Cosmic Queries – Discovering Exoplanets with Gáspár Bakos

How do we discover more exoplanets? Neil deGrasse Tyson and comedian Matt Kirshen explore telescopes, exoplanets, and more with professor of astrophysics and Principal Investigator of HATNet Exoplanet Survey, Gáspár Bakos.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  On the next episode of StarTalk, it's a Cosmic Queries, featuring the expertise of a colleague of mine from Princeton University. The name is Gaspar Bakos, and he is at the Department of Astrophysics there, where he has developed a system of small telescopes to discover exoplanets. So we're going to find out, how does that work? Why does a small telescope still get to contribute to a field that's on the frontier? And we'll also learn how these satellite trails that we've read all about and seen videos of, launched from rockets, and how they affect the data that he's searching for, as well as the beauty and majesty of the night sky

• 0:44Neil deGrasse Tyson?

  that we've all missed ever since cities have become electrified. All coming up on StarTalk.

• 0:53Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.

• 1:05Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson here, your personal astrophysicist. And this is yet another Cosmic Queries edition. I got with me Matt Kirshen. Matt, my co-host, how you doing, man?

• 1:17Matt Kirshen?

  I'm very good. I'm excited about this topic, not least because a couple of weeks ago, as a birthday present from my wife, I went to Mount Wilson Observatory for a lecture and then a look through the big telescope. So I'd never-

• 1:31Neil deGrasse Tyson?

  Look, see, very good, very good.

• 1:33Matt Kirshen?

  Yeah, so I feel like I'm up at an amateur level now on this, but I want to hear from the pros.

• 1:38Neil deGrasse Tyson?

  Excellent, excellent. So there are people who are experts in all of the things I listed, one of whom is actually just across the river, across the moat here, we call it the Hudson River, over in New Jersey, is a colleague of mine from Princeton Department of Astrophysical Sciences, Gaspar Bakos. Gaspar, welcome to StarTalk.

• 2:00Speaker 02

  Yes, hi, everyone. I'm glad to be here.

• 2:02Neil deGrasse Tyson?

  Excellent, excellent. And you are a P I on a project called HatNet, which is search for exoplanets. And of course, people, I don't think everyone thinks much about the fact that at any given spot on Earth, where most people live, you don't see the whole sky. So if you're going to find exoplanets in a place you're not looking, what do you do?

• 2:27Speaker 02

  Indeed, there is a project called HatNet, which is a, which is an automated telescope system, because finding exoplanets with the naked eye would be really very challenging, I would say impossible. But the idea behind robotic telescopes is they can actually scan, monitor big areas of the sky nonstop, and then we can use computers to analyze all the data. And we can place these robotic telescopes to like fancy astronomical locations which have clear skies, high mountains, and have internet and power. That's getting very difficult.

• 3:04Neil deGrasse Tyson?

  And they're not very large, so it's not a big disruption to the physical location.

• 3:08Speaker 02

  Oh, yeah, yeah. They're actually tiny. This is a, this was an amazing thing that we realized about sort of 20 years ago, that that we can actually do cutting-edge science with tiny telescopes. Because stars, when a planet goes in front of them, they blink, and that blink can be detected with a small telescope if it's all carefully engineered and run, so.

• 3:30Neil deGrasse Tyson?

  But HatNet, you apparently, it's not, you have telescopes in multiple places on Earth, and why, why did you do that?

• 3:36Speaker 02

  Oh, yeah. So the transits are elusive, and the transit of a planet, that the time instance when it goes in front of its star, will have nothing to do, whether it's daytime or nighttime, on Earth from a given location. So it might actually go in front of its star, and the star blinks when it's broad daylight here in Princeton. So the idea is to put telescopes around the globe at tactical longitudes, so we can observe round the clock. In other words, the sun never rises above our telescope empire.

• 4:08Neil deGrasse Tyson?

  Ah, or never sets. It also never sets.

• 4:11Speaker 02

  It never, it never sets. It depends.

• 4:13Neil deGrasse Tyson?

  That's an equivalent, this whole British empire, the sun never sets. It never rises either, but logically, it also never rises. But, okay, so, so you can cover it. So you've got, I love your phrase, tactical longitudes. But now, what about latitude?

• 4:30Speaker 02

  Yeah, you can also be tactical with latitude, because here's the thing. If you go too far to the south, you freeze to death. And I don't like that. If you go too close to the equator, then you have too much humidity and jungles, which are lovely things, but it's just not good for astronomy.

• 4:46Neil deGrasse Tyson?

  Oh, too far south, if you're in the southern hemisphere.

• 4:47Speaker 02

  If you're in the south. In the north, it's the same thing. I mean, and plus, in the north, if you go too far north, there's no ground. You can, you can touch, that's another problem, so.

• 4:57Neil deGrasse Tyson?

  Yeah, most, most people don't know that Santa Claus lives on an ice floe. Okay?

• 5:01Speaker 02

  Yeah, exactly, yeah.

• 5:02Neil deGrasse Tyson?

  Most illustrations of Santa Claus at his, his workshop, they have mountains and tree, you know, pine trees and things. It's like, no.

• 5:10Matt Kirshen?

  So that's worrying with, with climate change. He could like, it could disappear. He could end up swimming in it.

• 5:14Neil deGrasse Tyson?

  This would be sad. Yeah, this would be Santa Claus in a bathing suit, right? Just sitting there on a float.

• 5:19Speaker 02

  Well, it's already happening. Last year, the Arctic did not freeze over. That was in the news. Ships can be crossing it at any time or something. So it's like.

• 5:28Neil deGrasse Tyson?

  So where are your, where are your southern hemisphere telescopes? Where are they?

• 5:31Speaker 02

  So the first station we built is in Chile at Las Cabanas Observatory in the, in the Andes.

• 5:38Neil deGrasse Tyson?

  So it's a pre-existing observatory.

• 5:39Speaker 02

  Yeah.

• 5:40Neil deGrasse Tyson?

  Location, right? So you, you didn't have to build roads. You didn't have to put in the internet. Like you said, you just ride the pre-existing infrastructure.

• 5:48Speaker 02

  Yeah, exactly. But we did pour the concrete piers. We pulled in a container, like a shed for instruments. And we hold in all the things and build all the infrastructure up for our local installation. But there is other infrastructure already there. The second one is in Namibia, in the Kalahari Desert. There is an existing installation there called the HES, HES telescopes. So again, we had internet, we had power, sort of, you know? It was, it was a bit tough in the beginning. But it's an amazing place. And the third one is in Australia and out back at Siding Spring Observatory, which again has sort of very good infrastructure.

• 6:32Neil deGrasse Tyson?

  All right, well, very cool. And the last I checked, the the catalog of exoplanets was nicely rising through 5,000. And you're gonna make predictions about how soon we'll hit maybe 10,000, doubling that number?

• 6:46Speaker 02

  Yeah, that's a that's a that's a very hard thing to extrapolate.

• 6:50Neil deGrasse Tyson?

  All right, let me ask a different question. At what rate are you discovering exoplanets? Um, yeah, yeah. Well, what's yeah. Are you good at this?

• 6:58Speaker 02

  Well, so our rate, we actually found 140 something exoplanets between 2006 and now. And our rate has been going down because our space missions have been contributing majority of the discoveries. But, you know, space missions have a limited lifetime. So Kepler was a famous one that flew from 2009 through sort of 18. And then TESS is now a highly productive mission, which will run for a limited time.

• 7:24Neil deGrasse Tyson?

  And TESS is itself a an acronym. Was it transit?

• 7:27Speaker 02

  Transiting Exoplanet Survey Satellite.

• 7:30Neil deGrasse Tyson?

  Satellite. There you go. Right, right, right. So I'm fascinated by this. So so but you'll continue cranking with or without the space observatories is what you're saying?

• 7:39Speaker 02

  Well, an idea what we do is we complement the the data coming from space. Let's say TESS observes an area for 27 days, nonstop, and it finds transiting planets. Now, some of the transits will be single transits. There will be just a blip in the light curve. And we don't know what's when the next blip is happening. We don't know. And but if we complement it with ground-based data, we can solve for the period and then.

• 8:03Neil deGrasse Tyson?

  Oh, excellent. So so TESS makes the discovery. Now you follow up to verify that it's that it's a repeating phenomenon.

• 8:10Speaker 02

  Yes.

• 8:11Neil deGrasse Tyson?

  Because if they just see one blip, that could have been anything.

• 8:13Speaker 02

  Oh, yeah, yeah. And there's many false positives. That's other thing that there's 5,000 planet candidates right now. But I think the number of confirmed planets with masses measured, say, is about 270 from TESS. So there's like a huge difference between between the two.

• 8:28Neil deGrasse Tyson?

  All right. So still a lot of work to to happen there. So now you're also involved in you're you're a part of a documentary called Dark Sacred Night?

• 8:39Speaker 02

  Yep.

• 8:39Neil deGrasse Tyson?

  That's that's some powerful words there. So what's going on with that?

• 8:43Speaker 02

  Well, I've been a I I grew up on the dark skies as a kid. I um.

• 8:49Neil deGrasse Tyson?

  Was that the moon? Where would you where did you have dark skies?

• 8:52Speaker 02

  Yeah, well, it's almost.

• 8:54Matt Kirshen?

  He was an ISS kid. He was.

• 8:56Neil deGrasse Tyson?

  Yeah, yeah, you were on an astronaut. Okay, fess up to us. Where were you when you grew up?

• 9:01Speaker 02

  I grew up in the northeast part of Nigeria, on the border with Cameroon.

• 9:07Neil deGrasse Tyson?

  Oh, my gosh.

• 9:08Speaker 02

  On a farm, and there was...

• 9:10Neil deGrasse Tyson?

  Well, there it is, there it is.

• 9:12Speaker 02

  Yeah, there was no electricity and no TV, no internet, no phone. But we had the dark sky, and it was really amazing. I remember as a five-year-old looking up and I would see the Milky Way going down to the fence, or whatever, the horizon.

• 9:30Speaker 02

  And then I realized when we moved back to Europe that this is not something I see from there. And especially not...

• 9:36Neil deGrasse Tyson?

  At all, at all. Yeah, you don't even know it's there, yeah, yeah.

• 9:40Speaker 02

  Yeah, I mean, it's just like all that beauty is sort of missing for... I felt pity for all of us here. We just don't see this thing. And I felt, is it actually a necessity or is it a stupidity? And after a while, I realized it is more of a stupidity. If lights were properly designed and aimed down, it was not wasted, then we would actually see the Milky Way from majority of the US.

• 10:04Neil deGrasse Tyson?

  So we'd have both civilization plus a dark night sky, is what you're saying?

• 10:07Speaker 02

  Absolutely, yeah.

• 10:08Matt Kirshen?

  So not having our cities any less lit, but just having smarter lighting that is less wasteful, less pointing up and escaping less?

• 10:17Neil deGrasse Tyson?

  Matt, you know what I tell people when I'm in an airplane and we're about to do our final loop to the airport around a city? I'd say to the person next to me, "You see that area of streetlights down there?" And they say, "Yeah." And I say, "Someone is paying money to send photons to me in an airplane." It is doing no good for whatever that purpose is down on the ground.

• 10:39Speaker 02

  To estimate now is something like 50% of the light emitted in the US by light fixtures goes up straight in the sky. And that's pure geometry, they are not shielded, it's not rocket science. It's like the simplest thing. And the amount of money which just Neil referred to is, right now, the estimate is about $3 billion per year is converted into photons that go up in space, simply because of the

• 11:05Matt Kirshen?

  Just to light clouds.

• 11:06Speaker 02

  Just to light clouds.

• 11:08Neil deGrasse Tyson?

  Just to light the clouds and airplanes so we can see this.

• 11:09Speaker 02

  Yeah.

• 11:10Matt Kirshen?

  We, I've talked about this before on this show, but it, because I grew up on the outskirts of London and then now I live in Los Angeles and Neil, you grew up in New York and it's just, I, I remember the first time I was somewhere that was sort of remote and in the middle of nowhere and you could really see the sky and I was like, oh, that's what stars are. That's what people used to write poems about and draw pictures of and stuff.

• 11:31Neil deGrasse Tyson?

  So Matt, that moment for me was in the Hayden Planetarium.

• 11:33Matt Kirshen?

  Oh, really?

• 11:34Neil deGrasse Tyson?

  Oh, that's what the sky looks like. So, so Matt, you, uh, this is a hybrid, nice conversation with our guest, but also we solicited questions from our audience.

• 11:44Matt Kirshen?

  We absolutely did.

• 11:44Neil deGrasse Tyson?

  Matt, what questions do you have for?

• 11:46Matt Kirshen?

  Yeah, so a bunch, a load of Patreon, patrons came through with some great questions. So Shane McDaniel says, when you use long exposure detectors, how do you keep them in the same line of sight through the exposure so that all the data lines up, given the Earth is rotating and the cameras in space have their own velocity, et cetera?

• 12:02Neil deGrasse Tyson?

  Nice. Good, good.

• 12:04Speaker 02

  Um, I don't know if this refers to a space mission or, or a ground-based telescope, but whatever it is, we have developed tracking on the skies has been on, on Earth, we have what we call the polar axis of all side telescopes. You'll see on big axis pointed at the, roughly the North Pole, which is Polaris at our time. And the telescope spins around this with what we call sidereal rate. And they also have other fine things like the auto guide. We have a special detector which is sensing starlight and would like nudge the motors left and right to keep things exactly in the center. And for a space mission, it's, um, similar techniques. They have gyroscopes, they can orient. And plus, in, in space,

• 12:48Speaker 02

  it's somewhat easier actually to, to track because, you know, you have less external forces. You're not necessarily like spinning with the Earth itself. You're pointed at some direction.

• 12:58Neil deGrasse Tyson?

  Yeah. And just to add some emphasis there, you mentioned sidereal time because I don't know whether people know that the stars revolve around the Earth, if I may speak in that way, pre-Copernican, they revolve at a different rate than the Sun does. So the sidereal rate is the star rate that the stars go around the Earth, and that's every 23 hours and 56 minutes.

• 13:21Speaker 02

  Yes, that's

• 13:22Neil deGrasse Tyson?

  The stars make one complete loop, whereas the sun makes one complete loop in 24 hours. So yeah, so we got smart people figuring all that out. But you know what my iPhone does today is if I want to take a long exposure, it doesn't, it doesn't say, "Hold it really steady while I can do this." No, it takes multiple exposures, multiple short exposures. And then in software, when the exposure is done, it registers the light in that image, stacks them, adds them, and that's my final photo. And I don't even see the intermediate stages of it. So that's another way to accomplish the same thing. So Gaspard, what you're saying is we know enough about the rotation of the Earth to compensate for it when we're taking long exposure photos?

• 14:07Speaker 02

  Yeah, yeah, we have measured the spin of the Earth very well, so well that we actually even see. That's not something we correct for during the night, but stick to speaking, we see when the Earth spins down or spins up due to changing seasons. So we really, we really know it.

• 14:21Neil deGrasse Tyson?

  That's badass. That's just totally bad. We, we are so good at knowing the rotation of the Earth, we can say when it's varying. That's just, that's

• 14:30Speaker 02

  Yep.

• 14:30Neil deGrasse Tyson?

  That's, that's, that you're showing off now.

• 14:35Neil deGrasse Tyson?

  I mean, think about the Earth used to be our primary clock, right? Earth.

• 14:39Speaker 02

  Yep.

• 14:39Neil deGrasse Tyson?

  And you wouldn't know if the clock was varying if your clock itself was the foundation of your timekeeping. So now you have to be able to keep time better than Earth does to then show that Earth is either speeding up or slowing down.

• 14:52Speaker 02

  Yeah, exactly.

• 14:53Neil deGrasse Tyson?

  In its rotation rate. That's crazy, crazy.

• 15:05Speaker 03

  I'm Joel Cherico, and I make pottery. You can see my pottery on my website, cosmicmugs.com. Cosmic Mugs, art that lets you taste the universe every day. And I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 15:26Neil deGrasse Tyson?

  So Matt, what do you have for our guest?

• 15:28Matt Kirshen?

  Well, I'm gonna combine a couple of questions, because I love to do that. So there's a question from Mark Bode, firstly, from Boulder, Colorado, who says, "It's a question about the proliferation of low-Earth orbit satellites. Since it doesn't seem like the rate humanity is launching these things will reduce anytime soon, what is the best way we can ensure the skies remain clear and free of light pollution to enable important activities such as the search for extrasolar planets?" And then also Kevin Browning from White Deer, Texas, says, "How does low-orbiting satellites and space debris interfere with the search for exoplanets? What can ordinary people like myself, who care about the night sky, do to convince Congress or companies like SpaceX to reduce light pollution and the number of orbiting satellites?"

• 16:10Neil deGrasse Tyson?

  Okay, so that's why you have to answer that in three sentences. So, actually, first, why don't you distinguish for us the difference between light pollution and satellite pollution? Because it's not the same thing, is it?

• 16:25Speaker 02

  Yeah, there are some subtle bits here. I would say light pollution has a ground-based component, which is bright city lights, poorly-designed lights, going up in the sky and illuminating our atmosphere and the night sky, making it brighter. And the second component, which is fairly new and unexpected, so to say, is light pollution coming from thousands or so, maybe tens of thousands, of artificial satellites orbiting the Earth, reflecting back light from the Sun or emitting radio waves, which is also electromagnetic radiation.

• 17:00Neil deGrasse Tyson?

  A form of light.

• 17:03Speaker 02

  These are the two components. To deal with the first one, I would say technically, it's sort of a trivial thing. And yet, you're not doing it. And there are many other things in the history of humanity which were trivial, and we have not been dealing with it. This is another example of that. But you know, to give some hope, I think some of them were dealt with. So we used to pollute our rivers far more than we do now. We used to pollute our atmosphere with freon and with other pollutants that would decrease like...

• 17:34Neil deGrasse Tyson?

  Smokestacks. You know, I grew up, I have to brush ash off my shoulders, because every apartment building burned its own trash at certain times of day. So yeah, when I grew up, the sky was... It was bad for multiple reasons, yeah.

• 17:48Speaker 02

  So, you know, London used to be covered in soot for centuries and now it's sort of clean compared to that. But light pollution...

• 17:55Matt Kirshen?

  Yeah, the Thames River used to stink.

• 17:56Speaker 02

  Yeah, light pollution, which is basically shielding all the lights, aiming them down where they are supposed to be lighting, and dimming them to proper levels and not over lighting. This is it. And it has not been achieved. It's like stunningly bad. And I'm clearly amazed that this is still going on under, you know, there's definitely a trend and a recognition of going green and being less pollutant, and yet we're wasting like three billion dollars a year on lighting up the sky, which is very harmful for us. It's not about the stars, by the way, you know, it's this thing of, yes, we want to see the stars, but it's about our own health, which has been now clearly detected to be very, very

• 18:41Speaker 02

  bad for our health, having strong ambient nighttime lighting. It's very bad for for nature, for ecosystems, and even bad actually for safety, but that's a different topic. As for the night, going back to the question, the satellites up in the sky, that's a hard problem to solve. The problem is that the sun reflects back from these satellites and they're sort of useful in broadcasting internet. Now, almost everyone in the US has relatively broadband internet. If you think, like, there are 10 million people in New York, no one complains about having no internet. So, providing them with another internet is really about business and it's not about saving the world.

• 19:25Speaker 02

  There are some parts of the of the Earth where internet is very poor. Say in the middle of the ocean, the middle of the desert, there are very few people there. And historically, these people have been, if needed, have been using satellite phones for emergency communications.

• 19:44Speaker 02

  There have been some efforts in dimming the satellites, painting them black, they overheated, putting them on a sun visor, which reflects light in a different direction. I think one idea is to have a smart design of satellites, being very, very conscious about the light reflected back, and to have strong limits on the number of satellites through agencies and and regulations and by... Essentially updating the International Space Treaty, which is so outdated that majority of it is from the 1960s and 70s, completely unprepared for an wealthy individual launching his own satellites in numbers of thousands. You know, there's nothing in a space treaty like that.

• 20:27Speaker 02

  So it is a crazy situation that there is some treaty that has general policies about what we can use satellites for, you know, no warfare, you know, things like that. There was some ideas about like, you know, the Soviet Union was concerned about America broadcasting TV over the Soviet Union in the 1970s. That was basically the last major update of the space treaty. I think there is a risk of a runaway process that that companies will start competing for the number of satellites and trying to get even broader bandwidth and shorter response time. And so it might

• 21:11Speaker 02

  it might grow into the tens and hundreds of thousands, if not limited by some central agencies.

• 21:17Neil deGrasse Tyson?

  So that peace treaty came out of the United Nations. It has a much longer title, if I remember. Something like a treaty for the peaceful use of outer space. It's got some long title, which is very hopeful at the time. But I agree, it's now, you know, 50 years out of date practically. And yeah, it's it's got, it needs to be modernized. And many countries signed it, right? So it was a it had good intent at the time, for sure.

• 21:46Speaker 02

  Yeah, yeah. I mean, there's no real agency at the moment who would say, you know, there's agencies who let these tens of thousands of satellites to be launched. And the decision is essentially based on radio waves and orbital elements. But there is no environmental element in the consideration saying, no, guys, you can't do this. You can't paint the Hudson River red. It's not yours. You can't put anything in the sky. It's not yours.

• 22:16Neil deGrasse Tyson?

  Yeah, so our crack team of researchers dug up the full title of the treaty. I've got it here. I'll read it. "The Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies." See, they needed astronomers in there to make a good acronym.

• 22:35Matt Kirshen?

  Yeah. You guys call it the Tepukase.

• 22:44Matt Kirshen?

  There's definitely some really dodgy space acronyms as well, where they've just taken letters from the middle of the word as well. Like, you can't do that. It's gotta be the starting letter.

• 22:52Neil deGrasse Tyson?

  Not allowed. All right. All right, really good answer there. That gives us much deeper insight into what's going on and what the challenges are, and how hard the solution might be. But, that's where you said it's really just human stupidity for half of the problem. But, let me add, so, let me get back to one of the specific points of the question. Satellites trailing across the sky, does that affect your data-taking when you're trying to discover an exoplanet?

• 23:18Speaker 02

  Big time, it does. I actually see the trend in my own data now. Essentially, every image I take during the night, I would say up to three hours after sunset, and from three hours before sunrise, every image I take, anywhere in the sky, will have at least one trail, or more. And those trails cross stars, and so the light of that star, when I measure, will have a big bump in it, or some noise. So, it becomes like an intense noise filtering. Now, some people say, "Oh, if you co-add all these images in a smart way, then the satellite trace will disappear." Yeah, but I don't co-add them. I'm trying to measure individual images, and all the brightness of all the stars. So, it's a huge point.

• 24:01Neil deGrasse Tyson?

  Yeah, to co-add, that's lingo for, "We assume every picture you're taking..." Is of the same thing.

• 24:08Speaker 02

  Yeah.

• 24:09Neil deGrasse Tyson?

  So now you take them and find out one of them has this weird streak. It's clearly.

• 24:14Speaker 02

  Yeah.

• 24:15Neil deGrasse Tyson?

  But you drop that out and then everything else is fine. But if one of the pictures contains something you need, and that's the one that gets dropped out, you lose your data.

• 24:24Speaker 02

  Exactly, exactly.

• 24:26Matt Kirshen?

  Am I right in thinking one of the things you're looking for is specifically a change in the image when something, when a planet crosses the star?

• 24:32Neil deGrasse Tyson?

  Yes, precisely.

• 24:33Speaker 02

  I mean, last time I was, I was in Chile a couple of months ago. I, I let my camera, like my astrophotography equipment out to take a time lapse. And what I saw on this video in the morning, uh, when I reviewed it was I showed this, saw this bright shooting star that's been crossed by another shooting star. And I said, this is remarkable. I have this photograph of two shooting stars crossing and then came another like 500 on the horizon. This is a regular DSLR, you know, end user camera on a tripod. And literally there was like a shower of satellites on the horizon from Chile. And I'm not hundreds, but more. It looked scary.

• 25:13Neil deGrasse Tyson?

  Um, Matt, these are, this is the alien invasion that he's not telling us about. Okay.

• 25:19Speaker 02

  It looked like that, it looked like that, yeah.

• 25:21Neil deGrasse Tyson?

  It looked like the aliens are coming.

• 25:23Matt Kirshen?

  When we were up at Mount Wilson, there was, um, I guess, is it Starlink? Is that the most satellites? But there were, there was a sudden trail of about 10, maybe more satellites in a row, just crossing the sky in a straight line. And it did look, it looked very alien invasion like to me. It was just, I've never seen a series of, a series of things moving in a direct, straight line.

• 25:45Speaker 02

  And it's also a cultural thing. There are simulations showing how it will look like if it does proceed as it is now. Essentially, it will be very hard to point out, for example, for a child, where is the big dipper? There will be all these moving bright dots. And in between that thing, when you see that this thing that's not moving, it would be actually so confusing. It's, uh.

• 26:06Neil deGrasse Tyson?

  So we need a video game shooting down the satellites. So you can see that. Uh, one thing I forgot to mention, forgive me. Um, so Matt, you went to Mount Wilson Observatory, which was the observatory that Edwin Hubble used, Edwin, the Hubble, the man, not the telescope, used to discover that our Milky Way is not alone among galaxies in the universe and to discover that the universe is expanding. And so did they finally get that as a landmark? I think they wanted, because it's a landmark in our understanding of our place in the universe.

• 26:38Matt Kirshen?

  I don't know what what's his official designation is, but they're certainly, they make a big deal of that and they're very proud of that. And it was pretty cool to look through the same, the same telescope that Hubble looked through. It was, it was very, it was pretty impressive to go, oh, this is, this is where, as they put it in the talk, like that they discovered the universe essentially here. In that location.

• 26:57Neil deGrasse Tyson?

  Yeah, in a sense, that's correct, that's correct. Well, give me some more questions, see if we can get one in before the break.

• 27:01Matt Kirshen?

  Absolutely. So Augustine from Puerto Rico, who is the host of the Curios, Curiosidad's Scientifica podcast, on which I believe Neil has guested, talking about the Arcebo Observatory.

• 27:13Neil deGrasse Tyson?

  I have, and, and try to improve your Spanish the next time you read that, okay?

• 27:17Matt Kirshen?

  Yeah, that was, I, I took a, I took a very quick run at that and I was hoping to skip past unnoticed.

• 27:22Neil deGrasse Tyson?

  That was serious gringo Spanish, that gringo Spanish.

• 27:25Matt Kirshen?

  I was hoping it would be missed, but it was not. Neil did not, he didn't let that one slide. But Augustine asks, can an exoplanet have life like us on a binary star or red dwarf?

• 27:37Neil deGrasse Tyson?

  Oh, I love that, love that. Are you, yeah, guess what? Are you thinking about life on the planets?

• 27:42Speaker 02

  Yeah, oh, yeah, yeah. I think it's a fascinating topic. And I think the first sort of written record of someone contemplating about it is, is from Asian Greece. But there's also Heinz in the 18th century, pondering about all the stars being suns and why not they have, have planets and why some planets actually are like the earth. And he actually writes in his, there's a word cosmotheros, where he writes like, and there must be all these alien civilizations on these planets and some of them might be intelligent and looking back at us. So it was really ahead of his time, dangerously.

• 28:22Neil deGrasse Tyson?

  This is the Dutch astronomer, Christian Huygens.

• 28:24Speaker 02

  Yeah, yeah, exactly, exactly. I think he published his book sort of to say posthumous, just to make sure he's not burnt on some steak or something. But I do.

• 28:34Neil deGrasse Tyson?

  Speculating about life in the universe.

• 28:36Speaker 02

  Yeah.

• 28:36Neil deGrasse Tyson?

  Yeah, if, if, if the universe is divine because God created it and we are the divine creation of God, you would not expect to find life anywhere else but earth. So this is quite heretical, yeah.

• 28:46Speaker 02

  Amazing thing is now we know that the. I would, the estimates vary over time because we're refining it. But this basically about 20% of solar type stars have a planet that's rocky. So it's not like a helium or hydrogen giant, it's rocky like the earth. And is in what we call the habitable zone. So if you multiply the 400 billion stars in our galaxy, you take, there's about 40 billion of them similar to the sun. And then you multiply that by 0.2, that's about 8 billion rocky habitable planets just in our own galaxy. That's a lot of.

• 29:25Neil deGrasse Tyson?

  To be clear, the math you're doing on the fly there is you're multiplying big numbers by fractions.

• 29:31Speaker 02

  Yeah.

• 29:31Neil deGrasse Tyson?

  Right, normally when we think of multiplying numbers, we make them bigger. So I just want to clarify, you're, you're taking the fraction of the 400 billion.

• 29:37Speaker 02

  Yep.

• 29:38Neil deGrasse Tyson?

  Then the fraction of what remain, and then you, as you hack away at the large numbers, you get the numbers that have all the features that you're looking for.

• 29:46Speaker 02

  Yeah, yeah.

• 29:46Neil deGrasse Tyson?

  Still a massive number.

• 29:47Speaker 02

  I think it's an interesting thing, if you look up at the Milky Way, which is lost for 99% of Americans. But if you actually happen to go to one of the national parks or travel far, you look up at the Milky Way. What's the probability of someone looking back at you? I think that's a fun question, which we don't know the answer to yet.

• 30:06Neil deGrasse Tyson?

  Mm hmm. That's a little creepy though, but.

• 30:08Speaker 02

  Yeah.

• 30:10Neil deGrasse Tyson?

  But, but gospel, we left out a part of that question, which was what percent might be orbiting a binary star?

• 30:17Speaker 02

  Oh, I see, yes, that was indeed part of the question. So first of all, just to give a tiny introduction, we actually did not know that there are stable planets around binary stars. So meaning there's two stars orbiting each other very close in, and there's a planet far out orbiting this binary star. It was only in Star Wars, Tatooine is the only one. Now we know they exist. And we also know that some might be in what we call the habitable zone. So the probability is, is also exist, but these planets are much less frequent than the ones we, that around normal stars, so.

• 30:52Neil deGrasse Tyson?

  Right, so I guess that the point there that you imply is that if that planet were orbiting closer to the binary star, the orbit would become less stable because it would get really close to one star and then far from the both. But if you're far enough away. It just sees kind of one average gravity field. Is that a fair way to describe it?

• 31:12Speaker 02

  That's a fair way of describing it. And if it's very far away, it feels one gravity field, but it does not feel heat anymore, so it gets cooling.

• 31:19Neil deGrasse Tyson?

  Okay.

• 31:21Speaker 02

  You want to be in the right place. So for a binary star, that's somewhat more limited. And I don't have an exact number. I don't think anyone does. But we are closing in on that number by, first of all, knowing the frequency of planets around binary stars or getting a handle on it. And in the future, I think we will soon learn about what fraction of them are in this habitable zone.

• 31:47Neil deGrasse Tyson?

  And I'll add that most of the stars you see in the night sky are multiple planet, double and multiple planet systems. So it's not a question about a rare possibility, right? It's, binary star systems are not rare in the night sky. So it's a very natural question to wonder whether they could also be repositories of habitable planets.

• 32:10Speaker 02

  Yeah, yeah, but 70% of stars are in binaries indeed. And I have to add that there's another solution where the two stars are very far from each other, orbiting in, say, thousands of years or tens of thousands of years, and both of them host planets very close in. That's a different archetype.

• 32:26Neil deGrasse Tyson?

  That's the opposite of the other one, right? A planet orbiting far from the pair. And a pair is orbiting far from each other. So they carry their own solar systems around themselves.

• 32:35Speaker 02

  Yeah, exactly. You can have both.

• 32:36Neil deGrasse Tyson?

  That's crazy.

• 32:48Neil deGrasse Tyson?

  All right, Matt, what more questions you have for our guest?

• 32:50Matt Kirshen?

  Yeah, we've got some great questions. Well, the one that I had loaded up from Christopher Stowe was, has just been answered by you. It was about planets in stable orbits around binary systems. So you've covered that.

• 33:00Neil deGrasse Tyson?

  And just to be clear, when we talk about stable planets, it has nothing to do with their emotional state, just to be clear.

• 33:06Matt Kirshen?

  No, planets are notoriously unstable in many ways. They're, they can go off at any minute.

• 33:12Neil deGrasse Tyson?

  Orbitally stable, yeah.

• 33:14Matt Kirshen?

  Yeah, there are ways of erupting at short notice.

• 33:16Neil deGrasse Tyson?

  But just to be clear. An unstable planet can either fall into the host star or get kicked out. So that the orbit does not maintain itself around.

• 33:24Speaker 02

  Yeah, yeah, those are the two solutions. And curiously, we see the effect of both. The planets that fell in the star, they pollute the star. So you can detect elements due to.

• 33:34Neil deGrasse Tyson?

  Oh.

• 33:35Speaker 02

  The planets that fell in the atmosphere of stars.

• 33:37Neil deGrasse Tyson?

  Oh.

• 33:38Speaker 02

  And the planets that were kicked out. That's really amazing, I think, but they were detected through what we call micro lensing. They are dark. You don't see them, but they go in front of roughly in front of a star. And they lens the light of the star. Due to their gravity. And then you see the background star brightening up. And with this thing over a decade or two, they actually measured that there are roughly about forty billion free floating planets in our galaxy, like one tenth the number of the stars.

• 34:12Neil deGrasse Tyson?

  Of vagabond planets.

• 34:13Speaker 02

  Yeah, they have no star. So if you know you're a severe civilization that somehow developed on such a planet because they have, say, radioactive heat coming from the planet. They would actually have a very different view of the universe, like they don't have a central star. They will, at one point, might discover there are even planets orbiting stars.

• 34:35Neil deGrasse Tyson?

  Yeah, yeah, what a concept, right?

• 34:38Speaker 02

  Yeah, no, it's all, it's all, it must be all different.

• 34:40Matt Kirshen?

  So the ancient Catholic Church was right.

• 34:46Matt Kirshen?

  Well, that, that, that does segue quite neatly, I think, into a question from Scott Bringleau from Canada. Captain Scott here says, "With transits being the predominant method of exoplanet discovery, what characteristics of the exoplanet are you not able to identify using this method? And more importantly, what can you identify using this method? I find it fascinating you can glean so much info from what amounts to a very small dip in measurable light from light years away."

• 35:09Neil deGrasse Tyson?

  Yeah. Yeah, I guess we would compare this method to maybe direct, direct imaging, for example. Let's compare those two together.

• 35:16Speaker 02

  Yeah, okay, so.

• 35:19Speaker 02

  I'm fascinated by how much we can actually learn from a transiting exoplanet. And I think that's generally something is amazing about astrophysics, that we have a lab which is infinitely far away compared to what we can reach, and yet we can figure things out. So transit is, I think, the best example that you, first of all, from the deep, the depth of the transit, you can tell how big the planet is. That's pretty obvious. Like, if it's very deep, then the planet is big compared to the star. And if it's shallow, then it's tiny.

• 35:49Neil deGrasse Tyson?

  Because it's just blotting out light, and it just blots out more light.

• 35:51Speaker 02

  Yeah, yeah, that's simple. But you can also measure the period. You see how frequently you see these transits in front of the star, and you can tell the orbital period of the planet. So these are easy, okay?

• 36:02Neil deGrasse Tyson?

  Provided you kept monitoring it, so it's not just snapshots. You have to keep checking to wait for that to happen again.

• 36:10Speaker 02

  That's entirely true, yeah, that's entirely true. You need to...

• 36:13Neil deGrasse Tyson?

  All right, so there could be some transits where the orbit is like on a 20-year period or something, let's say, and we haven't seen it come back again.

• 36:21Speaker 02

  Yep.

• 36:21Neil deGrasse Tyson?

  Right, so we've got to be some of those, too.

• 36:23Speaker 02

  Yeah, there are some of those. And there are some where you have a transit, then you miss the second one because it was daytime or whatever happened. Your spacecraft was oriented in a different direction. So there's all of these. But you measure the depth, you measure the period. Now, the other things that are sort of less trivial, but you can also tell how far the transit is off from the center line of the star. Does the planet go exactly along the line of side, crossing the star along its diameter? Or it's like slightly offset? Or maybe it's even grazing? So you can tell this from the shape of the transit. I think that's sort of an interesting thing. You can also tell how far...

• 37:01Neil deGrasse Tyson?

  So the shape, by the shape you mean, as the light begins to dim, it will dim at a certain rate?

• 37:08Speaker 02

  Yep.

• 37:09Neil deGrasse Tyson?

  And the rate at which that light dims tells you whether it crosses the middle or above or below the equator. Interesting.

• 37:17Speaker 02

  Yeah, I mean, naively, if it's a grazing transit, the planet just barely goes in front of the limb of the star. You will see this very shallow, very gradually fainting, barely fainting star. Whereas if it goes close to the equator of the star, you will see a sharp decrease in the brightness of the star.

• 37:37Neil deGrasse Tyson?

  And and the brightness will stay low until it's worked its way out again.

• 37:40Speaker 02

  Yeah, yeah.

• 37:41Neil deGrasse Tyson?

  Whereas if it's grazing, it'll just dip in and come back out. So so it's amazing what you can deduce from the just the shape of that.

• 37:48Speaker 02

  Yeah.

• 37:48Neil deGrasse Tyson?

  Fascinating.

• 37:48Speaker 02

  And now comes the the so these are the what we call like geometric parameters which you can figure out. It's not very complicated, but I think what's what's amazing is, for example, you can tell.

• 38:01Speaker 02

  What's the angle, bear with me, between the planet's orbit? And the spin of the star? So is it like a star spinning, say, the axis of the spin points exactly up in some coordinate system? And is the planet orbiting exactly perpendicular to that? Or is it somehow misaligned? You can tell this from combined observations of the light of the of the transit and doing what we call variable velocities, like measuring the the red and blue shift of the star during the transit. Um, I mean, that's amazing thing because in our own solar system, um, we are, the sun is about seven degrees misaligned with respect to the general orbit of the of the planets.

• 38:46Speaker 02

  But in we discovered planets which orbit close in, like they orbit around their stars in two days. And the star is spinning exactly the opposite direction as the planet's orbit. So it's like upside down spinning and the planet is orbiting in the same direction as you would expect. Um, and what else? I mean, you can, um, here's an interesting quiz. If the planet is going in front of the star and then during that transit, there's actually a spot on the star. Then for a short time instance, the planet will not be covering the star's bright surface, but the spot. So you will see a brightening in middle of the transit.

• 39:25Speaker 02

  So you can actually, you can actually scan the spots on the star using the planet going in front, which has been done.

• 39:32Neil deGrasse Tyson?

  And and Matt, our official term for spots on stars are called star spots.

• 39:36Speaker 02

  Yeah.

• 39:37Neil deGrasse Tyson?

  That's our official term.

• 39:38Matt Kirshen?

  And that stands for solar temporary.

• 39:44Neil deGrasse Tyson?

  Yeah, because sunspots, and we didn't know what they were until long after they were named, but the name stuck. And they're dimmer than the surrounding

• 39:51Matt Kirshen?

  Wow.

• 39:52Neil deGrasse Tyson?

  brightness of the star. So that's so you so your planet crosses the star and crosses a spot. And so because the spot plus the planet had a certain brightness dimming and then the planet covers the spot.

• 40:06Neil deGrasse Tyson?

  And so now, I mean, and then the star brightens up a little bit because now the spot is not adding to the planet blockage. Fascinating.

• 40:13Speaker 02

  Yeah, yeah. And I left out the most, maybe most important one, which is measuring the atmosphere of the planet and the elements or molecules in the atmosphere. So what you can do is to take a spectrum of the star when the planet is not in front of it. So you take a spectrum, you see the starlight split into wavelengths. And from, it's a very complicated spectrum, and from that you can figure out what elements there are in the spectrum of that star. And then you take another one when the planet is blocking the star and the starlight is actually shining through the atmosphere of the planet. And the planet's atmosphere will be absorbing some of the starlight. If you compare the two,

• 40:57Speaker 02

  the spectrum of the star without the planet in front, with the planet in front, you can tell what the atmosphere of the planet is made of. Wow. And I think that's, you know, you can tell, okay, there is an atmosphere here which has water molecules in it, or it has sodium in it. These have been all detected.

• 41:14Neil deGrasse Tyson?

  Or if it has oxygen, that'd be kind of interesting because oxygen is not stable. And so something would be making that oxygen.

• 41:20Speaker 02

  Yep.

• 41:21Neil deGrasse Tyson?

  And then this would be, these are, this would be your first indication, or at least your first hint of life, I guess.

• 41:26Speaker 02

  Yeah, so that's why I mentioned it because exactly the, the best bet right now for what we call a biomarker is ozone and oxygen because if there's no life replenishing these, they would basically oxidize the planet. So the planet would become big, red and rusty instead of what it is.

• 41:46Neil deGrasse Tyson?

  Mm-hmm. Yeah. And, and in this case, in Earth's case, it's the plant life that's making the oxygen, not humans or any other animal life.

• 41:55Speaker 02

  Plus, you know, in the first 2 billion years, we were not producing oxygen, we were producing methane. So this is not saying that if you see a planet with no oxygen, it has no life. We can't say that yet, but.

• 42:07Neil deGrasse Tyson?

  Right, right, exactly.

• 42:09Speaker 02

  It is one of our best bets.

• 42:10Neil deGrasse Tyson?

  But if it does have oxygen, that's a good bet.

• 42:12Speaker 02

  That is a good bet, yeah, yeah. I think the question also is what we cannot discover from this. And I mean, the transit is such that obviously what's on the, on the dark side of the planet facing towards us, we don't see any details. We can't resolve the planet. A transit will not resolve spatial features on this planet.

• 42:36Neil deGrasse Tyson?

  There you go. Whereas a direct imaging of one, the hope is one day we'll have enough resolution to actually see oceans or clouds or something on it.

• 42:45Speaker 02

  Yeah, yeah. So the direct imaging is where you can actually see the planet directly.

• 42:50Neil deGrasse Tyson?

  That's a separate cottage industry that's unfolding right now in our field. Yeah. Matt, give me some more. See if we can fit in a few more before we...

• 42:59Matt Kirshen?

  Yeah, well, I'm gonna combine two again because I've got two good questions.

• 43:03Neil deGrasse Tyson?

  You're such a combiner.

• 43:05Matt Kirshen?

  Well, this is also, you know, our expert here combines images from small telescopes, and that's what these questions are about. David Lee's from Chiang Mai in Thailand says, "Dr. Bakos, considering your specific interest in small telescopes and their application in your research, could you elaborate on the advantages and disadvantages of using these in exoplanet detection as compared to larger telescopes?" And Jose Marcelino says, "As someone interested in instrumentation, I'm curious on your perspective on the challenges and opportunities of using small telescopes for astronomical research. What are some unique advantages they offer?"

• 43:40Neil deGrasse Tyson?

  I like that.

• 43:41Matt Kirshen?

  And also, "In the realm of extrasolar planets, what are some of the most intriguing findings or trends that have emerged in recent years? Are there any specific characteristics or planetary systems that have captured your attention?" So I guess that's two questions from the second one.

• 43:53Neil deGrasse Tyson?

  Okay, and I want to try to get yet another question in after that. So, Gus, see if you can answer that quickly.

• 43:58Speaker 02

  Yeah, yeah. This is, this question, I would need a lecture on this, basically. I will try to be quick. The trends are very quickly. First, most important, there's plenty of exoplanets. Essentially, every star has statistically an exoplanet. That's something that came out from the past 20 years. Second, the planets in the universe are very different from our own planets. There are ones that are very strange. They are orbiting just a few days around their suns. They're orbiting the opposite direction as the stars spin. Third, there are planets that are completely unexpected, like much bigger than Jupiter in mass, much, much bigger. There are planets that we don't have in the solar system that

• 44:38Speaker 02

  are between the mass of Earth and Neptune, or Neptune and Saturn, all kinds of weird things. There are many eccentric planets, not nice circular orbits like in a solar system, but they go on these widely eccentric orbits.

• 44:53Neil deGrasse Tyson?

  And once again, the eccentric is not a psychological state.

• 44:56Speaker 02

  No, no, yeah.

• 44:58Neil deGrasse Tyson?

  Just to be clear.

• 44:59Speaker 02

  Yeah. And I'm on, I think we now know that small planets are far more frequent than big ones. We now have a handle on the frequency, the occurrence rate of planets. And we know that long-period planets are also far more frequent than short-period ones. This has been measured, it's not some rough, you know, we actually know the numbers.

• 45:20Speaker 02

  I think those are the most important ones, and so the small telescope stuff, the charming thing is, a small telescope is obviously much, much cheaper than a big one, and yet you can do a lot of science with it. And then big telescopes can selectively follow up on the gems that you found. So it's a much more optimal use of resources. Another thing is, many people are capable of, and many nations or, say, institutions who are not well-funded are capable of running small telescopes.

• 45:51Neil deGrasse Tyson?

  Even students, student programs.

• 45:52Speaker 02

  Exactly, but to run a space telescope, where is the 10 billion coming from, you know? It's a bit money.

• 45:58Neil deGrasse Tyson?

  And a space agency and a...

• 46:00Speaker 02

  So any nation...

• 46:01Neil deGrasse Tyson?

  So here's the, I think the bottom line of that question is, how many stars of the night sky do your small telescopes have access to? Because if the star is too dim, you're not gonna, you can't do it. But where's a big telescope can monitor a dim star? So how many stars, you have enough work cut out for you?

• 46:22Speaker 02

  Yeah, so I'm just developing a new small telescope system, which will consist of 64 small telescopes in an array, each having its own detector, and it will see the whole sky above, you know, reasonable elevation of, about, above the horizon. And it will measure the brightness of about 100 million stars every 30 seconds.

• 46:43Neil deGrasse Tyson?

  Plenty, okay. We're done here.

• 46:48Matt Kirshen?

  A hundred million every thirty, we're good. You good?

• 46:50Neil deGrasse Tyson?

  Yeah.

• 46:54Matt Kirshen?

  Well, then I think that leads quite neatly into, I think that if there's time for one final question.

• 46:57Neil deGrasse Tyson?

  One more, let's slip it in, slip it in there.

• 46:59Matt Kirshen?

  Troy from Virginia says, Dr. Bakos, do you foresee the creation of a detection method that will expand our current model of the visible universe?

• 47:07Speaker 02

  Wow, like a brand new one, other than, I mean, the latest one, which it was gravitational waves, right? We have detected neutrinos, right? That was amazing. We do cosmic, we detect cosmic rays, particles directly coming from far away. We have electromagnetic radiation and we have gravitational waves.

• 47:27Neil deGrasse Tyson?

  Just to be clear, each one of these requires a different kind of, quote, telescope to observe.

• 47:32Speaker 02

  Yeah.

• 47:32Neil deGrasse Tyson?

  Right. So the gravitational waves, that was LIGO, and then you have neutrino detectors, there's underground, that's, all right. And then you said electromagnetic, that would be traditional telescopes. And is there anything left? I mean, what's left?

• 47:47Speaker 02

  Well, I think what's left is, for example, detecting dark matter through

• 47:52Neil deGrasse Tyson?

  Okay.

• 47:52Speaker 02

  fancy detector. So we don't know what dark matter is. All we know is that it does not interact with electromagnetic radiation, that is light.

• 47:59Neil deGrasse Tyson?

  Okay, so a dark matter detector, why isn't that just detecting its gravity? Because that's what, I mean.

• 48:06Speaker 02

  Well, so we have detected its gravity through looking at the spin of galaxies or the properties of galaxy clusters.

• 48:14Neil deGrasse Tyson?

  I get it. It's effects, but not the thing itself.

• 48:16Speaker 02

  We would like to see like, what was, like, what's the particle? But particle is really annoying because it does not interact with anything. So, and of course, the gravity of an individual particle, you can't measure, you need big lumps of this dark matter to see. So that's sort of a new thing. I think that that's the one I would list for this. Otherwise, I guess, improving the detection methods for all of these, having big space telescopes, large ground-based telescopes, clear skies, all together will hugely improve our capabilities.

• 48:47Neil deGrasse Tyson?

  Why don't you take us out with just a, a, a, a commercial? For the Veroubin telescope and what that will do for the measurement of transient phenomena. And then you can wrap it in how bad the satellite trails would be in the face of those data.

• 49:04Speaker 02

  Yeah, so the Veroubin survey will be commissioned next year, starting scanning the sky from Chile using a giant telescope. It has a mirror diameter of six and a half meters and it will scan the sky every three days. So it will constantly work every night, but every point in the sky will get an observation roughly every third day. And it will see very deep down, very faint things. So it will be very rich with exploding things in the universe very far away. Now, having said that, it's an extremely sensitive telescope. So a satellite going through will

• 49:43Speaker 02

  it leads to this giant, bright streak across the image, spoiling a big part of the image.

• 49:50Neil deGrasse Tyson?

  Are you going to have to only use it outside of the twilight zone? Ooh, I like the way that came out. Okay, the evening twilight and morning twilight is where you get the reflection of the sun. So maybe the telescope would only be at its best between the two edges of twilight.

• 50:07Speaker 02

  Well, these twilights are very long. So there's a ton of that because of for the satellites, what we call twilight is they're orbiting further up at 400 kilometers.

• 50:15Neil deGrasse Tyson?

  Even higher up.

• 50:16Speaker 02

  So you can easily see them three, four hours after sunset and three, four hours before. And then you have the whole night already. So in a summer night, the whole night is twilight for the satellites. In a winter night, there might be a couple of hours in the middle where there's less. Fine, but you're losing majority of your time.

• 50:32Neil deGrasse Tyson?

  And so if it repeats the sky every three nights, it can see, it should detect anything that varies on that kind of time scale. Is that a fair expectation for it?

• 50:41Speaker 02

  Yep, that is. That is a fair expectation and it will see many things that that change, either move asteroids or blow up supernovae or dim collapsing stars into a black hole or all kinds of interesting things. Yeah.

• 50:57Neil deGrasse Tyson?

  Okay, all right.

• 50:59Matt Kirshen?

  Well, you convinced me. Let's shoot them down. Let's shoot these satellites down.

• 51:02Neil deGrasse Tyson?

  In a video game, as a minimum, in a video game.

• 51:04Speaker 02

  I mean, you could with lasers that that are used for like used for adaptive optics. I think if one hit a satellite, I'm sure. Military has the technology of doing that if they really want to.

• 51:20Neil deGrasse Tyson?

  So Guswar, when does your documentary come out, Dark Sacred Night?

• 51:23Speaker 02

  That documentary was, it came out on the Garden State Film Festival and it even won a prize. I forgot what prize, but.

• 51:32Neil deGrasse Tyson?

  Garden State is New Jersey, for those who didn't know, that some people think of New Jersey as a garden.

• 51:37Speaker 02

  And it's publicly available on YouTube.

• 51:39Neil deGrasse Tyson?

  Oh, it's available out, okay.

• 51:41Speaker 02

  For a while, it was only through, you know, buying a ticket to the cinema.

• 51:45Neil deGrasse Tyson?

  Yeah, but thank you for highlighting that for me.

• 51:47Speaker 02

  Now it's all open, yeah, so I highly recommend. It's a short documentary, it's 10 minutes maybe, or 15.

• 51:54Neil deGrasse Tyson?

  Okay. Well, Guswar, it's been a delight to have you on StarTalk and share your expertise with us, especially from my old stomping grounds of Peyton Hall on the campus of Princeton University.

• 52:05Speaker 02

  Yeah, we miss you. Thank you for inviting me.

• 52:08Neil deGrasse Tyson?

  All right, excellent. And Matt, always good to have you, man.

• 52:11Matt Kirshen?

  So always good to be here.

• 52:12Neil deGrasse Tyson?

  All right, this has been Cosmic Queries. Neil deGrasse Tyson here, your personal astrophysicist, as always, keep looking up.