 Welcome to the public night, everyone. So my name is Adam, but before I start, I'd just like to acknowledge the traditional custodians of the land that Mount Stromlo and Canberra sit on, the Nunawal and the Nemri peoples, the first astronomers, and so I'd like to pay my respects to their elders past, present and emerging. So I'm the first speaker. My talk is going to go for about 10 minutes and then we'll have some questions. If at any point you have questions, please just pop them in the chat below and I'll get to them in all of the end. So we'll have about maybe 10-15 minutes of questions depending on how many you throw at me. So once I'm done, Brad, who you just heard, will come back and he'll do some stargazing. And then we'll hear after Brad's done from our next guest at about 7.40 or so, Dr. Noelia Martinez, and she'll be talking about how you can use lasers to improve your, our view of the night sky. And after that, Brad will do some more stargazing and then we'll wrap up probably around quarter to nine. But with that out of the way, I will get started. So I like Jupiter and hopefully by the end of this, I can give in some of you that Jupiter's a pretty great planet as well. But let's, you've seen now probably a few loops of this video I've got going. And this video was taken in 1979. And it was as the NASA's Voyager 1 spacecraft was heading towards Jupiter. And it was, it took a picture about every 10 hours, which is the time it takes Jupiter to turn around. And it did this for about 28 days as it was getting closer and closer and closer, literally millions of kilometers covered in these 28 days. And you can see some beautiful motion on Jupiter here. But what, who am I? What am I doing here? Why am I talking to you? So I'm the PhD student at Mount Strongwell Observatory at the Australian National University. And what does a PhD student mean? That means that I'm studying and trying to answer questions that science doesn't know the answer to yet. So I'm trying to answer questions about our natural world. And for me, I use the biggest telescopes in Australia to study stars red in color and cooler in temperature than the sun. And I do this by using their light and I split their light into rainbows. And every star has a unique rainbow. And I can tell a lot about a star from its rainbow and maybe even something about their planets too. But I'm talking about our sun and the planets around it tonight. So we'll leave that for another talk. So here's our solar system. And we've got a lovely graphic here and I'll point out that the planet's sizes are to scale. And what that means is that Jupiter is really that much bigger than the Earth and really that much smaller than the sun, for instance. But the distances between them aren't to scale. So Jupiter isn't actually that close to Saturn. But what we can see here, we've got the sun on one side and we've got our four rocky planets. We have Mercury, Venus, Earth and Mars. And we have our asteroid belt, which is full of leftover rocks and material from when the planets were born. We have our two gas giants, Jupiter and Saturn. Then we have Uranus and Neptune, who are our ice giants. And then we have a kyber belt, which is where Pluto hangs out. And you can sort of think of the kyber belt sort of like an icy asteroid belt. But I'll just draw your attention to this bar that's blown up and it was just down the bottom of the center. This shows the distances in the solar system to scale. So you can see that Venus and all our other rocky planets are all quite closely packed together close to the sun. And then we've got Jupiter and Saturn and there's quite a big distance between that and the rest of the planets. And Pluto's way off and it really just shows how big our solar system actually is. But what do I mean when I talk about a gas giant or indeed any of the kinds of planets? So Mercury is a rocky planet and it essentially has no atmosphere. There's some gas there, but really it doesn't have an atmosphere. Earth, we're well aware it has an atmosphere. Indeed, we're quite thankful for its atmosphere. You can sort of think of its atmosphere like the skin on an apple. It's quite thin, but it is definitely there. Neptune is a bit bigger again and it has a really big atmosphere and it's what we call an ice giant. And we might say something like 20% of the stuff that's in Neptune is gas. Jupiter, on the other hand, has about more than 90% of the stuff that's in it is gas. But that doesn't mean that we could just like fly straight through Jupiter like it's a cloud because for the same reason when we go to the bottom of the ocean, there's a lot of water above you that's pushing down on you and it's why you need to stop marine to stop the pressure crushing you. Jupiter has a really high pressure on its inside, so any spacecraft we sent into its atmosphere would need to be really tough. But still, what's the difference between an ice giant and a gas giant? Well, Jupiter is mostly made of hydrogen and helium and that's mostly, the sun is mostly hydrogen and some helium as well, plus some other stuff. But Neptune on the other hand, most of its gases are heavier than that, stuff like oxygen. And when we mean ices, if we took the stuff that's inside it out, you'd get stuff like water or ammonia that would freeze in space. So there's a lot to talk about about Jupiter, but let's talk about one of the things that everyone knows about the Great Red Spot. It's a storm that's been raging for more than 100 years and it's literally about the size of the Earth. Like the planet we are on, there's a storm that big of another planet. And so we've been observing it, astronomers have continuously since the late 1800s. And in the 1600s actually, a permanent spot was observed by an astronomer called Giovanni Cassini. And Cassini is the namesake of the mission that we sent to Saturn. But Cassini saw this permanent spot, but then no one else really looked at it or wrote anything down for 100 years or so. It might be the same spot, it might not be, but in any case, just imagine that there was a cyclone or a big thunderstorm just above your house and it was there for like your entire life. Because that's no one alive today has ever been around, you know, for a Jupiter that didn't have this big storm. But the storm is shrinking though and it's different colours at different times. Sometimes it's more red, sometimes it's a bit lighter. And the red colour we think is probably from the sunlight, the ultraviolet sunlight, the kind of light that gives you a sunburn, breaking apart chemicals in its atmosphere into different chemicals that are red in colour. So let's go somewhere different. The pole, the north pole of Jupiter. And so we didn't really have a good idea of what was here until NASA's Juno spacecraft went there and that's a picture of Juno in the top of the slide. And Juno can, you know, all the Jupiter top to bottom and so it can see both the north and the south pole. And what we're seeing here is a bunch of cyclones. There's one in the middle and there's a whole bunch of ones around it. And each of those storms is more than 4,000 kilometres across which is about as big as Australia is wide. And the colours are a bit funny here because Juno is actually looking in infrared lights. And what this means is it's the kind of light that's too red for our eyes but it's the kind of security cameras or night vision goggles use. And so it's seeing heat. So the dark regions are colder and higher up in the atmosphere. And the bright regions are lower down in the atmosphere and much more hot. And so Juno can actually see 50 to 70 kilometres beneath the atmosphere using this fancy camera. And we didn't know this was here before. How about Jupiter's stripes? And they're all different colours. They go at different speeds and some of them go in different directions. And so what we think is happening here is that the light coloured bands are where the gas is rising up. And you get once it gets cooler as you get to the top, you get clouds of ammonia forming. And ammonia is what we use in fertiliser on Earth. And when these clouds form they're lighting colour. But then in the dark regions the gas is going down and the clouds evaporate and you can see the darker regions beneath. And so these stripes are visible with a small telescope. And before Juno we really didn't have a good idea of how deep they went into Jupiter's atmosphere. Is it just like a painting? Like you got a ball and you painted some stripes on it? Or does it go deep inside? And now we know that they go about 3000 kilometres right into the middle of Jupiter. And 3000 kilometres is about as tall as Australia. And that's the last time tonight I'm going to use Australia as a measuring stick. On to Jupiter's moons. These are the four Galilean moons that were discovered by Galileo hundreds of years ago with one of the very early telescopes. Each of these is about the size of our own moon. And just think on Earth the tides in the ocean, you get a high tide, a low tide of course by the way the moon is. The moon is pulling on the Earth and pulling on the ocean. Just imagine how wild the tides would be on our planet if we had four moons the size of our moon. Pretty wild but that's what's happening on Jupiter. And so each of these moons is not only pulling on Jupiter but they're pulling on each other. And so what that means is you're actually kind of changing the shape of the moons and heating them up. This is why Io is a volcano moon and why Europa you would think it's too far away from the sun to have water but underneath its icy crust there is a liquid water ocean which is one of the best places we think in the solar system to look for life. Ganymede is the biggest moon in the solar system and Callisto is the furthest out of them so it's a bit different because it doesn't get tucked on as much and by these by these really strong tides. So here's just two pictures of Io. The one on the left is an image actually and it's showing a volcano on Io just shooting erupting into space. And the one on the right is Io casting a shadow on Jupiter which is pretty beautiful. So one thing that you may not know about is that Jupiter helps us explore the solar system. And so here I have a gif showing off a little movie showing what happens when we launch the Voyager 1 spacecraft which I mentioned earlier. The speed that a spacecraft goes is limited by the rockets and our rockets are only so big. So if we wanted to get really far out to Jupiter or Saturn or further you know we're limited by our rockets but we can do a trick. We can use the gravity of the planet to go faster and change directions. So what we're seeing here we launch Voyager 1 which is the the magenta the pink line and from earth which is the dark blue and then it goes by the light blue which is Jupiter and you'll see it kind of turns a corner and it starts going faster. It goes from about 13 kilometers per second up to 23 and then gets all the way out to Saturn. Voyager 2 did this in an even more extreme way because it slingshot it around Jupiter and Saturn and Uranus and Neptune and this was made possible by the fact that all those planets were lined up at that point in time but it allowed us to visit them all and it saved literally years of the trip versus if we didn't do this slingshotting. So finally Jupiter can take a hit so in 1994 a 1.8 kilometer diameter comet so I think the size of like a suburb broke apart around Jupiter actually Jupiter pulled it apart just tore it to pieces with its gravity and it collided with Jupiter and this comet is called a comet Schumacher Levy 9 after because it was discovered by Carolyn and Eugene Schumacher and David Levy it's what we're seeing here the the big circle is Jupiter the one that's off to the side that's IOL volcano moon and the bright light that appears is coming like the explosion from when the comet hits Jupiter's atmosphere and we see a lot of light in heat that it gets that it makes uh here we can see it happening as well and this was actually uh taken by the Galileo spacecraft which was on its way to Jupiter at the time and these let's scars on the planet were visible for months because lots of different pieces the comet fell in and astronomers all over the world were looking at this because it allowed us to it was the first time we saw something hit another planet other than the earth and it allowed us to see what's deeper in Jupiter's atmosphere because the comet kind of you know part of the clouds so to speak for us but why am I talking about Jupiter tonight and so the reason for that is because Jupiter and Saturn actually are doing something special at the moment and so if you imagine that you've got the sun here and you've got the earth Jupiter is on the on the same side of the sun and Saturn's just behind it uh which means they're close to earth because you could imagine earth could be around the other side of the sun this means that they're really bright and they're really big so it's a really great time to look at them so if you go outside and look to the east about now you'll see what I've got here and you'll see two points of light Jupiter will be one of the brightest objects in the sky and there'll be another bright object here and these rise as the sun is setting and they'll set themselves as the sun is rising again and around midnight they'll be right above you and you don't need anything fancy to look at Jupiter either so this is a picture I took just with my phone through one of the telescopes we had announced we haven't announced from last year but actually the first time I saw Jupiter's moons was years ago it was just using a pair of binoculars leaning against the gun tree and you know even binoculars that you have today probably better than the telescope Galileo had back in the day so that's all for now I'll take any questions that uh you popped in the chat that uh thank you all for listening about Jupiter and I hope I convinced some of you uh that you know gone up in your ranking of favorite planets so I have a question here about how do different types of planets uh rocky ice or gas planets form and so for the rocky planets that's pretty pretty simple you imagine you just get if you get two rocks and you eventually rocks crap we'll start we'll start to begin with how the sun forms uh you'd have a big cloud of gas in the universe and gravity wants to pull it together but the thing is the cloud is spinning a bit and so sort of in the same way that when if you see a chef using uh making pizza and they throw the pizza dough in the air and it's spinning around makes a like a disk uh goes flat that's what's that what's that is what happens with the solar system so gravity pulls it flat but it's spinning so you get the sun the sun is born in the middle and you get lots of leftover gas and dust that the planets can form from and so as little bits of dust collide they stick together and make bigger bits of dust and this keeps happening and eventually it gets big enough that gravity can pull more and more bits to it and that's kind of how you end up with a rocky planet and for a something like a Neptune or an ice giant if it's a bit further out in the solar system because the sun uh the sun kind of blows a lot of stuff away a lot of the gas away and out further uh you can have ices form and not get blown away and so out here when you're forming that planet you can get a lot of ices falling onto your onto your planet onto your rocky embryo and there's more gas you can get as well and that's kind of how you get an ice giant because the bigger you get the more gravity you have so the uh once a planet starts growing and growing and growing it grows quicker and quicker and quicker and quicker and quicker quicker and so there's kind of two ways that a Jupiter can form a Jupiter like planet could form uh by the same way it just you know keeps pulling stuff onto it or there's some really weird physics that goes on in these these disks that are left over after the stars are born and what could happen is you can essentially get a a bunch of the uh the gas it's something kind of weird and it just all gravity kind of and the other forces like pressure will come together and it just the planet forms really really really really quickly and so in that way the the planet like Jupiter won't really have much of a rocky core it will have started uh from all this gas coming together quite quickly and so that's kind of two different ways and when we're looking at star uh planets around all the stars trying to figure out how they formed and trying to inform us of how the planets in our own solar system uh did form so I have a uh another question what would happen if a black hole that's small started sucking up Jupiter so Jupiter I mean wouldn't really be a planet for very long it did get eaten and torn apart in the same way that Jupiter tore apart that comet uh black hole a black hole would be able to tear apart Jupiter black holes are strong enough to tear apart stars but the thing is black holes don't really suck so if I like clipped my fingers right now and replaced the sun with a black hole that was the same had the same amount of stuff in it the same mass as the sun uh we wouldn't notice immediately like the earth would still keep going around the black hole because it would still have the same mass in the same amount of gravity what would actually happen is we're all freeze to death because there'd be no light from the black hole so black hole just has a lot of gravity but it doesn't just you've got to get really close to it to it for it to be dangerous but if you do black holes can and do tear apart stars so just don't get too close to it and please don't put my baby Jupiter too close to a black hole uh so another question is uh why did Jupiter form so far away from the sun so that's a funny question because we actually think Jupiter has kind of changed positions uh over its lifetime we actually think that the Jupiter kind of did a bit of roaming around early in the solar system when all the the gravity of all the planets was a bit you know pulling on each other and there was actually a lot more stuff then because the solar system made more planets than actually survived today some of them got fell into Jupiter and got eaten uh some of them got thrown out of the solar system and so Jupiter's moved about a bit as ended up where it has today but where a gas giant forms there actually needs to be a lot of gas and if you say too close to a star all the gas has already fallen onto the star all the stars blown it away so another question how many moons does Jupiter have so Jupiter has 79 moons and so the biggest ones are the Galilean moons which I spoke about uh but then there's lots that are much smaller and you know if you looked at it you would think that just looks like a better rock or like a meteorite because some of them actually are probably captured asteroids that came a bit too close to Jupiter and Jupiter said that's mine now uh is there an order to the planet formation that could be expected to be repeated in other solar systems uh e.g. i.e rocky gashes icy etc so we didn't really know what to expect when we started looking outside the solar system for other planets were we going to find other solar systems and have rocky planets close to their star or then the gas giants and then ice giants instead we found some pretty wild stuff we found so in our own solar system mercury has a year that's about 88 days long which means if you're on mercury you get a birthday cake every 88 days but it doesn't have any air so probably not a good idea to get a mercury but uh there are planets in around other stars like Jupiter or even bigger that all that their star in a few days or even a few hours and so as i've said Jupiter needs to form further away from its star and so for this for a Jupiter planet to get that close to its star it's probably had to throw away a lot of the planets on the way because if Jupiter and our solar system decided to come in uh you know it'd have to knock away Mars and go through the asteroid belts and you know earth and Venus and Mars uh mercury sorry so there are also other kinds of planets that we don't have in our solar system there's a kind of planet called a super earth that's kind of between uh earth and like a nexium or a Uranus and we don't have any of those and we didn't know those existed until we found them and so there's all different kinds of solar systems out there in it might even be that ours is the weird one um time will tell we know about 4 000 planets around other stars right now and i'm working to increase that number uh so question what is the red spot on Jupiter so yeah it's just a big cyclone that uh is the color it is because of uh the the chemicals that are in it uh and the a lot of the physics on Jupiter is a lot weirder than on earth because on earth this the the atmosphere is thin like an apple skin but on Jupiter the atmosphere goes much deeper so you can get some really weird stuff going on uh during the live stream i saw odd blobs on Jupiter what were they so if if you're referring to those videos the odd blobs that appeared were actually the moons so if you saw a black blob that appeared it was actually a shadow that was just briefly skimming across Jupiter or a bright spot was actually the front side like the day side of the moon uh skimming across Jupiter as we were taking our pictures and uh that's really neat and they just they look like they're you know errors of the image but they're actually the moons of Jupiter uh how many earths can fit into Jupiter uh quite a lot i can't remember the number quite off of hand right now but a lot a lot of earths uh what do we think of the theory that Jupiter was responsible for the rocky planets being so close to the sun and that well yeah as i said Jupiter has moved around during the uh its history i mean rocky planets will form closer to their star than gas planets will um but the actual present day positions of the uh rocky planets all the planets are probably due to what Jupiter and Saturn have done in the past and how they've moved around uh okay so an asteroid belt debris shows the possibility of becoming a planet or a moon so the solar system made a lot more planets than survived as i mentioned in the asteroid belt there's actually what we call a dwarf planet called Ceres and Ceres is round uh like what you would expect a planet to be and it's actually about a quarter of all the the mass all the stuff in the asteroid belt is in Ceres and but there's still a lot of stuff left around so there would have been a lot of things like Ceres a lot of dwarf planets a lot of things that kind of got to be the shape of the planet but a smaller than Mercury um that got kicked out of the solar system or eaten up by Jupiter um the asteroid belt's kind of just what was left over and the kite the belt the outskirts of the solar system is like the asteroid belt except there's a lot more ice is there and you know the rock on you know a planet like Pluto is actually like kind of water ice because the water ice is like rock hard there uh where are the voyages now okay so the voyager craft are actually just on their way out of the solar system they're not heading towards any particular star um but they're still working and we can still talk to them uh and they're learning about what it's like outside the solar system it's it's kind of really exciting because they've been going for you know many decades at this point um but anyway I think that's about all our questions so I'm going to throw back to Brad uh thank you all for uh taking the time to listen and ask me questions