 So good afternoon, I'm Carol Stern, I'm here at the North Carolina School of Science Math with Zoe Webster who is going to be speaking with us today about the search for extraterrestrial intelligence. This is a talk that she's given to college students and relates to work that she did at UC Santa Cruz and at the SETI Institute. So thank you, Zoe, for spending your afternoon with us. Alright, thanks Carol and thanks to all of you for attending today. I am pleased to be able to share this with you. I will be introducing some of the areas that you could extend this material into your teaching as well as we go along here. So I know you think you signed up for something fun and just joyous and light and airy but it's really actually a math talk. So we'll be discussing a math equation for the entire talk but don't be concerned, we'll go through each and every term one at a time. The equation we're going to be going through is the Drake equation and the Drake equation was invented by Frank Drake who's shown here. I work with him at the University of California at Santa Cruz. And the Drake equation is just a framework that allows us to explore all of the astronomical terms and the sociological terms involved with getting an estimate on the number of civilizations we might find in the universe. So this is the equation. Again, we will be going through each of these terms one at a time. So an overview of what we're going to be doing today will be, first of all, talking about where we should look for life and intelligent life specifically. And why am I so optimistic that there's life out there to be found? Why should we spend any resources on this? And the short answer for that is that there's water everywhere. And then, of course, what's intelligent life got to do with life and what's the difference as we're doing our search? And again, I want to tie this into some of the standards so that you might think about ways you can use this in your classroom teaching as well. So it's a really big universe. So one of the reasons I'm an optimist that there should be life for us to find is because it is so big. There's plenty of space. And in this image, I'm not sure if you guys can see the mouse when I do this, but everything in this image except this little bright piece is a galaxy. And there are hundreds of billions of galaxies in the universe. And every single one of those hundreds of billions of galaxies has hundreds of billions of stars. So each galaxy is just teeming with stars. And of course, our sun is just one of the stars in our own Milky Way galaxy. But the problem with stars is life does not live on stars. Life is a planetary phenomenon. Life, as we know, it exists on planets. So when we look at the first two terms of the equation, the first term is a rate, a number per year. How many stars per year are born? So that's a quantifiable question. And it gets at how many stars are there per year born. And then that second term, that f sub p, is a term that says, well, what fraction of all of those stars that were born? What fraction between zero and one, where zero is none and one is 100% of them, what fraction have planets? So we know our solar system has planets, but does every star have planets around it? So here's a representation of our solar system. We have eight planets. Yes, Pluto was demoted. It's no longer considered a planet. And we're looking for planets out there, and it's not the easiest thing to find. But as of today, we have found over 3,000 planets around other stars. So this does not include our eight. This is just planets around other stars. So 20 years ago, this number stood at zero, or maybe four. But for an astronomer, between zero and 10 is pretty much the same as zero. But now we're at a really big number, and we can attribute that in part to the Kepler mission, which I'll talk a little bit more about later. But we've actually found quite a few planets. So the question now becomes, are they good planets? Because we know in our own system that we wouldn't want to live on Jupiter. We wouldn't want to live on Neptune. We definitely would not want to live on Mercury. So how easy is it to find a good planet to find life? So is it just one good planet among billions, or is it common to have a good planet? So what do we mean by a good planet? Well, Earth's a great planet. Yay, Earth! So we want to have planets like Earth. Well, some of the things that make Earth a good planet is it's massive enough to hold an atmosphere, and it's warm enough to have liquid water. Well, the system shown here on screen is Gliese 581, and it's shown on the top of the diagram. On the bottom of the diagram is our solar system, which shows a representation of the Sun, Mercury, Venus, and Earth. And Gliese 581's representation, actually they have found four planets in that system. And Planet E, which is really, really close to the edge of that picture, is actually about twice as massive as Earth, and it should be warm enough to hold liquid water. So when we have the third term in our math equation, so we've started out with the number of stars that form per year, the fraction of those stars on a sliding scale from zero to one, the fraction of stars that have planets. But now we want to know, if you've got planets, how many of the planets in that system are good? So in our system, there's at least one good one. I might argue, and I will argue in a few moments, that there's a couple more than one. For example, in Gliese 581, we found four planets there, but only one of those four planets is a good planet. So the Kepler mission, as I mentioned earlier, has been looking for planets and is doing a gangbusters job of finding planets. And it turns out that at least one in six stars has an Earth-sized planet. That's a much bigger number than we had originally thought. But it's because of the sensitivity of this telescope that we're able to find these planets. Techniques from the ground make it much harder to find planets a lot like Earth. So the Kepler mission has really been a jump forward for us because its technology allows us to detect these Earth-mass planets. So if you're interested in finding planets or knowing about planets, there's a website Planet Quest that is devoted to planets and all the planets that have been found. And this again is a little snapshot of the site that's showing this Gliese 581e, the fourth planet around the star Gliese 581. And this website has all kinds of great stuff. It's very visual website. It includes an image of the sky where the star is. It includes an orbit with comparison to our own planetary orbit. So you can see in this particular system, Gliese 581e is inside Mercury's orbit. It's closer to its star than Mercury is, but it is not as hot there because it has such a dinky little star that it's orbiting. Gliese 581e is not a very bright or luminous star. It's an M-type star. So you can see on the very far right that the type of star is listed and it's listed as an M-type star whereas the Sun is a G-type star. It also lists the planet mass, which is almost twice Earth's, and when it was discovered and how long it takes to go around its star once. So in this case, its year is 124 days whereas Earth's year is 365 days. So this is a great resource if you hear about planets that have been discovered is to use this webpage. Let me interrupt you for just a second. And our participants, if you've got any questions and you want to ask while Joe is doing this presentation, there's a little green leaf at the top of the page. You can pull that down and click on the chat area and type in your comments and we will address those questions if you have any. So thanks for joining us. Yes, please do ask questions. It will make me feel like I'm talking to other people and not to my computer screen. So I've hinted at a good planet, the definition of a good planet. So a good planet, and this is where the biology starts to come in, as well as little physics. A good planet is one in which we have liquid water. So liquid water is important for life, but you can simulate just the habitable zone as it depends on the star with the simulator. I'm going to just try and share another piece of my computer with you if I can. So hopefully you can see this webpage. This is a fabulous free resource. It's a bunch of labs for astronomy and this is a habitable zones lab. And the students can actually see the zone and a zone is a three dimensional space on this two dimensional representation of our solar system. It shows as a range of distances from the star in which you can have liquid water. So you can see in our own solar system, neither Venus nor Mars are in the habitable zone, but you can change the settings. And that star that we were just looking at, Gliese 581, is a very, very small mass star. Its habitable zone is really, really close in to the star closer than Mercury's orbit, which is why Gliese 581e is in the habitable zone for its star. So Earth's in the habitable zone for our star and Gliese 581 is in the habitable zone for its own star. So this is just one resource that you might consider using for your teaching. So why do we care about liquid water? Well, from the chemistry point of view, water is a wonderful polar molecule. It dissolves just about everything. And if you are an amoeba and you are floating around, your food just drifts by all already dissolved for you. That is a great thing for you as an amoeba. So water is important for dissolving things and also providing access to food for a lot of single-celled organisms. The other important thing about water is its phase diagram. And water is really, really good at moderating the temperature of things because it's hard to get it to boil. It's hard to get it to freeze. It takes a lot of thermal energy to be transferred to get water to boil. And it takes a lot of thermal energy to be transferred to get water to freeze. So water is great at moderating the temperature of the environments for creatures. So one of the things that you may teach in biology is about the ecosystem and what makes a good ecosystem. Well, water is one of the things that helps make a good ecosystem for single-celled organisms because it moderates the temperature of those, for those creatures, if you will. And of course, in chemistry, we do teach about phase changes as we go through our teaching. And water should be one of those things that students are very familiar with, its phase diagram. So how do we look for water? We have spent a lot of energy in the United States via our NASA programs looking for water on Mars. And the most recent mission is the Curiosity rover, which has been in the news a lot. They have a lot of press releases about it. But its primary mission is to look for signatures of water on the surface of Mars. And it does that in some very simple ways and it does that in some very complex ways. And the way I've got pulled up here on the screen is a very simple way. It's just looking to see if it looks like river rocks. So if you've been out walking and hiking, you've probably seen pebbles that look like they've been ground up by water. And that would be similar to the ones on the bottom right here. First, gravel, rounded edges that have been worn away by water. Well, on Mars, we've got a great camera on the Curiosity rover and it has taken pictures where it landed of rocks that are too big to have been blown around by dust. Because you could also imagine they get eroded by just blowing around. But these are too big, so these really are gravel-sized rocks. But they have very rounded edges, a lot like the river rocks we see on Earth. So we think that we're looking at a river bed on Mars, except there's no more water in it now. So this is a past river bed. But so this is one piece of evidence that water did exist on Mars in a liquid form at some point in its past. Oh, this didn't come out very well on the screen. I'm sorry. This is a more sophisticated way that the rover is looking for water. And this is about a 10 centimeter across. So imagine two of your hands side by side is the entire width of this picture. This is a spectrum picture. So if you teach about flame tests in chemistry, for example, using the colors you see in the flames to identify compounds or elements, this is a very similar process except we're looking at the different colors of light reflected from the rocks. And using the colors of light reflected from the rocks as a signature as to what type of materials these rocks are made up of. So we have a color code on the right. The red means more likely to have water in them. So this, if you are a geologist, which I am not, I just used to work with them. But geologists, of course, love to go take rocks and then take them back to the lab and examine what they're made of in the lab. But if you are really, really far away from the nearest lab, all you can do is take pictures of your rocks. So we take as many pictures as we can and then use the pictures to analyze it. This is a spectrum. We've broken up the reflected light into many colors and certain rocks reflect certain colors better. And so we're able then to make an approximate identification of the types of minerals in those rocks. And again, the red ones are the places that have a lot of water in them. So we think that this is a riverbed. There's not just rocks that look like they were worn down by a river, but it looks like there's rocks that were made in processes that would require water to make those rocks. So Mars is a place that we have spent a lot of time looking for water and finding water. But we found water in places that we didn't expect to see water. And I wanted to share one with you, which is Enceladus. And this is one of Saturn's moons. This is a Cassini orbiter who's in orbit around Saturn right now and has been up there for nine years, is still up there. If you look at this picture, which is just a fantastic picture, it looks like the moon is an ice moon. I just got that white color. And then there's these blue streaks at the bottom. They call them the tiger stripes. It looks like rivers, and maybe it is water. So we had an opportunity to take a picture of Enceladus while it was backlit by the sun. And you've probably taken photos before that have been backlit by a window and had disastrous results because of it. But one of the nice things about backlighting here is that it gives you the opportunity to see the... So I'm going to play this little video and I'm going to turn up the volume a little bit. Let me make sure that I'm sharing this. I'll just pause that. We had not expected to find water and we did. So this is why I'm an optimist about finding life because water is just apparently everywhere in our solar system and even liquid water. But one of the next places we might consider looking and branching out. We're talking about how many planets in a particular system and sub-E are good for life. To start asking the question, does it have to be water? Does it have to be liquid water that we're looking for? And Titan, which is Saturn's largest moon, has an atmosphere, a lot like Earth's atmosphere. But it's freezing there. There's definitely no chance of liquid water happening on Titan unless you've got a situation like Enceladus with an internal heat source that's warming up the water. But we see these things that look a lot like riverbeds on Titan. So the question is, what is making riverbeds? Doesn't that look like a meander that you see here on Earth? Well, this looks a lot like liquid methane. So Titan has liquid methane and liquid ethane. And those are carbon, long carbon chains. I mean, here on Earth, we fart methane and we could burn methane for fuel if we so desire. And sometimes we do in landfills. But on this planet, it is so cold that methane is... On this planetary body, there's the so-called methane is a liquid and you can actually have it raining from the sky and forming riverbeds. Now, we don't think this is the common phenomenon on Titan, but it does let you ask the question, if you just need a liquid that dissolves things, could liquid methane be good enough? Could you make liquid methane become your medium to form life in? So again, using the Drake equation as our framework, we have the rate of star formation, the number of stars per year, what fraction of those stars make planets, and then how many planets in each of those systems are good Earth-like things. And we're kind of branching out our Earth-like definition here to maybe even include something like Titan. So the next term in our equation is the fraction of all of those Earth-like planets that make life. And if you're familiar with Earth's history, Earth was formed about four and a half billion years ago, and life happened almost immediately in geologic time after that, practically instantly after that. And it seems that life is everywhere. So this is an image of one of those hot smokers or black smokers. It's very inhospitable down at the bottom of the ocean, very cold, very high pressures. I mean, if you're a tin can, you're going to be crushed flat down there. And yet we find life by these hot smokers because there are little places in the Earth's crust that have been open. They're much warmer. There's a lot of sulfur coming out, and certain organisms can use sulfur to get their life going. That's what they use as their energy source. So everywhere on Earth, we find life. And it seems on Earth that life is a cosmic imperative, that there's nowhere that we look that there's not life. So one of the other resources here is for if you're looking at life on Earth is to look at microbial life on Earth. And one of the resources I have provided here is an astrobiology link, but it's a link about microbial life. So you can go to the Educator's Collection here and look at some of life in extreme environments, which is a resource. But you can also take a look at the, did not bring up the right page, I'm sorry, some of the life that happens in very cold environments. So we find life on Earth in Antarctica. We find life on Earth in extremely acidic environments. We find life in extremely alkaline environments. So this set of web pages has a number of links for different types of extreme environments and then give some examples of life that lives there. So when you're talking about ecosystems, you can talk about how different ecosystems are good for different types of life. So the Dead Sea is a very hyper-sailing environment and we do find things that live in those environments. So when we talk about the fraction F sub L of planets that might have life, we have to think about more than just places that we normally think of on Earth for life. We need to think about some of these extreme places that we find life here on Earth as well. That could be a teaching opportunity to branch out from the regular environments that we normally teach about. Well, life is great, but I don't communicate with the two worms at the bottom of the ocean. I do not communicate with algae and bacteria. So we need to think about intelligent life. So I'm going to see if I can actually see you guys' hands. So how many of you think dolphins and elephants are intelligent? So maybe you can raise your hand. Okay. All right. So you vote that elephants and dolphins are intelligent and you are wrong. But only in my strict definition of intelligence, and I will explain what that is in a moment. So how about chimpanzees? Oops, clicking buttons. There you go. Your audio is good. All right. So chimpanzees, some people might consider chimpanzees intelligent. And again, I would say not in my definition. So where's the evidence that chimpanzees or elephants or dolphins are intelligent? Some of us are going to have different definitions of what it means to be intelligent. And I asked my high school students about this and they said, being able to mimic. And I said, well, boy, howdy. I don't think my dogs are intelligent, but they can mimic lots of behaviors that they see. Communication, is that a definition? So intelligence in the biological sense can be a very rich discussion to have with your students. But in terms of the searching for intelligence, there's another thing we're going to add on top of that. So the question then that you may have is, are people intelligent by this definition that I'm going to apply? And so you can imagine the most, yes, I will tempt you. So I had a wonderful photo of someone that I could not find a copyright free version of, but definitely a very foolish person. The question is, are all humans intelligent? So when we talk about this Drake equation, we want to include now not just the fraction of planets that get life, but the fraction of the life that evolves that is intelligent. So what fraction of the life is intelligent? So on Earth we may say, you know, 1% of the species is intelligent, but there's an even bigger, more important thing that Hollywood says, of course, is that thing out there is intelligent. And then they're all been visiting us in here. But Hollywood gets it wrong too, because the intelligent definition that we're going to use for our search for extraterrestrial intelligence is the ability to communicate across interstellar distances with some sort of technology. So our third term, our third F here in a row is the fraction of intelligent creatures that have also developed this ability to communicate across interstellar distances, F sub C. So it's not good enough to be intelligent, but you have to be able to use technology. So by this definition, you may consider an element intelligent, but it doesn't pick up a cell phone. A dolphin, it may be intelligent, but it can't even communicate from one ocean to another. It really is very limited in its ability to communicate. So what I've got here are some of the images of telescopes that are used to, or have been used in the past to search for extraterrestrial intelligence. The one on the top left is the CAC telescopes in Hawaii. And the one on the bottom left is the Lick Observatory in San Jose, California. And the one on the right is the Aracillo Observatory in Puerto Rico. And the one on the right here, you may have seen in movies as well. They have rented this out for movies when it was undergoing renovations. So the question now is what technologies are we going to look for? And being that we have ourselves as an example, we could communicate across interstellar distances. What should we be looking for? We're definitely pretty primitive, but we know some things that we can do and we can look for those things. Well, one of the things we need to do, and this was something I couldn't find a representative image for, but you have to be able to send signals that you can understand. So the joke is you've got two scientists standing by their big radio telescope and they say, you know, we sent a signal out into space. It was accidentally intercepted by some folks in Great Britain and they couldn't understand us. So the question is how are we going to understand what we're detecting if we detect something? So we have to be able to send, if we send messages, we have to make them something that is easily translatable to any alien civilization. But then when we're trying to detect an alien civilization, we have to think creatively about what sorts of signals they might send to us if they want to be detected on purpose. So again, just to summarize where we are in our math equation, we've talked about the rate of star formation, the fraction of those stars that have planets, the number of planets or moons even in that system that are good for us, for life, the fraction that actually makes life, the fraction of the life forms that actually turn out to be intelligent, and then the fraction of those life forms that develop interstellar communications. And then this is a great question for high school students. And the last term is L. And if you happen to be a physics person, you may have noticed that our units don't work out right yet. And I'm a physics person, so we're always checking our units. So the first term was number of stars per year, but the N on the very far left is just number. So we need something to get rid of the year's unit, and that is this term L. How long will a civilization that's capable of communication across interstellar distances, how long in years will they be actually detectable? So we can apply that question to our very own selves. The reason we, as a civilization, well, that is a good question. Will our civilizations exist at the same time? The Drake equation doesn't address whether it's simultaneous, just how many are out there in space at any given time. Communicating and having a discussion requires patience given the vast interstellar distances. But the reason we're detectable right now is because we have invented this fabulous technology called TD. And when we developed TV, we put antennas out on big hills, and we sent out signals in every single direction, including out into space. So it didn't just go right to your TV. It went out into space, and some of those signals are still going out into space now. I Love Lucy is out there many, many years out, possibly being detected by someone today. The problem is that as a technology, we have gotten better and less wasteful. And we have developed, yes, we have developed cable technology, and cable is not wasteful. It does not send its signals out into space. So we have a limited window here. When are we going to turn off our TV transmitters and just become a cable technology? So we may actually be a very short time scale for detectability because we've gone to a more efficient technology. So is this question of how long will we be detectable? Well, we were accidentally detectable. We weren't sending out signals to aliens to detect. We were sending out signals for our own use. And we've already decided that's a wasteful way to do it and changed our way. So that's one discussion you can have with your students is about the evolution or changes in technology. The other way you might see a discussion going is could as a civilization, we annihilate our ability to communicate across interstellar distances by having a big war. So the lifetime L of our civilization may be short if you're a pessimist about our ability to get along as a civilization with each other, with the different countries getting along with each other. So the lifetime is an open question. So this is just a summary of all of the terms and we're trying to find the number of broadcasting civilizations, not necessarily the number that we can communicate with right this second, but just the total number of them. And it depends on a bunch of things that we can explore in astronomy, but some of them you can also tie to your chemistry or biology or physics standards as well. So the rate of star formation, the fraction that form planets, the average number of habitable planets or moons per star, the fraction of planets where life emerges, the fraction where intelligence and specifically intelligence that can communicate across interstellar distances. These are some important factors to differentiate between because no one will be able to detect a dolphin on earth from space. It's just not possible. And then of course the last term here is a nice sociological question that your civilization remains detectable. So if you're on the web you can find all sorts of places where you can plug in your own estimates and see how optimistic you can be to get n up to a number you find useful. And I wanted to share just a couple more resources with you for teaching about astrobiology. And one, and these haven't been updated in a while, but they're very well constructed, and it's the AstroVenture series. And the AstroVenture series is designed for students to interface with this website, but there's a teacher website as well that includes educator guides. And there's a biology educator guide and a geology educator guide and a astronomy educator guide. And some of the astronomy pieces in the atmospheric science pieces actually tie very nicely to chemistry and physics as well. You can see that they have correlated these with the new national, or I think these are with the old national standards, not the new ones, but also for the two biggest states, California and Texas, they are not obviously correlated to the North Carolina standards. There's also an astrobiology website. So this is one of NASA's FOSI is Searching for Life in the Universe. So they have a whole web portal devoted to their astrobiology search, and they have an education and outreach tab. And they have a lot of videos on their website that talk about life in extreme environments, since that's the majority of what they're studying. So you can see they've got different links and blog posts there. And then the third link is another astrobiology life in extreme environments link. And this is another astrobiology related site. They have some ads on their page because they're not government funded, but they have a lot of good sites. So here's an example if you're talking about ecosystems. You may want to talk about how humans need oxygen, but certain bacteria do not need oxygen. You may talk about aerobic and anaerobic respiration. Well, does life on another planet require oxygen or not? So those are some good ways to tie in some of these other types of environments to your teaching in biology. So these, just looking at some of the... Well, let me ask our participant who's here. What is your teaching area? So if you could just type in the chat area what your system is. So you've got everything. So what I've tied into here is the next generation science standards. And the next generation science standards cover in the middle school they sort of lump everything together. So I've started with the life science part of the next generation science standards. First of all, these are paraphrases of the next generation science standards. I put these in my own words, not in their words. But homeostasis, the environmental factors influencing the growth of organisms, these are all things that you can bring in to this what makes a good planet and then how we can put life on that planet. So for earth and space sciences, there's a lot of links, but you can talk about, for example, extending to the lifespan of the sun at the high school level or the role of gravity in the solar system, which planets are good and which planets are not good about there. And at the high school level, the new standards expect you to be able to discuss evidence of simultaneous co-evolution of earth systems and life. So basically, as soon as you were able to get liquid water on the surface, you got life on earth. Physical sciences, we have a lot of change of state and thermal energy as well as apparently cut something off there in number two, gravitational interactions are, I don't remember what that was, sorry. But the other thing you can then extend is all the way into radioactivity and fusion, which are part of the standards that you have. You can talk about how stars make energy. So that would be an extension of the high school level. So the North Carolina standards are a little more condensed than the next generation science standards, but we can talk about single-celled organisms and water in populations and that would tie back to the life in extreme environments and the importance of water to life. Again, going to the habitable zone, why we care, why that phrase comes up. Okay, you've talked about nebula as well. So yes, where do the elements come from that make us up? So the supernova, blast, seeds, the nebula with heavy elements and forms the earth, for example. And again, the phase diagram of water you could include. This goes with the North Carolina essential standards as well. And then physics, you could include the heating of planets by radiation and the orbital motion of planets and that ties to some of the standards as well. Radiation and heat energy, electromagnetic waves, changing temperature of materials. So using astronomy as an example of some of these standards can help the students see that they apply more than one case and also give them something kind of fun to think about in your teaching. Yes, waves are a big part of the standards in the middle school and in the physical science as well. And then earth science, it's hard not to throw a stone at the earth science standards and find something that would be related to astronomy. But one of the things that ties specifically to biology and life is earth sustained life due to its location. That's just saying, hey, you're in the habitable zone. So you could bring up those resources. So one of the things that I wanted to share with you also, if you have some spare time, there's a lesson about how to find planets using the transit method. And this is because the Kepler mission is in operation right this moment. So this is a very relevant thing because we have a lot of press time devoted to things being found by the Kepler mission. So there's a lesson here and I would encourage you to do it yourself first before testing it on students. But essentially you use some simulations to explore and then you use an actual flash that the Kepler people have put together somewhere on here and then you can actually download, and here's the Kepler data, and then you actually can then extend and have students look at data that they download from the Kepler webpage. So this website, let's use the shares. So this is a very interactive piece here to explore how the Kepler mission does its thing. So students are actually taken through a simulation. You can drag and drop, which makes it very easy for students to understand. I have found that adults have a harder time understanding this than the students do. And then this is the students have to actually record the transit by watching the blinks. So they have to be paying attention and it won't let them move forward if they don't blink at the right time. You can use this to teach about graphing and reading scales as well as how we detect planets around other stars. So this is exactly the strategy used by the Kepler mission to find planets around other stars. It's recording the diminution of light output as you go through. So the students can see that you have to be looking. You can't not be looking and do this. So that's one of the reasons we put a satellite up. It's never daytime in space, and then you can use the axes to make measurements here, and then it will go through and calculate a bunch of properties about the planet for you, including the planet's temperature and whether or not it's in the habitable zone. So this is a great extension for actually getting into one of the ways we find planets around other stars. This is the only telescope right now that's dedicated to the search for extraterrestrial intelligence. And on that note, I will end this presentation and see if there are any questions from the participants. Yes, the shadows, exactly. All right, are there any questions? This is really fabulous though. The resources are wonderful. We will be sending to our participants a copy of PDF of the presentation so you can just find the link. We'll post a recording of the session on our STEM at NCSSM website. So if you wanted to share this presentation live with your students, they can view it at a later time. And one of the other resources is I have a bunch of links for solar system resources that I didn't have in the PowerPoint presentation here, but it's a list of some solar system resources in the short description of what maybe some of the useful features of those websites are since they're not all equally useful. So we'll get that shared as well. But thank you very much for attending today or whenever you did attend, recorded. Thank you very much. And I hope you can use these things in your teaching.