Galaxy Shapes in the attic
TRANSCRIPT
Moiya McTier 0:27
Hello, everyone, and welcome to Pale Blue Pod, the weekly astronomy podcast that helps you feel closer to space. I am just one of your hosts. My name is Dr. Moiya McTier. I'm an astronomer and a folklorist, and I'm joined by–
Corinne Caputo 0:40
Corinne Caputo, a writer and comedian and all around happy to be here kind of person. Lovely.
Moiya McTier 0:48
And Corinne, where are we recording from today?
Corinne Caputo 0:51
Today, we are in my reading room, which is really just like the attic with warm blankets. And it has like a window that overlooks like a cool tree. But the wind still comes in and it's in fall, it's the only room you want to be in. Yeah,
Moiya McTier 1:07
it's the perfect temperature. We can still see the outside and the gorgeous colors on the trees. Yeah, this is a nice cozy spot. Yeah.
Corinne Caputo 1:15
And that's the only place I want to learn about something big and scary. This is a Halloween podcast.
Moiya McTier 1:25
My mission is to help you feel less scared of big spacey things. So hopefully, by the end of this episode, you you won't be as scared of today's topic, which is galaxies. That's a really big topic to cover in just one episode. So more specifically, we are covering my favorite galaxies, and what galaxies are made of how do we know that we're in a galaxy in the first place? And once we learned that, how did astronomers start classifying these galaxies?
Corinne Caputo 2:00
Yeah, how do we know where anything you know?
Moiya McTier 2:04
I mean, honestly, most days I wake up and I'm like, How can I trust anything that I see or hear or sense or know at all? Like, how do I know that anything is real?
Corinne Caputo 2:14
That's when you just have to say, I don't want to know, that's when you turn your back on the question. And you say, it might be better to not know.
Moiya McTier 2:21
Yeah, honestly, sometimes you have to ignore the question of like, where are we? Or how did we get here, and you just have to go forward with your perception. Like, doesn't matter how I got here, I'm here. Now, what do I say? What do I want to do? That's kind of how I feel about space. Like, there's so much that we don't understand about the origins or the advanced physical laws underpinning our entire reality. There's a lot that we do know. Yeah. And I think that, especially for people who maybe get intimidated by the vastness of space by the scales of things, if you can find it in yourself to take a breath, and to rein in that overwhelm feeling and just start from what you can see in front of you now. Yeah, I think that that might help some people. Yeah.
Corinne Caputo 3:13
When I think about how big spaces and all the answers we don't have, I'm just like, Thank God, I'm not in charge. Thank God, it is not on me to figure it out.
Moiya McTier 3:23
Yeah, that's why I left research. I was like, I am not responsible enough to be adding never be responsible for this. Adding to the collective knowledge of humanity, like I'm not prepared. Let me just build fun worlds on my own. Yeah. So I understand this impulse to be very anxious. Yeah,
Corinne Caputo 3:43
I mean, Galaxy specific. Well, I can start off by saying, I was on the beach in Maine, one summer night, and I saw, like, part of the Milky Way, which blew my mind I like did not know you could see it with a human. I think I'd only seen pictures in you know, like, textbooks or online, things like that.
Moiya McTier 4:03
Right? Artists ideas. Those aren't like photos. Yes,
Corinne Caputo 4:07
exactly. And they're like colored and I had no idea you could see it on like a really clear night in a place with no light pollution. Like, I grew up in New York City. So it was like, I'm not here to see stars
Moiya McTier 4:20
like, right. You can see like, maybe five Yeah, exactly.
Corinne Caputo 4:23
If we're lucky. We can see the moon on a good night. So yeah, the first time I saw it, it was like shocking to me. It totally blew my mind. I felt so tiny. And not like insignificant, but just like totally. I was like relieved of so much anxiety or was like Oh, actually, I don't need to sweat the small stuff.
Moiya McTier 4:40
I love that for you.
Corinne Caputo 4:42
It did help me a lot. I mean, it didn't last. The anxiety came right back in the morning. But that night on the beach,
Moiya McTier 4:49
for that brief moment of reprieve. I was my best self
Corinne Caputo 4:53
that night. Yeah.
Moiya McTier 4:56
Yeah, I understand that urge to feel very small and like scared of that smallness, when you fronted with the size of space for the first time, I noticed the Milky Way and saw it in most of its glory. For the first time. A few years ago in Chile, I was on top of a mountain on an observatory trip, touring different telescopes and observatories around Chile. And we were in the super dark spot. And when everyone turned off their lights at like, two in the morning, we were all standing outside, and I saw my shadow cast by the light of the Milky Way. That's how it was. Yeah, it was like a very surreal moment almost of realizing that these photons, these particles of light from stars, like 1000s of light years away, yeah, they're traveling this vast distance through space only to be stopped from hitting the ground. My my stupid little human body like,
Corinne Caputo 5:58
so crazy. I did not think that was possible.
Moiya McTier 6:01
Yeah, just thinking of the different ways that we interact with space already. All the time, I think is helpful. When you're trying to get to know space.
Corinne Caputo 6:13
Yeah. Yeah, I think again, it it's like you don't feel bad. You just kind of feel part of it. Like, oh, I think I think what I was feeling was like my ego coming up against the scale of the universe, where you're like, oh, wait, we're not important in that very kind of dictionary definition of important. It was great. Good. Yes, I
Moiya McTier 6:36
love I love that feeling. So galaxies can give us that feeling. Seeing the Milky Way can give us that feeling. Although I will say that, like you see the Milky Way every day. If you if you go outside, and you see a mountain, if you go outside, and you feel the warmth of the sun on your skin. If you go outside, and you smell the salty brine of an ocean, all of that shit is the Milky Way. Like you. You are observing the milky way all the time. But to have that visceral experience of seeing the stars in the night sky. super valuable. Yeah. But yeah, how? How do we know what that stuff is?
Corinne Caputo 7:14
Yeah, I think that's what I was so shocked by I think I was like, Oh, if you're in it, how can you be seeing it? How do you know? How do you know?
Moiya McTier 7:22
How do you know? Let's answer that question for you. Okay, yes,
Corinne Caputo 7:26
I'm dying to know. Well, first,
Moiya McTier 7:28
I think we should talk about what galaxies are made of like now that we know we're in a galaxy and that there are a bunch of others out there. What do we know about them? What is the definition of a galaxy?
Corinne Caputo 7:39
I'm realizing that I don't know. I'm my brain is going to the definition of like a solar system. So I want to say it's like that, but scaled
Moiya McTier 7:47
up? What Yeah, what does that mean to you? If someone was like, what's the galaxy?
Corinne Caputo 7:51
Yeah. Is there some kind of center thing? Is there some kind of something in the center that we're like dancing around? Maybe? Galaxy is like a series of
Moiya McTier 8:03
solar systems? Yeah. Pretty much. All right. So you are very close. A galaxy is a collection of stars, which themselves can be the centers of their own stellar systems. But in galaxies, you also have a lot of gas, that gas can get turned into stars, you have a lot of dust left over from various interactions and events throughout the history of space. And very importantly, but very invisibly, we have dark matter. Dark matter is actually we don't know what it is. We have observed it out in space, we can see the effect it has on stuff in and around it. But the cool thing about dark matter is that it does not interact with light, light, just like does not care about dark matter. They don't realize that each other exist. So you can't see dark matter. You can only study how it interacts gravitationally with other things.
Corinne Caputo 9:05
That's so cool. And weird. Yeah,
Moiya McTier 9:09
and dark matter is 80% of all of the matter in the universe, we think so it makes up most of the matter. Most of the stuff that has gravity, but we don't know what it is. And it's kind of embarrassing.
Corinne Caputo 9:26
Oh my god, but it's so it's not like is it something that you can touch?
Moiya McTier 9:31
Yeah, because it does interact with gravity, like a physical form. If you had a giant hand, you could go out there and feel dark matter, but you cannot see it. That
Corinne Caputo 9:44
is so weird.
Moiya McTier 9:47
And that that's the definition of a galaxy. It's a very loosey goosey definition. Yeah, it's all of this stuff bound together by gravity, which is confusing to Do us humans who love categorizing things and love putting stuff in boxes, because a galaxy can come in a lot of different forms, as you can have collections of gas, dust, dark matter and stars in different shapes, and different like distributions of stuff. So we have, we've seen a bunch of different types of galaxies. And that's very exciting. How recently Do you think Corinne that we learned? We are one galaxy among many?
Corinne Caputo 10:28
Oh, good question. Um, I would say probably as long as we've had the Hubble telescope, maybe the
Moiya McTier 10:36
Hubble telescope launched like 20 years ago in 1995. Oh,
Corinne Caputo 10:40
my God in my head that launched when my great great grandfather was a baby boy.
Moiya McTier 10:47
Your great great grandfather, who from the previous episode knew nothing about Neptune.
Corinne Caputo 10:52
He never met Neptune. But he saw the telescope, but he knew we were gonna galaxy. Yeah, I would say 100 200 years.
Moiya McTier 11:02
Your first instinct was better, basically, exactly. 100 years. Really? Yes. So this was a topic of great debate in the early 1900s. So great that the National Academy of Sciences in April of 1920 invited two astronomers to participate in what they called the Great Debate. This debate was between Harlow Shapley and Hubbard Curtis, Harlow Shapley believed that the universe was all one big galaxy that the Milky Way was huge that the sun was not at the center of it, and that there wasn't anything outside the Milky Way. hepper Curtis, on the other hand, believed that there were many, quote unquote, island universes and that the Milky Way was just one of them. But he believed that the Milky Way was pretty small and that the sun was in the center. That debate did not have a satisfying ending,
Corinne Caputo 11:58
I was gonna say, Aren't neither of those things true? Right? Neither
Moiya McTier 12:01
of those things is true. There's like kernels of truth in each of them. And if you combine their hypotheses, then you get at the truth, but neither one was right. So they left that debate, not knowing the answer. And then three years later, this young astronomer Edwin Hubble started looking at a specific type of star called a Cepheid variable star in the Andromeda Nebula. That's what they called it back then, to measure distances to that Nebula, and Hubble realized that the most distant Cepheid variable stars in the Milky Way, were much closer to us than the Cepheid variable stars in the Andromeda Nebula. So he realized that there there's stuff outside the Milky Way. So there must be other Milky Way type things other galaxies, other island universes.
Corinne Caputo 12:54
Mm hmm. I love the term Island University too. And it feels like that I think in photos too, or like when you think of space, like in like a 3d concept, which is like blew my mind when I feel like when I first grasped that is like a kid. It does feel like islands floating and like this. I guess they're floating in dark matter.
Moiya McTier 13:13
Yes. That brings me that brings me to a very important point. Like, I talked about what galaxies are made of, but didn't talk about like the shapes of them. Because there are so many different shapes. Almost every galaxy that we have found, has like the the bright stuff, like the stars and the gas and the dust, the stuff that interacts with light. And then surrounding that is a big dark matter Halo. So yeah, we do think that galaxies float in these clouds of dark matter. But that is different than like the cosmic voids in between huge galaxy clusters. They're just floating through through the void of space, which is different than floating through dark matter. Wow,
Corinne Caputo 14:01
spooky, spooky, cozy way.
Moiya McTier 14:05
Yeah, I mean, there is something very cozy about having your own space to yourself. Like getting to move around and interact with other island universes, but still having your own your own space. Yeah.
Corinne Caputo 14:21
Everyone needs that everyone needs a large apartment, or a house. I guess I'm not living in a brain work for and you just need to stretch out get your own room. Yeah, exactly.
Moiya McTier 14:34
And some galaxies are more isolated than others. Most galaxies exist in little local clusters of galaxies that we call galaxy clusters. And then those clusters can actually gather into super clusters. And if you zoom out even further, and you start to see the really large scale structure of the universe, all of these clusters and superclusters gather together in long filaments in long strings that look kind of like a web when you zoom out. So we talk about the Cosmic Web. With these, these filaments of matter of all the galaxies collecting in these strings, and then in between those strings are huge voids of basically nothing.
Corinne Caputo 15:21
Whoa, nothing is so weird to imagine. Yeah, wait, so do they cut so when they are like kind of near each other? What's happening in that moment?
Moiya McTier 15:34
Great question. galaxies merge and interact like all the time, especially in dense clusters of galaxies. You'll see galaxies merging our own Milky Way galaxy has in the past merged with other smaller galaxies, they like each other. Basically, they absorb each other's gas and dust, their black holes will collide and grow with each other. But in about 5 billion years, the Milky Way will have its first major merger with another galaxy,
Corinne Caputo 16:10
who's merging, like via comm. And
Moiya McTier 16:15
now you know, there's no antitrust laws in space telling big galaxies that they can or cannot merge together. You know, in 5 billion years, the Milky Way and Andromeda will merge together. These are to spiral galaxies. And I'll talk in a bit about what what a spiral means. But they will eventually merge together, all of their gas will swirl together creating this cascade of new star formation, the stars themselves probably won't collide, because everything is so spread apart in space, but you'll still get a lot new stars and the orbits of things will get jumbled, so that instead of orbiting in a nice circular pattern through the spiral disc, it becomes a chaotic spherical jumble of stars moving in any direction they want. Well,
Corinne Caputo 17:03
that's chaos. That's not the place I'm gonna go.
Moiya McTier 17:06
We will be long dead by then. Yeah, our son actually will will not survive that long in its current state.
Corinne Caputo 17:14
I heard our son as an S O N. Like our son, Corinne and I, we have a son Do you have a son together and he will live to see that.
Moiya McTier 17:25
Little son son's name's Michael and he's lived to see Andromeda and
Corinne Caputo 17:29
the Milky Way. Same way my grandfather saw simultaneously did
Moiya McTier 17:33
not know about Neptune, but absolutely knew about island universes.
Corinne Caputo 17:38
That's just how men work. Simultaneously like
Moiya McTier 17:41
knowing things they shouldn't but also not knowing things. They definitely should
Corinne Caputo 17:45
a different plane of existence entirely.
Moiya McTier 17:49
Oh, what it must be like to be a man what it must be like, I wonder that like, at least once a week,
Corinne Caputo 17:56
we solved it. Well, we figured it out. And I'm boy my wandering that a lot. But now I get it. They must be very confused all
Moiya McTier 18:04
the time. Like, not knowing what they do and don't know, it's gotta be a confusing time. Couldn't make me do it. I would take money to be a man. I
Corinne Caputo 18:16
would publish a book under a man's name and see if it doesn't make a difference. But I would try.
Moiya McTier 18:22
Well, I just published a book that can be my control. And then the next time I'll publish under a dude's name. Yeah, you
Corinne Caputo 18:28
have to do a variable.
This is science just endemic tear.
Oh,
Moiya McTier 18:34
yeah, that's no one will trace that back to me. Same author
Corinne Caputo 18:38
photo just with a mustache.
Moiya McTier 18:42
I bet I look hot with a mustache and nice handlebar I'm
Corinne Caputo 18:46
sure you do. I've seen I've been on like the Tick Tock filter of like the beard and the mustache. And I'm like, That's the hot person. Oh, yeah.
Moiya McTier 18:54
When you when I use that filter, and it's like the one with tattoos and scars and like damn, oh my god, I love it.
Corinne Caputo 19:00
I'm like, wow, I should get that
Moiya McTier 19:03
was like I didn't think I was my type. But with better I am. We
Corinne Caputo 19:08
are all our own types in the end.
Moiya McTier 19:12
Speaking of types, would you like to know my favorite galaxies? Yes. When I say favorite galaxies, really? I mean, would you like to know the collection of five galaxies that I found easily on the interwebs? That also I thought effectively demonstrated the various types of galaxies that are possible. Yes,
Corinne Caputo 19:35
that is what favorite usually means. When I was a kid, the word favorite had so much pressure. It was like what's your favorite color? What's your favorite food? I feel like that was always the questions you were getting and like elementary school like projects. And it was like I have to pick one and I have to commit to this for the rest of my life.
Moiya McTier 19:54
Lots of pressure. What did you decide? What did you do? Well,
Corinne Caputo 19:57
I remember my favorite word was love. Not because I felt obsessed with that word, but just because I was like, well, that's probably an evergreen pic. Like, that'll always be a word we'll be using. I imagine. I love the strategy here. Yeah, there was a lot of creative strategy behind faking favorites.
Moiya McTier 20:22
That scene in Monty Python and the Holy Grail gave me a similar anxiety where I was, for a brief moment in my life terrified that if I was asked what my favorite color was, and I gave the wrong answer, like, I don't know what the wrong answer would be. But if something bad would happen, oh, yeah, you have to know. Oh,
Corinne Caputo 20:43
I know that fear. So specifically. Well, that is, I think that I would still have that overcome me. If someone asked today, just when you're grown up, nobody cares. Nobody's asking what your favorite color is. Anyone
Moiya McTier 20:55
know my favorite color is for screen for the record. That's my
Corinne Caputo 20:59
favorite color to wear.
Moiya McTier 21:01
Ooh,
Corinne Caputo 21:01
definitely my favorite color. were my favorite color. Right now I'm into like a really, like royal blue respect.
Moiya McTier 21:08
I don't remember what the actual word what the actual phrase was. But favorite, my favorite galaxies are number one, we have the tadpole galaxy. Oh, yeah. Picked in part because of its name. When I grew up, I had a little pond by my house, and I loved when the tadpoles would hatch every year, and I could see them swimming around with their little tails. So that's part of why I love this galaxy, but not the entire reason. So the tadpole galaxy is a bard spiral. It has a big bar across its center, and then the spiral arms come out from the ends of that bar. It's about 420 million light years away from us.
Corinne Caputo 21:53
Whoa, that sounds extremely far it really does look like a tadpole. We
Moiya McTier 22:00
have a lot of these galaxies that are named after what astronomers just think they look like. It does. If you look up pictures really look like a tadpole with a head and then it's long tail that gives the Galaxy its name is a stream of stars that extends like 280,000 light years. So it's pretty long. And it's thought to be left over from a merger with another galaxy, a much smaller galaxy about 100 million years ago. Wow. Eventually, that tail will disappear just like the tail on a tadpole. As the Galaxy continues to rotate. Stars will get pushed ahead or pulled behind. Eventually, that stream will break up and not be visible to us anymore. But that's that's going to take many 1000s of years to happen. That is the tadpole galaxy.
Corinne Caputo 22:51
Oh, it's so cute. I
Moiya McTier 22:52
love it. With this little bright, star forming region. Yeah, see the bright spots in it? If you look at the pictures, that's number one. This isn't in any sort of ranked order, by the way. Okay. Yeah. So that's yeah, I'll
Corinne Caputo 23:05
rank them. Yes. I'll put them in order.
Moiya McTier 23:10
Right. So in no particular order, a tadpole goes first. And then we have the Whirlpool galaxy, also called M 51. Now a lot of galaxies will have multiple names, they'll have the the nickname The the common name that astronomers give it like Whirlpool galaxy. And then they'll also have different names based on catalogs that the galaxies are in. Okay, so, M 51, means that this is the 51st object in the messy a catalogue of space objects. It was created by this guy named Charles messy a, who was a French astronomer who was going around looking at Nebula, these fuzzy patches in the sky, and just making a catalogue of them. And eventually, some of those nebulae turned out to be galaxies that we studied in further missions. So m 51. It also probably has other names out there based on other missions that have observed it, but it's a grand design spiral, which just means that it's like a beautiful kind of platonic ideal of a spiral is
Corinne Caputo 24:17
extremely gorgeous. I'm looking at it because I was going to say isn't, there are other galaxies with a shape like this. So I feel like Whirlpool is hard to use. It's hard to claim that because there's going to be multiple but this one seems like it really is the peak version of itself.
Moiya McTier 24:33
I know. It's like you ask a Renaissance painter to imagine a spiral galaxy and it gives you that like, perfectly symmetrical. Yeah, colors are nice. It's a beautiful spiral galaxy, about 30 million light years away so much closer to us than the tadpole galaxy. It is interacting with another galaxy that you can see at the end of its tail. Seeing that here yeah. Yeah, that other galaxy is called NGC 5195. And we use the Whirlpool galaxy because it has such a perfect spiral structure to understand more about the structure of galaxies and how it forms and how it can change or be maintained over time. Cool. Now, next up, we have the Sombrero galaxy.
Corinne Caputo 25:22
Oh, I had no idea. There was one called that. I'm dying to see a picture of this. Okay, I kind of see it.
Moiya McTier 25:34
Yeah, you kind of see it. It's nice
Corinne Caputo 25:36
when it's crazy looking at me. Okay,
Moiya McTier 25:39
so this is a peculiar galaxy. Like that's its actual classification. It also is about 30 million light years away, and is 50,000 light years across.
Corinne Caputo 25:49
This looks like a portal like this is absolutely some kind of hole to something else. Uh huh. Yeah,
Moiya McTier 25:55
it's weird looking like it's we saw that and astronomers were like, What is going on there? This is not how we expect galaxies to look at all
Corinne Caputo 26:05
is this just like the angle we're seeing? Is that what's going on? That's
Moiya McTier 26:10
part of it. So the the Sombrero galaxy is what we call edge on. There's edge on galaxies and there's face on galaxies face on galaxies are a lot easier to study because you can see all of it at once. edge on means that it's a lot harder to study because we we can only see like the edge of it, we can't see its face. So for those of you who aren't actively right now looking at pictures of the Sombrero galaxy, it's called that because it has this big bright nucleus in the center that's kind of like a spherical bulge. And then surrounding that is a disc that doesn't we think have spiral arms. But it has this huge dust lane this big, like dark, dusty patch that surrounds the entire galaxy. And that's where a lot of its molecular gas is that's where a lot of the galaxies cold hydrogen gas lives. So a lot of cold gas in this dust lane on the edge of the Sombrero galaxy. I'm
Corinne Caputo 27:09
on the NASA's like page for it the image and like the image is so such a large image that like you get the magnifying glass and I just got scared when it zoomed in. I was like, Whoa, it's so big.
Moiya McTier 27:22
Yeah, this is, this is a galaxy, you have a picture of an actual picture of a galaxy on your computer right now,
Corinne Caputo 27:29
this is freaking me out.
Moiya McTier 27:32
So that is the Sombrero galaxy. Next I had to wrap the ellipticals, I can't do a list of galaxies without naming sickness a this is one of the most well studied elliptical galaxies in the universe, it's about 600 million light years away. It has really bright emission in the radio part of the electromagnetic spectrum. So when you look at this galaxy in the visual range, like in the light wavelengths that we can see, it probably doesn't look that spectacular. But if you look in the radio wavelengths, it gets super bright. It's actually the second brightest radio source in the entire sky. Even though so far away. It has a supermassive black hole at its center that is a billion times more massive than our Sun, making it like 2000 times more massive than the black hole at the center of our galaxy. And if you look at this galaxy in the radio, you can see these big bubbles, these are jets coming out of the black hole at its center that clear out a lot of the gas and dust.
Corinne Caputo 28:42
That's what I was gonna say the pictures I'm looking up, it's like nothing. It's almost like a like a barbell or like a handle. Where it has these like heavy sides and nothing in the middle. Yeah,
Moiya McTier 28:53
and those bubbles extend out beyond like where the stars stop. And they're really, really big. Cygnus A is the galaxy that the aliens from the book and movie contact
Corinne Caputo 29:08
are from. That's really funny. So that's
Moiya McTier 29:11
Cygnus, a repping, the elliptical galaxies and then we have our little homie NGC 1052 hyphen, d f two,
Corinne Caputo 29:21
easy to say easy to remember, I love it.
Moiya McTier 29:26
This is an ultra diffuse galaxies. So it's the stars in it are very spread apart compared to other galaxies that we've studied. It's 60 million light years away. A has less than 1% the number of stars that the Milky Way has so quite tiny. But the really interesting thing about this galaxy think back to when I told you what a galaxy has to have. Yeah, stars, gas, dust dark matter. This galaxy has like less than one four hundredths of the amount of dark matter. It should have
Corinne Caputo 30:01
why that's scary where to go?
Moiya McTier 30:03
That's a great question. So we haven't been able to observe this directly with data. But based on some simulations, we think that the dark matter can get stripped away when different galaxies are interacting with each other. Oh, but we have since found a couple other examples of these dark, masterless galaxies. But DF two is the first one that we found just a couple of years ago, and it rocked the astronomy community. People were so confused. I'm sure
Corinne Caputo 30:32
this is so okay. How do we know that it is a galaxy if the stars are so kind of far apart, like rim? I know. It was like kind of a flexible definition this this morning, five minutes ago, and you said, but what made us realize that this one was a galaxy? That's
Moiya McTier 30:49
a great question. It is. It's its own island of gravitationally bound stuff. So we can see the stars, like orbiting around that galaxies body, so we know that they are all bound to each other.
Corinne Caputo 31:04
That makes sense. I'm seeing a YouTube video called the galaxy with no dark matter.
Moiya McTier 31:10
It made a lot of headlines. Yeah, that's really
Corinne Caputo 31:13
kind of spooky to me. Now that I just got on board with dark matter. And now you're telling me you're telling me it's gone. Now?
Moiya McTier 31:21
I mean, it's the exception that proves the rule. Yeah, you're
Corinne Caputo 31:25
right. You're right. I learned that from he's just not that into you. That movie really taught me about exceptions and roles. So
Moiya McTier 31:32
yes, the educational tome of our time. So wow, what do you think of these galaxies? Yeah, okay,
Corinne Caputo 31:40
I am going to rank them. Here's here's my overall vibe I'm getting from each one. Tadpole obviously the cutest one. Cute appropriately no
Moiya McTier 31:48
argument there.
Corinne Caputo 31:49
No argument. We love it. It's a top contender. World pool is almost so beautiful. That it's like untouchable. Like a little too cool. You know, but like an influencer type galaxies. Oh, yeah. The Sombrero galaxy scared to me. That one was scary. When I clicked on the picture. And there's no reason it should have scared me. I'm just a scared person. So but I still have to knock it for that. That's fair sickness. A. That one is hard to see. And I do think it it has aliens now. We have to think that contact was based on facts right? And NGC 1052 DF two it's kind of spooky. That one not one is ripe for for a contact type movie, I think because it doesn't have dark matter. Some kind of horror movie that takes place out there where it's like, we got to find out where the dark matter went. And then they go out there and then it's like some monster is hiding behind a star or something. Yeah. I
Moiya McTier 32:49
love that you went there because I feel like the the name that we have given dark matter is definitely a misnomer. I'm a big fan of Dr. Chandra Prescott Weinstein who would prefer to call it like transparent matter, or, like clear matter, because it's it's not that it's dark. It's not the absence of light it's just the lack of interaction with light. So we have given it this name that makes it feel very dark and spooky and mysterious. And I know a lot of people who get scared by dark matter, but I love that we have that association between dark matter and scariness but then I showed you a dark matter with Galaxy and you're like that's scary.
Corinne Caputo 33:31
Yeah, that is actually scarier when there is no dark you're so right clear manner. not scary at all. That reminds me of like, you know, the 90s kind of books that were clear with the glitter in the liquid in it and you could like push it around gel pens, clear matters gel exact clear matter is fun. Cool. Cute. Love that. So in that case, well I think the ranking is the ranking you read them in? I think it goes extremely creative. Number one, okay, let's start at number five. What countdown to reveal number five is NGC temporarily GGF to because kind of a little underwhelming Hard. Hard to see. No doc matters very creepy. I don't want to look too hard into that someone else is in charge of that. Sickness A. Okay, interesting shape. I like that. It's hard to get one of those like artsy style laughs or pictures of it that it's like these kind of radio wave colored images. I think that's fun.
Moiya McTier 34:30
Yeah, it's a rebel. It refuses to have his picture taken by NASA. Exactly.
Corinne Caputo 34:35
And I like that because I don't always want to get my photo taken. Sombrero galaxy. Very cool. Very cool. Actually, you know what? It's gonna go NGC sigma se, then Whirlpool. Hmm, then sombrero. Then tadpole is number one because
Moiya McTier 34:51
it's the cutest and the most because it's the
Corinne Caputo 34:53
cutest and it's also to me, the one that would be most welcoming to me if I were to visit. This is about me. In the end, yeah, it's about me and making little trips out to all of these galaxies. And which one do I think would be good to talk to you? And I do think it would be tadpole.
Moiya McTier 35:11
Although by the time you get there, because it's 420 million years away, that it would it would be a frog galaxy by them.
Corinne Caputo 35:18
I'll have nothing to talk about. It will be a frog galaxy by then you're right. And I don't care about frogs the way I like tadpoles so Oh, interesting.
Moiya McTier 35:28
I would love to meet a frog galaxy. Just rebutting and hopping around the universe, there's
Corinne Caputo 35:34
like fully a frog shaped. You can clearly see the legs.
Moiya McTier 35:41
Yes, I'm done with spiral arms. I'm over them. I want to see frog legs. On galaxy.
Corinne Caputo 35:50
Where are the frog legs?
Moiya McTier 35:52
That is the question of the century. You know what, 100 years ago? We didn't know we were in a galaxy. We didn't know that. There were others out there. Maybe 100 years from now we'll find a frog galaxy.
Corinne Caputo 36:03
We need to zoom out far things. We're not zooming out far enough. It's probably what it is. Maybe all of these galaxies together. If you're looking at the universe, from a god type characters perspective, it's just one large frog.
Moiya McTier 36:17
Everything is a frog. Uh huh. Oh, I love that. Okay, so we have we have ranked these galaxies, definitive ranking of them? Oh, yeah. And obviously, this little sub section, this little slice of galaxies is representative of all of them. So you ranking these five is also you ranking all of the galaxies that exist now hundreds of billions of them?
Corinne Caputo 36:46
That's completely right. And also, if anyone out there listening has a question and wants to know where I would list rank another galaxy that you're you might be familiar with, let me know, I can easily pop that into this definitive chart.
Moiya McTier 36:59
Now we can have a throughout the pod, just a running ranking,
Corinne Caputo 37:04
you need to know this is a living ranking. It's a living document. It's a living ranking. It's going to be changing all the time. So you're gonna have to check back.
Moiya McTier 37:13
Don't hold us to anything we say. No, to change.
Corinne Caputo 37:17
Yeah, just like Pluto's on a planet anymore. Science changes all the time. That means it's working. Exactly. And that means science is
Moiya McTier 37:24
working. So we have ranked these galaxies, and we will continue to have a running living document of careers Galaxy rankings. But ranking galaxies is different from classifying them from putting them into different categorical boxes. So I wanted to tell you a bit about how astronomers classify galaxies. Yes. And actually, this is not a very satisfying lesson because there is no single way that astronomers classify galaxies. You You might hear some astronomers classify galaxies according to their size. So we would call the Milky Way is, is a galaxy. But the Large and Small Magellanic Clouds are dwarf galaxies. So named because they are just physically smaller, they have fewer stars than a bigger galaxy. But there is no set cut off. There's no threshold and the number of stars or in size or in mass. It's it's just a subjective thing. People can say that galaxy is a dwarf, but that galaxy is full grown. I'm
Corinne Caputo 38:30
hearing a lot of like these astronomers not really all defining something super specifically, or they are when they do define it, specifically, other people are like, no, no, no, no, no, no,
Moiya McTier 38:41
we can't catch a break. There is no right amount of categorization. But this is what happens when humans as they're trying to understand the world around them create classification schemes, as they learn more stuff, right? Because as you're learning, you're going to encounter something that doesn't fit neatly into the scheme you've already made. And humans are stubborn. So we often don't want to adjust our classification scheme and we just add another category and it gets messy, I get it. I have a lot of feelings about how humans tend to classify things and then just, it's wrong. In all sciences, in biology and chemistry, like it's we are so hell bent on classifying stuff, but so bad at doing it.
Corinne Caputo 39:27
That's so funny. I feel like that's true even in like, I do that in my personal life, where I'm like, I need to define this. I'm this kind of person, or like, I'm doing this and I'm not I'm really not all
Moiya McTier 39:40
those social media posts that you see like there are two types of people. Oh, my God, yes. No, no, no, there's more than two types of people. But there are only two types of galaxies and it's fourth galaxies and not. Yeah, so you might see astronomers classifying galaxies by their size AIS, you might also see them classifying galaxies by a combination of their brightness, their color and the wavelength that we observe them in. So the cygnets a galaxy, for example, is a radio loud galaxy, we describe it based on the wavelength where most of its energy is emitting, we sometimes would call some galaxies, an ultra luminous infrared galaxy, a you lurk you li RG, and that is classifying based on its brightness based on its wavelength, ultra luminous, and infrared. We also sometimes referred to galaxies as blue versus red, a blue galaxy is very young, with lots of newly formed stars that are shining blue and very bright and hot and energetic. A red galaxy would be something with older stars that aren't actively forming and they're less energetic, they're cooler, they shine in the red part of the spectrum,
Corinne Caputo 40:58
I would never think of red as cooler. Another
Moiya McTier 41:02
way that astronomers differ from from non astronomers. Yeah, it's actually a constant struggle. When I'm doing my science communication. And I'm trying to show temperature of something. Do I make blue hot or cold? Because to my astronomer brain, yeah, blue is hot, very energetic, but to my like, normal human brain. Blue means cold. So it's, it's it's a constant struggle.
Corinne Caputo 41:27
That is wild. Good luck with that, Moiya.
Moiya McTier 41:30
Thank you.
Corinne Caputo 41:31
Again, I'm glad I'm not in charge.
Moiya McTier 41:35
Thank you, I appreciate that. The most common way to classify galaxies to separate them into groups is by their shape. Edwin Hubble, the same guy who basically confirmed that there are other galaxies out there, and then also confirmed the accelerating expansion of the universe. He looked at a bunch of different galaxies through his telescope, not the Hubble telescope that was created and launched after he died. But he had his own telescope that he looked through to see galaxies and make notes on their shape, like what did they just physically look like? We call this galaxy morphology. And so in 1926, Hubble came up with this classification scheme called the Hubble tuning fork, where he separated galaxies into two broad groups. On one side, you have the spiral galaxies that have a flat disk with that gorgeous spiral shape, perfectly demonstrated by the Whirlpool galaxy. On the other side of this tuning fork, you have elliptical galaxies, they're spherical, they're more chaotic, the stars are moving in any direction, and they don't have a defined disk or spiral shape. At the time. They had this notion that galaxies evolve from ellipticals into spirals that they like develop their spiral structure over time, we now know that it's the complete opposite that spiral galaxies form and then they merge and through the chaos of their collision, they create an elliptical galaxy so in the Milky Way, and Andromeda collide, we will be an elliptical galaxy after their merger. But still Hubble not knowing what we know now called the ellipticals, early type galaxies, and the spirals, late type galaxies. And this is a convention that we still use today, even though we know it's wrong, really.
Corinne Caputo 43:37
Oh my gosh, yes, really, while
Moiya McTier 43:40
so astronomers will literally call a spiral galaxy, a late type galaxy, knowing that it's actually pretty young and will eventually turn into an elliptical. That's a really funny, it's really frustrating.
Corinne Caputo 43:53
And in their heads are they constantly just like redefining it in their head? That's what I do. Yeah,
Moiya McTier 43:58
I translated in my head. I'm like, Oh, okay. Late type galaxies. They mean a spiral. They mean it. Yeah. That means it's young. That means it's forming stars. It's blue. It's so funny. Yeah, that is just one way that astronomers use old jargon or old like classification schemes, even though it doesn't match our current understanding of the universe. There's a constant translation going on. In conversations about galaxies
Corinne Caputo 44:22
that is like so ripe for errors to be like, Wow, we're really opening the door wide for miscommunication. Yes.
Moiya McTier 44:33
I cannot agree with you more. So yeah, the biggest differences between spiral and elliptical galaxies are their age and color. Spiral galaxies are younger and bluer than ellipticals, which tend to be older and redder again, because they formed through the collision of young spirals, but also there's this fun difference in how their structure is maintained. A spiral galaxy has a flat disk with the spiral arms in the disk and the stars are moving in circles around that disk. The shape of a spiral galaxy is maintained by the circular orbits by the rotational motion of the stars around the galaxy. An elliptical galaxy doesn't have those neat circular orbits, I told you that it's just chaos, and the stars are moving in any direction that creates what astronomers call pressure. It's not pressure in like, the way that someone pushing on your body is this is pressure. But like the chaotic motion, the fact that these stars aren't moving in one direction, but are moving in all directions together, that creates a pressure dominated structure. So the these elliptical galaxies are essentially held together by the random chaotic motion of their stars.
Corinne Caputo 45:54
Wow. Well, that's how I function. I'm really flying by the seat of my random acts, my random little hobbies I'm starting and stopping.
Moiya McTier 46:06
That's a great point. If you feel a little chaotic in your life, if you feel like you're bouncing from one thing to another,
Corinne Caputo 46:12
you can be a gorgeous galaxy. Hell yeah.
Moiya McTier 46:15
You're a gorgeous elliptical, you are maintaining your structure through pressure. That is just as valid as maintaining your life structure through order and control like a spiral galaxy does.
Corinne Caputo 46:27
Absolutely. Wow, we really cracked the code. We did.
Moiya McTier 46:33
Yeah, that's all I have to say about galaxies and their shapes.
Corinne Caputo 46:37
I mean, they're really stunning. This is gonna sound weird, but they are iconically space. They are like facts. Yeah, when you're thinking of space, it's like some beautiful picture of a galaxy.
Moiya McTier 46:50
Listeners, I want to know what your favorite galaxy is. Yes, I want to I want to see a picture, please tag us. We're @PaleBluePod. We want to see your favorite galaxies. We didn't say this in the last episode. So let's say it now. Now that people have listened to us for two episodes, and they've obviously fallen in love with our charm and our wit.
Corinne Caputo 47:10
I know. I can hear him now. cheering
Moiya McTier 47:13
for us. cheering for us and our chaotically stabilized structures. Oh, we are Yeah, Korean. Where? Where can people find you on the internet? I
Corinne Caputo 47:24
love that question. I am currently electional which is just the word intellectual with the C O R at the beginning on Instagram, Twitter, and yeah, those that's where I am. I'm not hanging out in the other spots. I'm just a lurker on tiktoks.
Moiya McTier 47:43
Yes, I'm mostly lurk there these days as well. You can find me on those platforms Twitter, Instagram, lurking on Tik Tok. Go Astro Mo. So please follow us. Please follow Pale Blue Pod. And we will be back next week with another episode. Corinne, you wanna tell them what we're talking about next week?
Corinne Caputo 48:05
Gosh, it's gonna be space. Yeah. notes in front of me.
Moiya McTier 48:14
No, that's okay. I think that maybe that's all the end we get. Next week. We'll be talking about space.
It's an Easter egg. See if you can narrow that down. We'll be talking about the origins
of space. Oh, right. Yes, next week. So join us back for another episode. It's about time for us to leave Katherine's Reading Room. I'm getting a little hungry. But
Corinne Caputo 48:38
I do think we can see the stars right now. I think we could go see the tail of the Milky Way if we try let's Yeah, let's
Moiya McTier 48:44
let's leave this reading room and go see if we can find our shadows cast by the Milky Way. Yes.
Corinne Caputo 48:50
Okay, everyone keep it Spacey? Yeah, keep it spacey keep spaces.
Moiya McTier 49:06
Pale Blue Pod was created by Moiya McTier and Corrine Caputo with help from the Multitude Productions team. Our theme music is by Evan Johnston and our cover art is by Shea McMullin. Our audio editing is handled by the incomparable Mischa Stanton.
Corinne Caputo 49:20
Stay in touch with us and the universe by following @PaleBluePod on Twitter and Instagram. Or check out our website palebluepod[dot]com. We're a member of Multitude, an independent podcast collective and production studio. If you like Pale Blue Pod you will love the other shows that live on our website at multitude[dot]productions.
Moiya McTier 49:39
If you want to support Pale Blue Pod financially, join our community over at patreon[dot]com/palebluepod. For just about $1 per episode, you get a shout out on one of our shows and access to director's commentary for each episode. The very best way though to help Pale Blue Pod grow is to share it with your friends. So send this episode, this link, to one person who you think will like it and we will appreciate you for forever!
Corinne Caputo 50:05
Thanks for listening to Pale Blue Pod! You'll hear us again next week. Bye!