WEBVTT - Are there planets without a star? 0:00:08.480 --> 0:00:11.920 Hey, Daniel, did you ever want to be an astronaut? Well, yes, 0:00:12.039 --> 0:00:15.600 but I didn't because I'm terrified of the danger and 0:00:15.640 --> 0:00:18.480 the adventure. Yeah, I'm not ready to travel in the 0:00:18.520 --> 0:00:21.240 space until it's safe and routine. Yeah, it is pretty 0:00:21.320 --> 0:00:23.439 dark and scary out there, But isn't that kind of 0:00:23.440 --> 0:00:26.040 the point of space exploration to go out there and 0:00:26.560 --> 0:00:29.560 discover and find new things hiding in the darkness. Yeah, 0:00:29.600 --> 0:00:31.560 and I want other people to go out there take 0:00:31.600 --> 0:00:33.519 those risks, and then I can just read about it 0:00:33.520 --> 0:00:52.600 in the newspaper. Hi am or Handmay, cartoonist and the 0:00:52.640 --> 0:00:56.639 creator of PhD Comics. Hi. I'm Daniel Whitson. I'm a 0:00:56.680 --> 0:00:59.880 particle physicist, and I'm a stay at home adventurer of 0:01:00.040 --> 0:01:04.399 the mind couch Explorer. I'd like to explore this vast 0:01:04.480 --> 0:01:07.360 universe from the comfort of my office. But welcome to 0:01:07.360 --> 0:01:10.560 our podcast, Daniel and Jorge Explain the Universe, a production 0:01:10.680 --> 0:01:13.280 of I Heart Radio, in which we take you on 0:01:13.360 --> 0:01:17.959 an exploration of all the amazing, crazy, monkers, beautiful, nasty, crazy, 0:01:18.040 --> 0:01:21.040 weird things in this universe. Did I say crazy twice? 0:01:21.280 --> 0:01:25.000 That's because the universe is that crazy. It's double crazy. 0:01:25.240 --> 0:01:27.760 I feel like the things we're learning in science every year, 0:01:27.800 --> 0:01:31.000 every decade, every generation are crazier than the things we 0:01:31.080 --> 0:01:33.399 learned before. It's not just that we're learning more, but 0:01:33.480 --> 0:01:37.120 the stuff we're revealing is just more bonkers than anything 0:01:37.160 --> 0:01:39.240 we could have imagined. Don't you feel that way? Well, 0:01:39.240 --> 0:01:41.840 do you think it's crazier than what we thought it 0:01:41.959 --> 0:01:45.240 was before? You know, is it crazier than Greek gods 0:01:45.319 --> 0:01:50.040 and Norse mythology? Well, I think it's maybe less creative, 0:01:50.160 --> 0:01:54.440 but it's definitely crazier. Every generation has had to absorb 0:01:54.560 --> 0:01:58.400 ideas which were very difficult to swallow because they completely 0:01:58.440 --> 0:02:00.640 conflict with our view of the world. You know, the 0:02:00.760 --> 0:02:05.560 universe is expanding, there is no sense of location and time. 0:02:05.680 --> 0:02:09.160 You know, things are fundamentally random. Space curves like these 0:02:09.200 --> 0:02:11.240 are hard things to get your mind around, and they 0:02:11.280 --> 0:02:14.240 get harder and harder as we discover them. Yeah. We 0:02:14.280 --> 0:02:16.640 are not the center of the universe, and the universe 0:02:16.760 --> 0:02:20.560 is not like what we see around are where we are. Yeah, 0:02:20.600 --> 0:02:22.680 and every time we look out into space we discover 0:02:22.800 --> 0:02:26.160 new stuff, weird stuff. Places we thought were empty turned 0:02:26.200 --> 0:02:29.960 out to be filled with interesting, fascinating, weird kinds of matter. 0:02:30.520 --> 0:02:32.840 M Yeah, because that's kind of the history of humanity 0:02:32.880 --> 0:02:35.480 and science. Right, Like, we look around and we assume 0:02:35.600 --> 0:02:39.000 that the whole universe is kind of like where we're at. Right. 0:02:39.040 --> 0:02:42.240 We thought the world was flat because everything seems flat 0:02:42.280 --> 0:02:45.120 around us, And we thought that the Earth was the 0:02:45.200 --> 0:02:47.679 center of the universe because everything seems to provolve around this. 0:02:47.840 --> 0:02:49.919 But then as we learn more that we learn that 0:02:49.960 --> 0:02:52.520 there are more and more different things out there. We 0:02:52.919 --> 0:02:56.440 keep learning that the assumptions we make, that the generalizations 0:02:56.440 --> 0:02:59.560 we make about what we learned here, cannot be applied everywhere. 0:02:59.560 --> 0:03:01.840 And that's the exciting part. That's the moment of discovery, 0:03:01.880 --> 0:03:04.320 when you realize, oh, I thought the universe was this way. 0:03:04.320 --> 0:03:07.040 It turns out it's actually totally different in a way 0:03:07.160 --> 0:03:10.600 I never imagine. We're intellectually maturing as a species by 0:03:10.680 --> 0:03:13.720 discovering our universe and coming to grips with it. And 0:03:13.760 --> 0:03:15.960 it's not always the way we liked it, but it 0:03:16.000 --> 0:03:18.200 turns out to be quite fascinating to the other program 0:03:18.280 --> 0:03:21.520 will be tackling one such idea that you know, maybe 0:03:21.520 --> 0:03:24.040 a lot of people even today think is true, but 0:03:24.120 --> 0:03:27.040 actually it turns out to be much more complex than that. 0:03:27.040 --> 0:03:29.520 That's right, that darkness out there is more filled with 0:03:29.600 --> 0:03:33.600 interesting stuff and rocks than you could have ever imagined. Yeah, 0:03:33.840 --> 0:03:37.120 stuff that's out there hiding in the darkness, other worlds 0:03:37.160 --> 0:03:39.600 out there looking at ours and wondering what would it 0:03:39.600 --> 0:03:41.800 be like to be so close to a nice, warm, 0:03:41.840 --> 0:03:44.320 toasty star. Yeah. So today on the program, we'll be 0:03:44.320 --> 0:03:53.520 tackling the question are there planets without stars and not 0:03:53.640 --> 0:03:57.160 just a movie stars? Right? We're talking about are there 0:03:57.280 --> 0:04:00.720 places in the universe then don't have a son or 0:04:00.760 --> 0:04:03.360 a star near them? I like the one you asked though, Like, 0:04:03.400 --> 0:04:06.480 are their planets out there with only being C list actors? 0:04:07.680 --> 0:04:12.360 That's right? Where everyone uh it only has five seconds 0:04:12.360 --> 0:04:15.160 of fame. You can only be in one movie and 0:04:15.200 --> 0:04:18.000 then your career is over. It's like turn limits for 0:04:18.000 --> 0:04:21.720 for Hollywood actors. That's great, and then that'd be great 0:04:21.760 --> 0:04:27.359 if we got rid of celebrity culture in our society. Yeah, well, 0:04:27.360 --> 0:04:29.680 that won't appeal to any of our celebrity listeners, you know. 0:04:29.760 --> 0:04:32.440 So Hey Brad Pitt, don't worry. You can still come 0:04:32.480 --> 0:04:35.800 on the program. But apparently it works if you If 0:04:35.839 --> 0:04:38.240 you speak badly about somebody don't want to come on 0:04:38.240 --> 0:04:43.680 our show, then that's true. To defend themselves, maybe to 0:04:43.800 --> 0:04:46.800 grab any kind of publicity they can. That's true. Stay 0:04:46.839 --> 0:04:49.800 tuned for our episode in which science fiction authors come 0:04:49.800 --> 0:04:53.240 on the show and respond to our critiques. And when 0:04:53.320 --> 0:04:55.720 we're thinking about the broad universe, you know, you are 0:04:55.839 --> 0:04:58.200 used to thinking about your planet is having one very 0:04:58.240 --> 0:05:01.719 important feature, which is the on And every time you 0:05:01.720 --> 0:05:05.200 think about a planet, you imagine, well, planets form around stars, right, 0:05:05.680 --> 0:05:08.800 and so it's a bit mind bending to imagine that 0:05:08.880 --> 0:05:11.599 the universe might be different. Yeah, a lot of people 0:05:11.640 --> 0:05:15.280 might be surprised to learn that not every planet out 0:05:15.320 --> 0:05:18.919 there is centered around the star. You may be shocked 0:05:18.920 --> 0:05:22.520 to discover that rogue planets are not that rare. That 0:05:22.600 --> 0:05:27.360 the universe may be chalk filled with these floating dark bodies. Yeah, 0:05:27.400 --> 0:05:29.960 and that's the official physics name for them, right, like 0:05:30.360 --> 0:05:34.960 a planet without a star. It's officially called a rogue planet. Yes, 0:05:35.040 --> 0:05:37.359 but you will not be surprised to discover there is 0:05:37.400 --> 0:05:41.640 some controversy about what exactly gets called a rogue planet. 0:05:41.839 --> 0:05:44.640 Oh wow, physicists arguing about what to name something that's 0:05:44.720 --> 0:05:48.400 so rare, not only arguing about whether something is a 0:05:48.400 --> 0:05:51.760 good name, but like what exactly falls into this category? 0:05:52.000 --> 0:05:54.039 You know, the whole Pluto, like is it a planet? 0:05:54.080 --> 0:05:57.120 Is it not a planet? Thing? That's this same controversy 0:05:57.680 --> 0:06:02.400 large interesting because I guess everything is sort of being 0:06:02.440 --> 0:06:05.600 pulled by every star in the universe, So technically there 0:06:05.640 --> 0:06:08.320 there isn't this a planet that's not being pulled by 0:06:08.440 --> 0:06:10.559 a star. I like that. You're sort of saying every 0:06:10.560 --> 0:06:12.560 planet is part of a sum solar system, even if 0:06:12.560 --> 0:06:16.240 it's sort of distant from its star. Right, Well, technically, right, 0:06:16.760 --> 0:06:19.360 don't all solar systems sort of overlap with each other? 0:06:19.480 --> 0:06:24.160 Technically because the force of gravity is infinite has infinite reach. Yeah, 0:06:24.200 --> 0:06:26.480 that's true. The force of gravity is infinite, but at 0:06:26.520 --> 0:06:28.360 some point the force of gravity from these stars is 0:06:28.400 --> 0:06:32.800 basically negligible and there's essentially no effect on these planets, 0:06:33.160 --> 0:06:37.880 and they're more affected. Yeah, negligible, They're more affected by 0:06:38.000 --> 0:06:40.839 the mass of the galaxy. So I think the distinction 0:06:40.880 --> 0:06:43.000 is are you orbiting a star or are you orbiting 0:06:43.080 --> 0:06:45.240 the center of the galaxy? All right, Well, I was 0:06:45.240 --> 0:06:48.000 a little surprised to find out that there are road 0:06:48.040 --> 0:06:50.560 planets out there, and that there are apparently not just 0:06:50.640 --> 0:06:52.760 a few of them. But we were wondering how many 0:06:52.760 --> 0:06:55.280 people out there knew the same fact that there are 0:06:55.320 --> 0:06:58.599 planets out there in space without stars. So I walked 0:06:58.600 --> 0:07:01.120 around campus a you see, Irvine, and I asked folks 0:07:01.160 --> 0:07:03.320 what they thought and if they had a guess for 0:07:03.480 --> 0:07:06.480 how many rogue planets there might be in the universe. 0:07:07.320 --> 0:07:10.240 To think about it for a second, how many planets 0:07:10.240 --> 0:07:12.480 out there in the universe? Would you, guys are out 0:07:12.520 --> 0:07:16.320 there floating without a star. Here's what people had to say. 0:07:16.560 --> 0:07:19.360 I have no clue how many there are. My guests 0:07:19.520 --> 0:07:22.240 understanding from what I think I know is that they're 0:07:22.720 --> 0:07:24.840 by one way or another of something flying by the 0:07:24.920 --> 0:07:28.120 end up injected from the star that they'reth I have 0:07:28.200 --> 0:07:33.120 not do you think does exists? I don't think. I 0:07:33.160 --> 0:07:37.560 can't imagine that that would be not true, honestly, like 0:07:37.600 --> 0:07:39.760 a lot of just like ten, I would have no 0:07:39.840 --> 0:07:41.920 idea how to give a number, Um I would I 0:07:41.920 --> 0:07:44.040 would actually have to say probably a lot, just because 0:07:44.080 --> 0:07:47.640 gravity is so you can get a star really close 0:07:47.680 --> 0:07:49.880 to another set of planets and then it throws them 0:07:49.920 --> 0:07:53.160 off in space. So probably a lot, probably, I think. 0:07:53.160 --> 0:07:57.840 So you think it's like seven or like a billion? Jeeus? Um, Well, 0:07:57.880 --> 0:07:59.680 in a in a big universe, I don't know if 0:07:59.680 --> 0:08:03.560 we could count. No, I think every planet. I think 0:08:04.280 --> 0:08:07.480 interested pretty good mix of reactions. Yeah, a lot of 0:08:07.480 --> 0:08:10.360 open minds. I love the people who say the universe 0:08:10.480 --> 0:08:13.160 is so big you can never say no, you can 0:08:13.200 --> 0:08:15.640 never say that something doesn't exist. I think that's a 0:08:15.640 --> 0:08:20.200 great attitude because technically, in an infinite universe, anything can happen, right, 0:08:20.800 --> 0:08:24.840 and anything is happening. Yeah, in an infinite universe, everything 0:08:24.880 --> 0:08:28.560 that can happen eventually will happen and is happening somewhere. 0:08:28.920 --> 0:08:31.040 So it's a good attitude. Now, we don't know the 0:08:31.080 --> 0:08:34.760 universe is infinite, but it's definitely pretty big right somewhere 0:08:34.800 --> 0:08:36.960 out there. There's a version of this podcast in which 0:08:37.040 --> 0:08:40.199 you and I are the A List celebrities. That's not 0:08:40.440 --> 0:08:43.800 this version. What are you saying? I don't I'm confused. 0:08:44.880 --> 0:08:49.839 I think we're run out of letters letters. That's right 0:08:49.880 --> 0:08:55.920 with the Triple A. We're the Triple We're Triple A celebrities, 0:08:56.000 --> 0:09:00.040 which sounds good, but really, welcome to the minor the 0:09:00.080 --> 0:09:03.920 Ego podcast, folks. Yeah, so, um, but people seem sort 0:09:03.920 --> 0:09:06.520 of skeptical. I mean, some people said yes, but it 0:09:06.640 --> 0:09:10.560 sort of seemed like yes, probably, but probably it's probably 0:09:10.559 --> 0:09:13.760 not very common, that's right, and it's immediately a fascinating question. 0:09:13.800 --> 0:09:16.120 It's the kind of thing you might not ever think about. 0:09:16.160 --> 0:09:17.960 You think, oh, well, planet is of course they form 0:09:18.000 --> 0:09:21.960 around stars, and that's reasonable because stars form from the 0:09:22.440 --> 0:09:25.800 gravitational collapse of stuff, and plants do the same thing, 0:09:25.840 --> 0:09:28.720 and so you should imagine they formed together. They're probably 0:09:28.760 --> 0:09:32.000 associate with each other. You probably don't ever think that 0:09:32.040 --> 0:09:35.480 there are dark bodies floating out there in between the stars. 0:09:35.720 --> 0:09:38.280 But as soon as somebody suggested to you, then you 0:09:38.320 --> 0:09:40.960 have to wonder, well do we know, how do we know? 0:09:41.120 --> 0:09:43.840 Have we looked? Could we see them? And immediately it's 0:09:43.840 --> 0:09:46.360 a question you need to know the answer to. Yeah, 0:09:46.480 --> 0:09:49.080 because if it's a lot, then they would be pretty 0:09:49.280 --> 0:09:52.360 uh interesting, I guess, or dangerous because what if one 0:09:52.360 --> 0:09:55.640 of them hits us? Yeah, it's a little bit dangerous. 0:09:55.679 --> 0:09:58.080 But also it just changes sort of your your view 0:09:58.200 --> 0:10:00.960 of the universe. I mean, what if there are more 0:10:01.400 --> 0:10:04.800 rogue planets out there than non rogue planets, then your 0:10:04.840 --> 0:10:07.280 whole view of like what is a planet has to 0:10:07.320 --> 0:10:09.760 all of a sudden change from oh, they're all around 0:10:09.800 --> 0:10:12.880 stars to well, my sense of a planet is unusual 0:10:13.000 --> 0:10:15.280 is a typical? Oh I see, it could be that 0:10:15.480 --> 0:10:19.160 our kind of planet is the minority. Yeah, exactly, Just 0:10:19.240 --> 0:10:21.680 like we discovered that our kind of matter is a 0:10:21.720 --> 0:10:24.600 small fraction of all the matter in the universe. All 0:10:24.640 --> 0:10:27.320 of a sudden, things we thought were typical are now weird. 0:10:27.520 --> 0:10:30.800 It'd be like discovering their more continents out there. Or 0:10:30.920 --> 0:10:32.839 you know, you grow up in your family eats a 0:10:32.880 --> 0:10:34.439 dinner a certain way, and then you go to a 0:10:34.480 --> 0:10:36.959 friend's house you discover, oh man, my family is weird. 0:10:37.400 --> 0:10:39.560 We are and we don't use utensils at home or 0:10:39.559 --> 0:10:42.280 whatever it is. You know, it's it's maturing in that 0:10:42.400 --> 0:10:46.360 same way, right, It's expanding your horizon and your idea 0:10:46.400 --> 0:10:48.280 of the universe. And that's why this is such a 0:10:48.360 --> 0:10:51.640 fun opportunity to learn something new about the universe. All right, 0:10:51.679 --> 0:10:55.360 so let's get into it. Daniel Wood exactly is a 0:10:55.480 --> 0:10:59.679 rogue planet. Right, So let's begin with technical definitional stuff 0:10:59.679 --> 0:11:01.760 that we could argue about easily for half an hour. 0:11:04.040 --> 0:11:06.760 And and and very importantly, is there a first rogue 0:11:06.760 --> 0:11:10.960 planet called rogue one? Well, the movie rights for that 0:11:10.960 --> 0:11:14.520 one I've already been locked up, unfortunately. Yeah, Well they're 0:11:14.520 --> 0:11:18.480 not definitely not making a sequel of that one. I 0:11:18.520 --> 0:11:20.800 liked it. I liked it, but you know, Rogue two's 0:11:20.840 --> 0:11:23.360 agent is not exactly getting a lot of traction in Hollywood. 0:11:24.000 --> 0:11:26.880 But a rogue planet is a planet that's not orbiting 0:11:26.880 --> 0:11:29.680 a star. And you said earlier, and you're right that 0:11:30.040 --> 0:11:34.199 every planet feels the gravity from every star in the galaxy, 0:11:34.280 --> 0:11:36.320 but you have to look at its motion, like the 0:11:36.320 --> 0:11:38.960 motion of the Earth is that we are orbiting our star. 0:11:39.400 --> 0:11:41.600 We're moving around our star. But if we were a 0:11:41.679 --> 0:11:44.680 rogue planet, then our primary motion would just be around 0:11:44.720 --> 0:11:47.479 the center of the galaxy. Would be the same category 0:11:47.559 --> 0:11:50.720 as the stars, like our star orbits the center of 0:11:50.720 --> 0:11:53.800 the galaxy. It's a planet that's not sort of trapped 0:11:53.920 --> 0:11:59.400 by the gravitational well or pool of a star. Yeah, 0:11:59.520 --> 0:12:01.280 we liked to in goo a Solar System as an 0:12:01.320 --> 0:12:05.720 object because it's gravitationally bound that the dominant gravitational force 0:12:05.760 --> 0:12:08.240 on every object in the Solar System is the Sun. 0:12:08.640 --> 0:12:11.040 So it's like the Sun has its own little neighborhood 0:12:11.320 --> 0:12:15.000 in which it's gravity is more powerful than any other gravity. 0:12:15.360 --> 0:12:18.600 Or I guess maybe not not just that it's more powerful, 0:12:18.720 --> 0:12:22.920 but it's powerful enough to to sort of trap things 0:12:23.640 --> 0:12:26.240 in its vicinity. Yeah, it's a stable to let it 0:12:26.280 --> 0:12:29.439 go exactly. But you know, the galaxy is big, and 0:12:29.559 --> 0:12:32.480 there are a lot of stars, but they're not that many, 0:12:32.559 --> 0:12:35.880 and so there's a lot of room out there between stars. Remember, 0:12:35.920 --> 0:12:38.960 we're you know, light years away from the nearest star, 0:12:39.040 --> 0:12:41.440 which makes a huge amount of space for stuff to 0:12:41.440 --> 0:12:43.800 be floating between the stars. Oh, I see, So there's 0:12:43.800 --> 0:12:45.520 a lot of room for you to be out there 0:12:45.800 --> 0:12:49.920 without falling into the you know, the trap of the 0:12:50.000 --> 0:12:52.840 gravitational pool of a star. Yeah, if you mapped the 0:12:52.840 --> 0:12:55.840 Milky Way onto Earth, for example, you know, you have 0:12:55.920 --> 0:12:58.680 like one house here in Los Angeles and another house 0:12:58.720 --> 0:13:01.520 like in Kansas, and another house like in New York City, 0:13:02.000 --> 0:13:04.440 and there'll be a lot of room between those that 0:13:04.520 --> 0:13:06.439 you could rogue around it. Yeah, you can have a 0:13:06.520 --> 0:13:08.839 rogue cabin in the woods and never have to get 0:13:08.880 --> 0:13:12.400 close to anybody. And I guess more importantly, you could 0:13:12.440 --> 0:13:15.080 be so far away from my house and your house 0:13:15.080 --> 0:13:18.120 in Kansas, Dad, you wouldn't feel the need to sort 0:13:18.120 --> 0:13:20.559 of go visit. Yeah, and you could largely ignore them. 0:13:20.559 --> 0:13:23.400 You know, those stars would just be other slightly more 0:13:23.440 --> 0:13:25.880 bright stars in the sky, and you wouldn't feel their 0:13:25.880 --> 0:13:28.920 gravitational pull strongly enough to get sucked into one of them. 0:13:29.000 --> 0:13:30.839 All right, So then what's the definition then that it's 0:13:30.920 --> 0:13:35.280 it's a planet, meaning like a ball of stuff? Is 0:13:35.320 --> 0:13:37.920 that what it means? What is exactly a planet? Yeah? 0:13:37.920 --> 0:13:41.320 Well that's where it gets tricky, right. Um. These are 0:13:41.559 --> 0:13:46.640 either things that were formed in other solar systems and 0:13:46.679 --> 0:13:51.480 then ejected, or you could also think about stars that 0:13:51.600 --> 0:13:55.240 never sort of got started, like failed stars. You know 0:13:55.280 --> 0:13:57.520 what if a star never sort of turns on because 0:13:57.559 --> 0:14:00.400 it's not big enough to burn, is that a rogue 0:14:00.400 --> 0:14:02.960 planet or is that a failed star? Is a heated 0:14:03.000 --> 0:14:05.800 debate in astronomy, But both of those things are out 0:14:05.840 --> 0:14:08.000 there well in a way sort of Jube, isn't Jupiter 0:14:08.160 --> 0:14:10.280 also kind of a failed star? Like it could have 0:14:10.280 --> 0:14:13.200 been a star but it wasn't. Yeah, And if Jupiter 0:14:13.280 --> 0:14:15.960 had formed far enough away from the Sun on its own, 0:14:15.960 --> 0:14:17.800 if it was like the center of its own little 0:14:17.800 --> 0:14:21.760 gravitational neighborhood, we would call it a sub brown dwarf star. 0:14:22.280 --> 0:14:24.480 But because it formed around our star, we call it 0:14:24.520 --> 0:14:26.920 a planet. And so there's a lot of energy spent 0:14:26.960 --> 0:14:30.160 in astronomy arguing about these names and definitions. And wait, 0:14:30.160 --> 0:14:33.200 you're saying that if Jupiter wasn't in our solar system, 0:14:33.240 --> 0:14:35.720 if it was out there, it would be considered a 0:14:35.760 --> 0:14:38.200 star even though it's not burning. Yeah, there's a whole 0:14:38.240 --> 0:14:41.880 category of stars called brown dwarfs and sub brown dwarfs 0:14:41.920 --> 0:14:45.400 that are just not big enough to ignite fusion and 0:14:45.480 --> 0:14:48.080 to burn and to glow. But why still call them 0:14:48.080 --> 0:14:50.840 a star if they're not ignited? I'm burning, see what 0:14:50.880 --> 0:14:52.960 I mean. People have strong feelings about this, like you do. 0:14:53.040 --> 0:14:57.280 Apparently in your mind you think, you think, if it's 0:14:57.280 --> 0:14:58.920 got to be burning to be a star, right, Well, 0:14:58.960 --> 0:15:01.280 other people think, oh know, it's a failed star. That's 0:15:01.280 --> 0:15:03.080 a kind of star, all right, So that's kind of 0:15:03.120 --> 0:15:06.200 the definition. It's a ball of stuff, or maybe the 0:15:06.200 --> 0:15:08.640 definition is kind of fuzzy, but generally speaking, a rogue 0:15:08.640 --> 0:15:10.720 planet is a ball of stuff. It could be gas. 0:15:10.840 --> 0:15:15.000 Could be rock too, right, rocks or gas or you know, 0:15:15.000 --> 0:15:19.000 it's compressed matter kind of um just to make it 0:15:19.000 --> 0:15:21.720 different than a cloud. And it's floating out there in space, 0:15:22.320 --> 0:15:26.920 not in the orbit of a star. Whatever that could mean. 0:15:29.480 --> 0:15:31.560 That's right, it's a it's a dense blob of stuff. 0:15:31.600 --> 0:15:34.520 Primarily orbiting the center of the galaxy instead of orbiting 0:15:34.520 --> 0:15:37.560 another star. All right, let's get into how we can 0:15:37.600 --> 0:15:40.120 see them even though it's dark out during space and 0:15:40.160 --> 0:15:42.360 how many there are out there in the universe. But 0:15:42.480 --> 0:15:57.560 first let's take a quick break. All right, I know 0:15:57.640 --> 0:16:01.320 there are floating planets out there in the universe in 0:16:01.320 --> 0:16:04.880 our galaxy that don't have a star. They're called road planets, 0:16:04.960 --> 0:16:07.880 and there might be a lot of them. So first 0:16:07.920 --> 0:16:09.880 of all, I guess, how do we even see them 0:16:09.880 --> 0:16:12.440 if it's they're not burning bright and they're not near 0:16:12.440 --> 0:16:15.280 a star for them to shine, Um, how do we 0:16:15.520 --> 0:16:18.360 know they're there? It's tricky, right, These are dark objects. 0:16:18.400 --> 0:16:20.640 They are not shining, they're not emitting light, and as 0:16:20.640 --> 0:16:22.680 you say, they're not close enough to any star to 0:16:22.760 --> 0:16:26.960 reflect light like like exoplanets are. So it's not easy 0:16:27.000 --> 0:16:28.720 to spot them, which is why for a long time 0:16:28.760 --> 0:16:31.720 we didn't even know that they existed. Um, but there 0:16:31.760 --> 0:16:34.960 are two ways to see them. One is you get 0:16:35.040 --> 0:16:38.200 really lucky, and one is close enough that we can 0:16:38.240 --> 0:16:42.840 see them in the infrared. Remember, these things are not burning, 0:16:42.920 --> 0:16:45.720 so they're not shining visible light, but they still have 0:16:45.840 --> 0:16:49.000 some heat to them and everything in the universe that 0:16:49.080 --> 0:16:53.720 has a temperature also radiates some energy, usually in the infrared, 0:16:54.240 --> 0:16:56.520 and so sort of glowing in the infrared. And we 0:16:56.600 --> 0:17:00.160 have infrared telescopes, I see, because we I think we're 0:17:00.240 --> 0:17:03.520 used to thinking of like asteroids and things out there 0:17:03.560 --> 0:17:06.760 in spaces being cold, but you could have, for example, 0:17:06.840 --> 0:17:09.280 like the Earth is kind of warm by itself. The 0:17:09.320 --> 0:17:10.960 Earth is kind of warm. And even if we were 0:17:11.040 --> 0:17:14.280 ten or fifty kelvin. And I want to give props 0:17:14.280 --> 0:17:16.000 to the person out there who wrote in to remind 0:17:16.000 --> 0:17:19.199 me that it's not degrees kelvin, it's just kelvin. But 0:17:19.359 --> 0:17:21.520 even if we were just ten or fifty kelvin, we 0:17:21.520 --> 0:17:25.960 would still radiate. Everything that's above absolute zero radiates some energy. 0:17:26.000 --> 0:17:29.080 It's called black body radiation. Oh, I see. It sort 0:17:29.119 --> 0:17:33.200 of shines in the infrared. Yeah. And there's a telescope 0:17:33.240 --> 0:17:36.600 called the Wise telescope w I S E, which is 0:17:36.600 --> 0:17:38.400 really good at seeing this stuff, and it's really good 0:17:38.400 --> 0:17:41.080 in the infrared. And so if it's close enough that 0:17:41.240 --> 0:17:44.240 you can spot them directly with the Wise telescope, but 0:17:44.320 --> 0:17:46.560 it has to be pretty close. So like if our 0:17:46.600 --> 0:17:49.280 son suddenly went out and there was no more light 0:17:49.320 --> 0:17:51.920 in our solar system, you could still maybe see the 0:17:52.040 --> 0:17:55.200 Earth and all the other planets. Yeah, you could, precisely. 0:17:55.280 --> 0:17:58.159 And we do this to study other solar systems. We 0:17:58.200 --> 0:18:00.000 look at them in the visible light and we also 0:18:00.040 --> 0:18:02.360 look at them in the infrared to try to get 0:18:02.359 --> 0:18:04.360 a glimpse for like, what is the stuff out there 0:18:04.400 --> 0:18:07.359 that's not blowing. It's still there, it's giving off different 0:18:07.400 --> 0:18:09.640 kinds of radiation. So we have lots of different ways 0:18:09.640 --> 0:18:12.719 of looking at the sky. The infrared, X ray, radio, 0:18:13.000 --> 0:18:15.240 These are all just different kinds of light though. They're 0:18:15.240 --> 0:18:18.800 all just different parts of the electromagnetic spectrum. But different 0:18:18.800 --> 0:18:21.320 things out there glow in different parts of these spectrums. 0:18:21.320 --> 0:18:23.480 So the most direct way is to look for them 0:18:23.520 --> 0:18:26.320 in the infrared. But they have to be really close by, 0:18:26.520 --> 0:18:28.520 Oh I see, because otherwise it would be too faint 0:18:28.600 --> 0:18:30.919 to see them. Yeah, Because these things are small and 0:18:31.000 --> 0:18:34.119 pretty faint, and so they're pretty hard to spot. The 0:18:34.160 --> 0:18:36.600 best way to see these things is to look for 0:18:36.640 --> 0:18:40.440 a little star eclipse. What well, if you have a 0:18:40.480 --> 0:18:43.000 big dark object somewhere out there in the universe and 0:18:43.000 --> 0:18:46.240 it passes between you and a star, then what happens 0:18:46.359 --> 0:18:49.480 It blocks the light from that star momentarily like a 0:18:49.560 --> 0:18:53.080 one time eclipse. Yes, like a one time eclipse, one 0:18:53.080 --> 0:18:55.679 time ever eclipse, one time ever. Yeah. And so you 0:18:55.680 --> 0:18:58.600 can see these things if you very carefully watch all 0:18:58.600 --> 0:19:00.960 the stars in the sky and wait for a blip. 0:19:01.200 --> 0:19:04.720 But there's something really fascinating because you might expect that, 0:19:04.840 --> 0:19:07.560 like a star eclipse would dim the star, that it 0:19:07.600 --> 0:19:10.199 would go out for a minute and then come back, right, 0:19:10.200 --> 0:19:13.600 that's you'd expect, But this is really weird. Gravitational effect. 0:19:13.600 --> 0:19:16.639 If the rogue planet or whatever it is alien ship 0:19:16.960 --> 0:19:20.920 is big enough, then it has a gravitational lensing effect. 0:19:20.960 --> 0:19:23.920 It acts like a big lens in space. Because remember 0:19:24.240 --> 0:19:27.840 gravity is the bending of space. So gravity can change 0:19:27.880 --> 0:19:30.720 the direction of light. We'll just block the light, they'll 0:19:31.160 --> 0:19:33.520 bend the light. I mean that sort of happens here 0:19:33.560 --> 0:19:36.200 on Earth too when there's an eclipse, right, doesn't the 0:19:36.320 --> 0:19:38.560 light sort of go around the Moon when it's blocking 0:19:38.560 --> 0:19:40.600 the sign a little bit? It does a little bit. Yeah, 0:19:40.800 --> 0:19:43.520 And in this case it can actually enhance the strength 0:19:43.520 --> 0:19:45.720 of that star because it acts like a lens. It 0:19:45.800 --> 0:19:48.720 gathers more light and it focuses it all on the Earth. 0:19:49.119 --> 0:19:51.639 So what actually happens when you get a micro lensing 0:19:51.680 --> 0:19:54.160 event they call it, is that the star gets brighter, 0:19:54.440 --> 0:19:57.920 not just a darker or like darker and lighter. Yeah, 0:19:57.960 --> 0:20:00.520 it actually gets brighter. It gets enhanced, right, it gets 0:20:00.560 --> 0:20:04.240 amplified by this micro lensing, and so the very center 0:20:04.280 --> 0:20:06.720 of it is blocked out. But you're gathering light from 0:20:06.720 --> 0:20:09.440 nearby and focusing it onto the earth. You actually get 0:20:09.480 --> 0:20:12.000 more of the starlight when it goes by. It's an 0:20:12.000 --> 0:20:15.760 eclipse that makes it the start look brighter. Yeah, recisely. 0:20:15.800 --> 0:20:18.680 It's really fun. And the telescope to see these things 0:20:18.800 --> 0:20:22.800 has a really awesome name. It's called the OGLE telescope. 0:20:23.400 --> 0:20:27.920 I thought I thought it was already too much to 0:20:28.000 --> 0:20:32.360 have a wise telescope. W I s e this one. 0:20:32.680 --> 0:20:35.320 I want to look at things called the OGLE if 0:20:35.359 --> 0:20:37.560 you want to sit on the couch and ogle the universe, 0:20:37.880 --> 0:20:43.880 and you do it using the optical Gravitational Lensing Experiment OGL. Wow, 0:20:44.720 --> 0:20:47.480 you guys probably pop some champagne when you came up 0:20:47.520 --> 0:20:49.240 with that name. So those are the two ways you 0:20:49.240 --> 0:20:51.680 can see him. You can see them either through micro 0:20:51.760 --> 0:20:56.359 lensing or anti eclipses or directly through the infrared. And 0:20:56.440 --> 0:20:58.399 so what do we know about them? Do we know 0:20:59.200 --> 0:21:02.119 are they sort of round like our planets necessarily, or 0:21:02.160 --> 0:21:05.800 do they look like giant asteroids or what do we 0:21:05.880 --> 0:21:08.360 expect them to look like? Yeah, we expect that they're 0:21:08.400 --> 0:21:12.080 mostly round because anything that's big enough gravity will make 0:21:12.080 --> 0:21:15.399 it round. You know, gravity is powerful, and if you've 0:21:15.400 --> 0:21:17.560 got a bit that's sticking out, eventually it's going to 0:21:17.720 --> 0:21:20.480 roll down. And so you have something that's big enough 0:21:20.520 --> 0:21:23.360 to have strong gravity, it's going to get around. Oh, 0:21:23.440 --> 0:21:25.720 I see, And you expect these to be big, right, 0:21:25.760 --> 0:21:28.760