WEBVTT - What are globular clusters? 0:00:08.480 --> 0:00:12.800 Hey, Katie, do you have science words that you especially like? Yeah, 0:00:13.000 --> 0:00:16.560 I really like apoptosis. It makes me think of popcorn. 0:00:17.920 --> 0:00:20.400 That does make me want to have a snack. Well, 0:00:20.560 --> 0:00:24.959 I like the word fundamental. It sounds so important, it's 0:00:25.000 --> 0:00:29.880 got fun in it, it does. So what science words 0:00:30.120 --> 0:00:35.600 don't you like? Um, coagulate, I was afraid you're gonna 0:00:35.640 --> 0:00:39.559 say moist coagulates pretty gross. Also, I'm not such a 0:00:39.560 --> 0:00:43.400 fan of the word had drawn. No, the problem is 0:00:43.440 --> 0:00:45.400 a lot of people end up with a little typo 0:00:45.520 --> 0:00:47.519 that swaps a couple of letters and you end up 0:00:47.560 --> 0:00:51.680 with something very not safe for work. Yeah, that gives 0:00:51.720 --> 0:01:10.760 the lard hay drown collider a whole different connotation. Hi, 0:01:11.000 --> 0:01:13.960 I'm Daniel, I'm a part of Old Physicist, and I 0:01:14.120 --> 0:01:19.080 definitely am colliding hay drowns at the LHC. And I 0:01:19.120 --> 0:01:23.480 am Katie Golden. I'm stepping in for Jorge this week, 0:01:23.640 --> 0:01:26.200 and I am the host of Creature Feature. I'm a 0:01:26.280 --> 0:01:31.199 science podcast interested in evolutionary biology, human psychology, and hate 0:01:31.240 --> 0:01:36.200 also physics and Welcome to the podcast. Daniel and Jorge 0:01:36.280 --> 0:01:39.000 explain the universe, in which we take you on a 0:01:39.120 --> 0:01:43.440 mental journey to understand everything about the universe, from the 0:01:43.520 --> 0:01:46.320 tiniest things between your toes to the things you see 0:01:46.360 --> 0:01:50.200 in the night sky to the vast weird, crazy bonker 0:01:50.280 --> 0:01:53.560 stuff going out in the depths of space. We take 0:01:53.640 --> 0:01:55.760 all of it, roll it up and try to make 0:01:55.800 --> 0:02:01.560 sure that you understand it. Like a cosmic burrito. How 0:02:01.640 --> 0:02:04.760 much hot sauce you want is up to you. And 0:02:04.800 --> 0:02:06.960 we love to talk about stuff that we see in 0:02:07.000 --> 0:02:09.480 the night sky, but we also love to talk about 0:02:09.520 --> 0:02:13.000 stuff you might not have even heard of. When you 0:02:13.000 --> 0:02:15.080 look up in the sky, you see stars, and if 0:02:15.120 --> 0:02:17.440 you have a nice telescope you can even see further 0:02:17.520 --> 0:02:20.960 in meb see those smudges that our galaxies. But there's 0:02:21.000 --> 0:02:23.560 a lot of other stuff out there in the universe 0:02:23.880 --> 0:02:26.440 that we are not familiar with, that most people don't 0:02:26.520 --> 0:02:29.400 even know exists. Okay, so if I'm looking at the 0:02:29.520 --> 0:02:32.800 night sky, I see a bunch of stars. Sometimes I 0:02:32.880 --> 0:02:36.800 see like, like you said, it looks like someone spilled 0:02:36.840 --> 0:02:39.400 a bunch of sugar up there, and it's a galaxy. 0:02:39.520 --> 0:02:42.760 But what can I possibly be missing? I mean other 0:02:42.800 --> 0:02:45.680 than yeah, I guess I can't see them in detail 0:02:45.720 --> 0:02:48.440 with a telescope, But but what what's up there? Like 0:02:48.480 --> 0:02:52.799 you mean giant alien eyeballs. Well, there's a lot of 0:02:52.840 --> 0:02:55.120 stuff out there. And basically, every time we turn on 0:02:55.160 --> 0:02:58.079 a new telescope or a new kind of device for 0:02:58.160 --> 0:03:01.480 we're listening to the Cosmos, we find something new. And 0:03:01.520 --> 0:03:04.480 every time we ap peer deeper and deeper into the sky, 0:03:04.600 --> 0:03:08.360 we see stuff that we didn't expect. On the podcast today, 0:03:08.360 --> 0:03:10.640 we'll be talking about a weird thing that's in the 0:03:10.680 --> 0:03:14.400 sky that astronomers have known about for hundreds of years, 0:03:14.800 --> 0:03:18.080 but most people aren't aware of. All Right, well, what's 0:03:18.120 --> 0:03:22.480 this big secret? What if astronomer has been keeping from us? Well, 0:03:22.560 --> 0:03:25.359 unfortunately it's got a really strange and kind of an 0:03:25.440 --> 0:03:32.079 ugly name. Oh, it's not coagulated. It stars don't coagulate. 0:03:32.240 --> 0:03:34.720 I guess if a galaxy cuts itself right, a bunch 0:03:34.720 --> 0:03:36.760 of like stars could rush in to fill in the 0:03:36.800 --> 0:03:41.000 gap planetary platelets. No, Today on the program, we'll be 0:03:41.080 --> 0:03:53.320 asking the question what are globular clusters? You? Doesn't sound 0:03:53.360 --> 0:03:55.400 like something you want to order on the menu, does it? No? 0:03:56.960 --> 0:04:01.120 It sounds like the worst kids cereal? Ever, like, be 0:04:01.240 --> 0:04:07.160 sure to get globios for your globular clusters. I know, 0:04:07.280 --> 0:04:10.640 I imagine some like scoop of some very viscous kind 0:04:10.680 --> 0:04:13.760 of stuff. It's like jello mixed with gravy or something. 0:04:13.880 --> 0:04:16.960 Oh man, I don't I have a texture thing when 0:04:16.960 --> 0:04:19.880 it comes to food, Like I don't like cottage cheese 0:04:20.000 --> 0:04:25.440 or other like things, little chunks suspended within goo. So 0:04:25.640 --> 0:04:28.719 I don't know about this globular clusters thing. This does 0:04:28.760 --> 0:04:31.560 not sound good. Well, fortunately it was not designed as 0:04:31.560 --> 0:04:34.640 a menu item. It's an astrophysical object. It's something out 0:04:34.680 --> 0:04:37.479 there in our universe that might teach us something about 0:04:37.520 --> 0:04:40.760 how the galaxy was formed, and how old the universe is, 0:04:40.880 --> 0:04:43.560 and weird new kinds of stars, and so it's an 0:04:43.560 --> 0:04:46.839 opportunity to learn something. Unfortunately, we don't actually have to 0:04:46.880 --> 0:04:49.280 taste it. That's good, that's good, all right. I'm still 0:04:49.320 --> 0:04:51.839 with you then, But if you try to give me 0:04:51.880 --> 0:04:56.560 a spoon on one of these globular clusters, I am check. Please. 0:04:57.920 --> 0:05:03.320 So we asked what people think globular clusters are, and 0:05:03.400 --> 0:05:06.240 this is what people have to say. I don't know 0:05:06.560 --> 0:05:13.159 what a globular clusters. I think it might be something 0:05:13.200 --> 0:05:18.200 found in out space, but I don't actually I'm not 0:05:18.279 --> 0:05:21.000 sure entirely, but I think it's just some type of 0:05:21.040 --> 0:05:25.560 grouping of stars, assuming it's a term from cosmology. A 0:05:25.600 --> 0:05:30.320 cluster is a collection of stars, and globular means that 0:05:30.400 --> 0:05:34.560 it's round like a globe, and you'll as in molecule 0:05:34.960 --> 0:05:38.719 or module, suggests that it's small, so it's a small 0:05:38.839 --> 0:05:43.680 round a bunch of stars. This one is like a 0:05:44.760 --> 0:05:51.600 gathering of stars spherical. It's not a galaxy. It can 0:05:51.640 --> 0:05:56.440 be within a galaxy, but it may look like a galaxy, 0:05:56.520 --> 0:06:00.719 like a spherical galaxy. I've heard the phrase globular or cluster. 0:06:01.480 --> 0:06:04.279 I'm not sure what it means. I thought that it 0:06:04.360 --> 0:06:09.640 had something to do with a group of stars, maybe 0:06:09.720 --> 0:06:13.680 that are clustered together in a spherical shape. This is 0:06:13.880 --> 0:06:20.200 a gigantic group of stars sit outside and I think 0:06:20.240 --> 0:06:23.320 maybe even all of it the galaxies. This has something 0:06:23.360 --> 0:06:26.360 to do with a group of stars, maybe that they 0:06:26.400 --> 0:06:31.520 all formed from the same nebula or um other event. 0:06:31.920 --> 0:06:36.000 Thanks to everybody who volunteered to speculate baselessly without getting 0:06:36.040 --> 0:06:39.040 to do any research or googling. If you'd like to 0:06:39.080 --> 0:06:42.160 participate for a future episode, please write to me two 0:06:42.320 --> 0:06:46.200 questions at Daniel and Jorge dot com. I think it's interesting, 0:06:46.279 --> 0:06:49.839 so most of the answers more along the same lines 0:06:49.960 --> 0:06:54.760 like this is probably a big cluster of stars or 0:06:54.880 --> 0:06:59.359 some kind of space junk, some kind of space junk. 0:06:59.640 --> 0:07:01.480 But then no clue in there that it's a cluster 0:07:01.560 --> 0:07:04.240 of stars, right, it could have been a cluster of anything, 0:07:04.360 --> 0:07:08.360 you know, jello or gravy or breakfast cereal or whatever. 0:07:08.640 --> 0:07:11.400 I think when people think about space, you think of 0:07:11.440 --> 0:07:15.520 it mostly stars. Right, you look out into space. What 0:07:15.640 --> 0:07:18.760 do you see? You see stars. All the other stuff 0:07:18.800 --> 0:07:21.520 that is out there is either hard to see or 0:07:21.720 --> 0:07:26.200 isn't really perceivable. Yeah, but you hear some people speculating 0:07:26.240 --> 0:07:29.760 like maybe it's a cluster of galaxies or a cluster 0:07:29.800 --> 0:07:32.880 of galaxy clusters or something like that, because there's this 0:07:32.960 --> 0:07:37.320 fascinating sort of hierarchy of structure out there in space. Right, 0:07:37.360 --> 0:07:40.560 It's not like they're just stars everywhere. Things are sort 0:07:40.560 --> 0:07:43.320 of grouped together into galaxies, and those galaxies are grouped 0:07:43.360 --> 0:07:46.200 together into clusters of galaxies, and so there's like this 0:07:46.400 --> 0:07:49.800 really fascinating sort of hierarchy of structure is getting bigger 0:07:49.800 --> 0:07:51.880 and bigger and bigger. And so I guess the question 0:07:51.880 --> 0:07:54.120 then is, you know, like what are globular clusters a 0:07:54.120 --> 0:07:58.080 cluster of Yes, what kind of pyramid scheme is a 0:07:58.080 --> 0:08:04.080 globular cluster. Who's the downstream and who's the upstream? Who's 0:08:04.120 --> 0:08:08.200 really making money off globular clusters? Right? Who's behind big 0:08:08.240 --> 0:08:13.200 globular taking globular clusters to the moon. So the answer 0:08:13.320 --> 0:08:17.600 is that globular clusters are clusters of stars. And to me, 0:08:17.720 --> 0:08:21.120 the fascinating thing is that there's something in between, sort 0:08:21.120 --> 0:08:24.560 of like our Solar system and the galaxy. Do you 0:08:24.600 --> 0:08:28.040 think about like our cosmic address. We're here on Earth, 0:08:28.080 --> 0:08:30.520 we're zooming around our star, and then we think that 0:08:30.560 --> 0:08:33.440 our star is just like one of many stars of 0:08:33.640 --> 0:08:37.320 hundreds of billions of stars in the galaxy. But it 0:08:37.360 --> 0:08:40.080 turns out that there's an intermediate step there. It's not 0:08:40.200 --> 0:08:43.040 like just Solar system and then galaxy. You could have 0:08:43.240 --> 0:08:48.920 organizations of solar systems. So when you zoom out, like 0:08:49.240 --> 0:08:52.120 when you see these videos of here you are on 0:08:52.240 --> 0:08:56.400 planet Earth. You're tiny and significant, flee like creature on 0:08:56.440 --> 0:09:00.160 this huge planet. Then you zoom out to Solar system 0:09:00.200 --> 0:09:04.760 and usually goes right from Solar system to galaxy. But no, 0:09:05.240 --> 0:09:08.640 there's an extra step. You're saying, there's an extra step. Yeah, 0:09:08.960 --> 0:09:13.400 some stars, some special stars grouped together into these big 0:09:13.520 --> 0:09:18.120 clusters of stars called globular clusters. Now, not every star 0:09:18.520 --> 0:09:20.840 is in one of these things. It's not like, you know, 0:09:20.920 --> 0:09:23.400 another layer in this hierarchy is sort of like a 0:09:23.480 --> 0:09:26.440 special clumping. Like most stars are just sort of like 0:09:26.640 --> 0:09:28.760 out there on their own, sort of like out in 0:09:28.800 --> 0:09:31.439 the middle of the countryside by themselves. But it turns 0:09:31.440 --> 0:09:34.200 out that there are these like urban areas where stars 0:09:34.280 --> 0:09:38.920 clump together really densely and make these things called globular clusters. 0:09:39.080 --> 0:09:42.440 And they're like a fascinating relic of the ancient formation 0:09:42.480 --> 0:09:44.320 of the galaxy and can tell us a lot about 0:09:44.400 --> 0:09:46.520 how things work out there. So it's like you've got 0:09:46.520 --> 0:09:49.400 a bowl of granola, and yet you have your little 0:09:49.520 --> 0:09:52.000 oatmeal pieces in there, but then you have the big 0:09:52.080 --> 0:09:57.360 clusters of oatmeal too. Those are the best ones. Those 0:09:57.360 --> 0:09:59.680 are the best ones. Those are nice. Yeah. I always 0:09:59.679 --> 0:10:01.520 fish those out first, and then I'm left with just 0:10:01.559 --> 0:10:04.120 sort of a bowl of sugary oatmeal and that's not great. 0:10:04.720 --> 0:10:07.160 But so that whole bowl is like the galaxy, but 0:10:07.320 --> 0:10:12.360 within that bowl you have the globular clusters of the 0:10:12.480 --> 0:10:16.280 nice crunch granola's. Yeah, exactly. The stars are not evenly 0:10:16.360 --> 0:10:19.320 distributed through the galaxy. I mean, the overall pattern is 0:10:19.360 --> 0:10:21.720 that there's more stars in the center of the galaxy 0:10:21.760 --> 0:10:24.120 with a gravity stronger, and then it's sort of peters 0:10:24.160 --> 0:10:28.080 out along the galactic disc. But inside there it's not smooth. 0:10:28.360 --> 0:10:31.200 There are these clumps where you get these big collections 0:10:31.200 --> 0:10:33.840 of stars. And we're not talking like, you know, five 0:10:34.000 --> 0:10:37.559 ten stars. We're talking like a few hundreds of thousands 0:10:37.679 --> 0:10:40.960 of stars. It's a big deal. Sounds like when they're 0:10:41.000 --> 0:10:43.560 making the galaxy that just didn't stir enough. That's what 0:10:43.600 --> 0:10:45.480 I learned about. Like when I'm trying to make polina, 0:10:45.800 --> 0:10:48.000 you know, it gets clumpy. You just didn't stir enough. 0:10:48.679 --> 0:10:52.880 Katie's globular polenda. That's not the foundation for your next 0:10:52.920 --> 0:10:55.839 food truck, right, And so these things have like a 0:10:55.880 --> 0:10:58.800 few hundred thousand stars in them, but they're not actually 0:10:58.840 --> 0:11:01.400 that big, right there only like ten to sometimes like 0:11:01.480 --> 0:11:04.800 three hundred light years wide. Okay, you say that's not 0:11:04.960 --> 0:11:09.000 that big. However, how long would it take me to 0:11:09.160 --> 0:11:12.080 drive from one end to the other of three hundred 0:11:12.120 --> 0:11:14.319 light years? Yeah, it would take you a while. I mean, 0:11:14.400 --> 0:11:17.800 even in your light speed polenta powered vehicle, it would 0:11:17.840 --> 0:11:20.800 take you three hundred years to go across three hundred 0:11:20.880 --> 0:11:24.200 light years obviously, and in a much slower, more reasonable 0:11:24.200 --> 0:11:26.440 ship it would take much much longer. But the reason 0:11:26.520 --> 0:11:28.679 I say that it's not that big is that there 0:11:28.679 --> 0:11:31.640 are so many stars in there. So would you end 0:11:31.720 --> 0:11:35.360 up with is stars in a very unusually dense collection 0:11:35.679 --> 0:11:38.200 like in our part of the galaxy in our neighborhood, 0:11:38.240 --> 0:11:40.959 there aren't that many stars, like the nearest stars more 0:11:40.960 --> 0:11:44.760 than four light years away, right, I mean, it seems 0:11:44.840 --> 0:11:48.880 like there would be conflict with stars being that close together, right, 0:11:49.040 --> 0:11:52.920 because I know every body in the universe has some 0:11:53.040 --> 0:11:57.400 kind of gravitational poll and stars are so big they 0:11:57.440 --> 0:12:00.200 seem like they would be acting on each other there, 0:12:00.200 --> 0:12:02.760 So it's it's odd that you would have them so 0:12:02.840 --> 0:12:06.239 close together. Yeah, And that's exactly what makes them fascinating 0:12:06.320 --> 0:12:09.120 because in these clusters we get to see stars doing 0:12:09.200 --> 0:12:12.200 something they don't normally do, which is like dance around 0:12:12.200 --> 0:12:14.640 each other and tug on each other and form new, 0:12:14.679 --> 0:12:17.280 weird kinds of stars. And we're gonna dig into all 0:12:17.280 --> 0:12:20.560 that crazy stuff that's happening inside the globular clusters in 0:12:20.600 --> 0:12:23.080 a minute. But here's some numbers for you, Like the 0:12:23.160 --> 0:12:26.320 density of stars in our neighborhood. Like around where we 0:12:26.360 --> 0:12:29.360 live in the galaxy is like one star per three 0:12:29.640 --> 0:12:33.240 hundred cubic light years, so that's pretty big area just 0:12:33.280 --> 0:12:35.760 to get one star. But inside one of these globular 0:12:35.760 --> 0:12:39.760 clusters there's like two stars per cubic light year, so 0:12:39.800 --> 0:12:43.160 it's like six hundred times denser than it is in 0:12:43.200 --> 0:12:45.559 our neighborhood. It's like going from the middle of nowhere 0:12:45.600 --> 0:12:49.320 to Manhattan. Really packed in there, like star deans. Yeah, 0:12:49.760 --> 0:12:52.440 they really are. Imagine what it would be like to 0:12:52.679 --> 0:12:56.120 live around a star in a globular cluster. You would 0:12:56.160 --> 0:12:59.400 have so many other like bright stars in the sky 0:12:59.480 --> 0:13:02.360 at night. The night itself might be a lot brighter 0:13:02.400 --> 0:13:04.240 than it is here. Yeah, it seems I would be 0:13:04.600 --> 0:13:07.959 as bright as daylight. You just have too many suns 0:13:08.000 --> 0:13:10.280 going on. Yeah, if you're near the center one of 0:13:10.320 --> 0:13:12.720 these things, I mean, the globular cluster itself is like 0:13:12.800 --> 0:13:16.080 twenty five thousand times brighter than the sun. These things 0:13:16.200 --> 0:13:18.400 are really bright. Some of them are up to like 0:13:18.559 --> 0:13:21.160 fifty times brighter than even that. You'd be in the 0:13:21.160 --> 0:13:23.920 middle of like a lot of light bulbs all the time. 0:13:24.160 --> 0:13:27.079 Maybe a pretty crazy experience. Well, I need to get 0:13:27.200 --> 0:13:30.840 some more high tech sunglasses. It seems like to be 0:13:30.880 --> 0:13:34.960 able to live here some of that those polarized shades. 0:13:35.160 --> 0:13:37.080 But before I do that, why don't we take a 0:13:37.200 --> 0:13:40.800 quick break and I will return with all new sunglasses. 0:13:52.480 --> 0:13:56.880 All right, I've got my super polarized super extra anti 0:13:56.920 --> 0:14:02.000 glare globular cluster sunglasses on. I can't see a thing indoors, 0:14:02.040 --> 0:14:06.000 but I think it'll help me see within the globular clusters. So, 0:14:06.000 --> 0:14:09.120 so what's going on around me? Yes, So these globular clusters. 0:14:09.160 --> 0:14:12.320 You have this big collection of stars all packed into 0:14:12.400 --> 0:14:15.760 one spot. And one of the amazing things is that 0:14:15.880 --> 0:14:19.240 there aren't actually that many of these, Like the galaxy 0:14:19.400 --> 0:14:22.480 has hundreds of billions of stars, but they're only about 0:14:22.520 --> 0:14:25.520 a hundred and fifty, maybe up to two hundred of 0:14:25.560 --> 0:14:29.720 these globular clusters. Well why are they so rare? We 0:14:29.800 --> 0:14:32.000 don't really understand, and we can talk in a minute 0:14:32.000 --> 0:14:34.720 about how they form, but one clue is that they're 0:14:34.760 --> 0:14:39.200 also not always contained within the galactic disk. Like when 0:14:39.320 --> 0:14:42.040 you look at the galaxy sort of from outside, which 0:14:42.040 --> 0:14:44.000 we can't do what we can look at other galaxies. 0:14:44.040 --> 0:14:46.680 Of course, you see that it's mostly a flat swirl, 0:14:46.920 --> 0:14:49.280 and that's because of how the galaxy formed. Right, the 0:14:49.280 --> 0:14:52.400 galaxy form from a huge collection of gas and dust 0:14:52.440 --> 0:14:56.240 which collapsed into stars and then gravity took over and 0:14:56.320 --> 0:14:58.600 try to pull all those stars together, and that's why 0:14:58.640 --> 0:15:00.720 you have a galaxy. But it's my it's harder for 0:15:00.880 --> 0:15:04.320 gravity to pull along the galactic plane because that's how 0:15:04.360 --> 0:15:08.120 the galaxy is spinning. That's spinning keeps things from falling 0:15:08.160 --> 0:15:11.200 in only along that plane. Perpendicular to that plane, you 0:15:11.200 --> 0:15:13.840 can squish it flat like a pancake. Is it sort 0:15:13.840 --> 0:15:16.320 of like when you have a bicycle wheel, You have 0:15:16.640 --> 0:15:18.920 some torque there, so you have that kind of like 0:15:19.160 --> 0:15:24.160 inward energy of the galaxy spinning, So it's easier for 0:15:24.200 --> 0:15:26.520 it to be flat and spinning inward than it is 0:15:26.560 --> 0:15:30.840 to spin another direction. Yeah, exactly, if you spin a 0:15:30.840 --> 0:15:33.040 bicycle wheel, then it's harder for things to sort of 0:15:33.040 --> 0:15:35.520 fall in towards the center. Or if you think, for example, 0:15:35.560 --> 0:15:37.720 about like a merry go round with ping pong balls 0:15:37.720 --> 0:15:40.160 on it, right you spin that thing, the ping pong 0:15:40.200 --> 0:15:42.000 balls are all going to fly out, but they're gonna 0:15:42.040 --> 0:15:44.880 fly out along that plane. So that's what we call 0:15:45.280 --> 0:15:48.800 rotation supported. The rotation of the galaxy is keeping things 0:15:48.840 --> 0:15:52.000 from falling inwards, but again only along that plane. There's 0:15:52.080 --> 0:15:55.240 nothing that prevents the collapse perpendicular to that plane, which 0:15:55.280 --> 0:15:57.680 is what makes it flat like a disk. Well, next 0:15:57.720 --> 0:15:59.560 time I go on a Merry go around, I'm bringing 0:15:59.600 --> 0:16:02.440 a bunch of ping pong balls with me. This is 0:16:02.440 --> 0:16:05.920 probably why I'm banned for most Merry go round. Maybe 0:16:05.920 --> 0:16:07.760 also because you try to eat polenta and you end 0:16:07.880 --> 0:16:12.840 up throwing up globular chunks of polenta. Oh man, When 0:16:12.880 --> 0:16:15.640 I was a kid, I was a throw upper kid, 0:16:15.720 --> 0:16:18.520 and I had some moments. I had my moments, especially 0:16:18.600 --> 0:16:22.080 on the teacups. All right, well, we don't want to 0:16:22.080 --> 0:16:24.760 revisit that with too much to jail. But the interesting 0:16:24.800 --> 0:16:27.760 thing about these globular clusters is that they don't tend 0:16:27.760 --> 0:16:31.160 to be along this galactic disk. Like if you looked 0:16:31.160 --> 0:16:33.240 at a diagram of where they are, there's some of 0:16:33.240 --> 0:16:35.040 them that are in the disc, but they're also sort 0:16:35.040 --> 0:16:39.280 of just spherically distributed around the galaxy. It's almost like 0:16:39.560 --> 0:16:42.600 they come from a time when the galaxy was a 0:16:42.640 --> 0:16:46.600 big puffy sphere before collapsed. Right, And I'm looking at 0:16:46.680 --> 0:16:49.120 this image and what it looks like to me is 0:16:49.200 --> 0:16:52.440 like a side view of like a fried egg, and 0:16:52.480 --> 0:16:56.400 then above it, like scattered around it are little little 0:16:56.480 --> 0:17:01.440 yellow dots like you just spilled a bunch of salts around. Man, 0:17:01.520 --> 0:17:04.520 I keep coming back to food on this globular cluster episode, 0:17:04.560 --> 0:17:08.840 don't I. We've gotta stop recording these at lunch. Whoever 0:17:08.880 --> 0:17:12.080 thought globular clusters would make you hungry? Like, I gotta 0:17:12.240 --> 0:17:16.080 bring a positive spin to it. So they're falling outside 0:17:16.240 --> 0:17:20.840 of that disk. You're saying that maybe these had formed 0:17:21.119 --> 0:17:24.760 back when the galaxy was sort of this big puppy cloud, 0:17:25.480 --> 0:17:30.080 and even as it flattened down to the disk, they 0:17:30.080 --> 0:17:33.600 didn't come with the rest of the game. Yeah, precisely. 0:17:33.840 --> 0:17:37.000 And there's a bigger topic here of the galaxies halo. 0:17:37.320 --> 0:17:40.960 Remember that galaxies are not mostly stars. Most of what's 0:17:41.000 --> 0:17:44.000 in the galaxies actually dark matter. And if you look 0:17:44.000 --> 0:17:46.879 at where the dark matter is in a galaxy, it 0:17:46.960 --> 0:17:50.240 doesn't collapse the same way that normal matter does. It 0:17:50.320 --> 0:17:53.880 tends to spin. And so this is big spherical halo 0:17:54.000 --> 0:17:57.119 of dark matter around the galaxy. And that's the original 0:17:57.160 --> 0:18:00.040 thing that's sort of like clustered together the gas of 0:18:00.160 --> 0:18:03.440 dust that made our galaxy. And so these globular clusters 0:18:03.440 --> 0:18:06.640 they're sort of in this larger galactic halo, but they 0:18:06.680 --> 0:18:09.960 haven't collapsed down into this disk, and we don't know 0:18:10.080 --> 0:18:13.800 exactly why. It could be that they didn't form with 0:18:13.840 --> 0:18:17.080 the original galaxy but are like their own little mini 0:18:17.160 --> 0:18:20.560 galaxies that were then captured later and that's why they're 0:18:20.640 --> 0:18:23.480 orbiting around. Or it could be that they formed with 0:18:23.520 --> 0:18:26.360 the rest of the galaxy but then didn't collapse as 0:18:26.400 --> 0:18:29.240 well as the gas and dust because they don't collide 0:18:29.280 --> 0:18:31.320 with each other as much as the gas clouds do, 0:18:31.720 --> 0:18:35.159 so they avoided like losing all that angular momentum and 0:18:35.200 --> 0:18:38.240 they can keep spinning around out there in crazy orbits. 0:18:38.600 --> 0:18:40.960 Or maybe they just prefer to hang out out in 0:18:41.000 --> 0:18:44.119 the dark matter halo. Dark Matter Halo is a really 0:18:44.160 --> 0:18:47.800 good metal band name, I've got to say. Yeah, So 0:18:47.880 --> 0:18:50.679 that that's interesting. We can't see dark matter, but it 0:18:50.800 --> 0:18:56.120 is there, and so it's like this halo around the 0:18:56.160 --> 0:19:00.520 galactic disc. And suspended in that halo are these little 0:19:00.560 --> 0:19:05.560 dots and those are each a globular cluster, yeah, exactly, 0:19:05.600 --> 0:19:08.240 and some of them happen to fall within the galactic disc, 0:19:08.359 --> 0:19:11.080 but most of them do not. You know. The closest 0:19:11.119 --> 0:19:14.800 one to us is about sixteen thousand light years away. 0:19:15.040 --> 0:19:17.679 It's called the Omega cluster. But there's a bunch of 0:19:17.680 --> 0:19:21.240 these things, and what's really interesting is how they form. 0:19:21.320 --> 0:19:23.600 And as you said earlier, they might tell us something 0:19:23.720 --> 0:19:27.040 about the age of the Milky Way, because we think 0:19:27.080 --> 0:19:30.399 that they formed very very early on as the galaxy 0:19:30.520 --> 0:19:32.639 was forming. You know, the way these things happened is 0:19:32.640 --> 0:19:34.760 that you get, you know, a big clump of gas 0:19:34.800 --> 0:19:36.439 and dust, and it may have been that you just 0:19:36.480 --> 0:19:39.160 got sort of like an over dense pocket of gas 0:19:39.200 --> 0:19:41.240 and dust something which was like, you know, got more 0:19:41.280 --> 0:19:43.480 of a serbing of globs than the rest of the 0:19:43.480 --> 0:19:46.199 stuff around it, and it collapsed all at once and 0:19:46.240 --> 0:19:50.200 made a big bunch of stars. And so these globular clusters, 0:19:50.359 --> 0:19:51.879 when we look at them, we see a bunch of 0:19:51.920 --> 0:19:55.040 stars and no gas and dust in between, which means 0:19:55.119 --> 0:19:57.880 like they're not forming any new stars. So there's sort 0:19:57.880 --> 0:20:01.080 of like a little time capsule from very very early 0:20:01.119 --> 0:20:03.920 formation of the galaxy. So when you say it happens 0:20:03.960 --> 0:20:07.520 at the same time, what are we talking about, Like 0:20:07.560 --> 0:20:10.520 it all happens within sort of one of our human 0:20:10.640 --> 0:20:13.840 years or is it literally like within a few moments? 0:20:14.080 --> 0:20:17.240 Oh wow, now we're talking like in within millions of years. Okay, 0:20:17.920 --> 0:20:22.160 star times. We humans are sort of like dogs. We 0:20:22.200 --> 0:20:25.520 live in dog years and they live in star years. Yeah, 0:20:25.560 --> 0:20:28.119 they live in star years. We think that these globular 0:20:28.119 --> 0:20:33.639 clusters are about eleven to thirteen billion years old. I remember, 0:20:33.680 --> 0:20:37.360 the whole universe is only just under fourteen billion years old, 0:20:37.400 --> 0:20:40.240 which makes these things some of the oldest things in 0:20:40.280 --> 0:20:42.480 the galaxy, which is how we can sort of use 0:20:42.520 --> 0:20:45.080 them to help understand the age of the galaxy. And 0:20:45.160 --> 0:20:48.080 also when we see them in other galaxies like Andromeda, 0:20:48.320 --> 0:20:51.040 we can use them to help understand the age of Andromeda. 0:20:51.640 --> 0:20:53.560 And one way we can do that is because we 0:20:53.640 --> 0:20:56.360 think that all the stars in there were formed at 0:20:56.400 --> 0:20:59.040 the same time, which means they all sort of like 0:20:59.320 --> 0:21:01.920 start their own clock at the same time. And you 0:21:01.920 --> 0:21:04.320 remember that the life cycle of a star is that 0:21:04.400 --> 0:21:06.680 it burns for a while and then ones is done 0:21:06.680 --> 0:21:09.000 with all of its fuel. It either goes nova or 0:21:09.000 --> 0:21:12.359 collapses or something. But the lifespan there depends on the 0:21:12.400 --> 0:21:15.400 original size of the star. The more mass it has, 0:21:15.680 --> 0:21:18.879 the faster it burns. The smaller it is, the longer 0:21:18.920 --> 0:21:21.119 it burns. So we can tell something about the age 0:21:21.119 --> 0:21:23.240 of these things just by looking at like the distribution 0:21:23.280 --> 0:21:25.880 of stars, which ones have burned out already, which ones 0:21:25.920 --> 0:21:28.239 have not. But the fact that they've all formed at 0:21:28.240 --> 0:21:30.439 the same time makes it very easy to sort of 0:21:30.480 --> 0:21:33.760 like reverse that back and understand how this thing started. 0:21:33.920 --> 0:21:37.639 It's nice from a scientific perspective because you control for 0:21:37.720 --> 0:21:40.800 the factor of age. You've got like these little test 0:21:40.800 --> 0:21:44.240 tubes out there that you can look at as physicists. Yeah, exactly. 0:21:44.600 --> 0:21:47.840 And they're also an interesting collection of stars because they're 0:21:47.880 --> 0:21:51.440 not stars like our sun. Our universe has gone through 0:21:51.480 --> 0:21:54.160 a few cycles of making stars. You know, the very 0:21:54.160 --> 0:21:57.479 early universe, you had hydrogen helium and that fell together 0:21:57.600 --> 0:22:01.240 to make the original first generation of ours, which weirdly 0:22:01.280 --> 0:22:06.080 astronomers called population three stars. And those were really big 0:22:06.119 --> 0:22:08.320 and didn't burn for very long, but they made some 0:22:08.440 --> 0:22:11.480 like helium and some heavier stuff and things that astronomers 0:22:11.520 --> 0:22:14.080 called metals. And then when they blew up and they 0:22:14.119 --> 0:22:16.320 spread their stuff through the galaxy, there was a second 0:22:16.320 --> 0:22:20.160 generation of stars which formed, and those are called population 0:22:20.240 --> 0:22:23.480 two stars. Some of those burned up and collapsed and 0:22:23.800 --> 0:22:26.880 spread their stuff through the galaxy to make population three stars, 0:22:26.920 --> 0:22:29.720 which is like our sun is a population three stars. 0:22:30.359 --> 0:22:33.640 But these stars in the globular clusters are only population 0:22:33.680 --> 0:22:36.800 two stars. There weren't any of the population one stars, 0:22:36.800 --> 0:22:40.160 the ones like our sun when these things formed. So 0:22:40.359 --> 0:22:42.560 you may have explained this. It counts down. It goes 0:22:42.640 --> 0:22:46.800 pop three pop to pop one is the newest or yeah, exactly, 0:22:46.800 --> 0:22:49.240 which I guess makes the next generation of stars are 0:22:49.240 --> 0:22:52.080 gonna be what pop zero and then pop negative one? 0:22:52.240 --> 0:22:56.879 Like nobody really thought this through pop zoomers. And the 0:22:56.920 --> 0:23:00.440 other fun thing about these is that that very low metallicity, 0:23:00.560 --> 0:23:04.080 Like there's basically just helium and hydrogen because that's what 0:23:04.200 --> 0:23:07.560 was around after the first generation of stars, the population 0:23:07.640 --> 0:23:10.720 three stars. You know, astronomers have this weird naming system 0:23:10.760 --> 0:23:13.480