Peter Abraham Cottrell. Schmear. Some. Mark. Steven. Rasmus. Philip. Grand. James. Roger. Alex. Rain, Gabriel. Gelfand, Paul L Hayden, Dwight. Elk, Benjamin. Davies, and Glenn McDavid. Thank you all for everything you do. 

Fraser Cain [00:29:07] Thanks everyone and we’ll see you next week. 

Pamela Gay [00:29:10] Bye bye. Astronomy cast is a joint product of the Universe Today and the Planetary Science Institute. Astronomy cast 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 Doctor Pamela Gay. You can get more information on today’s show topic on our website. Astronomy. Cars.com. This episode was brought to you. Thanks to our generous patrons on Patreon. If you want to help keep the show going, please consider joining our community at Patreon.com Slash Astronomy Cast. 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 Astronomy Cast.