Planet 9 from Outer Space: Searching for a Distant Planet in our Solar System

[Music] good evening everyone my name is andrew fracknoy i'm the emeritus chair of the astronomy department at foothill college and it's my pleasure to welcome all of you around silicon valley and around the world to this lecture in the silicon valley astronomy lecture series now in its 21st year we're delighted to be able to bring you distinguished astronomers discussing their latest research this series of talks is co-sponsored by the foothill college stem division the seti institute the astronomical society of the pacific and the university of california observatories which includes the lich observatory past lectures can be found at this very same youtube website where you're new now tuned in to our lecture tonight uh tonight we are delighted to welcome back one of our favorite speakers in the series uh dr michael brown dr brown is a professor of planetary astronomy at the california institute of technology where he teaches classes from introductory physics all the way to the study of the solar system he is the author of a best-selling and award-winning book how i killed pluto and why it had it coming which is uh was the topic of the previous talk he gave in this series uh which was all about his discoveries that led to the demotion of pluto as a planet he has discovered dozens of dwarf planets and interesting objects at the edge of the solar system and he received many prizes for his research including the kavli prize in astrophysics for his fundamental contributions to our understanding of the extent and the history of our planetary system he and his research group spend their time searching for and studying the most distant objects in the solar system of which we are part and in addition to his award-winning research dr brown is also an outstanding pioneer in the outreach of astronomy he has given lectures all around the world and i've known him since graduate school where he already showed a great interest in how to share astronomy with the public so tonight he is going to speak to us about planet nine from outer space searching for a distant planet in our solar system and he's going to take questions at the end of this talk so i encourage everyone to send questions to our email address astronomy foothill.edu so now ladies and gentlemen it's a personal pleasure and a professional privilege to be able to introduce to you dr michael brown thanks andy it is it is uh it's great fun to be able to talk here again even if i'm not quite here again but this is i've always had a uh a warm spot in my heart for this particular um talk series i remember the first time i spoke here was very shortly after our discoveries of the very largest things out in the the kuiper belt and um it's been fun to continue to update this audience on what we're learning about the outer solar system and i have to say that this this one that i'm going to be telling about you today this search for planet nine is um i i have to say i think it's the most exciting thing that uh that that we're up to so the story of this search for this new planet out beyond neptune really is is a is a a continuation of some of the same stories that i have been telling before since i have been um speaking on this stage which is the the exploration of the outer solar system the understanding of what is further and further out there but the beginning of that story i would say really started in uh as early as 1781 so i'm going to i want to set you back not 1781 but 1780. in 1780 if you looked out at the sky and if it was a night like it is tonight uh you could look out at the sky and see all of the planets further away than the earth you can see mars right now rising if you're here in california it's just rising over in the east you see jupiter and saturn setting in the west and that was it those were the planets beyond the earth and if you if you go look at things that were written back in that time period i i have not been able to find anybody writing about speculating about thinking about the fact that there might be more planets out past saturn i just i just don't think it was in the the the idea of the cosmos of people at the time that there could be another planet other than these obvious ones that we see out there this all changed in in 1781 when william herschel was using his new telescope and it was the best telescope in the world at the time it had made very very crisp images so he could see stars as little points of light and he looked he was mapping the locations of stars across the sky and he went to one location and well the star was not a little point of light the star was a little bit of a blur and that's strange but not entirely strange there are many things up in the sky that are not points like stars there are galaxies there are nebulae as we know them now he was careful though so we went back the next day and that little blur moved and that was it as soon as you realize that something is moving in the sky it's not a star it's not a galaxy it has to be part of our solar system so herschel immediately knew as part of our solar system but he didn't really know what it was it even for him who had just discovered uranus even for him it took a while to to really believe that what he had found was a planet he thought maybe it was a comet people knew about comets coming and going um he just didn't quite know what it was one of the big questions that people had before they really were convinced that this is a new planet was how far away was it what sort of orbit does it have around the sun does it go in a circular orbit like planets do or is it like a comet where it comes close to the sun and goes far away and right now we just happen to be looking at it far away this question was answered it took a while but this question was answered in about 1820 by by a french astronomer named alexis bouvard and alexis bouvard doesn't doesn't get nearly as much credit in my view for all the cool things he did uh for the discovery of uh neptune which is coming up lexus bouvard let me show you his this uh book that he wrote when you're when you're in in paris in 1820 you get to write these uh really boring titles with some really spectacular subtitles here so it's basically tables of jupiter saturn and uranus he was basically publishing a book of where jupiter and saturn and uranus were in the sky and then he gets to put all of his accolades down at the bottom of this member of the academy royal of sciences uh london and munich and all these things that uh really we should go back to doing that i would love to be able to write things like that what he did though is he tracked the position of uranus in the sky and he then realized that other people in the past had seen uranus before actually herschel had in 1781 other people had charted it as a star and didn't realize they didn't do like herschel and go back and look the next day and see it move they just charted it as a star and he and so bouvard went back he found one he said okay if that's real let's go back some further and there's another one and there's another one and he went all the way back i'm going to show you this he went all the way back to 1690 was his first observation that he found of uranus so here's the discovery of uranus in 1781 and you can see data starting in 1781 a ton of it but before 1781 there's a decade earlier there's before that there are a lot of observations of people who accidentally saw uranus and didn't recognize what it was what bouvard did was write down a bunch of math that you can see here and he he used that math to predict where uranus should be and you know we all know that planets go around the sun and they go on ellipses around the sun but they're always tugged a little bit by the other planets so uranus is being tugged along by jupiter and saturn and so to really figure out exactly where uranus should be you have to take into account the gravity of jupiter and saturn so when you do that with all this math right here you get a prediction of the location of uranus and when you do that prediction there are errors you can see he says errors here and there's sometimes it's a little bit in front of where it's supposed to be sometimes behind sometimes in front sometimes behind a lot of behind there's some in front again and bouvard being a theoretical astronomer one of the preeminent theoretical astronomers of the day um was very much like the preeminent theoretical astronomers of these days and and you've probably had some give talks and if you've had them they you they would probably say the same thing is that the errors that you see here are not errors in my theory the errors are all due to the astronomers who made the measurements and astronomers need to make better measurements he did say okay there's a chance maybe there's something else going on there but but really i blame the astronomers it's all their fault they'll do better so astronomers worked hard to make better measurements starting here in 1820 which is when this was published they did 20 years of very very careful measurements and it was still not in the right place by 1840 it was clear i think to all the astronomers who were paying attention that something was happening that there must be another planet out beyond uranus that was tugging at the orbit of uranus and and making it move a little bit faster sometimes a little bit slower sometimes the problem was in 1840 nobody knew how to figure out where the planet was 1846 another french astronomer urbain leverier came along and worked out the math to be able to use these data that you're looking at right here where uranus is in its orbit to pinpoint the location of his new planet he predicted loki did the math he predicted location and he sent that prediction to the berlin observatory and the berlin observatory opened up their telescope and found it found neptune in the very first night of looking for it to me this remains one of the most amazing stories in in in science of of an observation uh a a prediction that something was wrong re-measurement re-prediction and then triumphant discovery and it there's there are very few stories as good as this one i think it's such a good story that of course leverier got really really famous at the time uh he's one of only i forget the number i think it's like 90 people whose names are carved into the eiffel tower in paris uh it's pretty good if you can get your name like you know he didn't go up and do graffiti and carve his own name into it somebody else put it there for him uh pretty good um there's a statue of him in in paris right at the uh observatoid perry he's he's standing pointing straight north looking um right up towards luxembourg gardens and towards the center of paris like it's a pretty good place of honor it got pretty famous for finding as they said at the time of finding a pencil a finding pencil finding a planet at the point of a pencil so you know what happens of course if anybody gets really famous for finding a planet all the other astronomers out there like i'm going to do that too i'm going to go find me a planet so almost literally the next day astronomers everywhere started predicting the existence of new planets they they used the same data they used data uh new data that that suggested maybe uranus and neptune were not quite where they were supposed to be maybe there's still something else out there and they made these predictions um and there were i i tried to count them all one time and i found as many as 35 independent astronomers making these predictions and well turns out none of them are true but the but the most famous of these predictions came from american astronomer percival lowell percival lowell uh was was uh predicting the location of what he called planet x again he thought it was due to perturbations of of uranus and neptune he made predictions and he went off and went to a telescope looked didn't see it made new predictions went look didn't see it he eventually founded the lowell observatory in in flagstaff with a mission to go find this new planet lowell passed away before this this search came to fruition but um after he passed away the the lower observatory hired clyde tombaugh and told clyde tombaugh go find this planet clyde went to the sky looked at the location closed you know was searching the region where the prediction of the new planet was and he took a picture looks like that um no planets there so he was like well you know i don't actually know what a planet is supposed to look like so the only way i know to look for a planet is to take a picture and then take another picture and watch it move did anybody see it move no nobody saw it moved let's try again here it is there it is again did you see it nope one more time still didn't see it fourth time's a charm i'm sure there it is there it is these are the discovery images of pluto pluto was more or less in the location where percival lowell had thought that planet x should be and this is how science can sometimes go wrong clyde tombaugh was looking for planet x planet x was supposed to be massive clyde tombaugh found something in about that location and so the answer was well that must be planet x planet this this thing in the sky must be huge so if you go to the new york times headline for the day of the announcement of the discovery audience planet discovered on the edge of the solar system lies far beyond neptune so far so good cited january 21st observatory staff there spots it through special photo telescope awesome well done the sphere possibly larger than jupiter oh possibly larger than jupiter meets predictions that's the bad part so possibly larger than jupiter no this is wrong by a factor of 250 000. meats predictions kind of that was the problem it was a it was predicted to be there um it was found therefore it must be it so it turns out of course that uh pluto is not planet x turns out that uranus and neptune are not being perturbed at all there's nothing massive out there changing their orbits and pluto was just a lucky find by clyde tombaugh and it happened to be well i i shouldn't say just lucky it was a careful find but it was it was by luck it happened to be in one of the earliest places he looked by clyde tombaugh who who was doing this thorough survey of the sky so the other weird thing about pluto if you can find it again it's one of those things it's one of those things it's this little guy down here it's really small when you look at it in these images and and people were confused for a while about why i was so small but after a while it became apparent that the reason it's so small this is actually a surprising fact a lot of people don't know the reason it looks so small in these images is because well it's it's because it's really small how small is it people often are uh misinformed about just how small pluto is compared to the other to the rest of the solar system and i like to just throw this in there just to do a little uh size of planets education um you'd never see a picture that looks like this of planets um but let me tell you what it is here we have jupiter here in the background the big one saturn even without its rings quite big uranus and neptune the terrestrial planets mercury venus earth mars quite small even these little guys here's series the largest asteroid and and the other asteroids that are big enough to be one powerpoint pixel in through here um usually when you see drawings of planets they're all kind of the same size because it looks better on your daughter's lunchbox that way as far as i could tell but they're not they're really wildly different sizes and here's if we now throw pluto on there pluto's tiny pluto really does not fit this planet this pattern of giant planets jupiter saturn uranus neptune oh there's pluto but at the time in 1930 when it was discovered there was kind of nothing else to call it and even though it progressively over the years we realized it was smaller and smaller and smaller and smaller until 1978 when we realized just how small it really was you know it was weird it was this oddball out the edge of the solar system but okay we could just keep it a planet there was nothing else to call it this all changed as we started to really explore the outer parts of the solar system here's here's a view that i also like of now here the orbits of jupiter saturn uranus neptune pluto with its really weird elongated orbit that sometimes takes it inside the orbit of neptune but usually outside the orbit of neptune you know pluto is so weird not only does it have that non-circular orbit um unlike the planets and also if you look at it on the side it's tilted with respect to the planets super weird but again you know what else are we going to call there's nothing else out there so uh you might as well call it a planet like the other planets and just move on well there are other things out there it turns out that as of today we know of something like uh 4 000 objects in this ring of material that we now call the kuiper belt out beyond neptune and if you put all the orbits of all those objects in the kuiper belt on the plot you realize that pluto fits exactly with the rest of those objects in the kuiper belt pluto is not some oddball at the edge of the solar system it's just yet another kuiper belt object and it happened to be the first one that was discovered excuse me it's this beautiful picture of what the solar system really looks like and it really drives home the important thing is that there are these four massive giant planets dominating everything and then many many tiny objects out there beyond neptune that are the debris that was left over from beyond from when the solar system was formed everything in the solar system makes sense everything in the solar system is where it's supposed to be we can predict their positions just by taking looking at the gravity of the things that we know well okay this was true until about 2003 in 2003 everything changed and everything changed with the discovery of one weird object that one weird object oh i was going to show you i've got ahead of myself forgot to show the sizes here the sizes of those objects in the kuiper belt pluto in case you lost it pluto was that one and there are objects that are about the size there are smaller ones pluto really does fit very nicely with this kuiper belt object that one weird discovery from 2003 was well here are the objects that i just showed you that one weird one was the object that is known as sedna sedna is on this orbit that is huge compared to the rest of the kuiper belt sedna takes 70 sedna takes i i i have been talking about sedna for nearly 20 years now and i suddenly forgot how long said it takes to go around the sun sedna takes something like 10 000 years um to go around the sun on this tremendously elongated orbit and what's strange about sedna is that not just the elongated orbit but that is never comes close to the giant planets any giant planet at all it's it's it is really even though on this scale it doesn't look so it's really kind of pulled away from the rest of the solar system and that's very strange something had to have pulled sedna away from the rest of the solar system and in 2003 we had no idea what that something was we speculated at the time that probably it was a star that came screaming by the outer part of the solar system pulled sedna a little bit out of its orbit left it as this fossil remnant of of when we had stars excuse me when we had stars streaming by but we didn't really know what was strange is we we kept on looking for more objects like sedna and we were we were wildly unsuccessful finding them um until finally uh one of my uh one of my colleagues a pair of my colleagues found a second object a little bit like sedna and then we started looking at other objects not the ones that were necessarily pulled away like this but objects that went on these really distant orbits and we realized something really strange here's the really strange thing all of the objects that go on these very distant orbits here's now the same this is the orbit of neptune here in blue sedna is one of these i am going to forget which one it even is i think it might be the purple one right here that's sedna all of these other i should actually i can tell by how far away is they're said right here that's sedna all of these other objects are uh very distant they're on these very elongated orbits and what's really strange about them is they all look like they're pulled away from the sun in one direction it's a very strange thing um there really is nothing that we could think of that would pull everything away from the sun in one direction and what's what's also strange is uh if you take these objects and you tilt them on their side although take the orbits and tilt them on the side you realize that not only do they go off in one direction they're all actually tilted up a little bit in the same direction too it really is this as if there's something out there that's tugging them along their way this is where uh five years ago i walked down the hall to my my friend and colleague um constantine bategan and i i showed him some of these day and i was like what the heck is going on here and and and you know it's funny i'm really sorry i gotta cough just a second okay we'll stop that it's funny because every time anybody finds anything weird and the outer solar system it's just like those astronomers from 1846 it's like there must be a new planet out there so um most people would immediately jump up and down and say new planet new planet new planet and we absolutely did not want to do that because you know we knew the idea that there's a new planet out beyond neptune was crazy and and people had been saying it for 200 years and they'd all been wrong and we didn't want to be the same sort of people so we started looking for any other thing that could be tugging these objects in their orbits and sadly the answer is we we couldn't come up well maybe not sadly we tried we tried everything we could think of and we could not find any other process that would pull all of those objects in one direction like that except for a massive planet on an elongated orbit so we did out the math and we realized that it works math i say we did out the math actually constantine does all the math and i just kind of look and pretend like i know what he's talking about but we did the math and it all worked out perfectly and these things were supposed to be elongated and we still were kind of dubious that this really made any sense so we we did a massive set of computer simulations where you take well let me actually show you these massive computer simulations you take a planet here you can see it in red barely this is the orbit of a planet neptune is way inside of here each of these little blue things is a test particle a kuiper belt object that we put on a very elongated orbit and the question is can this planet after four billion years or so pull all these objects into orbits that are all kind of lined up so what should it be well uh we were pretty sure that we knew what was going to happen is that this planet would pull a bunch of objects into orbits that look sort of like this after four billion years so we let the computer run and you see a couple things first off very quickly you'll notice that things uh very quickly you notice that things don't run as nicely on zoom as they do uh uh in real life but here we go um that things things disappear really quickly first thing does is the planet ejects tons of these objects the other thing is notice is that orbits change a lot the presence of this giant planet is pulling orbits towards it it's pushing some away but we're waiting for and also you can see that these green ones on the inside just sit and spin nothing much happens in there it's only the distant ones that are really affected and we're waiting for ones to get caught right here like this one this one gets oh no it does this one gets caught nope uh these guys that one no this one get caught no that one no nothing's getting caught um so our bright idea that everything was going to get caught over here uh is wrong turns out um we missed one critical point when we did the math this time i'll blame constantine because he did the math we missed one critical point which is that we we made a simple assumption that was important for doing the math which is that we were going to ignore orbits that cross the orbit of the giant planet because those are hard to mathematically handle and it turns out all of the ones that are stuck that are saved are the ones that are across the orbit of the giant planet this is really strange and we were surprised at first but but now we realize what's going on what happens is that as you know when a planet goes around the sun just like a comet going around the sun it spends most of its time way out here it goes slowly and then it gets goes here it goes faster and faster and zip through there like that and slow and then zip so it's almost always out here same thing with these guys these guys spend all their time out here very quickly and through here what that means is that nobody spends too much time in through here where they're close to each other it's not that these guys get stuck in these regions here it's that these guys are the only ones that have survived after four billion years because they spend the least amount of time close to this giant planet the objects that were over here well the planet spends most of its time here the objects would spend most of their time there they would get close to that giant planet they would just get ejected so instead of having them all this way they were all this way um once we realized what was going on we we redid the math and of course it all made sense and we realized that we should have done that way to begin with but it was nice to have done these computer simulations to see so now we realize that the existence of these objects in orbits like this meant that there had to be a planet in an orbit like this and if you actually turn the planet and the objects on their side like we did before you realize that like like the objects being tilted in one direction the planet has to be tilted in this direction too so this was pretty cool and we were like okay this is we should we should we should write this down we should publish a paper we should tell everybody about it but we were a little bit reluctant and we were a little bit reluctant because well we really didn't want to be the 36th and 37th astronomers to stand up and say we just found a giant planet at the edge of the solar system and be wrong because that would seem pretty silly so we sat back and we thought how can how can we prove to ourselves that this makes sense and one of the ways that that we we did it is one of the ways you do that is you make predictions you make predictions of things that you didn't try to explain explaining things is easy coming up with a theory well easy coming up with a theory that can match the data that you already know is a lot easier than making a prediction about things you don't know and having that come true but making that prediction about things you don't know is really the right way to do science and convince yourself what's going on so we made some predictions one we would find more and more objects aligned like these objects but that was going to take a while but we made a really interesting prediction that almost killed the entire theory which is that we realized that in addition to these these very distant objects that were lined up there should also be another set of objects that are not lined in the direction that the the lined up ones are but actually perpendicular and also on orbits that are perpendicular to the plane of the solar system you know we said pluto is crazy because it's tilted by about 20 degrees i'm talking about things that are tilted by 90 degrees to the plane of the solar system and oppositely directed as as these objects here it's a crazy prediction because we didn't know of any objects like that that existed anywhere in the solar system and so uh it was sufficiently crazy and and because we didn't know of these objects we were almost ready to throw our theory out the window it just didn't if it it predicted that these objects must exist and we didn't know of any and it turned out the only reason we didn't know of any is because i forgot to look in the right place this is so constantine's fault for doing the math wrong my fault for uh forgetting to look at another set of objects i was actually only looking at the objects that stay pretty far away from the sun when i looked at the objects that come close to the sun but go far far away there were five objects that were exactly like i described their orbits are tilted by about 90 degrees and they go really far away and what we didn't know is how they were lined up compared to these objects here and so constantine came into my office and i was like okay i'm going to plot these on the screen for you and we're going to see are they lined up exactly where we think them remember we want to see them perpendicular to where the things are now i showed them i didn't show them this plot but i showed them a plot that did this and the answer is there they are those five blue objects are exactly what we predicted their orbits are perpendicular to the plane of the solar system and also perpendicular to the alignment here and i think at that moment uh constantine and i both had our jaws hit the floor and we went from this is a cute theory that's kind of fun to think about to oh there's actually a giant planet out there at the edge of the solar system and we're the only people that know it's out there so we we wrote this paper explaining these observations um it was uh it turned out to be the most downloaded paper ever in the astronomical journal it was downloaded by something like 200 000 people seven of whom probably understood uh the math that was in it but uh but everybody downloaded it which was which was kind of fun um to watch and um we set out to do two things one is that this was this was really preliminary uh just like an existence proof there is a planet out there we really wanted to figure out um where that planet was and describe what it was like and then we wanted to find it so that first process where it was describe what it was like was really came about by just continuing to do more and more and more computer simulations and matching them more and more precisely to the data and we learned a couple of really interesting things one is oh i should tell you one more thing is that as we continue to do that people kept on finding more and more distant objects and the more and more distant objects all match so the first prediction was that there should be these perpendicular things and that worked out perfectly well but the second prediction that's i think the stronger one is that more and more distant objects should be lined up correctly turned out to be true so that's pretty exciting so we put all those in together and we can make some really good predictions one is how massive planet nine is how massive it has to be to make those effects and the answer is well our first preliminary results were that had to be about 10 times the mass of the earth which is an interesting mass because uh neptune is about 17 times the mass of the earth uranus 14.5 earth turns out is precisely one times the mass of the earth planet nine is midway between the earth and these giant planets we think that that means it's like a gas giant but we did learn as we did more and more of these simulations that it's actually 10 was our rough number a much better number we now know is about six it's about six times the mass of the earth with an uncertainty of about one we think which is which is pretty good that we can without having seen it we can we can already uh do a pretty good job of seeing how big it is we know about how far away it is it's something like 500 times the distance from the earth to the sun that that puts it at something like 15 times further away than neptune and on on a inclined and eccentric orbit that makes it have those effects on the outer solar system so um this has been the the predicting of where it is and how big it is has been years and years of analysis but it's it's it's really interesting to think about something that's this size sitting out there in the outer solar system because it's if i go back to this plot of what the planets are and sometimes when i say oh yeah there's planet nine we think there's a new planet people are people say oh you know we're just gonna argue is it a planet is it not a planet but i just want to remind you there's pluto where people who are misinformed continue to argue planet nine is is this big planet nine is the fifth largest planet of our solar system planet nine is no is it or isn't it a planet it's uh it is pretty unmistakably uh a huge member of our of our solar system that it'll be incredibly fascinating to uh learn about once we once we actually go find it so how are we going to find it well as i said we do these computer simulations we match we do uh it's actually been um four years of of developing what i what i think is some pretty sophisticated computational and mathematical methods to turn the observations into predictions and it feels a little bit like uh okay maybe i'm this sounds a little full of myself i shouldn't say it but it feels a little bit like leverier therefore i think i should have my name in the eiffel tower uh no um it's a little bit like la verrier who turned the observations of where uranus was into a prediction we are we are turning the observations of where the um where these kuiper belt objects are into predictions of where the planet should be so where should planet be well it looks oh how are we going to find it where it should be so uh this is not the slide i want to show i want to show you this slide which is where it should be this is our latest and uh uh greatest we like to call it the treasure map of where planet nine should be as we look across the sky so here's the sky here's the um the celestial equator this is the whole sky shown in a single projection celestial equator is like this the ecliptic where the planets are um right now is is uh goes like this actually jupiter and saturn are right over here right now mars why is mars in the milky way right now mars must be right here the milky way galaxy is this region in through here that that you can see planet nine is somewhere along this path right through here and and the the colors show you the the probability of finding it in any particular location along this path so highest probability out here highest probably out here because that's the part of the orbit where planet nine is farthest away and it moves the slowest so that's where it's most likely to be lowest probability over here where it's close and moving the fastest you can also see this plot above is how bright planet nine should be at any of these locations in the sky when it's further away it's faint so this high uh the high numbers mean it's faint when it's further away it's faint when it's closer it's brighter and you can see quite a range for the astronomers out there these are magnitudes at its very brightest it's 18th magnitude i bet there are people watching this right now who have telescopes in their backyard that can see 18th magnitude objects sadly i don't i don't think it's 18th magnitude that would have to put it close to the sun close meaning it's only 300 auwa so still not very close but it'd be at its closest position to the sun uh it would also be in the southern hemisphere so if you're watching from the southern hemisphere and you have a big telescope they can look to 18th magnitude go take a look i don't think it's there i think we've ruled that part on it already most of these predictions are between about 18 and 22-ish at the faint end it could be as faint as 24. okay so for those of you who don't speak astronomer magnitudes that means really big backyard telescopes modest size professional telescopes pretty big professional telescopes the biggest professional oscilloscopes that's your your calibration point so we're somewhere between backyard telescope and the biggest telescopes we have on the earth the good news is we're not beyond that range if if we're coming up to numbers like 27 and 28 i would say we don't have the telescopes to find planet nine go give it up somebody somebody's have to do this next generations but we do have those telescopes and here here are those telescopes um normally when i give this talk in the past i would talk about this telescope these are these are telescopes i use a lot these are the keck telescopes on mauna kea but right next door to the keck telescopes that i use a lot is my favorite system well used to be my favorite system for looking for planet nine this is the subaru telescope the subaru telescope is the japanese national telescope and and it's fantastic um because they have built the biggest astronomical camera currently on a telescope in in the world and it can cover huge areas of sky all at once and that's fantastic but we now know uh back back when we first thought we were looking for planet night we were looking for planet nine we didn't have this prediction of how bright it was we thought it was pretty faint and we thought we were going to need this biggest telescope we now know that a lot of this range of predicted magnitudes requires not the biggest telescopes in the world but can be found with a modest sized telescope my favorite monastized telescope in the world is over here you can't see it it's on maui it's on the summit of haleakala not on the summit of mauna kea and it's the uh it's the pan stars um telescope pan stars is some terrible acronym who's that i can't even remember pan chromatic something else um terrible uh but the pan stars telescope did a survey of the whole sky that he could see from mauna kea over the course of about six years and it took you know every year it took something like 10 to 15 images of every spot in the sky and if you look at a spot in the sky where it took 10 to 15 images of every spot in the sky you will see that there are stars there are galaxies and then there are what astronomers like to call transients transients are any time where you see something in a spot in the sky where you didn't see something before there are a lot of reasons you could see something in a spot in the sky where you didn't see something before it could be like the mundane reasons like uh z equals 10 gamma ray burst or something boring like that or it could be something interesting like something in the solar system and an asteroid moving across the frame is only there once it's a transient could be you know the merger of two black holes making a little flash all these sorts of things might be a little flash in the sky there are a lot of little flashes in the sky and if you if you look at all of them in this one little patch of sky tiny little patch of this guy you might see something that looks sort of like this um this is one little two degree patch of sky two degree patches guys if you hold your arm at uh as far as you can and make a little circle with your hand like that that's about two degrees in the sky that's about how big this is every one of those little dots is a transient that pan stars found over a five year period um okay some of them you might kind of guess what they are this you can see this big splotch right here well that's where there was a bright star and their little spike coming from the bright star but the computer software still finds it as little dot more stars garbage i don't even know what these streaks are but they're clearly something sometimes you see these little streaks here who knows what these little streaks are in this frame however is the most massive known dwarf planet in the solar system eris anybody see it well what's it going to look like i'll tell you over the course of five years eris goes on a path that looks like this every one of these little loops is a one year loop one two three four five this is six years over the course of six years eris makes these loops across the sky the loops are because uh of it's the retrograde motion of as the earth overtakes in the orbit and then it comes back again so to find eris here you would have to figure out which if any of these match this particular orbit and to find it without knowing that it was there and not knowing the orbit you would have to find which if any of these match any arbitrary orbit in the sky i'll show you turns out eris is there those are all observations of eris by pan stars across this five-year period eris is bright in that magnitude system that i was showing about eris is about 19th that means it's it's it's not quite bright enough to see in most backyard telescopes or even even very few backyard telescopes but it's plenty bright to see on on modest-sized telescopes and it's only a little brighter than some of the predictions of planet nine so the question is can we take observations like this and process them to find unknown objects in them the answer turns out is yes um it is a computationally uh humongous task there are um trillions of these little dots in the sky that are the transients and we're looking for the small number that might fit an orbit of an object across the sky we have a bank of computers working on processing all of the pan-starrs data in the track of planet nine and we're getting there i actually just made this next plot um from this afternoon here's here's what we have done so far it's an ugly plot because it was never intended to show anybody um but these are these are all the fields we've looked at uh it's the same if you notice this same swath across the sky we basically covered this part which is the biggest part and we covered the galactic plane down here uh there are a couple gaps because well i did i did the milky way galaxy first because i thought it might be hiding in the milky way galaxy so i did this chunk and this chunk and then i started doing this chunk and i the seams aren't good i'm gonna have to go back and fix the seams and i'm missing a spot here because this is data that are being processed right now but these little chunks just finished today and within six months we'll have the whole set of data from pan stars each one of these little blobs that you can't quite see very well it doesn't just show you where we've looked it actually shows you a fake planet nine that i inserted into the data that was found by the algorithm so we have ten thousand fake planets nine inside there based on our simulations and with any luck we have one real planet nine i will tell you it's not any of the data we've looked at so far there was one object there's one like right here that we found there where seven points were just perfectly situated to be an object just about right and um i went back and looked so then once you find something that might be real you go back and look at the raw data and you could tell that two of those detections were just glints from a star one of them was a streak from a satellite and like it's not real so so far no hits on the planet nine but i will tell you i know what it's going to feel like because i did accidentally almost find convince myself i found planet nine once because i have all this fake data in here and i have to make sure that i don't confuse the fake data with the real data but one time seven of my fake data points matched with one real data point so it made eight data points and the the real data point was first and i was only checking the first data point to see it was fake and it was a real data point and i was like it's real and it was perfect and it was right we're playing at should be and i was called my family and to come look at it and i was like oh yeah that's fake never mind but it was pretty exciting so with luck this is going to happen um is it really going to happen well i don't know um pan stars is gonna peter out right around 21 and a half so we'll we'll finish all these objects in here 21 and a half will still leave these most distant predictions these famous ones could still be hiding out there um and we'll miss them and in fact as you've seen we've gone through this whole section and through here um maybe we'll find it here i i was really hoping we'd find it in pan stars i really felt like um like the history of the discovery of uranus you know uranus uranus was discovered in 1781 but it was seen as early as 1690. neptune was discovered in 1846 it was seen by galileo pluto was discovered in 1930 it was seen in photographic plates taken at the request of clyde tombaugh in 1916. eris that i just showed you was discovered by me in 2005 we went and traced it back to images that were from 1950 it was imaged in 1950 if we had known how to take all those old images process them correctly we could have found eris much earlier we could have found uranus earlier we could have found neptune earlier it seems to me like we should be able to do this it seems to me like this is the era when we shouldn't have to go to a telescope and take pictures to find stuff it should be all there i think planet nine is hiding in the data somewhere and i still think we're going to find it by processing data before we find it by going to a telescope nonetheless if it is this faint we're going back to this telescope and then we really are going to this telescope the the subaru telescope on the summit of mauna kea it's got this ridiculously large camera the camera is so large that it is even larger than an anime character um and it is this this is the camera this is not a telescope this is the biggest lens in the world it was made by canon for the for the japanese telescope um and the the the electronic detector is up here it covers well okay remember i was just excited about things that cover this much of the sky it covers about this much of the sky at once it's a tremendous amount of sky for a telescope that size it can cover really faint objects so uh constantine bategan and i have been heading out there uh yearly at the right time of year to take a look at it here we are at the telescope that the camera is way up there at the top constantine you know he's a theorist you probably shouldn't beat a telescope i i you don't want to zoom in on this picture because he'll be embarrassed to see that as a theorist at 14 000 feet he has to be breathing oxygen because he gets loopy at 14 000 feet real astronomers don't need oxygen at 14 000 feet so that's why i'm not having any um but there we are we're observing it we will continue we're going to be out there in january taking a look again in january february um to cover some of those regions where the fainter things are and i and i think so if not pan stars subaru and if not past ours or subaru because maybe uh maybe we just miss it at the moment when we're looking maybe it happens to be in front of a bright star right when we look it's always possible if if not these two telescopes then then the backstop is the lsst the vera rubin telescope which will be online pretty shortly and you know when we started this project i used to say gosh i hope we don't have to wait till then but now it's it's actually coming up pretty soon and so one of these is going to find it and i'll tell you at this point there's been so much new data and so many new calculations that the probability that there is no planet out nine out there to my mind is is as close to zero as you can imagine there really has to be a giant planet out there to describe the things that we're seeing to explain the things we're seeing out in the outer solar system and i and i think uh it is only a matter of time before we find it in old data we find it new data or we find it in this brand new telescope that's going out there and i just want to end uh uh with uh a plot of of where it might be in the sky if we ended up finding it in the subaru data it's right here it's it's basically in this cosmic battleground between orion the hunter and taurus the bull and and planet nine is right there in the middle and i and i kind of hope that turns out to be true because i just i just kind of think that it's it's a it would be delightful to explain to people you know this new planet is out there you can't see it but go look at the one constellation everybody can track down um orion and and look at this this location this guy um this is where we've been looking with subaru we've covered a pretty good chunk of the subaru region we still have more of it to do but uh but i but i think as i said i think it's out there i think we're about to find it so i just want to leave you with one really interesting thought um from from the title slide so of course some people will recognize this title slide as the uh uh as the as the as the trail as the the movie poster from the uh absolutely fabulous movie plan nine from outer space when i say absolutely fabulous i mean the worst movie ever made if you haven't seen it um it's good because it's the worst movie ever made if you go to wikipedia and look at plan 9 from outer space it is literally called on wikipedia the worst movie ever made some people think it's so bad that it's good it's not it's actually just bad like it's on it's on youtube you could try to watch it i dare you it's terrible so there's vampires and there's space aliens and there's there's uh i like to think this is constantine it kind of looks like constantine if you think so um but what's really interesting so this is ed wood this is 1959 this is still when uh pluto was well and good a uh a a member of our our planetary system and yet there is this this this uh graveyard scene in in the movie where they're they're digging up the zombies because the the space aliens made the zombies come i don't i tried to watch it i don't really know what happened but ed wood made this poster in 1959 and you know he was brilliant director could be the worst and the best all the same time but this movie poster if you if you if you zoom in to the graveyard scene it's kind of astounding like look look at that what if you look up there it is r.i.p pluto um i think edward knew even back in 1959 how this was all going to play out uh it's okay pluto we will have a real ninth planet and uh i think we're gonna see it soon and i will be happy to take questions thank you very much for that wonderful tour of what might be in our future uh the the large member of our solar system that we can truly call planet nine um i want to now encourage people to send questions if you haven't already to the email address that's showing uh it would be it's astronomy at foothill.edu and i'm going to turn things over to dr jeff matthews the astronomy instructor at foothill college now who has been looking at the questions that have been coming in don't stop sending them you will be looking at the ones that come in as well so let me now turn things over to dr matthews thank you andrew i really appreciate it and thank you dr uh mike brown for the uh the great talk this evening and so i would also like to thank all of the members of the audience who have been sending in questions so and i'm just gonna apologize right now uh we're not going to be able to get to all of them we'll be able to take you know eight or nine questions here and so uh here is the first question that that we have um and a bunch of people have asked questions along these along the lines of this one um so this is a question from lana asking what do you think about the possibility that it's not a planet but instead a brown dwarf or a tiny black hole and with also the the added question what's your best advice for a current um undergraduate astrophysics student okay so okay so so 100 certain it's not a brown dwarf and and the reason why is that if it were brown dwarf it would be so close that you could see it with literally any backyard telescope i mean it's that a brown dwarf that uh that close plus brown dwarves are massive brown dwarfs are are something like 10 or more times more massive than jupiter planet 9 is 20 times less massive than jupiter so if there was a brown dwarf there it would basically rip the whole outer solar system to shreds so there was this uh there was this paper uh a year or two ago proposing that perhaps planet nine might be a black hole so we know about the existence of planet nine only because of its gravitational effects on the outer solar system so i cannot rule out the possibility that it's a black hole all we know is that there is something that six earth masses out there and we know approximately when its orbit is so it could be a black hole it could be a planet it could be as i like to say a sex earth mass hamburger um we don't know is it a black hole no it's a it's i i i'm trying to think of a kind word to say but i'm not going to say it i'm just going to say it's a silly idea the reason it's a silly idea is because the the argument is well the reason we don't see it is because it's a black hole um that's the argument the reason we don't see it is because the sky is a big place it's faint and we haven't searched the whole sky yet um the fact that we haven't seen it is zero evidence for being a black hole and i just for those who've been following astronomy i i would like to point out that like there there are plenty of planets that we know of in the universe where we only see the gravitational effects where we don't actually see so so most of the original planets discovered around other stars were discovered by radial velocity where you just see the wobble of the star that's just gravity just gravitational effects we don't all sit around and say well we don't see it maybe it's a black hole i mean yeah maybe it's a black hole but it's not a black hole probably also not a hamburger although it's a delicious thought i have to admit um advice for undergrads uh i'm gonna forget exactly what the question was advice specifically for what because i could i could give advice to undergrads all day long which is what i do all day long astrophysics students astrophysics um advice for astrophysics students is uh do your homework um let's see is there better advice but dude do your homework um my advice is man you're in a you're in a great undergraduate major i i actually didn't major in astrophysics as an undergraduate i was a physics major it was pretty fun too but if you are interested in astronomy and you you know you can you can do it and you and if you go off and get your your astronomy phd it is i i think it's the most fun thing that you're allowed to do and get paid for in the world i actually still can't really believe that people um pay me to sit around and do all this cool stuff uh the other cool thing is that astrophysics is is a fun major even if you end up not doing astronomy it's a it's a great um background it's a great great preparation for almost anything technical that you might want to do so i haven't had my i have students of mine get their phd in astronomy and planetary science and have ended up doing many other things besides just academic astronomy and academic planetary science so it's just it's a great major um because it gives you technical background for all kinds of things and it's super fun unlike like who would not want to spend their time really trying to understand how to apply physics to uh to the universe i mean really is there anyone who would want to do that all day long nope i don't see anybody okay i i have to agree with uh with your with your bias there on this issue it is a lot of fun uh so here is uh a second next question from uh les asking uh you touched on terrestrial aka rocky planets versus gas giants do you have any speculation on the material composition of a theoretical planet nine yeah it's a hamburger that's you know that's it's pretty clear uh no so i so um this is this is relevant to the last question though um which is again it's six earth masses and that is that is really all i know but that doesn't stop us from from speculating it's a good good phrasing because it is speculation at this point but it's speculation guided by what we know about other planets in our universe so when we look at other planets around other stars uh we see planets of this size we don't have any other planets in our solar system between earth mass of one and and uranus at 14 and a half so so we don't know in our solar system what that might be like but in other planetary systems we see these things and typically a six earth mass planet tends to be like a miniature version of neptune rather than a large version of the earth tends to be a icy core with a big gaseous envelope as opposed to a big rocky chunk i also think and this is also speculation and someone may have asked us to uh which is how did it get there um this is related to how it got there i think actually planet nine formed in the solar system uh in the same region as uranus and neptune and then it just got a little bit too close to uranus or neptune or jupiter saturn and it got flung outward and it has been basically flung outward and and hanging out at the edge of the solar system lurking waiting for us um ever since then that is such an uncontroversial idea that that we actually wrote papers about a fifth giant planet and how it would have affected the early solar system long before we even thought about planet nine we were writing these papers we tracked them through the formation and through the rejection from the solar system we never really thought very hard about what happened when they left turns out they can stick around i think might not be true but that's at least our speculation okay so we have a another question uh from al here asking uh could these orbits on one side originate from uh an observational bias from observatories predominantly viewing at certain times of the year yes so the answer is they could and that's that is a huge thing to worry about in astronomy are observational biases because if you notice they all come close to the sun at the same location which means the same location in the sky which means the same time of year to be looking at them that time of year it turns out is right now so many of these objects were discovered in november uh uh sedna was discovered on november of november 11th in fact that's today i think it's uh i think november 11th i have to go back and check that it might be it might be said in a discovery day 11 i named them after their day of discovery um but i might might not be remembered that right but anyway um so if if if you can imagine like you had bad weather every other time of the year and only good nether in november you could imagine that could be the case november is really not the best weather month um pretty much anywhere on the planet certainly not mauna kea where many of these were discovered certainly not in the southern hemisphere where many discovered so so the first thing to notice is probably not uh it doesn't really make any sense but it's still a hugely important question so to answer that question um i actually spent a couple of years doing an analysis taking every single observation of every single object that had been discovered in the kuiper belt figuring out when they were detected how they were detected what they could have detected and doing an analysis and asking the question could the objects that we see now have come from a uniform distribution but it's just bias that we're saying and the answer is uh we can rule that out at the 99.8 percent confidence level uh which is i would say pretty good so the answer is no it was it was it's a question that is 100 worth asking and really being careful about um but we now know for for certain that that can't be a problem okay great and now so here's a question uh i'm several people have asked similar questions to this one so i'm just going to pick one um version of this have y'all ever have people ever tried looking for kuiper belt objects in or other objects like planet nine indirectly using occultations in various ways so occultation and radio of say the cosmic background radiation or occultation of stars so so it's a great question uh and it's a it's a a great way to think about things so so the the difficulty is occultations of any specific object that you care about in the sky are exceedingly rare they're so rare that like when we want to we occultations are great because so an occultation um if if if people don't think about it as a star is right here the object goes in front of the star star blinks out star reappears and so by timing how long that star has disappeared you're actually measuring the size of the object the cord of the object there and so they're they're really important so astronomers spend a lot of effort predicting when an occultation will occur um traveling to where on the earth one will occur uh the last trip i took was last december 28th my daughter and i drove to phoenix to observe an occultation of an asteroid that's uh the target of the lucy mission to the trojan asteroids and so we really wanted to know how big it was for the lucy mission so we drove over there and participated in a big occultation event where with many many astronomers who were trying to observe it but what that tells you is occultations don't happen very often you have to really get lucky to even be able to see one so you're not going to be able to find one by accident find an object by accident unless there are so many objects that occultations are happening frequency so it is possible that if you look at smaller and smaller and smaller objects in the solar system eventually you'll get to the size where occultations might be relatively frequent such that you could watch one star and see it happens we haven't we haven't reached that ability yet and we people keep talking about it like maybe we can find really small kuiper belt objects by just staring at particular stars and waiting for them to flicker um but it hasn't happened yet and so it someday but it but it it won't happen for planet nine because the probability of any star doing it will is is low but once we find planet nine occultations will be a really important thing to measure its atmosphere to see how big it is and to learn other things about it okay uh dr brown um so now i have several questions from people uh sort of asking about other alternative hypotheses um yeah so so some of these are are names that i'm not familiar with so somebody mentioned a work by anne marie madigan somebody mentioned work by a group called um aussis i'm not sure if i'm reading that correctly both of those so so um so uh anne marie madigan had a really clever idea um uh she was working actually i believe she was working at nasa ames at the time now she was at berkeley she was she was summer up in the bay area and it was right early on when we were first realizing about the existence of planet nine and she had she had an explanation for some of these very distant objects um at the time when we didn't realize that all the distant objects were lined up there there were some other things about them they were they're all tilted in little weird ways and she she had this very clever idea on how they could get themselves all tilted the same way basically due to self-gravity um and once we realized that actually that's not what's going on it's not that they're all just tilted in some weird way they're all actually pointed in one weird way and and her self-gravity idea um simply doesn't work uh with the with the current um observations it would have worked if it had been what we knew of at the time so i i still think it was it was a clever idea and it's a cool thing that probably happened somewhere in in the universe but it's but it's not explaining why these things are lined up in this way the aws observations were all about that bias that we talked about earlier they they early on um were the ones who were who were trumpeting uh most loudly about this observational bias and um which is which is good uh they should and uh i think we pretty thoroughly showed that it's not an issue um they still they they still you know it's a little bit to to be uh to be to be a little mean here it's a little bit like those people after you know the very found found uh found neptune everybody else tried to do something they they really you know so we said there's a planet and astronomers always you know if you find something cool and and say it's out there the the next best thing you can do is show that somebody who got uh had this cool result did it wrong and so they really wanted to be wrong um and and part of their argument is that their observations themselves are incredibly biased because they did they did the survey that basically only looked at two patches of the sky they found a lot of objects in those two paths of the sky but it's incredibly biased because they only looked at two patches of the sky that's why we use all of the observations that people have done so their argument still remains but but we've proved that there's bias and the answer is yes you know but just because you only look west every day and you see the sunset in the west every day doesn't mean that the the sun actually sets everywhere and you just happen to be looking west it really is that that's where these things are okay so we're coming up on just our last couple of questions now and so uh we have a question from gary asking and several other people actually have various variations on this um you're wondering about uh would it make more sense to be searching in infrared versus visible light and some and several people emailed mentioning some things like jwst yeah so all good questions um so so jwst hst space based telescopes are going to be fantastic for studying planet nine once we find it but they're they're terrible for searches they look at tiny tiny tiny tiny tiny little areas of the sky so they're they're not designed at all for uh for searches they're designed for studying kind of individual objects or small areas this guy interesting question about infrared versus optical versus radio so so right now the the technology the technological sweet spot is in visible and just like you know the light that your eye can see and there are two reasons for that one is that's where the sun is the brightest we're looking at it in reflected sunlight and so we want the most sunlight so the sun is brightest in the yellow as we see it so it's going to reflect the most there and just as importantly our our technology for detecting light at those wavelengths is fantastic all of those digital cameras that all of you have have have really fed into making the astronomical cameras better and better and better so these these huge cameras like that one that i showed you from subaru um have benefited from from decades of commercial digital cameras and so we can build those better we can build anything else it is true though that as the technology improves not in the infrared the infrared will never reflect enough light but as you move longer further to the radio at radial wavelengths you'll start to see not the reflected sunlight but the heat coming from the object and that matters a lot maybe not for planet nine but possibly for planet ten and the reason why is because we're looking at reflected sunlight reflected sunlight has to go all the way out there it's getting fainter as one over r squared as it goes all the way out there s come all the way back that's another factor of one over r squared that means it gets uh every time you move twice as far away you get 16 times fainter that's terrible for trying to find something that's really far away the heat coming from planet nine well it gets a little cooler as you go further out but probably not much because it's probably mostly internal heat but as it moves further away it only gets fainter as one over r squared so eventually that thermal emission becomes a better way to do it right now our telescopes our radio telescopes for doing broad surveys of the sky aren't great but they will be soon so as time goes on radio telescopes might really give us our best view of what else might be out there besides planet nine okay and so now going into our final question uh for the evening and again i would love to thank all of the people dozens of people who emailed in questions and for the q a and i'm sorry that we can't get to get to all of you um but uh so our final question here is actually related to the idea of commandeering uh some of the deep space probes so uh so could any of the deep space probes such as the probe that photographed pluto helped detect planet nine yeah yeah so it's it's it's always a great idea to think about uh alternative ways of doing things um so again these these probes you know they're designed to be super small super lightweight so they don't have these they don't have huge telescopes or huge cameras on them that that are very good at finding things they're really good at flying close by and uh studying it once you know where you're going and sadly planet nine is probably a u-turn for new horizons so it's going the wrong direction right now but there are clever ideas of of repurposing um probes my favorite one is actually the cassini spacecraft of course it's gone now but the data are still there and one of the the most uh the the very first i think really clever idea um coming out of france soon after we published our paper was the realization that one of the things that planet nine will do is even though it's really far away it will very lightly perturb all of the planets in the solar system and the amount of perturbation kind of grows the further you get away from the sun and if you could measure precisely the distance to a planet over time you would see this oscillation of the planet as as the planet goes around the sun if planet nine is here as the planet goes around the sun it's pulled a little bit toward it over here and and not here and it goes further away here so it makes this kind of stretching and if you could measure that it would point to planet nine and you can so what they realized is that the cassini spacecraft in orbit around saturn sending bat signals to the earth is basically giving you a precise distance between the earth and saturn um every time it makes a uh communication back and and um an analysis of those data the preliminary analysis suggested it was just on the verge of being able to do it the the new in-depth analysis is really close they they they they almost they sort of detect us a a whiff of something maybe and completely independently of of us they don't use any of our data to say where it should be it's basically right in our path where we predict it should be and it's right at about the distance we think it should be and it's right around the mass we think it should be but it's it's right on the edge it'd be too bad it'd be really nice if a cassini were there for another 20 years we'd really have that information done well but but there are other clever things you could do the best thing you could possibly do i've been proposing this to anybody who'll listen so if anybody's there here's what you do send a brick into orbit around saturn send a brick into orbit around jupiter and just have those two bricks talk to each other and measure the distance between jupiter and saturn the hardest thing about the cassini measurement is the earth is actually moving around too much due to the uncertain masses of asteroids that fly by but jupiter and saturn don't get kicked by asteroids so if you could just basically measure that jupiter saturn distance continuously you would have planet nine you would have any other planets out there be fantastic so if anybody's got bricks that can talk to each other across space come talk to me well thank you very much for that wonderful talk so often in astronomy we hear only about things after they've been discovered so i want to thank you especially for taking us with you on your journey toward the discovery this is this is very exciting and we wish you the best of luck in actually finding planet nine thank you thank you very much it's it's uh it's great fun to be able to uh come come give a talk to all you guys well thanks again and i want to remind our audience that this series continues our next lecture is going to be february 3rd of next year in the evening when we're going to have dr john mather the winner of the 2006 nobel prize in physics who's going to be talking about the history of the universe and how the james webb space telescope which dr brown mentioned the successor to the hubble for which he's the project scientist how it's going to help us understand even better the history of how the universe and we came to be so join us again february 3rd 2021 for another silicon valley astronomy lecture good night everyone [Music] [Music] you

Channel: SVAstronomyLectures

Views: 28,104

Keywords: astronomy, science, astrophysics, science news, solar system, Planet 9, Kuiper Belt, Michael Brown, planets, planetary astronomy, astronomy news, dwarf planets, Pluto

Id: I-Yru-KndIs

Length: 77min 50sec (4670 seconds)

Published: Thu Nov 12 2020