 Alright, thank you for playing our random trivia for the day. If you've completed your trivia sheet, please bring it up to the table where the laptops are, and just drop it anywhere on that table for now. That'll do. Just make it get there somehow. We will grade them during this talk. I have the special privilege of introducing to you today's first speaker, who is a friend of mine, a mentor of mine, who got his PhD at the University of Washington. Unlike the majority of the speakers that we have here, he's actually from Washington. And he would love it if you subscribe to his YouTube channel, where he tells you what it's like to be an astronomer every day. Please subscribe to Jim's channel, and he will love me more. Join me in welcoming Dr. Jim Davenport. I'm also Brett's beard mentor. Am I waving? What am I doing? If you do not grab it, it's right here. I'm very happy today to talk to you about a map of the sky. But before we get into the amazing science and the beautiful pictures, I want to take one second to thank you all for being here, not just for supporting local business, blah, blah, blah, but for supporting local science. In a week that is best characterized, maybe as a dumpster fire, it is good to remember that there are awesome things going on in this world and other worlds. So thank you for supporting your local scientists, the tax-funded scientists, and the universities. Alright, I'm going to talk about a map that recently came out. This is the picture of the satellite, artist rendition. And this is a mission called Gaia. Some of you may have heard of it, others of you may have not. If you haven't heard, now you've heard. This is called Gaia. And we're going to talk about a map that it's made. And here's the map. There you go, that's it. That's the map of the night sky as made by Gaia. Okay, it's not the greatest picture in the daytime. I'll put the slides online, you can check it out. You can Google it on your phones. Map of the sky from Gaia. This is a map of over 1.7 billion with a big B stars in our galaxy in the Milky Way. That's a lot, thank you. This is not just a photograph, this is actually a mosaic of a crap load of photographs. I think it's the approximate number. There's an amazing amount of detail in this picture that is underappreciated from where you're sitting, but trust me as I wave my hands up here. You see right here the two satellite galaxies, the Milky Way. This is the large and small Magellanic clouds. No one's were guessing who discovered those. You can see the plane of the Milky Way where it got its name, Milky. This looks like a glass of spilled milk or something that you don't cry about in the night sky. If you live here in Northern Hemisphere, oh my God, you see this part. We see this half of the sky. This is sort of a tilted image. This spacecraft obviously is an outer space. It gets to see the whole sky. But this is not just to talk about a picture. This is to talk about a map. And the Milky Way is not a two-dimensional thing. It's a three-dimensional thing. But I want to start by telling you a little bit about maps because they're cool because my mom's a traffic engineer and I grew up looking at maps. And so I love maps. This is a really old map. This was like the best map of the world, circa about 1100, 154, by Muhammad al-Isidri. No, Idrisi, excuse me. And what I love about this map is it's not that he went everywhere and drew... He went everywhere and drew this, but he used every little stitch of information that he could find about the known and somewhat known world from where he lived. He sort of understood this coastline. He sort of knew a little bit about, like, England and this kind of stuff. This part of Africa is looking a little uncertain about his mapping. Their smile is not really clear about... But this is incredible wealth of information. However, this is not something you could sail by or navigate with, right? This does not accurately represent the picture of the Earth. But it contains a ton of knowledge. And I will make the sort of quasi-argument that this was kind of our state of knowledge about the Milky Way pre-Gaya. We sort of had this picture. We sort of understood what it looked like. We had a rough photograph of the night sky. We had, in fact, very deep photographs of the night sky and lots of wavelengths. But we only sort of knew where things were. Like, we had to really understand what the Milky Way looks like. We stitched together lots of little disparate pieces of information. Just like this guy did a century, a millennium ago. It was very inhomogeneous, we would say. Very uneven information. Fast forward a few hundred years and people are going more places with more regularity. And we have what I think is a good approximation of the Gaia map of the night sky. This is what I would say the Gaia map of the night sky looks like. It's a portion of our galaxy. There's a lot of detail. You could actually sail by this. There is relative scale. There's tons of details. What we'd like to do in my lifetime, in your lifetime, is take this and map everything. We'd like to have Gaia 2.0 that maps the entire galaxy. We have a piece of the galaxy with Gaia. Not the whole thing, but a piece. We have it in swizzed detail. Like this map. We'd like to do it with a little less colonialism. We'd like to map our galaxy in the way that we understand our Earth now from this vantage point. And it's because maps and old pictures are cool and Wikipedia is great. Here is a similarly aged map of the night sky. Now you laugh because it's covered in bears and snakes and things. But actually this was done by a real cartographer at the time. This was done, in Latin it says the globe of the sky. This is what it says in Latin. And this actually contains all these little dots that you can't see in the projected view. All these little dots are precise locations of stars. This is the pre-pre-pre Gaia map of our night sky. And the Milky Way is on here and all the constellations that you can tell your future from are on here. And then lest you laugh too much about this this actually contains a ton of information including a hypothesis this is the Copernican hypothesis. This is 1670 so people are still debating about what it looks like up there. This is a good picture. Here's the sun, here's the earth, here's the moon. Not bad. Not bad for 1670. We can do a little better today. Okay, so here's the picture one more time. Here's the map. Now here's a sweet animation of Gaia launching. This is a European mission so scratch where I said about tax dollars. Thank you Europe for paying for this. This was launched in 2013. It's been up there a few years. It took a while for it to get into its parking orbit and then it took a couple of years to gather enough data to cover the whole night sky. So cool it launches. I was hoping I had a little longer spiel so we could get to like the, ah, and then it opens like a beautiful flower. I just think that's kind of cool. I don't know. There you go, that's Gaia. That's what it looks like. This is what we call L2 or Lagrange 2. This is a quasi-stable point on the backside. So here's the sun, here's the earth, so here's you, and here's Gaia, slightly not to scale, but you understand that there is a stable gravity minimum point between the earth and the sun, the point where the gravity from the sun and the earth would be equal, and there's a point, a quasi-stable point back here, it has nothing to do with the moon, back here called L2. There are points like this relative to the moon. There you go, relative to the moon as well. So it lives out here. This is where other famous telescopes like James Webb Space Telescope will eventually land. So this is a very cool place to be because you're always on the backside away from the sun. You're permanently stuck back here in the sky. This is Gaia's job, measure something we call parallax. Now, I think a lot of you have probably heard of parallax in a lot of different contexts. I'm going to explain to you astronomical parallax and in the end of four slides you will all be deep experts in this theory. It is currently June, I believe, not wanting to watch. It is currently June. If we were to look at a nearby star and take a picture of it, here, here's the sun again. Again, slightly not to scale. If you take a picture, you face this direction. If you take this picture, this star appears to be close to this little background star back here, this little blue one. Six months later, okay, we all know the earth goes around the sun once a year. Again, if you didn't know, now you know. Six months later, approximately January, if you looked at the same star it would appear to be next to this set of pair of stars here. This nearby little red star or big red star would have appeared to move back and forth. Six months apart, January to June, there is some angle. This is drawing you back to high school math that you all loved. You can measure this angle and then you know this distance because we understand where we are in the solar system. You have some right angle triangle that you can call your math teacher and figure out how to solve and that gives you a geometric measurement, measured distance to this star as if you took a cosmic ruler and walked it 10 light years away and set it down and you had a geometric measurement of that star. It is an incredible method. This was thought of by the Greeks. At least they wrote it down. This should be happening. They looked for it. They didn't see it. I promise you most of you are intimately familiar with this concept as well. Parallax is also how you see what we call depth perception. Here is a lovely to scale image of my face. You can see the two eyeballs attached to my head unit here make a little brain triangle and this is how you tell that things are closer or further away. You can take your hand and put it in front of your face and blink left eye, right eye and your hand appears to jump back and forth. I see a couple of you trying it. Bless you. If you put your hand further away it seems to blink smaller. The little backward fourth blink because the separation between your eyeballs doesn't change. In fact, a great lab and if you have kids who have been doing this carefully take a ruler and measure the separation between your eyeballs carefully. Don't poke your kids eyes out. Measure the separation between your eyeballs and then set up a big yard stick or something in the background and then put things in the foreground and blink back and forth and count how many inches or angles or whatever whatever measurement you set up and you can figure out how far things are away. If you know the separation between your eyeballs and if you have a protractor built into your head it's a cool thing to do. We do this with students in undergraduate labs sometimes because you can actually measure the distance of things with your eyeballs and the separation between again, it doesn't work if you're a cyclops but for everybody else you can measure things actually remarkably accurately and again, this is how you understand depth perception. Now this also shows in video games that people like to run back and forth and they get really annoyed if things don't move realistically if the whole background just moves like a still image then it doesn't seem realistic and it's the parallax effect. You want the foreground things to move faster than the background things. There you go. You are all deep experts now on parallax. This is Gaia's full time job. We threw it in outer space just to do this. Now, I said you could do this with your eyeballs but take a moment to appreciate actually an unbelievably small angle. Thank you. I brought a prop to demonstrate this. Here's a quarter. I actually had to find this. Here's a quarter. If you want to understand how small this angle is that Gaia measures for the nearest star so close that it actually is annoying to measure for Gaia place this quarter four miles away four miles away and then measure the angular size of that. That's unbelievably small. This is why the Greeks couldn't see it because the nearest star is a quarter four miles away and you know, other stars are further away. So this becomes increasingly difficult. Gaia Oh my god. Did I kill it? Oh, the whole like dramatic point is just totally lost. Amazing. Quick on the presentation. There. Gaia does that angle 10,000 times better. That's like putting a quarter 40,000 miles away. That's the precision of Gaia. Woo, that's a small angle. Alright, this is how it does it. This is a sweet animation that the Europeans put out explaining Gaia. Gaia actually has two telescopes and it spins around in this circle. It takes a year for it to spin around. Again, it's always pointed behind us so we're animating in the Gaia rotating reference frame or something. But it takes a year for it to do this little spinning scan of the night sky and as it does that these twin laser cannons or whatever map out the night sky. They're fixed at a perfect 90 degrees and it's this measurement between the two and they're slightly offset. They're able to measure this angle incredibly precisely. This is the sweet animation and it does this, it takes a couple of years and it passes and then it can measure that angle. Okay. Cool. So Gaia measured the positions just the locations on the sky of 1.7, 1.69 billion stars. That's the picture I showed you. 1.7 billion stars. It was able, for the vast majority 1.3 billion stars it was able to measure this parallax effect. There's also an effect called proper motion because some stars kind of wander so while you're blinking back and forth the stars are also kind of wandering away. So for some of them you can measure this proper motion as well. We have all these other statistics. We're able to measure the color of the stars how red or blue they are. For a bunch of them we can measure the temperature of the stars. We call it the radial velocity. Gaia does it all. Gaia is awesome. Gaia measures everything. I'll talk about this very last little box here in my last slide. But that is a ton of stars. Again, go back to these old drawings. Before Gaia we had a map so here parallax and proper motion 1.3 billion. We had a map of 100,000 stars. That was the previous best record holder. Incredibly also the Europeans launched that satellite so I don't know why we haven't actually invested it yet. So I'm hoping we have a parallax race at some point. Okay, wow. So what? Like that's cool. Take a quarter. Throw it in the low earth orbit. Whatever. That's fine. So what? So this would all be cool trivia. But let me tell you about some of the really cool science that Gaia has done. Things that I'm excited about. I'm going to show I think 9 or 10 different science examples from Gaia that aren't just like a map. But things that you get real science that you get when you make the most precise map of our corner of the galaxy The first is you can measure the bulk motion of all the stars in our galaxy. Here we've covered the stars by whether or not they're moving towards us. That's the blue ones. Or away from us. And you can see there is a net motion. Things are moving towards us over here and away from us over here. This is in fact, we've just been known for a long time. This is how you know that we're in a rotating galaxy. The Milky Way itself is like a giant pizza that's spinning. We are spinning along with it. So the stuff behind us appears moving towards us. The stuff in front of us is apparently moving away from us. Because we're in this big spinning circular river. What I love about this is the first time on Instagram it was the figure on the left the figure on the right was the update. These are real scientists. This guy is involved with the Gaia mission. Tweeting about this. I have a couple of these. I'm finding about real science from Gaia via Twitter. And as an aside, what I think is really cool about this is Gaia was released on April 25th. And I knew it was coming out that day. All my colleagues knew it was coming out that day. We all cleared our schedules to play with the Gaia data. The day came out knowing it would be amazing. And what do you do? We're spread out over the entire world. You get on Twitter and you share the graphs that you made. You share the results you made. There was this incredible flurry of science social networking done out in the open. And I think going back to my first point I love this. I love that taxpayer funded scientists are doing their science where you can see it. You can see the nitty-gritty details. You can see the experts saying like, oh, that's wrong. Let me tell you why. You can see people like, holy cow, what is this? And some of those resulted in real scientific papers. Just from things that looked weird on Twitter. I love that. I love things being done in the open like that. That's open source, open science. Alright, here's another one. The LMC. I talked about that large, non-gallant cloud, the satellite galaxy to our own Milky Way. You can just look at it and hear the color with a different bizarre color map. And you can see, again, it's rotating in its own little spinning river reference frame. That's cool. That's, I think, really cool. They were able to actually just straight up measure it on day one. No, it was a couple weeks later. I lied. Still pretty cool. Gaia is so precise. You can actually measure the rotation of other galaxies. This blew my mind straight off my shoulders. This is two... This is Andromeda. And I forget if it has another popular name. Two nearby galaxies. And when you put these little arrows, if you could see really carefully, these little arrows pointing at the bulk motions of the stars in these other galaxies. These are galaxies outside of the Milky Way. Far, far more distant than Gaia was ever intended to measure. And when you start stacking and adding stars together, you can start seeing these things spinning in the night sky. It's incredible. It's incredible. The first time this has been done. Here's the real paper that came out of it about a week later. Within our own galaxy, Gaia is able to discover what we call streams or little clouds. You can look for little groups of stars that are moving together in unusual directions, watering upstream or away from the bulk motion of the galaxy. And you can see, here, we put them by the velocity or the velocity they're moving with. You can see this big red stream. This one was known before. And this big blue one that's kind of wrapping around has been known. This is new. This tail over here is new. Nobody's sure what these are. There's a little clump over here. New little groups of stars moving in little filaments or clouds either passing through our galaxy or maybe other galaxies that have been really cool. Some known, some new. Some artifacts of weird systematics. I think this one's really cool. It's a little esoteric and hard to explain. Let me try to boil it down. This is a super zoomed in picture of two really close stars, really nearby stars. And Gaia has measured the motion of this guy, this bigger one, which is closer by. It's measurement of where this guy is going in the night sky because we know that later this year this star will actually pass in front of this background star. And it's apparent motion will pass in front of. And you'll get kind of this funky eclipse of this background star from this foreground star. And that will get people who understand Einstein's theory of relativity really excited because the light from this background star will get bent around the foreground star and you'll get this weird traditional cosmic lensing thing going on. Really cool. It may be precise enough to look for planets around this foreground star. That's wild. The planets would be like little ripples in your mirror or as your lens is moving in in front of a light bulb. Really cool. Gaia is so precise that we have a sample of about a thousand of these pairs of stars that we think in the next century will do this. That's unheard of. Really, really cool. I expect really neat like press releases coming out in like a year or two from these results. This is going to mark my words, this is going to be super sick. And hopefully they have a better graphic by then. Again, not a great graphic but a really profound result. When you measure the direction that all the stars around you are moving with great precision you can take a computer and back them up and figure out from whence they came. And you can get an idea of which stars might have been close to us previously. So close maybe that they could have knocked comets out of their orbit. So close those comets may have come down and rain destruction on the earth. Maybe 65 million years ago or so that's kind of the game. Can you figure out which star back in yesteryear knocked a comet out of its orbit and maybe made it rain fire and brimstone on the earth. That's really cool. So here they are the stars that will pass by in the future. The stars that were nearby in the past and how close they got. And there's a couple of these that got really close. Not like dangerously close but maybe. That's kind of cool. You step back a little bit we look at these nebulae here. So this is what we call star forming region a star forming nebulae. This is a big cloud of gas and there's lots of little baby stars in here being born. They come from. But when they get old enough to leave the nest there's a question of how they get out. Here is two examples I've highlighted them with big stars so you can see them. Of Gaia finding stars that are rocketing away from their nebulae. These are like the birds flying the nest. And these three vectors here are pointing back to the primal distribution of where it came from. So it came from somewhere in here and you can see it positively came back from this nebulae and they're flying out flying free into the world into the cosmos. That's really neat. And this is a new result from colleagues of mine up north in Bellingham So studying what's called lambda orionis this is the bright star here, Orion's head. This is beetle juice. Some day it may explode that'll be really exciting. This is in the middle of in the middle of a little cluster again a baby star forming region these are all young stars and Gaia is so precise this is a very nearby region it can measure the velocity, the direction that all the stars around this big guy are moving and they seem to all be moving outwards as if some big bomb has gone off and thrown them all out. These are all being ejected and leaving in mass from their nest. I think that's really an astounding. This came out like two days ago. This is an astounding figure I think. And the last thing that Gaia measured and will have a lot more of in future data releases is asteroids in our own solar system. So bring it way close way closer than Gaia was really intended. These are little dots. You don't measure the little parallax blinking back and forth. What happens is you're taking your little laser beam cannons and you're scanning around the night sky and these asteroids walk through your field of view very rudely. And they're like somebody interrupting the picture you're taking. So they sort of photo bomb Gaia as it's going. But they do it repeatedly. Can I get this thing to repeat? They do it repeatedly and they can then measure and track the orbits as they're going around our solar system and they've managed to track the orbits of 14,000 of these asteroids. That's pretty cool. This actually, incredibly, is not the largest catalog of asteroids gone. But in a couple years Gaia will start pushing that catalog and start making some of the biggest discoveries in the numbers of asteroids we know. And you know, when we talk about things that land on Earth like comets and asteroids, I would like to know where they are. So I, for one, grateful that we were finding out where they are. All right. So in summary conclusion with the launch and the data release from Gaia we had this beautiful map of the night sky which takes us really from this qualitative understanding of what our little corner of the galaxy looks like to a much more precise dare I say navigatable picture of what the galaxy looks like at least in our corner. Which is why I've highlighted just this one little corner of the globe. I think there's hope in the next decades to extend this map farther out across the entire Milky Way and maybe into nearby galaxies and the results will be profound. Where are the stars came from? Where the sun came from? How many planets are out there? This is all the really basic stuff that gastronomers are supposed to be working on and Gaia is going to get us there. Thank you. I see a hand back there eagerly waving. Yeah, you. So the question is WTF is going on with these? Why do you get lines of stars? Lines seem like an unusual thing to see in the night sky. And indeed you're right, they are. Probably most of these came from either little galaxies or little what we call star clusters a little beehive of stars that are wandering around together and when they pass through the Milky Way the gravity of the Milky Way tugs on these stars and it tugs on the leading stars a little harder and it kind of we call it like a spaghettification it kind of pulls them apart and when they do this passage through the galaxy it pulls them apart and they sort of form this little stream and they get, we call it gravity disrupted tidally as in the same gravitational tug that makes the oceans go up and down. Yeah, some of these they've just chopped out from really bright stars where you can't tell how precisely the stars near them are moving and then some of them are some of the chunks are from the Galactic center which is just a crowded mess and you can't measure the directions very precisely. It's so crowded in the past and future stars. Yeah, so this is a small star. Yeah, so what's up with this one that sees the past pretty close not so far in the future? Should we be concerned? The answer of course is no. So if the orbit is correct if its velocity is correct this is a small star a little bit smaller than the sun it is going to pass 10,000 AU that's a meaningless unit but 10,000 AU in a million years. So 10,000 AU is really close that's within the outer fringes of our solar system that's kind of in the edge of comet territory so that's close enough to possibly wiggle comets. Now those comets will take centuries at least to get here if they're even going the right direction. So it's no cause for concern at least in our lifetime somebody else can deal with it. Yeah, the question is is Gaia, is parallax the same technique we used to map super clusters of galaxies like Virgo and other giant galaxy clusters these are some of the largest structures on the universe the Milky Way itself would be one dot in those clusters. The answer is typically no those things are so far away that even Gaia with its incredible quarter at 40,000 miles precision couldn't possibly measure in fact we use background galaxies like that as a reference we use them as like those are so far they shouldn't move and if they move you did something wrong the question is does Gaia give us enough detail to say if any of these stars have solar systems, have planets around them not immediately but maybe with careful follow-up analysis. So the example of this star passing in front of that star as its brightness is gravitationally lensed we might see on this background star we might see small planets so you'll see the light from this star the brighter and fainter as this one passes in front of it and you see little hiccups in that bright and faint curve those are planets. So that's one possible way. The other possible way is we have stars that are moving sort of at a constant speed relative to us and if they're moving and they stop and move this way and then they move this way again that's overly dramaticized slightly that would be a planet tugging on its parent star which indeed would go back to the very definition the Greeks gave the word planet which is wanderer wander in the night sky because the planets, if you track the planets in the sky over the subsequent nights they tend to walk and then stop and move this way and then walk this way. Those little loops are how we knew they were close by yeah so we might see an analogous thing in nearby stars from Gaius we're going to be many years to do it a couple more over here in the sweet hat okay I don't know so the question is why is this why are these stars all shooting off in which direction? I think what happened and I may be wrong here so take this as a small grain of salt I think what happened is a supernova went off at some point and is pushing all these stars outwards. I think that's what happened I'm happy to be corrected by an expert in star formation yeah should we have seen that? yes we should have but it wouldn't happen in a long time yes so why was the whole thing mapped and what do you think is missing? so the question is it's a full sky map yeah it's a full map of the sky as we see it but it's not a full map of the entire Milky Way and this is because we're sitting in the forest and we can't quite see it for the trees right so that maximum distance that Gaius can measure things out to through the magic of triangles that maximum distance is something like a quarter of the way through the Milky Way so what you need is something that can measure a grain of sand at 40,000 miles right you need something that's another order of magnitude more precise to measure the other side of the Milky Way now that being said people are playing some very clever games to try to get that information out of Gaius so give it a couple of years and that little sphere in which we're mapping will get bigger yeah so the great question here Gaius publicly funded by the Europeans in this case but other data sets like this they're publicly funded through tax dollars they are publicly available but if they're publicly available and they are in scientific jargon what good are they what do normal people do to appreciate and use this data the shorter answer is it can be a big girl if you can program there are a lot of tools so astronomers spend most of their days actually being just kind of rubbish programmers so if you can code on a computer there's a lot of tools available to you but there are also a lot of tools available to people who can't code we make things like so Gaia, ESA the European Space Agency has made a lot of interactive tools to take the data turn it around, zoom in sort of mapping things so they've made a lot of those tools available that are on their website on top of that there are several projects with a group called the Zooniverse Z-O-O Zooniverse which is data publicly accessible to people and it means citizens can actually contribute to science so they make it web based and you can go on your computer and just help identify X or circle Y or pick this out of the noise there's a lot of projects on there not just astronomy and those are those are really great projects that I would recommend looking at okay I heard part of that so you can see one seems to be rotating one seems to be not rotating what's the question I think it's rotating in a different I think it's rotating in a different frame so it's not doing this you can't see I think that's why I'll get you in the back in a second oh I love this question okay so we're seeing asteroids these things whizzing by in the solar system could you see a spaceship I think the answer is yes provided it's a big spaceship thank you it's a very big spaceship you have to see it multiple times to know which way it's going and for Gaia to see it it would have to be out beyond Gaia's orbit it would have to be way far away so if you did see a spaceship the government would probably want to know because you would have discovered aliens but I don't think that's entirely preposterous there was maybe a question in the back so it would be hard on me enthusiastically okay hand me up anyways this right here in the center yeah this is actually the middle of our galaxy so there's some complex geometry going on here when you're in a rotating frame the things inward to you seem to be moving opposite in relative speed so to fully explain that we're going to have to sit down with a piece of paper or a piece of chalk to draw a diagram but it is still within our galaxy this is towards the center of the galaxy alright one more question how many times does Gaia rotate it's a map oh how many times does Gaia rotate I'm sorry I do not remember how fast it's spinning I failed the last question one more question I can answer the question is how does Gaia measure these other properties of the stars which I just lost like surface rotation because Gaia gets multiple passes of the star if the star is changing in brightness very slightly say if it's got a dark spot changing in and out of view that gives you a course measurement of how fast it's rotating and surface temperature it has a two color camera so the blue and red color is correlated temperature alright that's all I have time for thank you all so very much thank you so much