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Gravity Assist: It’s Raining Diamonds on These Planets

Season 1Jul 1, 2022

Uranus and Neptune are two of the many exciting and mysterious objects in our universe that the James Webb Space Telescope will soon begin to explore. Learn more about these planets and the Webb telescope’s upcoming observations from astrophysicist Naomi Rowe-Gurney, our guest on this week’s Gravity Assist.

Side-by-side photos of Uranus and Neptune, both taken by Voyager 2.

Side-by-side photos of Uranus and Neptune, both taken by Voyager 2.

Uranus and Neptune are two of the many exciting and mysterious objects in our universe that the James Webb Space Telescope will soon begin to explore. Temperature and pressure conditions are so extreme on these planets that carbon atoms could be crushed into diamonds in their atmospheres. And did you know that Uranus orbits on its side? Learn more about these planets and the Webb telescope’s upcoming observations from astrophysicist Naomi Rowe-Gurney, our guest on this week’s Gravity Assist.

Jim Green:We have two ice giant planets in our solar system, Uranus and Neptune. What will we find out about them when the James Webb Space Telescope takes a look?

Naomi Rowe Gurney:That will give us a massive insight into these other solar systems that we’re seeing.

Naomi Rowe Gurney:I had so many teachers and tutors, and just people in my life that said:

Naomi Rowe Gurney:Maybe science is a little bit hard. Like, try doing something else. And I’m really glad that I didn’t listen to them and I let my heart decide.

Jim Green:Hi, I’m Jim Green, and this Gravity Assist, NASA’s interplanetary talk show. We’re going to explore the inside workings of NASA and meet fascinating people who make space missions happen.

Naomi Rowe-Gurney is a postdoctoral research associate at NASA's Goddard Space Flight Center through Howard University.

Jim Green:I’m here with Naomi Rowe-Gurney. And she is a postdoctoral research associate at NASA’s Goddard Space Flight Center, through the Howard University in Washington, DC. Now, she specializes in the study of two of my favorite planets, Uranus, and Neptune. And she’ll be using the Webb Telescope to find out more about these fabulous ice giants of our solar system. So welcome, Naomi, to Gravity Assist.

Naomi Rowe-Gurney: Thank you so much for having me. I’m really excited to be here.

Jim Green:Well, I’ve got to tell you, you know, we just haven’t been back to the ice giants in so long after Voyager 2 flew by both of them [in the 1980s]. Not Voyager 1, Voyager 1 went on its way. But only Voyager 2 has observed, you know, those two beautiful ice giants. And you’ve been studying those for a long time. What is your favorite aspects of these ice giants? And why do we call them that? Why aren’t they just gas giants?

Naomi Rowe-Gurney:Yeah, so I love the ice giants. I think I love them mostly because they haven’t been looked at very much. I initially wanted to do my PhD on these two planets because there were so many unanswered questions. And we just really don’t know even like the fundamentals of where they came from, and why they are the way they are, and why they’re called ice giants. I mean, people are still kind of debating that name and whether it’s appropriate and whether they should really be called rock giants, because who knows what’s inside?

Naomi Rowe-Gurney:It really takes a mission, a proper mission with like an orbiter to look at the gravity of a planet to be able to figure out what’s happening on the inside.

Jim Green:Now the composition of the atmosphere has kind of given us that clue that they’re different than Jupiter and Saturn. And that’s because it’s got a variety of ices.

Naomi Rowe-Gurney:Mhm.

Jim Green:And you’ve been working on the thermal structure and composition, what is the most exciting things that you’ve been finding out?

Naomi Rowe-Gurney:Yeah, so that’s the reason why they’re blue, because they have high levels of methane in their atmosphere. I study the middle atmosphere, which is like the stratosphere and the upper troposphere. And that’s kind of down to around one bar, which is around the same pressure that we have here on Earth, on air. So that’s kind of the level that I look at.

Naomi Rowe-Gurney:And what we see there is that the Sun interacts with the methane in the atmosphere, and it breaks down the methane into lots of different hydrocarbons. So lots of these chains of different things with hydrogen and carbon in [them], with lots of fancy names like diacetylene and acetylene and methylacetylene, all of these. And we still don’t really know everything, like the composition of everything that’s in there, and we’re still finding new things all the time. And that’s why the JWST is so exciting, because we are going to be able to see a lot more of what’s going on, and a lot more of these like complex hydrocarbons and things.

Jim Green: A couple of news releases that I’ve seen have concepts where carbon gets hardened, almost to the point, or maybe to the point of being diamonds. Do we see those kinds of things and Uranus and Neptune’s atmospheres?

Naomi Rowe-Gurney:So I mentioned methane being the reason why these two planets are blue. Well, methane has carbon in it and that carbon can occur by itself and also be crushed by the immense pressures that happen, like, deep in the atmosphere, so much deeper than the levels that I look at. And inside the planet, when it gets really hot and really dense, these, these diamonds form and accumulate, and then they become even heavier. And that means that they kind of rain down in the atmosphere. But it’s not the rain that we see here because these pressures are extreme, and you’ll never be able to get there as a human. So even if these diamonds do exist, we would never be able to go and grab them. So… unfortunately.

Jim Green:Yeah, unfortunately. Okay. (laughs)

Jim Green:Well, you know, one of the really exciting things about planetary science is that when we go from planet to planet, we look at some things that are similar, in addition to the differences. And one thing we look for is lightning. Now here on Earth, we see our lightning but in the upper atmosphere there’s some really spectacular forms like “sprites,” we call them and “elves” and blue “jets” and all kinds of exotic discharges that happen in our own atmosphere. Do you think we’ll find those at Uranus and Neptune?

Naomi Rowe-Gurney:Yeah, definitely. I think that there’s already been some research done on the kind of traces that we find in, in chemicals that is left behind by lightning and things. That research has already been done using some ground-based telescopes. So that is exciting stuff that’s already happening on Uranus and Neptune that we’re seeing. The lightning on other planets is similar, I think, to the lightning that we have on Earth as well. So all of those, like elves and sprites and things are also things that we’re trying to look for, on, on other planets like Jupiter, Saturn, Uranus, and Neptune.

Jim Green:Well, you know, I think the Voyagers using the plasma wave experiment, did indeed find lightning, at least at Neptune, and at Uranus. That’s really exciting. So, so that changes chemistry, too, in the atmosphere.

Jim Green:One of the one of the really great things that that have happened, is we’ve been monitoring Uranus and Neptune with Hubble, you know. So we have many years of Uranus and Neptune data. Hubble observed some big spots on Neptune recently. What’s that all about?

Naomi Rowe-Gurney:Yeah, so Hubble looks at the near-infrared and the visible wavelengths and in visible we can look at what’s happening in every color that we can see with our eyes. So these spots on Uranus and Neptune appear as like these blue dark spots, just like the “great dark spot” that we saw with Voyager on Neptune. And we are trying to observe as many of these as possible, because we think they’re kind of like the Great Red Spot that’s on Jupiter, like a big storm system that creates lots of changes in the atmosphere, in all levels of the atmosphere. And it’s still unknown as to how a dark spot changes the upper levels and, and changes the chemistry and the circulation going on.

Naomi Rowe-Gurney:So that’s a major thing that the JWST is going to be looking at, because we’re using the mid-infrared in with JWST. And the mid-infrared is really interesting because it senses a little bit higher up than those visible and near-infrared wavelengths in the stratosphere. And that’s where all of that interesting chemistry is going on that I was talking about. And that we think is also being affected by these dark spots that might be these circular storms that are happening.

Naomi Rowe-Gurney:And that’s actually what my PhD was looking at with Spitzer. But the problem with Spitzer is that it’s so small, it’s only like naught-point eight five [0.85] meters in diameter, so less than, less than a meter and…

Jim Green:The telescope mirror itself.

Naomi Rowe-Gurney:Yeah, exactly. And that’s actually the same size as the secondary mirror of the JWST. So the mirror that is used to focus the big 6.5-meter mirror is the same size as the Spitzer’s major mirror. So.

Jim Green:Wow. Yeah, that’s a good metric. (laughs)

Naomi Rowe-Gurney:Yeah, right? That is a massive advantage. Because with Spitzer, we didn’t have any images, because they’re so far away, both Uranus and Neptune are so far. And they’re also quite cold, it means that we only had like a point of light. So we can look at it like we look at a star in the night sky. That’s how far away they are. And all we get is one spectrum. So one piece of light for just the whole planet.

Jim Green:So Hubble has been observing Uranus and Neptune. But there are specific proposals that come in and do that. Have you been involved in any of those?

Naomi Rowe-Gurney:Yes. So just recently, in fact, today, this morning, I found out that one of my proposals that I sent in to observe the ice giants is has been approved on HST 30. So cycle 30, which is really, really exciting, like Hubble Space Telescope is amazing. It was launched in 1990. And actually, that makes it the same age as me, which always makes me feel very, both old and also very young. (laughs)

Jim Green:Yes, indeed!

Naomi Rowe-Gurney:Yeah! So yeah, my project is going to be using Hubble to look at Uranus and Neptune to kind of increase the science that we have for, with the JWST. So it’s going to be looking at them, hopefully as close as possible to the JWST observations. And that will mean that we are getting even more wavelengths in there because JWST is looking at the mid-infrared, and near-infrared, but Hubble has capabilities all the way down to the visible, which is really exciting because using visible and also some of the near-infrared. So we can expand that that window and also the depths that we’re looking at in the atmosphere.

Jim Green:Wow, perfect.

Jim Green:You know, one of the things that really fascinated me about Uranus and Neptune is the heat that they produce. You know, all our planets are hot on the inside, they’re still cooling off from when they were made 4.6 billion years ago. But Neptune, correct me if I’m not right, is producing more heat on the inside than Uranus is. Do we know what’s happening?

Naomi Rowe-Gurney:That’s true. So it’s actually Uranus that’s the weird one. Neptune is, is creating the amount of heat on the inside that we would expect a planet to make.

Jim Green:Ah, thank you for correcting me, yeah.

Naomi Rowe-Gurney:Just like on Earth, we have like things like the mantle happening inside. It’s like the remnant of the, the creation of the planet is still hot on the inside and it’s only very slowly cooling down. And that’s what we expect to see with all of the other planets as well — a hot interior leftover from creation. And that’s not what we see at Uranus. We see a negligible internal heat. So it looks like there’s no internal heat really going on at all inside. And that’s very strange. And one explanation is that Uranus was hit by something really big, and kind of turned inside out. And all of that internal heat got lost.

Naomi Rowe-Gurney:And that would also explain why the planet is on its side, which is also another weird and very unique thing in the solar system. No other planet is just on its side spinning, like, on its axis in the wrong direction.

Jim Green:That’s fantastic. Well, you know, we’ve been looking at planets beyond our own in our own solar system, and Kepler came out with some amazing results. And those results indicated the distribution of planets that we see in other solar systems. And I always thought, “Oh, well, we got to be seeing oh, you know, a bunch of Jupiter’s.” but it turns out Jupiter’s now you know, big Jupiter’s are not one of the common planets. But indeed, more of what we call Super Earths, but also mini-Neptune. And so the ice giants Uranus, and Neptune hold a really special place in terms of how important that might be for other solar systems. What can you tell me about those kinds of capabilities?

Naomi Rowe-Gurney:Yeah, so that’s a major motivation behind looking at our own ice giants and why the entire planetary science community and science community is so interested in both of these planets now, it’s because we found so many of these Neptune-sized or Uranus-sized, just ice giant sized planets in other solar systems. And we can look at our own ice giants and try and understand a little bit more about how they’re formed, and their place in our solar system and how they got there. And that will give us a massive insight into these other solar systems that we’re seeing.

Jim Green:You know, right after Webb’s launch on December 25, man, you must have been busy!

Naomi Rowe-Gurney:Yeah, so straight off the launch, I didn’t have too much to do with launch. That was all the engineers and ESA doing all of that. But then after that first stage, we did deployment. That was like the first phase of commissioning is what we call it. This phase, this six-month phase, getting the telescope ready for science is called commissioning. And so that first stage was deployment, getting the telescope through to the L2 Lagrange point, which is where it all bits, which is 1.5 million kilometers away from here to make sure that the telescope’s nice and cold, so they can see everything that it’s looking at in its infrared images.

Naomi Rowe-Gurney:And then after that, when it reached there and deployed successfully, then after phase two, is the telescope alignment. So where it made all of these 18 separate movable segments into one seamless, like, giant 6.5-meter mirror. And then the third stage is the stage that I’ve been involved in, which is the science instrument commissioning. And I’ve been involved in a team called the Moving Target Vommissioning Team. And that means that we have been looking at asteroids. So asteroids that are in that asteroid belt mostly, and making sure that the telescope is able to track things that are moving, because everything in the solar system compared to distant objects is a moving target. And it means that the telescope actually has to move physically as it is looking at these objects. And that is definitely needed for everything in the solar system. So that’s what we’ve been testing in this last phase, and then that will be over soon. And then those first images come out on the 12th of July, which is very exciting.

Jim Green:So the first light science from JWST is going to be shown July 12. And then from then on, we’re going to see all kinds of fantastic stuff coming out in this regular schedule that it has. So when will Webb start looking at solar system objects?

Naomi Rowe-Gurney:So it won’t be part of those first images that come out on the 12th of July. But we will actually start to look at solar system objects. It’s just those images won’t be released to scientists until after that 12th of July date, and then they won’t be released as, kind of, science or anything until our scientists have done their analysis and calibration and everything. So probably, we’ll see those first things come out at the end of the summer, I would say, is optimistic.

Jim Green:Now, one of your jobs is, you’re a JWST Solar System ambassador.

Naomi Rowe-Gurney:Yes.

Jim Green: So tell me what that’s all about? And what are you doing?

Naomi Rowe-Gurney:So I help everybody who has guaranteed time observations, which means observations in this first year of the James Webb’s lifetime. And so everybody who is using JWST to look at solar system objects, or at planetary systems. So all four giant planets, Mars, also the rings, and all of the moons as well. So those ocean worlds and Titan and icy moons, and smaller moons as well of Saturn we’re going to be looking at. And I am there to kind of assist people in going from data all the way through to getting their science published.

Jim Green:Well, so you’ll be right on top of some of the latest discoveries.

Naomi Rowe-Gurney:Yeah, I hope so.

Jim Green:Wow, that’s fantastic. I know this is going to be such an exciting time for our scientists, and for NASA with a telescope so large, looking at wavelengths that we cannot see from the ground. Well, Naomi, I always like to ask my guests to tell me the person, place or event that propelled them to become the scientists they are today. And I call that event a Gravity Assist. So Naomi, what was your Gravity Assist?

Naomi Rowe-Gurney:My gravity assist was an event-slash-place. It was when I was about five years old, I went to the planetarium in London. And I hadn’t really thought about Earth or space or anything like that before then. And it just completely opened my mind. And I was just obsessed with space ever since then. And I loved cosmology, and astrophysics and planetary science and even Earth science. I was just obsessed with it. And I went through my entire school life, loving science, being terrible at math, but going through it just because I really wanted to do science. And obviously getting to where I am today, because of that first, yeah, gravity assist from the planetarium in London. So, love them.

Jim Green:Wow, that’s, that’s really neat. And I have to comment on your math mention, because there’s so much different types of math. You know, not all math is created equal, so to speak.

Jim Green: I was horrible in geometry. I just did not like it. But I mean, give me a differential equation, and I’ll solve it.

Naomi Rowe-Gurney:I’m the same. I hate numbers. I still count on my fingers because numbers just don’t make sense to me. So I’m great at algebra, though. So yeah…it’s all different types of math, so…

Jim Green: It is, it is. So I always encourage, kids in school to look past that not to be discouraged, because they have trouble in one area of math, because they’ll find out that in the end, the kind of math that they can really get into will help them be the scientists that they are, or the engineer that they are, in their future life.

Naomi Rowe-Gurney:Definitely.

Jim Green: So, so those challenges are important to overcome.

Naomi Rowe-Gurney:Yeah, I would say my advice would be: Don’t listen to people when they say that you can’t do something. I had so many teachers and tutors, and just people in my life that said, “Maybe you should do something a bit easier. Maybe you should, I don’t know, like, pick a different subject. Maybe maths isn’t for you, you know, maybe science is a little bit hard, like try doing something else. And I’m really glad that I didn’t listen to them. And I let my heart decide that even if it was hard, I was going to try. And I thankfully have a very supportive family that were always very supportive of me.

Jim Green:Well, Naomi, thanks so much for telling us about that fantastic science of these gas giants. And the JWST is going to give us so much more information about them.

Naomi Rowe-Gurney:Thank you so much for having me. This has been great.

Jim Green: Well join me next time as we continue our journey to look under the hood at NASA and see how we do what we do. I’m Jim Green, and this is your Gravity Assist.


Lead producer: Elizabeth Landau

Audio engineer: Manny Cooper