How I Killed Pluto and Why It Had It Coming

good evening everyone my name is Andrew frack nor I'm the Astronomy instructor here at Foothill College in Los Altos California and it's a pleasure to welcome everyone in the crowded auditorium and everyone watching us on the web to this lecture in the 12th annual Silicon Valley astronomy lecture series at Foothill College this lecture series is co-sponsored by NASA's Ames Research Center the Foothill College astronomy program the Astronomical Society of the Pacific and the SETI the search for extraterrestrial intelligence Institute and we thank all those sponsors for making these exciting lectures possible tonight's lecture is a particularly interesting one our speaker is dr. Michael Brown the man who is in many ways responsible for the big change that's come about for the definition of a planet dr. Brown is professor of planetary astronomy at the California Institute of Technology where he specializes in discovering and studying the bodies at the edge of our solar system in fact he and his colleagues have discovered most of the large worlds beyond Neptune he recently received the Fineman Award for outstanding teaching at Caltech and you will see he richly deserves that he's a wonderful presenter of astronomical information and he was also elected a fellow of the California Academy of Sciences he is the author of a brand new book called how I killed Pluto and why it had it coming just published by Random House and it's already climbing up the bestseller lists the wonderful personal description of all the exciting things that happen with and to Pluto he was named one of Wired magazines online top 10 sexiest geeks of 2006 something he says makes us vibe laughs so ladies and gentlemen it's a tremendous honor a great pleasure for me to present talking about how I killed Pluto and why it had it coming dr. Michael Brown thank you very much and it's a it's really exciting to see this whole auditorium filled up because you come in at first and there's like a couple people sitting back here you think god this is going to be really kind of scary but it's great to see so many people here I just want to say for those of you sitting in the front and we're sort of wondering about that 2006 top 10 sexiest geeks 2006 was a long time ago sorry so so this is this is a talk I'm going to give the talk that's that's a describe some of the science that also goes on in the book by the same title but an interesting thing happened on the way to giving this talk and a lot of you might have seen last week and just in the and the to that New York Times that anybody see this there was this whole big article about Pluto and Eris anybody seen this one yeah yeah and you might also notice it was also in USA Today but nobody will admit to reading USA Today and anybody see that no okay so because of its actually the the science behind all this is changing continuously so I've had to actually update the talk just this week and I'm trying out the new version of the talk which I've tentatively titled Pluto is still dead another good news but it's but it's there's an interesting part of the story now the first thing I want to do is find out is there anybody in the audience who's still kind of mad about the fact that Pluto is dead a couple of people okay so if you're kind of mad and you need to you need to send me hate mail or something I'm here at Caltech you can you can track me down you know where to find me so but what I think what I hope is that other than a few crazy people out there and I know who you are I think the button there you ride to see when I'm right there I think that by the end of the talk I'm going to convince you at least that astronomers actually did a very sensible thing in in killing Pluto and then it's much happier in its new undead state the story of why Pluto had to die really started with the discovery of Pluto back back in 1930 in fact it really started before the discovery of Pluto it started when people were first looking for the ninth planet on the edge of the solar system Planet X it was sometimes called and and astronomers had done calculus is to try to figure out where Planet X was and they thought they knew they thought they knew how to find it because they noticed that that Neptune the the most distant planet in the solar system Neptune was moving along and its orbit around the Sun but was moving along ever so slightly perturbed by something and very recently Neptune had been discovered because it was perturb in Uranus so it seemed very natural to say hey look there's something else out past Neptune another massive planet out there for Charming Neptune and we're going to go find it now before you go home and think okay there is this planet X out there we met we now know that all of the data that they used back then to think that there was this planet acts something for Charming Neptune was a little bit faulty and there is zero evidence for anything massive outside of Neptune but at the time astronomers were really convinced there was something out there and they set off to find it so one of the very earliest searches for this planet X was done at this telescope it's right above my house in Pasadena California it's a it's just above Mount Wilson and they went to this telescope up with top of Mount Wilson took a picture of the sky right where planet X was expected to be and there it is you guys don't see it okay so well the astronomers at the time didn't actually see it either and the reason they didn't see it is because they were looking for massive Planet X and massive Planet X if it were big if it were saying the size of Neptune would be something like this on the screen is this bright can you guys see this what if I move it really fast can you see that okay alright so it would've been this big on the screen and they knew that just like the discovery of Uranus and Neptune all you have to do is point your telescope in the right spot and you see it and you know what you've seen because it's big and massive they didn't see anything here so they went back to the drawing board many years passed by and until finally in in 1930 clyde tombaugh was hired to go to the Lowell Observatory in Flagstaff Arizona is anybody been to the Lowell Observatory in flax that a lot of people been so it's a great place if you're ever just driving through there for no apparent reason stop by it's actually really cool to see the old telescope that was used to discover the things and the techniques use their Clyde Tombaugh was hired to go there and his job was to find Planet X and he took a few pictures that look sort of like this and he knew that he was not going to be able to tell which of these things if any of these things more the Planet X and he realized he had the insight to realize that the only way to really know that something is a planet that something is in our solar system instead of a star in the very distant universe the only way to know is to take a picture come back another night and take another picture and watch it move you guys see it move all right let's try this again you guys would have never found okay on his first night here it is the second night anybody see it yeah sure you did let's try it again first night second night anybody see it okay I don't know why but the fourth time everybody always gets it right so let's try the fourth time first night second nights okay here it is without the arrows first night and the second we're at there it is it's this guy right here right yeah okay I always get confused it's it's these are actually the discovery images of Pluto taken by Clyde Tombaugh in 1930 these are the things he used to actually realize it was something there now he knew that he was looking for Planet X and he knew that Planet X was massive because he had been erroneously told that Neptune's being perturbed in its orbit so he and all the other astronomers of the time were convinced that this thing was massive even though it really looks quite small in fact it looks so small that that other than it's berries its motion here it looks just like any other faint star in the sky so being an astronomer in 1930 I think was was more fun than being an astronomer today because back in 1930 you got to make up crazy crazy theories and so people made up a lot of crazy crazy theories on why Pluto they named it at the time not why Pluto looks so small and yet is so massive and so my favorite crazy crazy theory that a lot of my favorite crazy crazy one that I read goes something like this Pluto is really mass but it looks small because it's got a core of solid uranium okay so this is 1930 so they didn't realize yet that that's a really bad idea core of solid uranium and then it's surrounded by a liquid oxygen ocean so the core of solid uranium is pretty big it would be maybe this big and then the liquid oxygen ocean would be this thing but not only that the liquid oxygen ocean acts like a lens and it's transparent liquid oxygen then it acts like a lens and makes that core of solid uranium look even smaller so Pluto is super massive but it looks small because it's you know core of uranium an ocean of liquid oxygen so it turns out that's not true and it's not just not sure it's actually just thoroughly nutty which as I said it was fun back in 1930 you know science was still in the process of being figured out when you're allowed to be totally speculative and crazy when you actually have to make sense and they went on the specular crazy side these days astronomers constrained a little more by reality have a much better explanation for why Pluto looks so small anybody know the answer oh yeah yeah that's right because because it's really small so how small is it really I'm gonna do a little quiz I've never actually tried this quiz and talked before but what the heck I'm gonna try a quiz just because the full moon was so beautiful out there tonight as you can were driving in anybody see the full moon it's that big bright thing in the sky okay all right let's just see how many people I'm going to give you three choices Pluto is the same size as the moon two times the size of the moon half the size the moon and I'm gonna give you a fourth one just for fun which direction we get we got three times the size of it okay who thinks Pluto is the size of the moon who thinks it's twice the size all right good good who thinks it's three times the size of them all right you think it's half the size of it oh you guys are good okay you guys are clearly a well-informed audience or or everybody's informed but I just don't know it but I it really is let me let me show you how big it really is here one of the reasons I think that Pluto has has grown on people so much is because so many people except for this particular audience have had the wrong impression about how big it is and think it's a fairly major body within within the solar system in fact it's really quite tiny it really is half the size of the moon but you would never know that from looking at things like my daughter's lunchbox she has a little Pluto Planet lunchbox because my friends that gets funny to give her Pluto Planet lunchboxes and and and on the Pluto Planet lunchbox Pluto is about the same size as mercury which is maybe you know a third the size of Jupiter and they're all more or less the same size and that solar system is so wrong and so different from the actual solar system that even I am sad about Pluto in that solar system but that's not the real solar system here's the real solar system here's the here's here's the tiny Mercury Venus Earth and Mars Jupiter is huge compared to these guys Saturn even without its rings is quite large Uranus and Neptune out there here in between Mars and Jupiter you can even see the the little asteroid belt all again at the the right size on this plot I've shown everything to the right scale and the asteroids are actually there Ceres the largest asteroid but the other dozen asteroids I show on here are the twelve biggest ones and the criterion for inclusion was it has to be big enough to fit in one PowerPoint pixel so there are 12 PowerPoint pixel size asteroids in the solar system if you put Pluto on this plot it looks like that yeah I mean you guys laughs and that was even a joke I mean that's just the reality it's really sort of a tiny tiny little thing that you might miss if you didn't look carefully in 1930 when Pluto was discovered not only was it thought to be much bigger and more massive but it was also there there was nothing else known in this region of the solar system and so astronomers think they think worried about it for a while but in the end decided you know we really don't have a choice but the call doesn't Planet but it was a weird planet not only did it turn out to be quite small it also it didn't fit the other part of the planets which has their orbits you look at the orbits of the giant planets now here's Jupiter Saturn Uranus Neptune now - they're real scales of where their orbits are you put put Pluto on this plot and Pluto is as most of you know it kisses the orbit of Neptune in here it goes much further out like that it's very elongated orbit unlike the planets which are all on these very nice circuit orbits what's more is if you take this screen and you were to turn it sideways so you guys can see that you would see that Pluto was tilted by about 20 degrees compared to the planets which are all in one nice very flat disk around the Sun it really made no sense at all and and even when I first started graduate school and Pluto was was a was a planet in good standing he was always just seen as this sort of weird oddball at the edge of the solar system that that you know we sort of understood where all the other planets came from Pluto no one quite knew and so no one no one quite knew what to do with Pluto then in 1992 for the very first time Pluto suddenly started to make sense ludo suddenly starting to make sense because astronomers got better at finding more objects in the outer part of the solar system out beyond Neptune the very first one was discovered in 1992 by the Year by decade later there were there were 500 of these objects known out there let me put them on the plot here I can't go all of these objects every one of these little diamonds out here is an object that some astronomers somewhere found the same way the clyde tombaugh found pluto take a picture of the sky come back take another picture the sky look for that thing that moves put it on the plot and this band of objects out beyond Neptune is what we now call the Kuiper belt Pluto actually does a really good job here Pluto is that blue one right there see that little dot right there that's Pluto Pluto does a really good job of defining both the inner edge of the Kuiper belt and also sort of the outer edge of this Kuiper belt here - if I put the orbits of all the planets on to this plot it would it would be a big mess you couldn't see anything but but what you would see I said planets and I put the orbits of all the other objects those diamonds on this plot what you would find is that every one of these diamonds has an orbit sort of like Pluto's there elongate in tilted in different directions they would fill up this entire space in the same way Pluto does to so even back in in 2002 when it was when it was a we were still sort of crazy enough to want to call Pluto planet still it was very clear that Pluto was part of this Kuiper belt rather than being part of the the planetary system but there are many people who really were sort of desperate to keep it called a planet and so everybody was still calling it a planet back in then let me show you these objects that have been discovered in this Kuiper belt we're getting increasingly larger the ones that were being discovered and in fact I'm going to add some of them down here in this lower corner there's Pluto again and there there's a couple of the biggest ones again the ones that are big enough to be a PowerPoint pixel showing up there and even in 2002 Pluto was was was was in danger but it was still if you look here still by far the largest object that's known in that region there and so so when astronomers were still desperate to keep it as a planet or them or astronomers were sort of unwilling to to incur the public wrath by having it not be a planet the excuse was yeah okay sure it's part of this Kuiper belt but look it's really the biggest member out here by by a large margin let's just leave it as a planet and not cause any problems okay so this was this was the situation about 2002 and I I was I was thinking about how how exactly to introduce this this next concept and really the the way that it came to me is a in the in the very first chapter of the book here which is that in about 2002 or actually at a couple years before that I was sitting up at the Palomar Observatory down south of Pasadena east east of San Diego sitting up at the Palomar Observatory one very very very cloudy night not using the telescope which is one of the most frustrating things you can do as an astronomer you you spend all of your time writing a proposal to go to the telescope you drive all the way down there you set it all up and then you sit there and don't do anything all night long and a friend of mine was was visiting and and she was asking me what some of the projects that was interested in working on and one of the factor after going through a whole list of things I sort of meekly told her and and said you know what I I think there's another planet out there past Pluto and she's like I you're crazy because astronomers all learned that there are no planets past Pluto and all that stuff in the past was just bad data she said that's nuts how can you possibly say there's anything past Pluto and when I explained was was something sort of like this was that well you know Pluto was found a long time ago these objects in the Kuiper belt were being found by very small targeted searches in it only you could figure out a way to look at the whole sky and see what's really out there you're certainly going to find something bigger than Pluto and if you find something bigger than Pluto what are you gonna call it well it's a planet obviously duh so I explained to her and she said you're crazy and and I didn't have any good scientific proof that there was something I just had this gut feeling and so as I as I tell the story in the book there's there's a moment when I had to try to explain to her that I really deeply believe this and so I thought the best way to explain this is is to make a bet so in in December of 1999 I bet her that within five years somebody would find a planet out past Neptune and we made we wrote down very carefully what our definition of the word planet was so because we knew it was still a little bit uncertain at that time and and we bet there'll be something and I I was really convinced someone's going to find it and mostly I was convinced it was going to be me because at that point oh because why not why bet if you know if you can't just if you're going to make a bet you might as well do the best you can to win the bet - so I was going to try to win it that the trick was to come up with the best system of telescope and and camera to cover the entire Scott astronomers actually had gotten much worse at covering large patch of the sky over the past 50 50 or 60 years Clyde Tombaugh did it very easily he he well not very easily he did it very tediously but with a with a technique which was to use photographic plates photographic plate is a big piece of glass on which you paint photographic emulsion on the back you slap it onto your telescope and you take a big picture of the sky by by the by the late 1990s astronomers all around the world we're now using digital cameras instead of photographic light cameras are fantastic for astronomy I'm sure many of you so many of you were amateur astronomers which are almost all of you who are amateur astronomers have some sort of digital camera that you use for something yes yes I see heads nodding and they're great because you get they go onto your computer right away there's so much more sensitive you see many more things the one thing they're not very good at is seeing large swaths of sky back in the 1990's when astronomers first started using digital cameras on their telescopes they were a lot like the primitive digital cameras that you guys all had in your pockets at the time you know the very first camera that I used as an astronomer was something like 200 pixels by by 300 pixels across I know us which is ridiculous now given that all of your cell phones are much better than that but at the time it was so fabulous but the only problem was he covered such a little part of the sky went about this much if you put your fingers together and push them together as much as you can they covered about that much sky at once and that's why so few objects had been found out in the Kuiper belt astronomers would take a big telescope look at a tiny area the sky may find something faint but what they didn't know may be something right there was really bright or right there it was really big and bright but they didn't have any way to see it in 2002 we finally got together and and did something which we thought at the time was was astounding we took a hundred and twelve of these little digital cameras and and sort of pasted them together with with bubblegum and baling wire and slap them on the back of this telescope at Palomar Observatory and we had the biggest digital camera that anyone had ever used anywhere at the time in 2002 it was astoundingly large it was 170 megapixels these days you know by next year you're going to have that in your in your camera but at the time 107 megapixels was big so we could cover not not this much sky but we could cover this much Scott okay so that's it still took as a decade but you can imagine if you can cover this much sky you can imagine taking a picture here and then here and then here and then here and eventually seeing whatever is really out there so we had the camera and then the other thing that we need it was this telescope this telescope that we used is is a fantastic telescope for the for the amateur astronomers out there this is the very famous 48 inch Schmidt telescope down at Palomar Observatory and it's not the big telescope at Palomar many of you been to Palomar down in Southern California yes and many of you have seen the big 200-inch telescope down there it looks sort of like this one because it's the same design of the dome but this is this is much smaller in the 40 inch telescope and the 48-inch telescope was was built as Palomar was built because when they built the Palomar telescope the biggest telescope in the world at the time they were actually under budget and so they had enough money to build another telescope I don't think that ever happens these days but they built this up a telescope because they realized that the big Palomar 200 telescope needed a wide field telescope to help it find places to go look so this telescope is designed to look at big area the sky it was designed to use photographic plates but we pulled out all the old photographic plate systems installed our new digital camera and added one other thing which is my favorite thing in the entire world and that's this this thing doesn't look like much it's a little microwave link that microwave link goes points San Diego so data go down to the san diego supercomputer center and then from the san diego supercomputer center up to my office in pasadena and that means that this entire telescope is allowed to be operated robotically in the ten years that I worked on this telescope almost every single night working on this telescope I actually went down to Palomar it's about three mile three hour drive from my house I went down to tau Palomar a grand total of zero tons all because of this and so in that decade when if I had been a you know good dedicated astronomer living down at Palomar and I would have never left the mountaintop in that decade I instead got to do things that normal people do like I got married and you know had a kid and so all these things I tribute to to this right here it's really I mean really it's cuz look I started sometimes say this is my wedding ring right here and it looks like okay so we had everything in place that we needed we have a the biggest digital camera in the world I have a bet that I hate to lose and we have this telescope that can be used robotically so what did we do so night after night after night we would look at a little patch in the sky and we would we would take three pictures over the course of three hours and we would compare those three pictures now when I say we I really mean my computer did most of the work and which is the data would come as I said from San Diego up to my my computers like I had a big bank of computers at Caltech and the computers would look at the images and try to find things that were moving it's just like Clyde Tombaugh dead but Clyde Tombaugh had to do it all by eye back in 1930 these days it's really this part of it really is a lot early a lot easier so let me show you the sorts of things that happen here's a tiny tiny tiny patch of the sky that that that we found something in one night and here's what happened that the computer would go through an image that looks like this a little postage stamp of an image that looked like this and the computer would say well there's a star it's in the same there's three images here the star is in the same place three times in a row here's a star it's in the same place three times in a row there's sometimes you see something that just appears once there's something that just appears once you never see it again the computer would pick that up but sometimes very occasionally you would see something that appears three times in different places and it looks very much like something that's moving because it is your eye is really good at finding things that move on images like this the computers are okay but the computer is easily fooled so the computer if there had been this for example this little blip right here I can look at that and I see the shape of it it's running right along a little column it has the characteristic shape of the sort of noise that the camera tends to have and I recognize it immediately the computer wouldn't if there happened to have been three of those in a row but computer would have picked those out too so every morning the computer would have picked up one or two hundred potential moving things and I would have to go through and pick out the one or zero or two that were actually real so every morning I would sit down to my office and I would I would flip through things like this until I found one that looked like this and these are you can you can tell a lot just from this image and you can tell a lot because the the you can tell about how far away the thing is by how fast it's moving so I told you that everything that's in the solar system is moving you can tell that it's in the solar system by its motion but you can actually tell how far away it is by how fast it moves so the closest things to us in the solar system move the fastest anybody want to guess the fastest moving thing we ever saw from a llamar nobody wants to get somebody way back in the back I see it guess Mars now Mars is pretty fast because you're right Mars is really close and we did see Mars one time and Mars is so bright because it's a big big planet that it actually would blast out this whole screen and that was a fast-moving one and we saw things even faster than Mars anybody want to go for faster than Mars yeah well okay so the moon we would be really dumb to look at the moon because we know where it is and it's so bright anyway but it'll be going faster you're right satellites even faster still but they're still more even faster all right over there aircraft that's the answer Palomar turns out to be in the landing pattern of the San Diego Airport so it kind of looks like this when it goes across it's actually it doesn't look like this here let me show it looks like I was waiting to do that I hadn't thought about um so so because because uh so we would just have to throw those away but then them and then all the other things satellites see we would see moving very fast but they would be a big streak all the way across the screen Mars and things like asteroids that are out by Mars would be pretty slow and we would be able to track them down and the things at the very edge of the solar system would be moving something like this this looks like a big motion to you but but only because I haven't magnified so much it's it's um if you if you pluck a hair out of your head and you hold it all the way at arm's length it's about a width by a hair width in a day that's how much it moves across the sky so it's a tiny tiny motion but by that tiny tiny motion we can tell how far away it is not only that but if you remember the Kuiper belt actually there's an inner edge of the Kuiper belt about where Neptune is and there's an outer edge of the Kuiper belt further up you can actually discriminate between things kind of on the inner edge and things on the outer edge this one is moving at about a moderate speed so it's about in the middle of that Kuiper belt region the other thing you can tell is about how big it is this is one of the fainter of the objects that we discovered and so since it's faint and about the middle of the island look hyper belt I know that it happens to be about two or three hundred kilometers across which in the only units that anybody cares about that's a that's about 10% the size of Pluto so this was not a particularly big one but it's the kind of thing that we would find day in and day out and I mean it's it's it's an exciting thing to go into work in the morning and know that you know this morning you might walk in and find this chunk of the sky that no one has ever seen before moving across there and you get to be the first human to ever see it I mean it was it it made walking into the office and sitting down and turning looking through those hundred things just just the best part of my day every day so I'm going to walk you through a few of these just to sort of get you the feel for what they look like for a minute here here's another one this one's a little bit brighter and it's moving it about it's about the same speed so moving at the same speed means it's in about the same distance which means it's in about halfway between the inner and outer edges of the Kuiper belt but it's brighter so why is it brighter well all these things they thin have any of their own light they only shine by reflected sunlight so to be to reflect more sunlight you have to be bigger so this one's about bigger this is about twice the size so this one's about 20% of the size of Pluto it's not a particularly large object in the Kuiper belt but it's still in the top 25 30 of the largest discoveries of the past century or so okay so keep going here's another one which is the same brightness as the last one but slower so this guy is actually on the outer edge of the Kuiper belt one of the most distant things we've found so on the outer edge of the Kuiper belt but it's the same brightness as the one that we had just seen that was sort of in the middle now to have the same brightness but be further away means obviously it have to be significantly larger this one's about half the size of Pluto this isn't about the top 15 of the largest Kuiper belt objects known there so I'm sort of just getting you the general feel of how these things work so you will understand my reaction which happens it was about 6 6 years ago it was January TIFF 2005 where I was I was flipping through these images and I came to this one and I almost fell out of my chair and I almost found my chair for three reasons the first reason is because I slouch too much ok so the second reason what's the second reason it's really slow this thing is it was slower than that last one that last one I said is at the outer edge of the Kuiper belt this is going about half the speed and it really is quite linear so if this is half the speed it's twice the distance so this thing is well beyond the Kuiper belt more distant than anything we had ever seen before and it was also the brightest thing we had ever discovered it's always exciting to find the brightest thing you've ever discovered because you get there they're easier to study there tend to be larger but if you take the brightest one and it also happens to be the distant one then we knew immediately that this thing had to be really really really really big we didn't know how big go I've been I've been sort of cheating all these times but I kept on saying how big things were and and we'll get to that part of the story in a minute but we knew it was big we knew it was at least the size of Pluto or larger and that was if you remember the bet that I made back in December of 1999 that was our criterion for what was to be a planet it had be bright enough to be at least the size of Pluto and larger so I had won the bet except it was January 5th 2005 and the bet expired on December 34 2004 so I was I missed by I missed it by five days which is pretty astounding really so I sent email to my friend I asked her if I could please please please have a five-day extension and and I learned from my undergraduates at Caltech how to beg for extensions and and and she she she kindly gave me an extension she said as long as I promise to tell her first what it is I found so I didn't actually keep that promise because immediately I called it my wife and said I just found the planet and I won the bet because she gave me the five-two extension so I was pretty excited although if I forget to tell at the end of the story at the end somebody asked me the question because the story is not quite over so anyway so this was very exciting it was it was at least the size of Pluto potentially much larger very far away what do you do next well the very first thing that we did is that we wanted to know well we all want to know how big it was of course but what we really want to know is what sort of orbit did it have around the Sun because it's really far away let me show you how far away it really is here's here's our favorite picture of the Kuiper belt again here's where it is it's way over there and the funny thing is this is actually real size it's actually big oz metric we didn't know what kind of orbit it had if it was if it was something like a planet like a real good planet and good standing even though Pluto was still playing at the time then you know we knew it should have a nice circular orbit like the big massive planets do but we knew that there was a good chance that it didn't that it actually belonged to the Kuiper belt and instead of having a circular orbit that it has a long gated orbit it just happens to take it out that distance but comes back into the Kuiper belt it's not hard to figure out what the orbit is all you have to do is wait and watch it for one orbital period and that's only 560 years so I'll be letting you know in another 554 years exactly what sort of orbit as well okay so we actually don't have the patience to wait 560 years and that's okay you don't have to wait a full orbital period you have to wait maybe 5% of an orbital period maybe 10% so 10% of that orbital period would be would be 50 years or maybe 25 years so you know we could probably get away with 10 years I don't really even have the patience to wait 10 years so astronomers invented this very clever technique not available to the rest of you which is which is time travel yeah it's really cool so the way it works for us is well I wish it worked then we could just actually go back and do it but what we do instead is over the past 50 60 years many many astronomers took many many pictures of the sky and they were actually good enough to archive all the data it's kind of like back when you actually you know took took took pictures and you put them in your albums and you knew where they were these days nobody knows where any pictures are anymore and they'll all be lost but back then everybody kept their pictures nice to catalogue and you know where to find them so we could go back into the past and find pictures approximately where this thing should have been and we first went back a year and and and and scanned a pretty big area of the sky and every picture we could find from the year earlier and we found something that was there a single blip a single star that had never been seen in that spot before now we didn't know that it was really it because no one took a second picture so nobody knew what was moving but but we saw it we'd spot that could be it we went back two years found another thing went back three years we finally went back and found the very earliest image we ever found of this object was taken in about 1950 and it was taken actually in sort of a fun bit of symmetry was actually taken by the 48-inch Schmidt telescope at Palomar we're where we discovered it and it was taken in one of those big photographic plates that was designed to look at the sky and but no one took the second photographic plate to see that the thing moved and I'm glad about that because I got discovered so what kind of orbit does it really have well the orbit actually is is not a circular one in fact it's a really quite elongated one here's that crazy Pluto again and and here's this one it is it is it is quite a bit more elongated than Pluto and and this time I'm actually going to turn it on side it's a it this one Pluto if you remember was tilted by 20 degrees this is tilted by 45 degrees to the planets of the solar system we don't know why usually whenever all of these objects member I told you that all these objects out here have elongated and tilted orbits and it's always because these are these are tiny little bodies that have been kicked around by the five giant planets if you have one of these big planets and a tiny thing goes by it gets a slingshot off of it then its orbit gets very elliptical or tilted or something but no no astronomer really knows how to make it tilted by 45 degrees like that we blame Neptune but we don't know what Neptune did but I know Neptune did something it's a sneaky planet it does these sorts of things so so it had a crazy orbit but it looked like an orbit more like an object in the Kuiper belt than it did like like a like a planet like a big massive planet so that was our first inkling that this thing was not going to be as huge as we potentially thought now how big did we think it might be well I keep saying as big as Pluto or perhaps larger and the reasons that I that I'd say that is because all we know about how big it is is how much sunlight it reflects and it reflects a lot of sunlight but you can reflect a lot of sunlight in in two very different ways you can be a really big massive body and be covered in you know dirt or something something dark and you'll reflect a lot of sunlight but you can be a lot smaller and you can be covered in snow or frost or something and you'll reflect the same amount of sunlight from our telescope here we couldn't tell the difference but we knew that there was a telescope somewhere where we could tell the difference between a very small body covered in snow and a very large body covered in dirt and the telescope that we were going to use was was this one this is my favorite telescope that's not on the earth and it's is of course the the Hubble Space Telescope it says here's its I think it's just been released by the space shuttle got bout to go and amend refurbish about to go fly off again still 20 years later fantastic telescope the great resource for astronomers to use and it's the best telescope for taking these very fine precise pictures of things in the universe and that's what we wanted we wanted to take a picture of this object and see just how big it really was so usually to get to get to use the Hubble Space Telescope you have to go through this long drawn-out proposal process but they do have this back door a way where you can you basically send an email to the director and you say we found something very exciting we'd like to use the telescope right away and we said and you know we found something as big as Pluto or larger can we take a picture of it they said uh uh-huh so we took these pictures I remember very distinctly that they were they were coming down through the space link and they were going to arrive in my office in Pasadena it's something like 2:00 in the morning on a Saturday night and I drove down there to my office to be able to open up those files the first time I saw him because I knew this was it this was going to be the the first ever view of the largest thing that anyone had discovered in 150 years and it was going to be the best map event maybe would have little features on it maybe to be a smiley face who knows what's gonna be I was so excited until I opened up the file and it looked like it looked like that yeah so I said so I did what I always do when I when I looked at files that look like that and think I did something wrong I I double checked that we were looking at the right place and we were and you could tell that it was actually moving because the telescope had to move to track it it really was it and and interestingly we also to figure out how big it was we also believe there was a star next to it that you can't see on this screen we had to carefully compare this little tiny star to this object here we realized that this this thing is not even as big as it looks even the Hubble Space Telescope distorts things a little bit so it's really only about that big that big is about five percent bigger than Pluto with an uncertainty of about five percent maybe six some not sure this was this was a big surprise so when we first got this result we did what we always do and we get exciting results which is to say Chad what'd I do wrong this time so went back and recheck that's over the data and still got the same result recheck the data and still got the result and then suddenly realized I understood exactly what's going on and we should have expected this why is it so small well there's only one way it can be so small and still reflects so much sunlight it has to be really really shiny it has to be covered in essentially snow this object reflects something like 80 percent of the sunlight that hits its surface 87 percent of the sunlight is is an obscenely high amount of sunlight to be reflected you know your most freshly fallen snow that you get when you're going skiing and you get all sunburn on your chin that reflects maybe eighty percent of the sunlight that hits it if it's really really super clean the the nothing else on the earth reflects nearly that much sunlight you know the only thing that I could think of that reflects more sunlight than this is is Saturn's crazy moon Enceladus you guys know this one is the one that has the the geysers at the South Pole and these geysers come and they recoat the surface of Enceladus like every ten minutes and so it has this incredibly pristine frost on it and it reflects something like percent of the snow that hits the surface this thing is reflecting something like that and I thought what's what could possibly be going on until I realized it actually makes perfect sense in hindsight and in hindsight you realize that that that this thing is is the size of Pluto it probably is essentially the same composition of Pluto Pluto has an atmosphere when Pluto is closest to the Sun this thing probably does too but this thing is so far away right now that that atmosphere is is plated out on the surface the atmosphere is probably nitrogen just like Pluto's atmosphere just like our nap atmosphere and that nitrogen is in a tiny tiny thin layer just barely covering the surface and turning this thing into an incredibly reflective billiard ball same thing would happen to the earth if you took the earth and move the earth out to that same distance the the nitrogen in our atmosphere and everything else would freeze solid on our surface we'd have like 30 feet of nitrogen ice on our heads on this it's only about half a millimeter of nitrogen ice there's not nearly as much but it's enough to turn it into that really bright object okay so now we know how big it is and we'll put it on the screen here there's here's the solar system as we knew it before this discovery there were a couple other objects we had discovered that I put on there too you can see Pluto was increasingly imperiled but with the discovery of this object suddenly well suddenly looks more or less the same you know here's the bad news I know you guys all took some time and effort to come out here on a Wednesday night you could be doing other more exciting things this discovery means absolutely nothing yeah it's I mean if you are the solar system let me let me ask you a question is this solar system is this solar system any different from this sources no of course not I mean they are the the small numbers of objects down here at the end even if one is a little bigger one is a little smaller they're exactly the same solar system with a little bit of noise on the edge now if I removed Neptune okay you're allowed to say it's a different solar system if you discover Neptune that's a pretty big thing but discovering this object really doesn't change anything about the solar system at all except that it of course changed everything and the everything that it changed is that the debate had been going on and on and on about what to do about Pluto but astronomers really didn't want to deal because they knew they would get themselves in trouble and they're generally chicken so astronomers we're not we're not dealing at all but but when you suddenly you find something that is same size as Pluto or potentially maybe five percent bigger you have to answer the question what is that is it a planet well Pluto's a planet then of course it's a planet right it'd be crazy not to go on the planet but do you really want to suddenly start to call that a planet what about that one shouldn't that one be a planet at the same time we found that when we found one there was two-thirds the size of Pluto is that a planet it was very clear that suddenly this entire box was opened and astronomers finally had to address this question that they really really didn't want to address for a long time now everybody knows the the solution that finally happened there was this fabulous astronomical meeting in Prague in 2006 astronomers fought like schoolchildren for two weeks it was I mean did you guys watch this in the news it was it was hilarious I actually wasn't there so I only would get the daily reports on the web and in the news and you know scientists bless them like to like to sit around and argue and have these scientific arguments but but but it's just as likely that when you see two scientists arguing they're not scientific arguments they're just scientists arguing and they they they just when there is emotional as everybody else but in the end everybody knows what happened Pluto got the boot I actually don't think it was much about Pluto although it was but it was really more about this thing that I had found that had to be answered and Pluto is just the collateral damage of that now this is the point in the talk where I often say you know I can give you a half an hour lecture on why this was a sensible thing to do but I almost feel like you don't even need to do that I mean if you just look at this this figure that has been staring at you from the screen for the last hour it's pretty obvious at least why astronomers decided to classify these eight things differently from these and differently from these the question that I think is more interesting to why astronomers did it because I think it's obvious why astronomers did it is whether or not it matters because sometimes you'll run into astronomer on you know you sit next to astronomer on airplane and the first question you always ask because I know the first question always ask is just what you guys do about Pluto and this is even if you don't know it's me that's sitting next to you on the airplane and then I'm like I am the guy who did doctor but so in astronomer will generally say well you know it doesn't really matter it's all semantics what you call it Pluto is still Pluto and then they'll spend the next three hour flight telling you why they're right and everybody else is wrong so I'm gonna spend the next three hours - no I'm not going to that part but but here's why I actually think that's wrong I think it actually matters quite a bit for the public understanding of what the solar system is and you know and so maybe it doesn't matter if the public understands the solar system maybe it's okay if my daughter grows up thinking her lunchbox as such is some reflection of reality but if it's not the actual solar system is is a profoundly interesting place it has four terrestrial planets tightly bound in circular orbits in the Sun it has four giant gas planets on the outer parts between the terrestrial planets and the gas giants there are these this little band of asteroid debris no one of which is particularly large but the aggregate or an interesting band outside of Neptune there's yet another band of basically cosmic debris an icy rockin band instead understanding that this is the solar system understanding that that that that these classes of objects are out there is really one of the things that the planetary scientists the solar system astronomers try the hardest to do try to explain this solar system astronomers don't try very hard to explain a solar system that has eight of these planets and then like maybe this is a planet and that's a planet that's planet just it's not it's not a very interesting or profound solar system nor is it actually very correct but understanding this is really the important task of planetary astronomers and the best way to describe that in the simplest possible terms to someone who's not a solar system scientists is simply to say and acknowledge that there are eight planets you miss out on these things which is kind of sad because I kind of like these things and you miss out on the asteroids but most people know about asteroids but if you just if you only wanted to know one thing about the solar system it should be that there are eight large dominant members of the solar system going in circular orbits around the Sun and then between those eight and outside and in the middle there are all these other little bodies flitting around and those are important and they hold important clues for understanding solar systems but the eight are the big important ones and I I think as a as a scientist as an astronomer and as someone who is very interested in educating you know kids and the public about what it is to be a scientist and what their local universe is like I think this matters a lot and so I'm actually thrilled that astronomers as crazy as they are actually decided to stick with the eight planets and stick to their guns and and finally put Pluto into its class with these objects instead of with these of it so I'm really happy that happened the other good thing to that that that final classification allowed to happen is that we've finally got to name the object that we found all this time I've just been calling it the object the object the object finally when it got to be classified it's now classified as a dwarf planet a dwarf planet is any of these guys that you see that's not one of the eight dominant things in the solar system and yet is round is a dwarf planet round because the larger you get the more likely you are to become around some people want all round things to be planets but we actually have a really good word for round things it's called sphere so I think we'll stick with X we don't have to call those planets but they're called dwarf planets it's a really poor use of the English language and so other people argue well you can't say a dwarf planet is not a planet I'm like well you know actually a matchbox car is not really a car you know we you can it's clunky it but and it's unfortunate but it's but it's okay we'll survive anyway so now that this thing is a dwarf planet I got to name it which I was very excited about the name of this object is now air PR is Eris's the Greek goddess of discord and strife which I have to tell you that this is enough to make me almost want to believe in astrology it's hard too hard to name things if you want to stick with Greek or Roman names mostly we didn't stick with Greek and Roman names for these but for eros we felt like eros had been a planet and good standing for a year so it deserved a Greek or Roman name like the rest of them but most of the Greek and Roman names had been taken starting in the 1800s because every time one of these things was discovered everybody called it a planet and they took all the good Greek and Roman names the only major God or God is left was eros and I think it's because people are a little bit uncomfortable with goddesses of discord and strife but I think she's awesome so so we're really happy about that so the goal of this project of course you know I said the goal was to find that the the tenth planet went back when I started in in 1999 I think as having found in and forced the world into a new appreciation of the way the solar system is is better than finding a tenth planet but there's also a lot of science we wanted to do when we did it so let me very quickly end by telling you about some of the very exciting science projects that we did after discovering these things so as soon as we find these things we would go to every telescope that they would let us get our greasy fingers on to go study I mean my favorite telescope to get greasy are the Keck telescopes out on the summit of Mauna Kea and why there's Maui in the background beautiful places in astronomy and they had just developed this fantastic system for doing astronomy from the ground that made it almost as good as doing astronomy from space the system was called laser guide star adapt about this and it works like as it sounds sort of science fiction it looks even more science fiction when you actually do it but it works sort of like this you take your telescope and out of your telescope you shine a laser into the sky if you can see anything in and the laser goes up into the sky right about there and it reflects off a little layer in the sky it's about 90 kilometres up and that little layer is the very top of the atmosphere where asteroids have burnt up and left debris in the top of the Atmos and so there's a little bit of stuff to reflect the laser often the laser reflects off the atmosphere comes back down and makes a little artificial star but the problem is as the laser has gone up and come back down it's gone through the Earth's atmosphere so it's all Wiggly and wobbly and makes a big mess as it comes down but you're a smart astronomer so in your telescope you have this little rubber mirror they call them the little flexible mirror that Wiggles around at a hundred times a second - perfectly compensate to make that laser instead of going all Wiggly Wagle suddenly go into a little point of light so you've just spent millions and millions of dollars to take a laser that you knew what it looked like to begin with made it back to how it was supposed to look but if you're smart you also pointed that full telescope system at something interesting in the sky and there's something interesting in the sky one of the very first targets we ever looked at is eros and it's me this thing works so incredibly well you you flip the switch first you have to contact US Space Command and ask if it's ok to propagate the laser they give you permission you propagate the laser and and everything you're looking at it in real time it goes wiggly wiggly wiggly inside and when you flip the switch it goes to a little point of light except sometimes it doesn't it goes and then there's a second little point of light right there - and that second little point of light was the discovery of the moon embarrass the moon of Eris of course universe gets a name - just like Eris the moon of Eris is Dyson Omiya as daughter of Eris and the demon spirit of lawlessness it's actually named after my wife it's kind of funny except it's actually true she is not entirely clear she appreciation but but the great thing about fighting ammonius is well as soon as we found on the moon everybody said well you know it's got a moon so it's got to be planet right like no no no in the Kuiper belt those those thousand objects that I showed you in the Kuiper belt something like a third of them have moons around them - so it's not uncommon to have a moon not only that of course Mercury and Venus don't have moons and their planets for now but what having a moon does is it lets you do is you know some very basic high school college level physics which is fabulous which is that you can use the mood and the motion of the moon to calculate the mass of the object in the middle so we could very precisely measure the the mass of eros with images like this from the Keck telescope and also like this from the Hubble Space Telescope beautiful little dot right there and we finally we find the calculate of the orbit and I was working with one of my graduate students there at the time and she was convinced just convinced it was going to be less massive than Pluto not because there was any scientific reason but just because you thought it'd be really funny for me to have to say oh sorry so we made a bet we seem to do a lot of it in meta bet and the good news is that we finally got the orbit of dice nomen Iran or Eris and it's it's 27% more massive than Pluto with an uncertainty thereof only about 2% so very comfortably more massive than Pluto so my student lost the bat she had to stay in grad school for an extra year so it worked out well for everybody so it's they're different uh there's there's a lot of really interesting science that we've been doing with these things that I'm going to don't have a chance to tell but I wanted to talk about what happened just last week that you might have seen in the New York Times not in the survey I'm sure and and that is that here's here's Eris again and I remember I told you that the size it is 5% bigger with an uncertainty of about 5% and it turns out we now know that much more precisely than we did when I made that first measurement because a team of astronomers in South America we're laying in wait as Eris passed in front of a star the cool thing happens what it passes in front of a star you know precisely how fast it's moving and so you can time the star disappears because it's in front of the star and as it passes in front of the star you time how long it takes and you get a very precise measurement of how big it is now you only get a measurement one one chord but the astronomers got lucky and they have two telescopes atop at the bottom they got a very precise size and that that 5% bigger with an uncertainty of about 5% well it turns out that it's on the lower side of that uncertainty and as far as anyone can tell right now Pluto and Eris are essentially the same size within we it's actually the funny thing is that Pluto is now known less well than Eris it says it'll get known better in 2015 when the new Horizons spacecraft gets there and we'll probably be able to say which one is really bigger right now you will hear different astronomers say different things because nobody can agree how big Pluto really is but I think that the fairest assessment is that the uncertainty and Pluto size is so large that they are they are basically the same size so I have to change this plot because I had it for the wrong size so let me change it ok so so as soon as this was discovered and this is one of the things in the New York Times last week and you know the discovery it's now Pluto might be a little bit bigger it might not we don't know but it might be a little bit bigger and so the big question is does that mean maybe we were too hasty maybe it should be a planet once again yeah no okay so that's the new part of the talk I mean as as when you if you just heard the news and I think a lot of people just have to do is Oh Pluto is not the knots is now the biggest thing out there again it should be a planet it almost makes sense because everybody has their lunchbox which shows it really big but the real solar system there's there's absolutely no change it doesn't actually matter even if Eris disappeared tomorrow it's not Eris that made Pluto not a planet it really is this whole band of other things and it's really Pluto itself being this tiny bit of debris at the edge of the solar system so let me end you with just one last of my object like there's so many things that we found that we're so exciting I don't have time to talk about then I'm going to I'm going to end with one just because it's it's really entertaining and one of my favorites here's an object that we found back in 2002 it goes by the name of upset enough said 'no in some well we named it Sedna 7 is the Intuit goddess of the sea and she lives in an ice cave underneath the Arctic Ocean and it was the coldest name I could think of and the reason for coming up with the coldest name I could think of was because at the time of the discovery was the most distant thing we had ever seen and the most disciplined Fitness way way way up there now if you're paying close attention which all of you are you know that it's about the same distance as eros eros was over here on that same plot at the time we hadn't found eros yet so Sedna seemed pretty distant but we had the same question about Sedna that we did later about Eris which is is it going to have a circular orbit like a planet or is it going to be an orbit like this that now we know Eris has an orbit like this where it comes back into the Kuiper belt and goes back out and the answer is none of the above it actually does that instead Sedna is on a twelve thousand year orbit around the Sun and to the Sedna is a Eris is without a doubt the most famous of the discoveries that we made in the survey the Sedna is also without a doubt the most scientifically important or the discoveries we don't know how Sedna got where it is now or exactly what it's telling us about the solar system but it is in some way a very profound fossil record of the earliest part of the solar system we're still trying to read that fossil record but entertainingly the other thing to think about is that Sedna remember I said it was got twelve thousand year orbit around the Sun we found it pretty close it's almost as close as approached and in fact we could only have detected it for about two hundred years if I was out here it would have been so far away moving so slowly so saying we would have never found it two hundred years out of twelve thousand year orbit that's one in sixty so we basically had a one in sixty chance that Eris would be in the right place Sedna would be in the right place to discover it so either we got very lucky and we should buy lottery tickets or more likely we didn't get particularly lucky and there are a lot of things like Sedna out there maybe there's sixty of them and we were perfectly even luck maybe they're only 30 of them and we got a little bit lucky maybe there's 90 of them and we got a little bit unlucky in any case the discovery even of just one object out in that region where Sedna is points to a huge new population in the very same way that the discovery of Pluto if we thought about a little harder back in 1930 pointed to a huge population of objects out there okay so now I'm going to why all the speck for your entertainment which is that subnet is is something like 3/4 the size of Pluto it's pretty big object if there are 60 objects 3/4 the size of Quito you're probably 20 of them that are the size of Pluto there's probably 10 of them that are twice the size of you that it's probably probably three or four that are that are two times the size of Pluto there's probably one or two that are three or four times the size of Pluto which is the size of mercury that's the size of Mars I think the discovery of Sedna is telegraphing the fact that this region out here about which we know so little that we don't even have a name for it yet but this region is going to be the next big place of discovery of truly large things in the solar system and I think some of them when we discover them will be the size of planets imagine what it would be like if we went from this view of the solar system to suddenly a view like this what would you call that would you call it a planet it's bigger it's the same size as Mars in fact I just cut and pasted Mars from here to here true I don't think that happens in the real solar system but that's I could get do you call it a planet you might be tempted to but now let me remind you that that's just the biggest one all of these guys are out there - do you call them all planets do you what do you call them up no astronomer has an answer for this one yet nobody knows what's going to happen when this happens but I guarantee you that when these are discovered and they will be either in the next sound within the next 10 years for sure maybe even sooner these will be discovered and the debate will reopen again in the end I don't really care how that final debate ends I don't care if people broaden the definition of the word planet as long as one thing is made really clear and that one thing is that these eight objects these eight objects in the middle part of the solar system going to dominate the entire solar system have defined the history of our whole solar system are the eight most special objects that we have our neighborhood you can call all these other things whatever you want this one's kind of big too but it's not in here dominating things and so it's a very different beast and as long as you know that as long as you acknowledge that you can ignore all the debates about what is and isn't a planet and just think about what is the solar system and that's the view I want to leave you with though so I want you to basically stay tuned I think that these things are out there I think they will be found I'm going to I'm going to leave you with the view from the current most distant object that's known as the view from from from eros here's eros there's there's Dyson Oh Mia this really is what the solar system would look like looking inward Sun Jupiter Saturn Uranus and Neptune the constellations are all in the right place as these things are discovered add these new discoveries are made feel free to follow along you can you can read as discoveries happen at my blog at Mike Brown planets or of course the much better way to find out what's going on is is always on Twitter so you can find you there it's better and and to follow up on my my name there Twitter right this somebody made this plot for me with all of all the planets back when this was all the planets but it has always bugged me so I have to get rid of that last one there okay much better and I'll take a few questions and let me just say one thing I'm going to eventually go in sign books and I see a lot of kids here at birdie kids who like have to go home and get well their parents have to get them home get them to see so anyway I'll take a few questions thank you very much in a second but I get to ask the chairs first question did you make a bet about the new belt of objects with anybody and the thing larger there Mars no no I haven't actually made made a bet about that one and I am as you now know and can read even more but I'm a very much a betting person because I think scientists don't bet nearly as much as they should because it's it's a scientist thing that they that they have to prove things to say them and a bet isn't this great thing that's not proof I can't prove something but I really truly believe it and I should be able to make a bet maybe I don't believe it enough you know my problem at but I'll bet what about we'll talk about it later all right so I'm going to encourage people to line up at the two microphones in the center of the room and we will ask dr. Brown to take the questions one at a time from either microphone and hopefully they'll be loud enough so you don't have to repeat them or you can just answer them so those of you have to leave thank you very much for coming we hope to see you in March and will now open the floor for questions at what diameter or mass does a rocky object turn into a sphere so the question is how big do you have to be to be a sphere and the answer is different depending on what you're made of so in the asteroid belt the largest asteroid series at 900 kilometers across is pretty good lease fee Racal the next largest asteroid Vesta is 500 600 corners across is not although it kind of looks like it isn't it it got hit by something so maybe it should have been so in in the asteroid belt that's the answer in the Kuiper belt we don't actually know because we can't see the shapes very well so but we know that these things are made out of more ice and rock then then just rock and asteroid belt so what we do is we look instead at things like moons of Saturn and in moons of Saturn that are made out of ice you can actually be quite small and still be spherical so two or three hundred kilometres and you're a spherical body so if you ask the question of how many dwarf planets are there in the solar system because it you don't have to be very big to be a dwarf planet in the Kuiper belt there are presumably hundreds and hundreds of round objects in the in the Kuiper belt somewhere we're yeah have you got a telescope in the southern hemisphere so the question is are every that we started out of a southern hemisphere yet so all of this stuff was done at Palomar and because of this quirk of nature we actually can't see through the earth so we can't see the southern hemisphere from from Palomar so there's this big strip of sky that we haven't scanned it we just got started with a telescope in Australia and interestingly for the first time there's actually competition you didn't have much competition back in the northern hemisphere but now there are two other groups doing this led by the two other people who I was working with when we did the northern hemisphere so all three of us are now going off and doing it and it's kind of fun actually I hope to win but if they win more power to them about something new like the pants band starts as northern hemisphere still but the one that we're using in the southern hemisphere is is the pan-starrs replicate the sky mapper Pluto has a moon also right widow has three words so actually perhaps you could settle your vet considering the planet Minor Planet moon mat total mass system I don't know but my question my question for you was that I was just wondering if there's any possibility or if you've considered whether the whether or not maybe some of these dwarf planets could possibly be ejecta from the maybe the inner solar system yeah but actually it's a very interesting question whether any of these things in the Kuiper belt could have been ejected from the inner solar system if you would ask me that question ten years ago I would have accused you have been crazy and I'm a soul cubed news being crazy but it but it might actually true we there are some of these objects that we're finding that are almost 100% rock which they shouldn't be these things out in the outer part of the solar system should be sort of half ice and half rock and we're finding very rocky bodies I think it's not because they came from the inner part of the solar system I think it's because they've been involved in a lot of collisions that knocked off a lot of ice but that's that's not settled so it's it's not impossible I think the answer is no but it's not at all what are you looking forward to finding out most when the new Horizons spacecraft reaches Pluto well okay I have two answers that I think the funniest thing the New Horizons is going to find is that their big discovery is that Pluto is actually smaller than Eris and finally cements it and that's going to be embarrassing for them but but that's just going to be funny so you know it's their show they're gonna be so many exciting things when New Horizons gets there in fact I'm more excited about New Horizons now than I was when New Horizons was was initially conceived and it was going to this weird oddball planet at the end of the solar system now it's going to something that's a lot like all these other objects we've been finding and so you're going to get to see one of these things up close and really the thing that I'm most looking forward to is is that first view that first sight of what it really looks like because it will be so different than anything we possibly thought of it always works this way whenever we send a spacecraft somewhere for the first time we have all these ideas of what it's going to be and all this scientific calculations of this net and we see it and we say oh look at that so I I just can't wait for this first picture that's gonna be fantastic thank you you're welcome throughout your talk you'd never mentioned the IAU and what they did in 2006 when they redefined a planet and they said you know that a planet has to be something oh don't even say that definitely well I mean one of the things I wanted to know is that valid well it's so there is there is now an official definition of the word planet that only a lawyer could love the funny thing is I mean look at the rest of astronomy can you think of anything in astronomy that has a definition written for it like that stars astronomers know what stars are they don't have a definition of stars they don't they don't have a definition of galaxies astronomy works it's astronomy as a descriptive science it works by concepts rather than lawyerly definitions what they trying to do with these definitions was to basically write down in a lawyerly way how you describe the difference between those eight dominant bodies and everything else they also did it something like 2:00 in the morning when the vote was coming at me literally the vote was the next day they had been arguing for two weeks it's a it's not just a bad definition it's it's an unnecessary definition the concept is rock-solid the definition is kind of me once you write down a definition in a lawyerly way then you get the lawyers involved and they're going to you know oh but this and then that is like oh shut up it's the great state they should have stuck with the concepts but but everybody wanted a solid definition but it's just not the way astronomy works is it was a bad idea and it's not a particularly good definition but it gets the right answer in it's bad way but it was there it was there it was their definition of a dwarf planet that kind of killed Pluto well it was so it was the concept that killed Pluto it was this is what is often confusing so I had this long argument when giving a talk I have long argument this this undergraduate woman who had come with her notes carefully prepared and she was shaking and she said it she said but it's because of that definition that's Pluto is not a planet it's like no actually it's not it's because they were trying to codify this concept is because of the concept the Pluto's not a planet and it's because it was 2:00 in the morning that the definition is the way it is so I I encouraged when I when I talked to like elementary school teachers I encourage them not to use that definition because I hate it when I see a class a third grade class memorized the three-part definition of what is the planet that is such a useless task and teaches you nothing you should learn what the solar system is and see why these things are planets not what these what the lawyers wrote down from the IU I would say you still use the idea the Oort cloud how's that vivid oh yeah so I don't even think I don't even talk about the Oort cloud so said no and we're Sedna is is this this huge not only to have the plot 31 but this this this huge region unexplored no one had thought of the Oort cloud is even further if I had to have the Oort cloud on those plots the Oort cloud would have been over there on 280 I think it's really really quite far away and it's the other source of comments it's so far away that I haven't yet figured out a way that we're going to see it in my lifetime but I'd like to it'd be fun to see how far away our clue to an heiress Pluto is is right now just a little bit outside the orbit of Neptune and it is so Neptune is about thirty times more distant than the the earth is from the Sun so go from the earth from Sun of the earth go thirty times further you get to neptune a little bit past that you get to Pluto if you want to get to Eris you have to go three times further away so it's really really really really way of them is Eris is the most distant thing that humans have ever seen in the solar system which is pretty cool um what's your theory on how the objects were made so the general story of how the solar system was created seems to work pretty well that the whole solar system was made when a big cloud of gas and dust collapsed down it had a little bit of spin to it and so as it started to collapse down it spun faster and faster spread itself out into a pancake and little bits of that pancake coalesced to be the planets some places there just wasn't quite enough stuff left to make into a planet and that became those debris belts like Eris and Pluto and the Kuiper belt in the asteroid belt in between that's the general picture that we've had for four centuries really the the discoveries here and also the discoveries of other planets around other stars are rewriting a lot of details of that but that basic story is still works out thank you watch is eros meadow what does air is made out of you know it's funny if you would ask me that question a month ago I would have said Eris you know it's probably more or less like Pluto it's a it's about its it's got a core of rock and then a big mantle of ice on the outside so sort of like the earth which has an iron core and then a rocky mantle this would be a rock a rock or an icy metal but we now know because Eris is small Eris is the same size as now but it's still 27% more massive so Pluto and Eris are actually much more different than I would have ever guessed so so Eris is almost entirely rock on the inside has a thin band of ice on the outside and on the very very very outer edge kind of like you know water on the outer side of the earth so very thin it has frozen gases it has frozen methane probably frozen nitrogen and frozen and carbon monoxide you're welcome okay one you can you can do the math one two three four five okay at the multiple database where scientists were arguing like children why weren't you at the debate arguing like a child it's a very good question so I actually thought pretty hard about whether to go to that debate my views on how the solar system should be described we're very well known and so I didn't feel like I felt like I was a distraction I was I was the single human with the most to gain from this debate in the sense that there was a very good chance at the end of this debate Eris would be declared a planet I would be the discoverer of a tenth planet that would be a pretty big deal but I didn't actually want it to be and so I was I was conflicted and confused enough and I also knew that my presence would just irritate people and I think yes I'm irritating but it's also just that it's hard not to be just generally irritated by you know the guy who's going to be the discoverer of the tenth planet when he walks cough syrup so so I didn't go so I went on vacation instead and tried to get as far away as I could I went to a little island in the San Juan Islands off of off of Seattle trying to trying to stay as far away from it as I could and then the press found me and I spent the entire time on the phone that my daughter was one at the time and just that perfect age where she would then start to pick up anything she could find on the desk and she would do this trying to imitate me so I should have just gone but but I didn't want to be there that's like that idea for getting away true there are searches on for Vulcan eight objects which may or may not be orbiting the Sun inside the orbit of mercury yeah if those are found to exist how would that change your view of the solar system would they matter in the same since the planets or would they just be another little banded debris no no they were so so the the question is about things inside of mercury and the name the classical name for a century for these things has been as well first I was the hypothetical planet Vulcan Vulcan for the Greek god of fire and volcanoes and stuff so I'm something and so that doesn't exist because we would have seen it so now it's there's maybe a band of debris and they are called Vulcan oints it would be the the objects in that band would have to be so incredibly tiny to have escaped detection so far but they will be interesting they'd be fun to find and tell us clues about the solar system but they will because we can't make the answer is already pretty clear they don't have any major effect on the solar system or they would been pretty easy to find the fact that we are desperately searching for any small hint of one of them shows you that they're pretty minor and the grand scheme of things although interesting bodies Department ok word eros and dis mo Nia originally named Xena and Gabriela welcome to those that were that change was there ever a chance that those names could have stuck it is not impossible that they were initially made those things so ok here's the short as soon as we find these things we study them in gory detail for as we're trying to write the scientific papers and we we being the the three of us guys who were working on this project together we come up with code names because the computer came up the first name for eros was K 1031 C really because it was found on a particular day predicted that so we make up code names for him one we found right after Christmas was Santa one we found right after Easter was Easter Bunny we had always saved the special codename Xena for one that was bigger than Pluto for good reasons I think because you know we wanted something started with the letter X because Planet X blah blah blah we wanted something that was a female because action we felt like planets didn't have enough women named women didn't have no planets named after them there's only Venus all the rest of them a male name so we want a female and it had to be mythological to fit in with all the other things and when you put those three together Xena is the only thing that works of course it's just TV mythology not real mythology but you know Pluto was named after a cartoon dog so that's okay so it's not actually true so and then when you when you name it Xena as your code name and then you find the moon you really don't have a choice but to name the moon Gabrielle so so those were the code names but because the debate about what to call these things went on for year the code names our internal code names kind of leaked out when I told a reporter from the air times and and so they got to be known for a year as Xena and Gabrielle they were never intended and I didn't actually want them to be theythey the the official names forever because I knew that when my daughter turned like 10 or 12 and she finally looked up to see what Xena and Gabrielle were she would say dad you're the biggest dork in in childhood and she still says that but I need to stop them so they were never intended to stick but I think I still fondly think of them as Xena and Gabrielle and was the cartoon dog Pluto named after the planet Pluto okay that's your plan yes yes yes exhume with them yes okay I think we're at three and so here's four have you ever seen a planet in a different galaxy well it's okay so in a different galaxy would be really really far away I mean it's it's it's hard enough to even see the distant galaxies unless you get big telescopes but astronomers have in the past 10 years 15 years now 20 years now been seeing many many many planets around other stars not different galaxies because that'd be really far away but the star is the very nearest stars seem to harbor large numbers of planets and if you you should should really if you're if you're interested this watch the news pretty carefully over the next months and year because there's there's so much new data coming down from spacecraft that that nASA has launched I'm sure that you'll have talks around here in the very near future about this kind of stuff because it's it's now is the time if you're if you're interested in that you're you're you're living in the exact right time because this is when the first discoveries are being made it's a very exciting time one word have you been able to do a do other for spectroscopy and some of the other objects and do a statistical survey of the composition routines object to that yes yeah it painful so so so you can you can you can take a spectrum you can take the reflected light off the object break it up into by a prism see what it's made out of and for the very largest objects which right that helps that's how I knew the answer to the question earlier about what's our surface of Eros methane probably nitrogen a lot of the other objects we've been looking at them and you take a spectrum of them and they're very bland they're very bland in the way that we think we understand we think you think that if you if you take basically you just take any sort of hydrocarbon and you irradiate it with sunlight for a long time it turns into the correct scientific term is and that book is composed of so many random molecules that it really doesn't have any distinct spectral features and so it makes it really difficult to understand what's going on but this has actually been the main work that I've been trying to do for the past decade has been to understand this book on all these different objects here who tried the Keck telescopes the Hubble Space Telescope we're making progress but it's it's slow going I just have one comment is that you got my email about the I want to put in a plug for Pluto's restaurant in Palo Alto oh it's good I just saw it I just saw it I didn't know is there but I just took a picture of it this afternoon as I was walking walking through Palo Alto I took a picture of it like looking like I'm strangling the sign you

Channel: SVAstronomyLectures

Views: 31,069

Keywords: Astronomy, space, solar system, planets, dwarf planets, Pluto, Eris, Makemake, Haumea, Ceres, Neptune, plutoed, definition of a planet, IAU, telescopes, astrophysics, planetary science, Michael Brown, Brown, astronomers, Kuiper Belt, Kuiper Belt Object

Id: 7pbj_llmiMg

Length: 87min 14sec (5234 seconds)

Published: Fri Feb 22 2013