 Well good evening everyone, thank you for coming out and thank you for finding the new venue. We're extremely honoured tonight to have Dr Heidi Hamill and when I was doing my research, there was no problem finding a lot of exciting things that Heidi's done over her career, some of which we're going to hear about tonight. Dr Heidi Hamill is the Executive Vice President of the Association of Universities for Research in Astronomy and they co-ordinate a huge number of activities, some of which you'll no doubt be familiar with, things like the Hubble Space Telescope. It's a very high profile kind of multi-university activities. She has an affiliate record working for places like NASA and MIT. But when I asked her just before this, well what drives you to do this and I was expecting some life changing story and I mean it's certainly a life changing story that the buyer to discover that. But what drives Heidi is the joy of discovery, of finding new things and I thought well that's just about the best answer because hopefully that's what's driving all good science and it's certainly that joy of discovery that's very important to I guess convey to the next generation and to convey to the general public which is something that Heidi does an awful lot of. She has a raft of awards for public engagement. She deserves another little extra award for coming along here tonight including things in the New York Times, in Newsweek, in the Oprah Magazine so really reaching out to the broadest possible section of the community as well as awards from the Carl Sagan Award and from the Exploratorium which is one of the most well-renowned science centres anywhere in the world actually. She feels a real obligation that if the community are funding this kind of research then scientists actually have an obligation to report what's happening. As a science communicator myself, I thought that was a particularly inspiring answer. I want to steal Heidi's thunder, I want what she's going to speak to us about tonight but it is about the impact on Jupiter and tonight I think we have Anthony Westley in the audience, do we? I'm going to make an example of you and because it's a fantastic example of university-based science working with amateur but obviously extremely talented astronomers and really coming up with groundbreaking discoveries so I think we should have a little play for Anthony because without his contribution we might not be hearing this talk tonight. And just before we kick off, I'd like to say a big hello to people at Ballarat Observatory which they are here with us on the internet and apparently they can see us all so in that spirit of community, can we all give them a wave? I hope the technology is working. Apparently they can see us, if you can see us, I hope that meant a lot I just wish I could see you back, that's all I can say but I think we should hand over to Heidi, let's make her feel very welcome. Thank you very much and I want to give some acknowledgement to some people who contributed quite a bit to the presentation that I'm going to give to you tonight, Clark Chapman, David Morrison and Mark Boslow Here's an outline of what we're going to talk about today First we're going to talk about Jupiter and me and how I ended up looking at Jupiter and then for those of you who are not interested at Savvy, the next thing is, oh my God, then seriously, then we'll do a reality check and we'll wrap it all up at the end So let's talk about Jupiter and me and how I ended up being in charge of all these common crash observations My interactions with Jupiter started with this picture of Jupiter which was taken in March of 1993 and for those of you who don't recognize it, that's Jupiter This is not one of the best pictures of Jupiter ever taken In fact, it was a pretty awful picture of Jupiter but Jupiter was not the most important thing in this picture This was the most important thing in the picture and if you can't make that out very well, here are some other images of it What this was was a comet that had been captured by Jupiter's gravitational pull and was in orbit around Jupiter and it got a little too close to Jupiter and got pulled apart and then the next time we tracked its orbit very carefully and we knew that this comet was going to collide with Jupiter that was known for tracking its orbit Here's a Hubble Space Telescope image of the fragments and let me turn off the light so you can see it a little better I got training in this How's that? A little better? Alright, so we being scientists named the individual fragments very creatively You notice that some of the letters are bigger than others because those are brighter fragments and therefore we assume they are larger pieces of the comet This was a comet because it was fuzzy in the sky You'll notice that some of them have double letters because those comet pieces actually broke up after the comet was discovered Alright, so we named a fragment P but then it started moving If you look closely, you'll see that there's some things missing Some letters missing? I, B, J, O, N Well, I and O we deliberately left off because they looked like ones and zeros so we didn't want to be confused but M and J actually were there when they were named and then they dissipated by the time that this particular image was taken And I also want to ask, I like to ask people why do you think the comet is red and yellow in this picture? Any guesses? Hot? Alright, a comet is made of ice It's a ball of ice So it's not because it's hot Any other guesses? Infrared image, that's a good guess People told me that this group would be really sharp but that's not the answer It's a visible light image Elements, yeah, potassium, sodium Good guess, no The answer is it's colorized red because the guy who made the picture thinks it looks prettier That's the only reason it is red Comets are actually balls of ice Dirty ice, what color is dirty ice? You get snow here? Yeah, it's like gray, right? That's what this actually looks like but it's colorized this way so that when you want to put it on the cover the New York Times it looks really cool Alright, so whenever you see pictures like that don't get misled, alright, so let's move on Now, people had predictions of what would happen You guys in Australia should be happy that it would only have caused a U.S. ice age I don't know, that actually didn't happen but in fact we did know that it was going to hit Jupiter and so every telescope on Earth and in space was going to be pointed at Jupiter when this comet crashed into it in 1994 Now, the reason I got involved is because I was at MIT at the time and the fellow down the hall from me at MIT was an atmosphere theorist and he put together this theory of what would happen and this theory said after the impacts occurred there would be these rings like ripples in a pond and I said, really? He said, yeah, I'm sure we're going to see this in a couple You have to help me write an observing proposal and I had never used Hubble but I had written a lot of observing proposals so I said, sure, I'll help you write your proposal and so I wrote a proposal and I sent it in with all the other proposals that went in and I got a phone call in January of 1994 and they said, we have selected your proposal and I thought, that's great and they said we have also decided that we're going to take all the separate proposals that we got and put them together into one thing and we want you to lead the team and I've never looked at Jupiter before and I think that was why because the other people were experts in Jupiter and I think they thought maybe they used the authority to do their own special science with Jupiter whereas I had no worse than the race because I studied Neptune, I didn't know any about Jupiter so that's how I got to be a team leader and when we were in the control room down in the basement of the Space Telescope Science Institute I got to sit in the front row because I was a team leader and we got amazing images and many of you have seen some of these images this is a little time sequence from the very first impact where you see this massive clue let me give you a sense of scale this is sticking out 5,000 kilometers above the cloud tops of Jupiter and then when it rotated to view this is one of the impact sites and we'll come back to this one later this was the G impact if you recall G was a big letter it was a big impact and the winds of Jupiter were smearing these things out alright so there's a few takeaway lessons it was an absolutely fabulous tracer of circulation in Jupiter's atmosphere normally in astronomy we don't get to interact with our test subjects we just look at what's going on but this is a case where nature injected dye into the atmosphere of this planet and we were able to track the dye as it moved through the atmosphere and it allowed us to trace atmosphere circulation in a way that we could never ever have done in any other way so we learned a lot about the circulation of the atmosphere of Jupiter we also learned a lot about large explosions and some of the people who were most interested in the common crash were the people who model extremely large explosions nuclear bomb explosions and they can't do those tests anymore this is not allowed by international tree so this was their opportunity to actually have models of real world explosions to test their models against and there were actually some very surprising results and you can ask me about that during Q&A if you want we're happy to share with you some of the surprising results where we've actually when I did this talk in the US we're enhancing US national security I can't really say that here for you but you should be happy that the US national security is enhanced I guess another really important aspect of this was we showed in 1994 that the solar system is still a dynamic place things change big things change there are cosmic collisions going on and you know we know that I mean I bet a lot of people in this room have actually seen a cosmic collision have any of you ever seen a shooting star? you would have seen a piece of a comet or an asteroid hitting yours atmosphere small piece not big like these but you've seen a cosmic collision but I'm going to talk some more about some really big collisions now how often did these things happen you know after SL-9 in 1994 people did a lot of thinking and modeling, a lot of studies and there was a paper published saying how often they happened and for relatively small fragments there were little letters every 500 years or so for big ones like Schumacher-Leigh 9 every 6000 years or so so I'm like wow I'm just really lucky to be in a one I've got to watch this one that only happens every hundreds or thousands of years right well let's fast forward 15 years after Anthony who with his own telescope right here in Australia where Baton actually is very close by he comes up one day and buys this spot on Jupiter and what I'm going to do now is show you my life the next 26 hours of my life after Anthony discovered this feature just so you know how these things really work alright so there's a little timeline going to go up here right so 2 o'clock Eastern US time is when we think the impact actually happened and I think Anthony you actually saw it how many mid-light local time which is how many hours after Anthony 6 or 7 6 or 7 hours after this he saw it email starts flying around the amateur community around 8 in the evening on my time no 1130 in my time where an amateur astronomer emailed me just out of the blue and I was up because I have 3 kids alright so I was up at 1130 at night and so here's an image of a probable common impact on Jupiter discovered by Anthony Wesley it's as dark as a moon's shadow with the wrong shape and how many shadows are predicted on the other hand I was imaging the same area 8 hours earlier it got nothing so that was my first hint that something was going on at 1130 at night and so I started googling what else is he going to do at 1130 at night and so I started seeing all these amateur reports about this so I emailed Amy Son Miller at 1130 in the morning I haven't gotten to that yet so Amy is a scientist at the Goddard Space Flight Center my last images of Jupiter were in 1994 that Amy had been actually doing real science using the Hubble Space Telescope looking at Jupiter since then so I emailed Amy if this is real do you want to collaborate on a Hubble director's discretionary request we asked the director please give us time I'm not sure yet whether I believe it or not but it's quite dark my phylogy's not convincing sorry Anthony but that's where Hubble may help your experience with Hubble Jupiter imaging is more recent than mine, what do you think and then I went to bed because I figured if this was real I wasn't going to get a lot of sleep for a while so in the middle of the night I thought this is when I woke up there was an email from Glenn Horton who was an astronomer at the Jet Propulsion Laboratory to Augustine Sanchez-Levega an astronomer in Spain and she's seeing Amy and I I'll see what happens what is serious over the long term he was observing and asked him for a telescope I'm copying this to Amy and Heidi any chance of mounting a very rapid Hubble director's discretionary type proposal I'll try to verify tonight with IRTF but it looks like Jupiter may have been hit again so when I woke up I wrote Glenn I'm already a few hours ahead of you on that I contacted Amy last night any chance that we get coordinates or predicted central meridian longitude transit time for the next few days I've also learned that Inka at the Potter at Berkeley she has kept time with the laser guide star the night after tomorrow and Inka and I actually planned Jupiter observations for the day after this we can't preserve it during the last alright so now look at the time so now the time dance is about six minutes I got this message from Glenn it's near to 300 degrees west and the system's between longitude observing now more later now Anthony knows Glenn and I know Glenn Glenn is one of these people in chapter chapter and when I got this email I'm like I know Glenn's working really hard there must be something going on so I emailed Matt Matt I'm the director of Space Telescope and just later saying Matt community is a buzz possibly impact on Jupiter people have already asked me about possible director's discretionary time for Hubble images I'm contacting you to see if we can do that Glenn's hearing up IRTL yada yada yada yada alright so then after I sent that email to Matt this is what I wrote to Glenn the question is, do you really think it's an impact? is it hot? it's certainly dark for morphology in one image I don't want to amount a huge effort if it's just a regular Jody in dark spot then I get this message from Glenn oh yes super bright near to microns and ammonia emission at 9.8 microns this is what he was seeing at the telescope okay so then then I get this message from a reporter at Science Magazine it's only 8.20 something in the morning and the reporters this just came in the Twitter emailed to HVH and the impact were just a brown spot so already the reporters are calling me asking me and I don't even know what's going on yet but we're making enough as we go along because that's what we do then Augustine emails Amy and Glenn and I saying attach this message we've just sent to the Spanish observatories in the Canary Islands and call out Alto with our predictions for the next transit when it's going to be visible we have the International Outer Planet watch we have received additional images we're navigating them now so I think we'll have better predictions for tomorrow so things are really going along here and it's only 9 in the morning alright time goes by I emailed to all those people including if it's a potter I said Amy and I have the Hubble proposal in the works I have alerted Inka for the CAC Observatory tomorrow night in contact with Doug he is the director of the Gemini Observatory I go offline at 11.15 Eastern for a few hours children have to go to the orthodontist and the doctor too hard to reschedule but he was paring out there you know what I'm talking about you don't blow off the orthodontist alright so then I emailed, just before I go to Donna they emailed Doug, I said Doug you may have heard about Cedent and Jupiter we request director of discretionary time on Gemini then I go off to the orthodontist so Matt, director of space health calls me on the phone in the orthodontist office so I'm sitting there, my child and I'm talking on the phone do you really want to do this Heidi you know what, stay here you don't understand this I'm like yeah I understand the whole thing because I did, I knew what he was going through it was really awful but then after our conversation he emailed the rest of the Hubble team off the phone to Heidi clearly she would like to do this and would like the UV and blue filters she has promised to send in a DD proposal today she understands the constraints we are operating under now I'm going to show you the constraints that we're operating under this was in the middle of the summer Hubble had just been serviced in May by the astronauts seven astronauts have just risked their lives to go up and service Hubble and put in all new instruments after they put in new instruments they have a period of time that they call the servicing mission verification period smoke servicing mission orbital verification this is a plan and I had seen this plan before and I knew this plan the black is the plan observations this was the servicing mission and then this period of time then you can see there from May through June, July, August, September this is when they're checking out the instruments that have just been installed on the telescope they're checking out the new advanced camera for surveys they're checking out the imaging spectrograph they're checking out the new UV channels the infrared cameras, the new cosmic Gordon spectrograph they're going through and putting everything through his paces to make sure everything works and then the red stuff up there the EROs early release observations these are the observations that the teams built that equipment planned for years to do to take the most beautiful images so that they would get the fabulous publicity that Hubble deserves nowhere on there does it say look at an impact on Jupiter so it's huge this is a very choreographed thing and you don't just interrupt it but we did and it was not easy here's what Matt then went on to say she understands the traits we are operating under and that we are separating the issue of getting the data from how and when we release the data because that was a huge political issue a contractual issue lawyers were involved and it had to go all the way to the head of NASA who turned the golden had to sign off on us changing the plan to take the observations but we did it was too important to pass up on thanks so Mike Wong then it's 3 o'clock now it's been just 24 hours since the impact less than 24 hours since Anthony saw the impact Mike Wong sends me a note and says he's at Space Telescope he says everything is doing one hour I don't know okay I know BPI we'll submit the phase 1 and then for 15 p.m. so it's 26 hours and 15 minutes from impact our submitted phase 1 director's discretionary time proposal is attached there it is so that is how you get from here in Australia to 26 hours later Hubble, Kepp, Jen and I are all online and ready to look at the impact site I thought that was pretty nice press release press release friends in Ballarat can't see so it's a little hard to put your hands down okay well then we won't be able to see very well they can't see me with the slides they can't see both so sorry put them on and we'll see most of it's pretty bright this is the impact site this is a Hubble image so you can see a lot of the detail in there how's that working for you guys different okay good now here's some results that Augustin remember the picture he's from Spain showed one of the first questions people asked us was is this just a piece of SL9 that missed Jupiter and came around again and so what we determined for this impact is the entry was coming from that direction and being ejected in that way whereas in Shoemaker-Levy 9 it was coming from the south and being ejected that way and there's no way that it could have changed its orbital direction so it's very clear this was not a piece of SL9 that missed it was a different thing and that's the priority here are some Hubble images showing the evolution of that impact site from the top where you first saw it further on down and that is just due to the winds of Jupiter spreading it around now some people said look at those dark clumps in there does that mean that maybe it was more than one thing going in so we looked at that and we'll come back to that in a second about this clumpiness so that's this impact 2009 in fact here's an example of something we saw in 1994 the H impact site and it looks clumpy too right but that's all due to the winds when this feature started it was a tight feature and we actually watched as this material got sucked up into this Jovian vortex so this clumpiness here pretty sure is actually just due to Jupiter's winds stirring up this black stuff and what is that black stuff anyway it's black clouds when this when these fragments hit Jupiter they're coming in at a very high velocity and they cause large explosions and the explosions turn into basically soot which rains down in the atmosphere making black stuff in the atmosphere so that's what this black stuff is it's not holes in the clouds so these are similar to one another but there were differences between Shoemaker-Levy 9 and this 2009 impact so let me just show you several of the differences alright first of all for Shoemaker-Levy 9 we saw a lot of halos if you look up there in the UV that top row is ultraviolet you see how this fuzzy around it it's sort of like kind of a body sort of nature when we looked in the 2009 data we didn't see that in 2009 the UV data looked just like the visible data so the way we interpret that is we know for a fact for Shoemaker-Levy 9 that it was a common fragment surrounded by debris like dust and this is a piece of evidence suggesting there wasn't a lot of dust surrounding whatever that object was alright so it didn't have a coma like a comet see this evidence that it was a solitary body ok so another piece of evidence comes from how long this stuff lasted this is 1994 and the sequence we talked about is something like 11 days and this dip is how dark the impact site was out to the bottom it stayed dark for like 10 days at least 10 days in 1994 but in 2009 the impact site faded away within 10 days and the way we interpret this is just maybe these are heavier pieces that precipitate out of the atmosphere so you don't see them anymore whereas in Shoemaker-Levy 9 it was fine dust that hung around but in the initial we don't know for sure but that's one way to interpret this data ok so it suggested that there were heavier particles in the newer 2009 impact here's another piece of evidence for Shoemaker-Levy 9 every time one of those fragments went in there was a big blip in the radio emission computer and so that was interpreted as saying the radio emission comes from the magnetic field part of this bouncing around the magnetic field and when someone of these conic fragments went through it disrupted the bouncing of these particles and that gave us a radio signal there was no radio signal for the 2009 impact again suggesting it was not a big coma of dust but some very small single body and finally what this is is infrared spectroscopy from the Gemini telescope and the 2009 is the silicate emission that was not seen as Shoemaker-Levy 9 the silicate emission says to us rock not ice but rock so any one of these lines of evidence taken by itself is weak but when you put all four lines of evidence together that really suggests to us that the 2009 impact was probably an asteroid and not a comet a single rock that hit the planet so all of those four things that I just talked about there's a second once in a lifetime event woohoo alright it was the state of mess on 9 and it actually had people starting to think well gosh what did we do belonging to that paper you know we're in 1997 where we said it was once in a lifetime clearly it's not once in a lifetime and guess what the next year we're third once in a lifetime event and it's funny about this one the previous one we had written all of our work up and it was in press and we had the proofs when we had this event so we added a line to the bottom of the paper saying oh by the way there is yet another impact on Jupiter now this one was detected by Anthony again and another fellow goes to forego and it's a video sequence it's two different ones here from two different telescopes and I don't know which one is yours Anthony can you tell by looking it's one or the other I think the top one is mine mine was red line this is a little video sequence showing us getting brighter and then disappearing so we again common-year in all the large telescopes and we looked and you look in those boxes that's where that flash occurred you don't see anything so what that was was a shooting star on Jupiter but it was not big enough to make a big impact site it just burned up as it went in but it didn't leave any impact site so now we know when we see these flashes we now know if it is only this bright we don't common-year the big telescopes anymore you know and all the directors of the big telescopes are very happy about that and it's good it's good to know because you know we can now constrain whether or not we ask for time and it's also good for the people who like to do models of these things because they can understand they can do models of big ones and now they can do models of the smaller ones as well okay so there are three key lessons I would say that we took away from these newer events first of all there's a variety of things that smash into Jupiter it's not only comets it's comets and asteroids it has helped us refine further the chemistry of these large explosions and the solar system is now more dynamic than we even thought and perhaps more dangerous and what do I mean by dangerous I like to show this to scale this is about the size of the Pacific Ocean and you know that you can say that but I don't think that really conveys really the enormity of these impacts so here's a picture of that G impact remember I talked about the G impact and so one of my colleagues John Spencer took that and mapped it to scale onto the planet Earth and that's what it looks like this is what we call in the biz a biosphere changing event another way to phrase that is we would all die if this happened on the Earth and this was in 1994 and maybe these little boys were around then but we all were this kind of stuff is going on right now right now in our solar system Anthony's seen two of them you know it's happening folks it's real oh my god alright impacts happen all over the Earth all the time and some places look like they have more Australia but that's just because it's easy to find them especially in the desert part of Australia because they just sit there big holes in the ground and they are big holes in the ground this is a crater that is in Arizona how many of you have ever been there meteor crater Arizona I guess still on the edge here can you see the road you see the road you can stand on the edge it's a really big hole in the ground all right meteor crater was formed by a low altitude air burst and I'm going to talk a little bit about that the kinetic energy that formed this crater according to people who modeled it was about 9 megatons that's a lot of energy but they think most of it happened in the air this is not where something hits the ground some of it hit the ground but most of it happened in the air there's two kinds of low altitude air bursts type 1 the explosion creates this fireball that comes down rapidly but it actually does not hit the ground the damage on the ground is mechanical shock waves things are knocked over and it happens between 1 and 10 megatons maybe up to 20 megatons happens on time scales of every 100 years or so the only known example in the recent past is Tungusco and I'll talk a little bit about Tungusco there's another type of low altitude air burst much bigger gets all the way to the ground the damage is caused by thermal damage in other words it just burns everything up about 10 megatons or above every thousands of years or so the best example is Lydian Desert Glass for those of you who like pictures here's a picture of what I just said type 1 blows up in the air type 2 gets to the ground both cause a lot of damage let's talk about Tungusco this happened in 1908 in a remote part of Siberia there were people who actually witnessed it no people were killed some reindeer were killed it was a massive massive explosion in the air these are artist's conceptions based on eyewitness accounts of what happened there 60 years after it happened people went, teams went and this is what they saw trees knocked down and they mapped out the pattern of tree fall and where the red dot is there were still trees standing but they had no branches and all around them trees were knocked down radiating away from them so this is the tree fall patterned Tungusco and this is a simulation by Mark Boslow of the actual explosion and from the shape of the impact he can predict the angle it came in the velocity it came in etc now showing pictures like this really doesn't give you a good sense of scale how about we put it into a local perspective can you bear can't bear I was a coach today there it is the impact of Tungusco to scale on camera here every tree knocked down inside that area every structure knocked over inside that area now do you feel the oh my god it's happened in 1908 your grandparents were alive when this happened thank goodness it happened in a remote part of Siberia I'd like to show this next slide that's Washington DC that's where I work nation's capital of the United States and this is to scale this would do a lot of damage if this happened today over a populated area millions of people would die instantly this happened fortunately in an unpopulated area scared ya so we're just talking about the type 1 let's talk a little bit about type 2 and like I said the best example is the Libyan it's called the Libyan desert type imagine imagine a massive explosion that hits the ground in the desert where temperatures are tens of thousands of degrees 40,000 degrees what's going to happen you're going to get glass and that's what you get this is a piece of glass found in the Libyan desert this is the sign that there was a massive impact and it was a long time ago you can tell that by doing isotopic dating of stuff inside that glass when it happened it was a barrier in a long time ago but how long was long well here's a little graph that shows you the TNT equivalent in megatons and then how frequently we expect them to happen we put Hiroshima and the atomic bomb and the US dropped in Japan and events like that happened in the Earth's atmosphere every year did you know that? I actually didn't know that until I started hanging out with those people at the Indian National Archives there was a 5 megatons explosion over the Pacific Ocean last week I didn't know but it does, it happens all the time it does happen roughly every century let's do the math 1908 plus 100 where does that put us? now fortunately most of the Earth is covered with water so the next to a ghost guy it's likely to happen over water but who can say? global catastrophe every million years or so Libyan desert 10 years ago seriously? really? am I just pulling my leg here? do we really need to take this seriously? yes we do there's lots of space rocks out there the more we look the more we find we call them here Earth asteroids here Earth objects potentially hazards whatever name you call them there's just some of the rocks that we visited with spacecraft let's show this plot this is 400 just 400 of known near Earth asteroids orbits every red line is near Earth asteroid and common near Earth asteroids because let me show you now I'm looking down on the solar system here's the Earth orbit now there's only 400 we know a thousand of them there are a lot of things out there a lot of them so we're looking there's a series of small telescopes that the NASA and the US Air Force has deployed I've got a real boost after Shoemaker leaving 9 we'll be able to show Congress pictures of devastation real time in the solar system and so here's a graph of years 1980s all the way through 2006 and all the near Earth asteroids are in blue and the large ones are in red 1994 a year or two to get Congress convinced another year to build your telescopes and woo! you're finding thousands of objects when this graph was made 2006 we were up to almost 5,000 now we're up to over 10,000 none of them are going to hit the Earth that's good but this doesn't get us all the way so we are building other telescopes to actually get all the way we're trying to get to 90% by the end of this decade if we build this machine which is the large survey telescope this telescope will help us get to 99% including the faintest asteroids it's a monster data machine 2 terabytes per hour 10 million objects in real time and so this is the telescope that we are working very hard to build because this is one of the things it's going to do is look for these things and it works here's an example of one that was discovered in 2008 and an email alert went down to the community today this object was submitted for impact monitoring probability of impact is according to different computations done in slightly different ways between 99.8 and 100% in other words the impact is before and is for tonight and it's actually seen the impact was seen by a Dutch pilot who was flying over Africa there's a picture of its remnants in the sky over the Sudan and it was discovered 20 hours before it hit and so we were able to track it all the way in and not when we were able to track it all the way in but using Google to track its path and find out where and make predictions about where the fragments would be and in fact they found the pieces they're all pointing to this piece they found the pieces of this on the ground so this process that we have of looking for things that are coming in a collide with the earth we actually, it works it works and we can find them so what happens if there's a big one alright well astronomers put together a scale, kind of like the earthquake scale they call it the tarino scale I'm not going to read all these words to you let me just say that if you ever hear astronomers say we found an asteroid with a tarino scale right between 8 and 10 go out buy nice bottle of wine buy your favorite stock just enjoy your last minute summer alright not likely to happen because we are looking but what do we do what do we do if we buy we have a lot of ideas actually conference is every year when people get together and say what are we going to do if we find an asteroid that has earth written on it so we know, we have different ideas some people say let's put a gravity tractor, you set a spacecraft right next to this thing that this takes years so you have to find your asteroid like 30 years before it's going to be earth which we can do because we can integrate the orbit's area and you set it there and the gravity of your spacecraft just very very slowly pulls this thing off course if you do it 30 years ahead of time you don't have to move very far it'll miss the earth some people have an idea, use a kinetic impactor where you sort of push it like with an explosion if you find this object coming in you only have 60 days alright there's not, none of these are going to work you're going to have to do the Bruce Willis you know that just when you ride up there you set out a nuclear bomb which is kind of dumb because let's think about it you got this giant rock coming in heading towards earth and then you blow it up what do we got a lot of rocks coming in the thing he knows that maybe some of them will miss maybe hit your enemies instead of you I don't know it's not a very good idea actually this is what I like the best actually if you find this thing 20, 30 years out you set up some kind of a big deployable mirror and you shine sunlight on it and you use that to create what we call non-gravitational forces in other words you make little jets of water that come off this thing and why restrict yourselves to one people come with this whole mirror beam thing we swarm this thing with sunlight this is just focused sunlight and push it off its course I'm just giving you some ideas there are people who actually say jobs do this kind of thing I'm just sharing it with you we do have ideas on how to deflect them should we find one that's coming in but let's do a reality check first okay what hazards do you worry about do you worry about anything but you're afraid of dying from car accidents yeah anything else diseases plane accidents absolutely I'm sure lots of things something about lightning sharks always big topic in the news sharks people does that happen in Australia just check airplane crashes like someone said already terrorism in the US big deal right now ever since 9-11 I worry about elevators it's my personal thing we all have our personal hangouts we all know big killer people around the world car accidents like we said obesity those are big killer diseases so those are the things that we really let's put that into context now Clark Chatman and Dave Morrison actually put together a list after Shoemaker leave 9 of what US citizens actually die from so this is US centric but I'm sure it's not that dissimilar in Australia and here's their list number one motor vehicle accidents that's what you're likely to die from in the United States murder, fire, firearms then comes the common asteroid impact now the reason this probability is so high is because if you hit it kills a lot of people a whole lot of people so that's why on this list it's high and there's actually a range there's the lower limit and the upper limit so you see there's a range there and there's things like aircraft, tornadoes floods you didn't have a lot of that in the United States floods then despite the stains I think that's more of an issue here that might be on the top it might be on the top for you guys and then fireworks accidents poisoning all this kind of stuff so this was Terrorism in 1994 but this chart was made but it comes in right about there so that was the range in 1994 since the space guard went off that range has dropped because we've discovered things and we've ruled out a lot of probability of impact it's dropped by 2000 and it dropped to here 2005 and it dropped further 2010 we're down to here so as of now you're far more likely to die of a plane crash or in the United States a venomous thing than it is so we're on top of this situation so let me back it up for you here there was a lot of science enabled by these Jupiter impacts and I talked about that tracking the winds in the atmosphere studying things about the planet studying things about the population and objects in the solar system but there's other takeaway lessons that I want you to leave here and one of them is the world today for amateur astronomers in studying the universe I'm just talking about comet crashes here but there are other observations that amateur astronomers make they are studying super-node the super-node are typically found by amateurs who are out looking for things and then the astronomers, professional astronomers like me use the really big telescopes to follow up looking for planets around other stars a lot of that work is being done by amateurs now and then we do follow up work so we've really changed a lot in how we do astronomy now it used to be that professional astronomers would just do their work now it's much more of a synergy between the amateur community and the professional community and I think that's a great thing and I want to encourage that second of all, the solar system is much more dynamic and dangerous than we thought but let's be sensible about it as we just went through I have insurance I have insurance on my house I have insurance for my car I have health insurance I do not have comet impact insurance it's just not something that I worry about on a day to day basis and you shouldn't either what you should do when you go home from this talk today to really take care of yourself and be safe sit buckle up ride safely yeah it seems to me that there are a lot of things hitting Jupiter so have you looked at the records of the long duration observations of Jupiter with HST for even tinier ones that you hadn't recognized before and have you found any? yeah so the question is seeing how many things are hitting Jupiter have you gone back through records to look for older ones to look for things we might have missed the first time around and the answer is yes we have especially after 1994 Schumacher Levy was such a big so obvious how many of you looked through a little telescope and saw the black spots on Jupiter I mean it was just so easy to see we actually had a program going in the 70s and 80s called the Pleasant Air Patrol where we had four telescopes 24 telescopes faced around the world and they were doing imaging of Jupiter and other planets so Mark Jutman went through them and looked at all the images and didn't find anything like Schumacher Levy 9 now he may have missed something like the 2009 event he may have missed that but he says no a quality of the images that we had was not as good as what Anthony is doing now and it's the kind of stuff that Anthony is doing with the very high speed imaging with electronic cameras is much better quality than the photographic work that we were doing in the 70s and 80s so it's possible even as something and there's another very intriguing story which is probably debated in the astronomy community but Cassini, the astronomer not the spacecraft Cassini himself in the 1600s in his sketchbook he showed a dark spot that evolved over a period of weeks and it looked a whole lot like Schumacher Levy 9 it was dark and then it spread out and I've been in the picture I showed there are people that say no and possibly me but it sure looks like that so the answer is we look, we haven't found any obvious traces in the data that we have but it's not as good as the data that people are getting today and so really I think the way we do this is we have to go forward and encourage our amateurs to keep looking so we can build up better statistics that one we think that the one that Anthony found was I think 300 meters across just something not very big but they're moving very fast so they take explosions are there questions? yes what's causing the explosion there's explosions you need to feel I mean in oxygen to react to the feel oh I love this question come up here please I need to hear some time I'm sorry Addie okay Addie so do you swim? okay so imagine Addie so you just step into it what happens to you? you float so now have you ever done a high dive? yes you get miserable fail did you land on your stomach? ow alright so you know that that that hurts alright that you have been thrown out of the airplane sure without parachute and you land in the pool down how hard did you do it? very hard bad it's very bad that's a bad thing now Addie I'd like to imagine you coming in from outer space at the velocity of 137,000 miles per hour and then you can pool down I exploded mine basically that's what happens now the pool is still liquid water right and you're still a guy it's the pool but it's the velocity that you're hitting the pool with and the atmosphere of Jupiter here is the same thing although it's a gas when you hit Jupiter going 137,000 miles an hour when you hit that atmosphere that's enough to cause a massive explosion but that's going to shatter me not explode it has enough fireworks what really happens here thank you what happens this is what the guys at San Diego do the models what really happens is this fragment is coming in alright it's coming in and it drills a hole and it creates a superheated column it's going so fast that it super heats this gases as it's going in and the temperatures get up to 40,000 degrees of superheated gases and when a gas is heated to 40,000 degrees what does it do? it expands and where is it going to expand into well the surrounding atmosphere maybe but in fact the best place is the superheated column that's just been evacuated by the fragment coming in so that's why the things come in at this angle but then they jet back out the path of entry and form these monstrous plumes thousands of miles high of superheated gases and it's those superheated gases that make the black stuff it's basically soot so it's not so much that there's oxygen there but it's superheated gases that are just jetting out of the atmosphere are there questions? yes you're mentioning that explosion in 1908 is a once in a century type event I hope they're not more common than that I was reading fairly recently about intax in 1930 and 1935 both in South America I don't know much about them apparently there's one in the Amazon Valley and one up in Kiana one's somewhat smaller but another it's actually large apparently I don't know anything about that but I'm not surprised as I said the people who monitor these things say these kinds of things do happen fairly frequently and so in the remote parts of the country at times when we didn't have instant communication everywhere like we do now we easily imagine a massive explosion occurs and nobody knows nowadays we all know if Lady Gaga blows her nose we all know it everywhere in the world so if there's a massive explosion everybody knows but 30 years ago that was the case 30 years you could have a massive explosion and if it didn't happen over Washington DC or London or Canberra then you wouldn't know about it what decides whether the impact that is going to explode in the air or in the air or in the ground as in the future of crater as yes so the question is what determines whether or not an object will make it all the way with ground and create an explosion there or whether it burns up in the atmosphere and it's a combination of factors there's two main factors one is the size of the body big ones are going to make it further than small ones the shooting stars that we've all seen are typically the size of a pea and they just burn up in the atmosphere things that are the size of gosh I don't know what you use here in America I would say the basketball bowling balls I don't know what you use things of this big typically will make it to the ground they won't cause craters like meteor crater the thing that caused meteor crater was probably the size of a giant bus or something like that big, really big and it's not just size though it's also the strength of the body there's different kinds of things flying around in outer space some asteroids are very hard, they're iron nickel, they're metal they're chunks of metal more than the inside of planetary bodies like when they formed and those things they're so strong they will get all the way to the surface of the earth even if they're only this big because they're metal but then there are other kinds of asteroids and comets that are stones rocks or in the case of comets ice and those things tend to break up higher in the atmosphere even if they're larger so it's a combination of the size of the body and the density or tensile strength of the body and it's a complicated interplay between those two that keeps the guys that sit in the international labs very busy doing that because you're at Molly that is just a question given the relative frequency of this what danger would be of an impact looking like a nuclear attack and unleashing nuclear on again so how would you distinguish between a nuclear bomb or above ground testing and one of these impacts well the answer is nowadays they're monitoring all the time and I didn't know this either until I started hanging out with these guys but they have satellites up there that are monitoring all of the earth and they can tell the difference between a nuclear explosion and one of these explosions they have the colors and the intensities and also by the fact that there's always some kind of incoming you can see it coming in so people are watching here carefully they have their ways they don't share the likes of me because that would be violating national security but they know how to tell the difference they the U.S. military the Australian military I'm sure they know how to tell the difference which is radiation you all know about that yeah we've seen impacts on Jupiter what about Saturn, Uranus and Neptune what does the modelling say about whether we should see impacts on that the models say that Saturn it should be possible if there are big events like we saw on Jupiter that we should be able to detect them on Saturn and this and Neptune are too far we would not even if they would give me Hubble to use every night to look at Neptune which they won't because they would look at galaxies and stars and other things but even if they gave me it wouldn't be enough you couldn't detect these impacts Jupiter is big gravity well it's a big planet and so it tends to it's like what we say in America it's the broad side of the barn it's a gravitational field it pulls in these comets and things so it's more probable that Jupiter will be here than Saturn but there are people who think that we could see a Saturn impact should work so keep looking now it's interesting now there is circumstantial evidence that these impacts do go on in the outer solar system and in the case of Neptune it's actually the carbon monoxide content of the atmosphere we look at in the atmosphere of Neptune and there have been raging debates about whether it's somehow coming it's internally generated endogenic we call that or whether it's exogenic coming in from the outside and that debate was going on for a long time in literature and then after SL9 people really started thinking this really could be comets and other material in the outer solar system going into Neptune's atmosphere causing that chemical change and so one of the signatures we're looking for is if one day suddenly there's much stronger detection of some carbon mirror species in Neptune's atmosphere that will be a clue something may have hit it so that's the kind of thing we keep our eyes out for so far we don't have that but it's a possibility it's a possible way to detect it out there