Our Universe Revealed, Part 7: Eclipses in Outer Space

Episode Topic: Eclipses in Outer Space

Lauren Weiss Ph.D., assistant professor of physics and astronomy, will explore how astrophysicists use eclipses of other stars to find new planets. Professor Weiss uses observational techniques to discover exoplanets, which are planets around other stars, and characterize their fundamental properties. Her goals are to understand the origin and evolution of planetary systems and assess whether some exoplanets could be habitable. One way to find planets around other stars in the universe is the eclipse transit method. It works for star-planet systems aligned in a way that, as seen from earth, the planet travels between us and the star, temporarily blocking some of the light from the star once every orbit.

Featured Speakers:

• Lauren Weiss Ph.D., Assistant Professor, Department of Physics and Astronomy, University of Notre Dame.

Read this episode's recap over on the University of Notre Dame's open online learning community platform, ThinkND: https://go.nd.edu/d00557. 

This podcast is a part of the ThinkND Series titled Our Universe Revealed. 

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Transcript

Welcome to Our Universe Revealed

Speaker 10 0:08

Good evening. Welcome to the R Universe Revealed Lecture series. My name is Deb Maher and I'm a professor of ecology in the, um, at Indiana University South Bend. And I'm serving as the moderator for this series. The R Universe revealed lecture series includes talks in science, music, and the arts. In other words, steam for everyone. Um, we feature current research and creative work that's being done in our region, and it it's an opportunity for us to be curious about ourselves our world and our universe. Um, this is a partnership between Indiana University South Bend, the University of Notre Dame, and the St. Joseph County Public Library. Tonight it's my pleasure to introduce Lauren Weiss. Lauren's passion for astronomy began early. She earned a bachelor's degree in astronomy from Harvard University. Completed a master's degree in astronomy at the University of Cambridge, and then a PhD in astronomy from the University of California at Berkeley. She served as a Trottier fellow at the University of Montreal at the Institute of Research on Exoplanets, and then she served as a principal investigator of a Nassau, uh, university of Hawaii Manoa program studying the diversity of planet interiors in Kepler's multi-plan systems in Hawaii. She observed over 160 nights at the Keck Observatory as part of the California Planet Search Collaboration. Dr. Weiss, uh, joined, uh, university of Notre Dame in 2021 and is an assistant professor in the Department of Physics and Astronomy. She has extraordinary research productivity. So an author on 91 research articles and peer reviewed journals and over 4,000 citations. We have a privilege tonight to learn from someone who has a lifelong passion for deepening our understanding of planets beyond our solar system. And so with that, introduce Lauren.

April 8th Eclipse

Eclipse Safety 101

What Totality Looks Like

Speaker 2 2:16

Um, hello everyone and thank you for that lovely introduction, Deborah. Can you guys all hear me okay? Alright. So first I wanna apologize for the weather with a solar eclipse coming up. I wanted you guys to just have sunshine clear weather so that you can see what's going on in the sky. Of course, we have wind and rain instead, so fingers crossed that things will clear up wherever you happen to be for the eclipse in the next few days. Alright, so with that, um, I'm here to tell you about eclipses in outer space. This upcoming eclipse. I, I'm sure who hasn't heard of the April 8th eclipse coming up? Good. You all have, at least from me, right? So I'm gonna tell you how I use eclipses of other stars to find their planets. And really the secret of this talk is it's the same physics, it's the same geometry of bodies moving in space. It just happens to be a lot farther away when it happens with planets around other stars. So let's start with with the history of eclipses. So the word eclipse comes from the Greek ec Eclipsis. I'm not a Greek scholar, so I don't know if I'm pronouncing this ancient Greek correctly. This just means the sudden failure or abandonment of something very dramatic. And in astronomy, what this means is the sudden, dimming of an object the sudden diminishment in brightness. And we talk about two kinds of eclipses that we see here on earth. One is the lunar eclipse where the moon will darken and even turn a beautiful shade of red. And the other is the solar eclipse. That's the kind that we're about to experience in a few days. So what's the difference? Is the configuration of the sun, the earth, and the moon. Where these bodies are in space is what determines what kind of eclipse you get. So I hope you all have figured out by now that we are on a round earth and it's, um, orbiting around the sun. Hopefully that's not news to anybody. And we also have a moon. That moon is orbiting around the earth. So up here we've got a diagram on top with the sun illuminating the earth, which then casts a shadow on the moon. That happens when the moon is in its full phase and the type of eclipse that produces is shown up in the right. That's the lunar eclipse. Now, that's that one you've probably seen before. But what we're gonna see on April 8th is the other type of eclipse. What we have here is the sun, and then the moon gets right between the sun and the earth and it casts a shadow. That shadow falls on the earth and directly in the line of that shadow, you are able to see a solar eclipse. The moon is in its new phase for this kind of eclipse, and hopefully we we'll be treated to something like this. So, as you guys know, there's a big eclipse coming up. Important things to know are that here in South Bend you can at most see a partial eclipse. A partial eclipse is what's shown in the upper right. It the sun looks like a funny crescent phase. The reason for that is the moon is actually physically in front of the sun and blocking out light right there. However, not very far from us. If you go down to Bloomington, Indiana, um, perhaps at the IU Bloomington area or Indianapolis, you'll see something quite different and honestly something more remarkable. So if I change your mind about one thing tonight, I hope it's to make the journey a few hours south of here so that you get to see this instead of that. So this is what we call a total solar eclipse, and it is what happens when the moon blocks out the entirety of the sun diminishing brightness from the entire limb of the sun. So the path of totality of where you can see a total solar eclipse. Is gonna travel through the United States like, so. You can see a few different cities pointed out, including Bloomington, Indiana. Noted right there. My hometown of Rochester, New York is also on the path, and that's where I will be going tomorrow actually. So I highly encourage you, if you haven't yet, take out your phone and scan this QR code. This is the NASA website of Eclipse information. I know there's a lot of information online about the upcoming eclipse right. You can read just about any news source and learn something, but why not learn from NASA itself? They're working hard, you're paying your wonderful taxpayer dollars so that they can tell you all sorts of great, accurate stuff about the eclipse, like how to view it safely. So I highly recommend checking that out. Alright. So here's just another figure showing the path of totality with a few timestamps. You can see as time goes on this shadow where the moon is completely blocking, the sun is moving up into the right. So speaking of safety there's a, a second thing you get from this talk, right? The first one is go south for the eclipse. The second one is don't hurt yourself. So there is a time when you don't need eye protection, and that is during totality. That is if you are in the path of the total solar eclipse, at that moment when everything is dark, you can take off your protective eyewear. That's kind of the point. Otherwise, you'll just be in the dark for four minutes. But at any other time, you need eye protection. If you're looking at the sun. I know this because astronomers who used to not know it would look at the sun through their telescopes and they all went blind. So don't let that happen to you. Safe options include using a welder's glass of a sufficiently high rating, Mylar glasses or special filters, things that are not safe. Your favorite pair of sunglasses, they're not made for looking at the sun. They're made for just reducing a small amount of brightness, regular glasses, transition lenses. No, no. Don't look at the sun with those. But binoculars are a telescope. Just'cause something is made for looking at astronomical objects doesn't mean you should point it at the sun unless it's properly filtered by someone who probably knows what they're doing. I wouldn't trust myself with a telescope with a filter. Just kidding. I, I would, anyway. Um, so you guys might remember the total solar eclipse of 2017. Um, a couple days after that event, it came out in the news that this solar eclipse burned a crescent wound on a woman's retina. She was not wearing proper glasses. And this is actually the image published in a scientific paper showing you the, the burn on her retina. And then someone had traced out the, the shape they saw. And it's this vague crescent'cause she was looking at a partially eclipsed sun, which will still damage your eyes. So second lesson of tonight is don't let that be you. So go to totality, always use proper protection. Okay. With those basics out of the way, let's talk a little bit about what eclipses look like. What's happening is the the moon. And sun are aligning with your physical location on the earth. So this is an example of time-lapse photography that shows a total solar eclipse. The moment of totality is when the sun and the moon are aligned right here. But as you can see at other moments, they're not quite as well aligned. You also might wonder, why is it, why are they moving in the sky so much? That's'cause we're on a rotating ball. The earth is turning and so at the time of the, of this eclipse, the sun is uh, either, either rising or setting. I wasn't there, so I don't know. Alright. But uh, better than a time-lapse photograph is a video. So for now, we'll travel to this beautiful land called Antarctica, which saw a total solar eclipse.

Speaker 3 11:05

So you see the sky darkens. There's this sudden abandonment, where did the

Speaker 2 11:16

sun go? It got very dark and then it comes back. Totality. That moment of total darkness is very short. Only a few minutes. This is still part of, uh, that same video, but now a different different time sequence, different angle, and also with different exposure settings. So you can still see a,

Speaker 3 11:45

uh, the sun's Corona, which is beautifully exposed there.

Umbra vs Penumbra and the Moon’s Shadow on Earth

Transit of Venus

Speaker 2 12:01

Okay, so. Let's see how much you got outta the first part of this talk. This is, this is the one and only quiz that you have to do. I, you know, we make my students do quizzes, so you guys are gonna do one. Alright, so we don't see a solar eclipse every year, right? This April 8th, total solar eclipse is really special. Why is that? Is it because one, the shadow of the moon only falls on a tiny fraction of the earth? Two, only people on the equator can see a solar eclipse. Or three, the sun is much, much bigger than the moon. So, go ahead, hold up whichever finger one, two, or or three you think corresponds to the correct answer. Alright, we, we've got it mostly correct in the audience. The correct answer is number one. The shadow of the moon is only falling on a tiny fraction of the earth. Two is not correct. We just saw a total, uh, solar eclipse in Antarctica, so that, that's clearly not right. Three is a true statement. The sun is much bigger than the moon, but that's not why we don't see a total solar eclipse every year. It's because that shadow is only falling in a small part of earth. So I'm gonna drive that point home here by showing you some eclipses from outer space. So this is from the International Space Station looking down at Earth during the 2017 total solar eclipse. So it was a total solar eclipse for various people in North America. You can see this big, beautiful shadow here. That's the shadow of the moon falling on the earth. And if we look closely, we can see that the shadow actually has some gradation to it. There's a very dark region called the Umbra, where the shadow it's a shadow where the sun is completely blocked. That's where you are seeing a total solar eclipse. The slightly lighter part here, the penumbra, is the shadow where the sun is only partially blocked by the moon. That's where you would see a partial solar eclipse. Incidentally, if you came here today with an umbrella like I did, that comes from the same, uh, route for casting a shadow. Alright, so let's take a look at an animation of a total solar eclipse as viewed from space. Right? So this is an animation, not real footage, but you can see the moon crossing in front of the sun. And even though the sun is much, much bigger than the moon. The moon is much, much closer to us than the sun is. And so from earth or low earth orbit, the moon can completely block the sun. Although it doesn't do that for every single solar eclipse. So we've got a taste of what eclipses look like from space. And there's another phenomenon that I would like to share with you. This is, uh, actually, who here saw this? Yes. Yes. Okay. If you saw the Ven transit of Venus, great. If you didn't, you have to live to like 21 something or other for the next one. So you've gotta live a really long life if you wanna see this from Earth again. So. In addition to our moon, of course, which is beautiful, we live in this wonderful solar system that has many planets including Venus. What's happening here is Venus is crossing between the sun and a very happy observer on earth who's taking these beautiful time TimeLapse photographs, right? This is Venus at various moments during its transits. And if you're wondering about that, that's not some dirt on the camera lens. Those are sun spots. Our sun is a place of wonderful magnetic activity and storms. And so there's plenty going on on the sun with or without these eclipses and transits. But here, Venus, which has an orbit interior to that of the earth, is crossing right between the earth of the sun. Now the word transit, you might know it from things like, I don't know, New Jersey Transit. I took that a while ago. It was bad. Transit just means cross crossing from here to there. So eclipse again is sudden abandonment. Sun dimming transit means crossing, but they're actually the same physical phenomenon. They're happening when one body in space goes in front of another. So this is the transit of Venus. So this is a planet in our own solar system, transiting our own sun. And perhaps you can imagine if you are measuring the brightness of our sun during this transit, it would be a little bit dimmer when there's a planet blocking a small amount of light, then when there's no planet in front of the sun at all. So we can use this fact to look at much more distant objects. This is a beautiful image of the Milky Way over a frozen landscape. We live in a galaxy with about a hundred billion stars, including tens of thousands of them that we can study to look for planets. So this is just what we do. This is an animation that will show you what we do. So if you have some star, and then a planet that transits or crosses between that star and your telescope, the brightness of that star dims very slightly while the planet is crossing in front of it. And when the planet finishes crossing the star, the star returns to its full brightness. So we are able to look for that phenomenon and we can actually measure something about the planets from these transits. The light that is blocked is the cross-sectional area of the planet. So from how much light is blocked, we can learn about the size of the planet. Now, earth is one, 100th, the diameter of the sun. And so if you were to place Earth in front of the sun, in just such a transit configuration, you would only block one 10000th of the light from the sun. It's not very much. This is very hard to detect. Fortunately, like many things in nature, these transits happen to repeat, right? The planet goes around again and again and again. The time between these transit events is the orbital period of the planet. So detecting exoplanet transits from space has led to a revolution in our understanding of planets in the universe. This is a video, uh, put together by NASA in celebration. The 5000th exoplanet that was discovered an event which happened just a couple years ago. So it's telling you this story of our journey and showing you a map of the planets that we've found some beautiful

Speaker 3 19:48

artistic impressions of what they might look like, and a few fun facts that we've found along the way.

Kepler Mission Highlights

Earth-Like Planets & Habitability

Speaker 2 20:46

So kudos to NASA for putting together that lovely video that went by a little quickly. I will walk you through some of the highlights of it now. So around the time that I left college. Graduated from college. NASA launched a telescope called the Kepler Space Telescope named after Johannes Kepler. You might remember him from Kepler's Laws your primary school days. So this is an artist's rendition of the telescope. This was a mission that lasted for four years, and its primary goal was to detect earth-like planets transiting in front of sun-like stars, which as I told you, is just gonna make a, a dip in the brightness of the star of one part in 10,000. So it had to be done from space, not earth.'cause our atmosphere gets in the way. Kepler continuously stared at 150,000 stars for four years to accomplish this task, right? It's looking for these tiny little dips. What's neat is this is actually a part of the sky that you can see and identify, right? It's spring now. Summer's just around the corner. Some of these constellations here, s the swan ULA, the Eagle, and, um, Lyra. The lyre. These, uh, form what's called the summer triangle, and this sunny grid over here is representing the region that we stared out for four years looking for Earth-like planets. Let me show you a little bit of what we found with Kepler. This graph is showing you the brightness of a particular star over 600 days, and what you can see is, well, there's a lot going on on the top and that's related to systematics of the spacecraft and variability of the star. But when you get rid of all of that unwanted variability and look at just the brightness of the star over time, you'll see these drops that fall like rain. These are tiny dimmings of the star by just a few parts per thousand. These were the transits of six unique planets that happened periodically based on the repeated transits and the characteristic dimming and duration of each of these transits. They were identified as belonging to six unique planets. So on the left, what I'm showing is these characteristic dimmings from each of the planets and the real data that, uh, revealed those, and on the right is an artist's impression of this system. We don't ever actually get to see the planets because these stars are just too far away. But remember, because these planets are transiting the star or eclipsing the star, we get to learn about them and know how many planets there are and what their sizes are and what their orbits are. The orbits of the Ke 11 system are remarkable. They would all of the six planets that are known, if you were to insert them into the solar system, they would fit within, within the orbit of Venus. And five out of the six planets would fit within the orbit of Mercury. Of course, in our own solar system, there are no planets interior to mercury. For a while, scientists thought there was, they called it Vulcan. Then they learned about general relativity and realized that there wa there was no Vulcan after all. It was just a behavior of, of objects in general. Relativity. All right. Let's see. So what's really neat about the Kepler mission is over the four years that it ran, it found thousands of planets. This is a plot. It's showing you the sizes of the planets in units of earth, radii. The orbital periods of the planets and helpfully it. Well, it did just tell you where we are, and as you can see, Kepler found thousands of planets about the size of Earth to maybe about 10 times the size of Earth. Most of them much closer to their stars than Earth is to the sun. But it did find a few that are encroaching on this region of Earth's orbit and earth size. Now, why is that special? Well, at Earth's orbit we're a very nice temperature, and if we don't keep warming up the earth with global warming, it will hopefully remain a nice temperature here. It's a temperature where the surface of our planet can support liquid water, which I hear is essential for life. So we'd like planets that are at the right temperature for liquid water so that maybe they might be habitable or perhaps even inhabited. We'd also like to find planets that are small, planets that are large, are generally not rocky. Actually something that I found in the course of my research is that planets should be smaller than about one and a half times the size of earth to be rocky. We want them to be rocky so that that liquid water has a surface to actually pool on and drive chemistry. Okay? So what we wanna know is how many earth-like planets are out there. That was the point of the Kepler mission. We can count the planets that Kepler found, but it also didn't find a bunch of planets. Planets can be detected when they block the star and cause that characteristic dip from the transit. But it's also possible to miss planets if they don't transit. Right? We're, we're so lucky. We're gonna have just the right alignment for this total solar eclipse in a couple days. Well, we have to get really lucky for planets to have the right alignment to transit as well. Fortunately, we know geometry so we can easily correct for all the planets that we've missed. If we just assume that there's nothing special about our location or point of view within the galaxy, hopefully that's a good assumption. A third scenario is that there's a planet that does happen to cross the star or transit, but we miss the transit because our data are too noisy. The variations in brightness are just are too great for us to identify that characteristic dip in the light. So putting all these different scenarios together. A few years ago, my colleagues came up with a remarkable result, which is that one in five stars hosts a. Earth-sized planet. Planet in an earthlike orbit. One in five stars has a planet that might be inhabitable. So when you look at the night sky with these hundred billion stars in our own galaxy and hundreds of billions of other galaxies that are out there, there are just so many worlds waiting to be discovered. I'm gonna finish up by giving you a quick teaser about, um, some of my recent research. So the other thing that we can do with these beautiful planets that planet eclipse and cast these shadows is look for patterns. We've found so many thousands of them. So a few years ago, I found that planets in the same system often have similar sizes. Regular orbital spacing that's exemplified by these systems in pink boxes. And we actually call these peas in a pod'cause they look just like little peas lined up in a pod. Alright. So I'd like to finish by bringing together these ideas of of this solar eclipse that's coming up and these beautiful transiting worlds we've been discovering. This is actually a video from, um, quite a while ago, and what you're about to see is not not an animation of a single system. This is actually, it's highly imaginative, the artist of this animation who's also an astrophysicist imagined. What if all of the worlds we've discovered were orbiting a single star? What would that visually look like? What you're about to see is, remember, this is not actually a physical representation. This is just a, a way to spark your imagination. And I think in particular, this video shows the remarkable effect of eclipses and transits.

Speaker 3 29:52

So let's watch this again. What you're seeing is not a real planetary system, but rather an imagining of what it would look like if all the exoplanets ever discovered. Orbit at a single star, how wonderfully full of eclipses and transits such a place would be. We zoom out now and see that

Speaker 2 31:04

almost all of these planets that were discovered are well within the orbit of Mercury in our own solar system, and that we're still just beginning to probe the planets out at orbits like Venus, the inner edge of the habitable zone and earth where we

Q&A Begins

Speaker 3 31:24

reside. So earths are common. And yet we're still just beginning to find them. All right. I'd like to thank you for your attention and take any questions. Yes. Oh,

Speaker 4 31:56

one of the things I was thinking about when you were showing your data and how you try to find like the goldilock zone of where the, I can be distance wise from the sun. I was thinking you, you must also take into, uh, account the, the relative heat of each sun.

Speaker 2 32:12

Yeah.

Speaker 4 32:12

To find that particular goldlock zone. That's

Speaker 2 32:14

right. Okay. So there's multiple ways to calculate sort of distance, right? And so what you really want is a temperature range in, in theory, but you know, um, for instance, IO is a moon of Jupiter. It's a volcanic moon that's resurfacing every 2000 years or something. It's extremely hot on the surface. There's flowing magma, but it's out at the orbit of Jupiter. So the orbital distance of a body alone doesn't actually tell you the temperature. You can just get a guess about the temperature based on what radiation you're you're expecting from the sun. But there can be other sources of heat too. Yes.

Speaker 5 33:00

What is the width of the shadow of the total eclipse at any given point? Is it?

Speaker 2 33:10

Good question. It. No, it changes over time. The reason it changes over time is actually the moon does not have a circular orbit around Earth, but it has an elliptical orbit, slightly egg-shaped. So during some solar eclipses, the moon will be a little bit closer to earth. And during some solar eclipses, the moon is a little bit farther from earth. You might remember from just this fall, we were supposed to have an annular solar eclipse, and then it was the day of a big Notre Dame home game. Very exciting. And then it poured rain all day. So an annular eclipse is what happens when the moon is far enough from the earth that, that it doesn't completely block out the sun. So the moon can be completely in front of the sun. But just like with, say, a transit of Venus or a transit of Mercury, it's, it's not actually blocking out everything. There's, there's a, a bright edge around the moon, an annulus, a ring, so that's why it's called an annular. Solar eclipse. We had one of those in the fall, but we didn't get to see it, at least not here in South Bend. A total solar eclipse can only happen when the moon completely blocks out the sun. And for that you need the angular size of the moon to be at least as large as the angular size of the sun. When the moon gets a little bit closer to earth and it's orbit, it has a slightly larger angular size, right? You bring something closer, it covers a bigger angle, and then that's when you can get a total solar eclipse. So, long answer, but the, the short version is know that there's not a, a fixed width and it's gonna change with each eclipse.

Speaker 6 34:47

Would you say it's within an hour distance? Like if you wouldn't travel? I go to,

Speaker 2 34:53

And

Speaker 6 34:53

then if I were to travel south. You know how long?

Speaker 2 34:57

Oh, I mean, you should just, you should look at a map and if you scanned the QR code from nasa, you can absolutely get like maps of totality and, and times too.'cause the further you go from that line of totality, the shorter the totality will be. Yes.

Speaker 7 35:17

Somewhere I called somebody or something I read was stating that the moon is the only moon in the, in the solar system that allows us to have totally equipped

Speaker 2 35:30

Yes. That's, I think that's correct.

Speaker 7 35:33

What a question. So you mentioned that it's a couple of other earth planets that have been discovered. So in terms of their boot wax zone how much less. In text, will the sun be that it would have to go around to have that goldlock mount since they're all inside the cor,

Speaker 2 35:57

right, right. So there are plenty of stars at the galaxy. Actually about half the stars in the galaxy are significantly smaller than and cooler than our own sun. Yeah. Red dwarfs and also, or orange dwarfs too. And so actually a lot of the small planets that have been found in the Goldilocks so far are around these orange dwarfs that are just a, a little bit cooler and a little bit smaller than our son.

Speaker 7 36:26

So now my understanding is that the, the Warf stars would have a longer lifespan. Compared our sun,

Speaker 2 36:35

the, the cool stars. Yeah. So these, these red dwarfs, yes. They, they are less massive. The lifetime of a star is related to the amount of fuel that it has divided by the rate at which it burns fuel. And it, it turns out that, uh, if you wanna live a long time, you wanna you don't wanna burn, what is it called? Burn a fast die young. That's, that's what the big stars do, but the little stars do whatever the opposite is. They,

Speaker 7 37:00

does that give us a better opportunity of if we could go to these plants, be better off going to one of the,

Speaker 2 37:06

um, probably not because, uh, at least the m dwarfs, the very red stars, uh, tend to have very active coronal mass ejections and solar flares that produce a lot of create a lot of ion ionized space particles, which, for which you would need to have a, a strong magnetic field on the planet to save you from that. We're just in the process of probing the atmospheres around some of these. Worlds around different types of stars, and exactly as you say, we're trying to understand do they have atmospheres that would make them nice places to live in the back.

Speaker 8 37:42

Okay. So in reference to what you said would art planet then be the only place where the moon mines up exactly in the circumference of the sauna? Was there other pitches that line up in that same diameter in circumference? Like in terms of it being like you say, like Mars has eclipses right, but its moons are shaped haphazardly. It's not like they're like a, it's not like a, just a perfect circumference.

Speaker 2 38:07

Yeah. Yeah. It's really, I I think it's actually really striking that the angular size of our moon is almost exactly the same angular size as our sun. Even though the sun is a hundred times the size of earth and Earth is several times the diameter of the moon. It's really funny. The distances work out such that the angular size of the moon just barely blocks out the whole sun. And actually in in geological timescales, the moon is actually slowly spiraling away from the earth. This, this is a title interaction between the earth and the moon, same as the tides that cause, cause our oceans to move around. So what's gonna happen in the future as the moon spirals away from the earth, is eventually it'll be too far from us to cause total solar eclipses. So we're very lucky that we live at a time where we can see this.

Speaker 8 39:08

To add to that question, I was gonna ask if there's any other places that the detective that have the circumference matching the, I guess the same way that eclipses would be, would be been modified. Is there any other exoplanet that they have?

Speaker 2 39:21

Oh, exoplanets. We have not yet discovered exo moons, but that's, yeah, that's, that's in the works. We would like to, that sounds fun. We're trying.

Solar Storms, Auroras & What You Can See During Totality

Speaker 8 39:31

Yeah. And then in terms of, um, you mentioned coal mass ejections. Has there ever been, uh, like an EMP during a solar eclipse? And how would the, um, I guess if the moon was covering up the, the earth during a solar storm, does that have any effect on the, I guess the magnetic field of the earth?

Speaker 2 39:51

Uh, yeah. So one phenomenon that we get during solar storms is aurora. So actually just a few days ago, there was a massive coronal mass ejection that hit the earth and caused beautiful Aurora in the southern hemisphere. I'm not, not sure if there were any in the northern hemisphere as well. It might, it might just sort of depend on sort of where the blob hits, earth's magnetic field. So that's one major outcome. Another is that satellite communications can be disrupted charged particles. All the charge particles moving in space are electric currents, and they, they produce electromagnetic radiation, which can interfere with satellite communications.

Speaker 8 40:32

In terms of the, a solar storm happened during the,

Speaker 2 40:35

oh, during the eclipse

Speaker 8 40:37

with the moons have some dispersal effect on the magnetic ray, or how would that work? Or once the eclipse was I guess out of that direction with the

Speaker 2 40:46

Yeah, well, it takes, it actually takes a CME about a day to get from the sun to earth. So if there's a CME that's just getting ejected from the sun. During the total solar eclipse, that would look awesome. And actually, I think in one of my slides, the, I think I've got the 2017 eclipse in one of these, and you can really see, yeah, this one, you can really see the sun's Corona with Corona means crown, same as coronavirus. That virus is named for having little crown lake spikes on it. So this sort of beautiful spiky pattern of this diffuse plasma. This is the Corona of the sun. It's about it's about 10 million degrees. It's actually one of the hottest parts of the exterior of the sun. And, uh, weirdly though, if you actually like put up a shield and went there, but were out of the way of the radiation space, there is actually very cold. So you could, you could freeze even though it's quite hot. It's, it's complicated. But, um, what you're seeing here is trace particles moving along magnetic field lines. So you could potentially see a coronal mass ejection, but what you would see wouldn't get to the earth till a day later. And then the moon wouldn't be like right in line with you and your spot on the earth. You can actually see a prominence right here, this beautiful pink thing. Pink is from the chromo sphere. Chrome is from the Greek word for color because of that characteristic pink color. So it's from a slightly deeper layer in the sun underneath the Corona. It's arching out because of a magnetic field. Let's see. Take this one first.

Speaker 9 42:22

Alright, so you mentioned that a lot of the exoplanets that have been discover are within the orbit of the mercury. And what I'm wondering is, is that something that that is

Speaker 10 42:34

likely to be. Feature of what exoplanets there actually are, or is it just a feature of what exoplanets we've been able to discover? Given that the closer a planet is to its star, the more light it will block out.

Speaker 2 42:47

Great. Great. Yeah. Excellent question. So the closer a planet is to its star, the more likely it is to have that eclipsing geometry. It turns out if something's really far away from its star, we've gotta get it really perfectly aligned to get that eclipse. But if it's closer, there's more wiggle room where you actually get an eclipse. So we're a lot better at finding planets that transit close to their stars. Something that we're working on right now is trying to understand how the inherent abundance of planets varies with for with location in the planetary system. One thing that we do know, based on these thousands of planets we've discovered within the equivalent orbit of mercury, one thing we do know. Is that at least one in two stars has one or more planets within the orbit of Mercury. So already our Sun, which has no planet interior to Mercury, we're in the 50% of stars that, that don't have planets there. And um, I didn't really have time to get into this, but um, something I've found in my research actually is that most of these other stars have not only one planet within the orbit of Mercury, but multiple planets in these beautiful patterns within the orbit of Mercury. Now, if our solar system had that, we would've found it. We're not very good at always at finding what's out there, but we're pretty good at finding what's in here. So the fact that we don't have this beautiful pattern that's prevalent in so many other solar systems is curious. That said, we're still exploring the earth-like regions, um, in other planetary systems. And it seems like they are quite common. At least one in five stars having such a planet out there. But yeah, there's more work to be done for sure. There was a question in the middle here.

Speaker 10 44:53

Oh, I here, I had my hand raised. That was exactly the question I was gonna ask too.

After Kepler: New Missions, Roman Telescope, and What’s Next

Speaker 2 44:57

Great minds think alike sometimes. Yes.

Speaker 11 45:01

Is there a follow on to Kaplan? Is there another satellite another, uh, satellite out there now to do the same work?

Speaker 2 45:06

Please give me like 25 million a year plus whatever the costs are for actually building a Kepler replica, which we've done it once already. We can do it again. Right. So I'd, I'd love to think that we could do another Kepler. I don't know if that's in the works at the moment. But we do have some other really exciting missions coming up, including the Nancy Grace Roman Telescope, which actually has a much bigger field of view than Kepler, and it's gonna be pointing toward, weirdly, toward the center of our galaxy. So we might find a bunch of transits that way, and they might be around a, a slightly different population of stars than what we've probed in the past. So keep your eyes and ears open. Yes.

Speaker 6 45:48

I had a question about telescopes, but the ones down here on earth, I understand why we, we put'em out in space, but why do we put the telescopes in different places of the, of Earth? You know, I, you mentioned Iceland and Hawaii, and I read somewhere with building one in Chile, but why those places? Why not?

Speaker 2 46:10

Wonderful. Yeah. Wonderful questions. So I, I was actually just fortunate, uh, in the past week to go to a conference in New Zealand, also called roa. It's um, in the southern hemisphere. So the sky that you see from the southern hemisphere is that way. We don't ever get to see that sky from here. I got to see the Southern cross. I got to see the large Magnic cloud. I got to see Alpha Santore, the closest star system to the solar system. And I got to actually see both stars of that binary alphas A and B through a telescope. It was very cool. So we can see things that are different in the north and the south. That's one reason. Uh, another is longitude. It is, um, only night for about half the day, and then the other half of the day we astronomers just sit around like drinking coffee and waiting. Or, you know, teaching or whatever, whatever it is we're supposed to do. Right? So what's great is if you have telescopes all around the world and you're like, Hey, there's this thing I'm trying to study. I don't know exactly when it's gonna happen. We'd like to monitor and look for it. That enables slightly better continuous monitoring from the ground. So there's actually a large uh, taxpayer funded program that, that does just that as well. Yes.

Speaker 12 47:36

How is all this data being shared and collected? I assume, well, you just mentioned all these telescopes all over and like you mean insights on that?

Speaker 2 47:45

Yes. Great question. Observatories are a little bit like medieval castles. You know, ev everyone kind of does their own thing. But what's great about public funded observatories is making the data public is a huge deal. So actually all of NASA Kepler data is public. You can go online tonight, go on the. Miss Luki, um, archives of space telescopes and just download all the Kepler data. I don't recommend doing that unless you have a big hard drive. But you can download the data, you can play with it. And actually, lots of astronomers have written beautiful tutorials. If you're a computer programmer, you can like just jump online, run through some of these tutorials, and within an hour you can be playing with, with real data from one of the best space missions that has ever flown to discover exoplanets. That said, other data's proprietary. Right. If I build my own fancy telescope in my backyard, I can do whatever I want with the data. So some telescopes are privately owned, some are publicly owned, and it just, it depends. But I'd say overall what we've been learning is. There's just so much beautiful data out there in the universe, and our lives are so short and crowded and complicated that it's better to just share it or err on the side of sharing. So more and more people have been reducing proprietary periods, making data public and accessible and actually creating citizen science opportunities as well. So seriously, if you want, you can go home tonight and find real data to work with at whatever your level is. Yeah.

Speaker 7 49:20

So why did they pick that particular passion on Sky and ke permission?

Speaker 2 49:24

Oh, a fantastic question. So it is

Speaker 3 49:27

just, oh, let's see this way. Okay,

Speaker 2 49:41

so apologies. This is sort of a low resolution image, but, what you can still sort of make out here is going from the lower left to the upper right is a beautiful band. That's the Milky Way, that is the plane of our galaxy, a spiral galaxy that we live in. So this is quite crowded with many, many stars, but also dense gas and dust. It's very complicated to try to look at. There's just so much stuff going on. So the Kepler field was chosen to point, just grazing along that galactic plane. You can see it's not quite pointing on the plane, but just off of it, a region of the sky that's still very dense with stars. There are actually millions of stars in the Kepler field, although only a hundred, 150,000 of them were continuously monitored. So it was very carefully chosen to to select many stars. Stars that we would be able to study without too much confusion and also astrophysical. Stars that are quite similar to our sun in terms of their relationship to the galaxy as a whole. Yes.

Speaker 12 50:54

Is there a minimum diameter? I'm kind of thinking like, how do you distinguish from the planet and space junk?

Speaker 2 51:00

Oh, space junk. Yeah, we're, I'd love to be able to do space junk. That sounds really cool. I mean, so far the smallest stuff we've found, which was with Kepler, is like Mars sized. Mars is definitely a planet and not space junk. But we, we would love to find smaller stuff. Actually. People who use infrared telescopes, including the beautiful new James Webb space telescope, are able to, uh, sense space dust, including tiny dust particles. Now they don't see the individual dust particles, but they infer the density of the dust and its temperature and general properties from the light that they gather from it. So people are also studying dust and planetary systems. So, so we're we, we can do dust and we can do Mars, but we haven't figured out the in between. Yeah.

Speaker 4 51:50

Is there any value in like using James Webb or Hubble to look at a transit of an exoplanet?

Speaker 2 51:58

Absolutely. Absolutely. At this conference I was at in New Zealand, we had I think three separate sessions on new results from the James Webb Space telescope. One of the main things that we are using James Webb to do is to study the atmospheric properties of these planets. We can measure their sizes. I taught you how to do that based on how much light they block. Uh, what I didn't teach you is how we measure their masses, which is also important because that tells us how well they're gonna hold an atmosphere. Once we know those two pieces of information, we can look at light that has filtered through the planet's atmosphere or try try to do that. It's very hard. It's just like the transit of a planet, but it's the transit, just of the outer atmosphere of the planet that we're trying to detect. It's very, very challenging. But James Webb is an enormous telescope, six and a half meters, and it's in space. So it's in one of the best possible conditions for doing this kind of science.

Speaker 4 53:00

Like its resolution is much

Speaker 2 53:01

Yes.

Speaker 4 53:02

Bigger than Kepler, I would imagine.

Speaker 2 53:03

Yes. Kepler was a one meter aperture. Whereas James Webb is six and a half meters. And the, the big difference there is the light gathering power, which is going to be six and a half squared times better. So about 50 times better.

Speaker 13 53:16

But it had different uses to just look at one.

Speaker 2 53:19

Yes. It doesn't just, it doesn't just look for planets transit, but we can point it at many different stars with planets when those, when we know those planets are gonna transit to study their atmospheres. I've just learned. That in, um, in some of these planets that are a bit bigger than Earth, but smaller than Neptune, we've, for a while we've been calling them mini Neptunes, but they're not act, we, what I just learned is they're not actually like mini Neptunes. Neptune has, uh, rock and ice, uh, rock in the middle, then some ice in a super critical state, and then a, an envelope of hydrogen and helium. But these Neptune like worlds, they're like Neptune in their sizes and masses, but they're much warmer than Neptune. They're inside the orbit of Mercury. They're, they're getting roasted, and that changes their atmospheric chemistry. And what actually happens, and we, we've now seen this based on how light filters through their atmospheres with James Webb, is that these worlds actually have this, um, it's called ible or like mixed water and hydrogen envelope on the outside. So it's like a suspension of both water. Hydrogen molecule is all mixed together. Another example of a ible fluid is vodka, alcohol and water mixed together. We have yet to find that atmosphere though. And anyone else who hasn't asked a question yet. Yes.

Speaker 11 54:44

And all your researching your studies and like you'll find all these different exoplanets and so forth, you ever reflect back on how unique our system really is? I mean, our sun is perfect. We have the right amount of planets that surrounds our planet. It's at the right distance. The type of star, I mean, all the other planets that we know have discover they're either too close or still non star. It's almost like a lottery. I mean, you're looking out there, it's like it gets bigger and bigger each planet you find.

Speaker 2 55:18

Yeah. So there are two competing philosophical principles here. The. You, you got me started on the big questions, right? The Copernican principle, which is we shouldn't actually be that special. We're just, we just happen to be observers in the universe. There shouldn't be something super special about where we are. But the anthropocentric principle is, well, hey, we actually are in the patch of the universe. That became conscious of itself. That's amazing. And maybe some of the conditions here are a little bit different such that, that happened. So those are two competing philosophical ideas. I think what will help resolve them is finding consciousness or life, or, I don't know, whatever you consider meaningful. As we continue to search the cosmos, whether that's life on exoplanets or, um, I actually think our best bet for finding life would be some of the icy moons in our own solar system. I mentioned IO earlier, which is volcanic and. Like way too sulfurous and pot for life. But, um, other icy moons, Europa, a Moon of Jupiter and Enceladus a moon of Saturn. They both have liquid water. They have, they have salt, they have ammonia, they have organic molecules, they have the ingredients for life. So in some ways, you know, what we've got here on Earth is, is wonderful and special. But also there are other configurations that can give rise to some of the conditions that we think might be suitable for life. So we're, we're still exploring. Can I take one more question?

Speaker 8 56:55

Don't you think that it's more likely that maybe the universe was fine tuned, especially our planet and its position in the fact that all of these celestial bodies and um, the markers of seasons and everything are so closely aligned to just the way that our, our world is run.

Speaker 3 57:13

No, I, I don't

Speaker 8 57:14

be a creator that made all of this and that was it. Able to you know, show his, his magnificence by, you know, showing all the, uh, I guess the signs to, to, I don't know, like that, that would be there for us to guide us in our life, in our daily life.

Speaker 2 57:29

I mean, I think you can get personal guidance from that. That totally makes sense to me. But for me, I mean, I'm, I'm still looking and we're like, we're still finding worlds that are approaching earth-like, and no, I have not yet found an exoplanet that has soy chai lattes, like, which is my criteria for habitability. Right. But

Speaker 8 57:51

who knows if there are other bulls that are in that, in each seven, discover one. Right,

Speaker 2 57:56

right. But it's, there's hundreds of billions of chances out there. So I'm certainly not ready to. To close the book and say, this is it. We are all there is. I think there's just so much out there to explore.

Speaker 8 58:10

There could be other roles out there that were also fine tuned in the same way that we we're fine tuned.

Speaker 2 58:15

Yeah. So actually what's interesting is with um, actually with, um, some pretty different physical initial conditions some of my colleagues have found other, other ways that that life could have emerged. So what you describe actually fine tuning is something that some of my colleagues have actually been exploring and we're not as fine tuned as you might think. So that's actually pretty exciting, including things like if the cross sections of carbon were even a little bit different, um, it could be a problem in some ways, but also in other ways might actually make life much more prevalent than what we observe. So. Fine tuning is an interesting problem, but really until we get more examples and see what the variety is, we don't have a way to answer that question through the purview of science.

 Closing Remarks: Series Wrap-Up and Where to Watch Past Lectures

Speaker 10 59:15

So I wanna thank you for coming tonight and let's see. Oops. And I just wanted to, so this is our last, our universe revealed, uh, lecture for this year. And in case you missed any of'em. So this year, uh, so in September we dived into fungal pathogens, uh, then thinking about eclipses, uh, a discussion on the Nobel Prizes that were awarded this year. And then in December we dove into music and creating music with understanding geometry. And then thinking about how bacteria communicate with each other. Then we got into origami. So again, geometry, but also folding patterns, what works, what doesn't. And then we got into, we explored a little bit of AI and then of course tonight we went out into the universe to see what's out there. So anyway, thank you so much for coming. If you missed any of these, you can go to Universe Revealed nd.edu. You can see previous, uh, lectures they've been videotaped by Steve to, and I'd like to thank him. He's been

Speaker 3 1:00:26

here

Speaker 10 1:00:30

and you can sign up if you wanna get notifications of things that are coming up. So what will come in fall of 2024. So thank you so much and if you have any additional questions for Lauren, not sure she'd be happy to answer. Thank

Speaker 7 1:00:44

you.