WEBVTT 0 00:00:00.480 --> 00:00:02.280 Andrew Dunkley: Hello again and thank you for joining us on 1 00:00:02.280 --> 00:00:04.800 another episode of Space Nuts. My name is 2 00:00:04.800 --> 00:00:06.600 Andrew Dunkley, your host. It's great to have 3 00:00:06.600 --> 00:00:08.600 your company. I hope you're well and I hope 4 00:00:08.600 --> 00:00:10.400 you can stick around. We've got some really 5 00:00:10.400 --> 00:00:12.640 great storeys today. These are fascinating. 6 00:00:13.040 --> 00:00:16.040 Remember that asteroid impact that led to the 7 00:00:16.040 --> 00:00:18.080 loss of the dinosaurs, you know, happened a 8 00:00:18.080 --> 00:00:20.880 couple of weeks ago? Uh, well, uh, it 9 00:00:21.120 --> 00:00:23.360 may have been much worse than we first 10 00:00:23.520 --> 00:00:26.280 thought. Lost lots of, uh, crispy critters as 11 00:00:26.280 --> 00:00:28.980 a consequence. We'll explain all that. Uh, 12 00:00:28.980 --> 00:00:31.400 there was a near Earth asteroid discovered 13 00:00:31.400 --> 00:00:33.820 around 30 years ago. 30 years ago. Well, now 14 00:00:34.380 --> 00:00:37.100 new evidence suggests it may 15 00:00:37.180 --> 00:00:40.140 have been a comet. And I love 16 00:00:40.140 --> 00:00:43.100 this storey. This is about a Canadian amateur 17 00:00:43.420 --> 00:00:45.580 astronomer who was planning a trip online 18 00:00:45.740 --> 00:00:48.660 using, uh, using online maps. And 19 00:00:48.660 --> 00:00:51.060 he made a massive discovery. We'll tell you 20 00:00:51.060 --> 00:00:54.060 all about it on this episode of space nuts. 21 00:00:54.140 --> 00:00:56.620 Generic: 15 seconds. Guidance is internal. 22 00:00:56.860 --> 00:00:59.580 10, 9. Ignition 23 00:00:59.580 --> 00:01:00.620 sequence start. 24 00:01:00.780 --> 00:01:01.485 Jonti Horner: Space nuts. 25 00:01:01.562 --> 00:01:04.175 Generic: 5, 4, 2, 1, 2, 3, 4, 26 00:01:04.252 --> 00:01:07.000 Jonti Horner: 5, 5, 4, 3, 2, 1. Space 27 00:01:07.080 --> 00:01:07.720 nuts. 28 00:01:07.800 --> 00:01:09.640 Generic: Astronauts report it feels good. 29 00:01:10.280 --> 00:01:12.840 Andrew Dunkley: And joining us, uh, this time around 30 00:01:12.920 --> 00:01:15.240 with Fred Watson, gallivanting around chasing 31 00:01:15.320 --> 00:01:18.080 solar eclipses is Professor Jonty 32 00:01:18.080 --> 00:01:20.079 Horner, professor of Astrophysics at the 33 00:01:20.079 --> 00:01:21.880 University of Southern Queensland. Welcome 34 00:01:21.880 --> 00:01:22.600 back, Jonty. 35 00:01:22.840 --> 00:01:24.560 Jonti Horner: Oh, uh, thanks for having me. It's good to be 36 00:01:24.560 --> 00:01:26.040 the substitute Yorkshireman again. 37 00:01:26.200 --> 00:01:28.520 Andrew Dunkley: Yes, we've got a whole set of them. 38 00:01:30.160 --> 00:01:31.120 It's really good stuff. 39 00:01:31.540 --> 00:01:34.400 Um, now we've got some amazing 40 00:01:34.400 --> 00:01:37.200 storeys. I know you've been a very busy young 41 00:01:37.280 --> 00:01:40.080 fellow for, um. Well, since we last 42 00:01:40.080 --> 00:01:42.840 spoke to you, uh, you do your own sort of 43 00:01:42.840 --> 00:01:45.760 gallivanting, but we managed to nail you down 44 00:01:45.760 --> 00:01:47.840 for a couple of weeks, which is fantastic. 45 00:01:48.200 --> 00:01:50.150 Uh, let's get straight into it because, um, 46 00:01:51.040 --> 00:01:53.480 these storeys dovetail. Well, we've got an 47 00:01:53.480 --> 00:01:56.410 asteroid that 48 00:01:56.410 --> 00:01:58.170 may have been a comet. Then we've got an 49 00:01:58.170 --> 00:02:00.770 asteroid that hit Earth that seems, uh, to 50 00:02:00.770 --> 00:02:02.690 have done more damage than we thought. And 51 00:02:02.690 --> 00:02:04.170 then we've got a hole in the ground 52 00:02:04.330 --> 00:02:06.290 discovered while someone was planning a 53 00:02:06.290 --> 00:02:08.090 holiday. All kind of related. 54 00:02:08.490 --> 00:02:10.450 So let's get stuck into the, uh, first 55 00:02:10.450 --> 00:02:13.450 storey. A near Earth asteroid that 56 00:02:13.450 --> 00:02:16.370 was discovered 30 years ago they think might 57 00:02:16.370 --> 00:02:17.290 have been a comet. 58 00:02:18.330 --> 00:02:21.210 Jonti Horner: Yeah, this is a lovely storey and it ties 59 00:02:21.210 --> 00:02:23.530 into something that we've talked about in 60 00:02:23.770 --> 00:02:26.010 different lights previously when I've been on 61 00:02:26.010 --> 00:02:27.350 the show, and I'm sure Fred Watson spoken 62 00:02:27.350 --> 00:02:29.870 about it quite frequently as well, which is 63 00:02:29.870 --> 00:02:32.430 that, uh, very human need to break things up 64 00:02:32.430 --> 00:02:35.310 into manageable chunks, you know, so you 65 00:02:35.310 --> 00:02:37.310 go from being a child to being a teenager to 66 00:02:37.310 --> 00:02:38.990 being an adult and there's A miraculous day 67 00:02:38.990 --> 00:02:40.550 when you wake up and you're suddenly legally 68 00:02:40.550 --> 00:02:41.350 able to drive. 69 00:02:41.510 --> 00:02:41.910 Andrew Dunkley: Yes. 70 00:02:41.910 --> 00:02:43.550 Jonti Horner: And in different countries, that's a 71 00:02:43.550 --> 00:02:45.430 different debt. But we all have it. But 72 00:02:45.750 --> 00:02:47.270 fundamentally, you're not really any 73 00:02:47.270 --> 00:02:49.270 different as a person the day before that and 74 00:02:49.270 --> 00:02:51.350 the day after it. What we're doing is we're 75 00:02:51.350 --> 00:02:53.310 breaking up this kind of continuum of human 76 00:02:53.310 --> 00:02:56.310 experience into chunks, where we group things 77 00:02:56.310 --> 00:02:58.350 that are similar together and we put things 78 00:02:58.350 --> 00:03:00.670 that are more different into separate groups. 79 00:03:00.910 --> 00:03:02.710 And I've talked about this in the past when 80 00:03:02.710 --> 00:03:04.750 we've talked about the difference between 81 00:03:04.750 --> 00:03:07.110 planets and stars and that amazing middle 82 00:03:07.110 --> 00:03:09.870 ground that are brown dwarfs, where in 83 00:03:09.870 --> 00:03:12.110 effect, you've actually got objects of all 84 00:03:12.110 --> 00:03:14.190 sizes from the size of a grain of sand, 85 00:03:14.430 --> 00:03:16.590 actually from the size of a single atom or a 86 00:03:16.590 --> 00:03:18.950 single subatomic particle, all the way up to 87 00:03:18.950 --> 00:03:21.350 the biggest galaxies and beyond in this kind 88 00:03:21.350 --> 00:03:24.310 of continuum of sizes. But you go through 89 00:03:24.310 --> 00:03:26.770 kind of rock to planet to brown dwarf to 90 00:03:26.770 --> 00:03:29.370 star. And we put these arbitrary divisions in 91 00:03:29.610 --> 00:03:31.610 so that we can group things that look similar 92 00:03:31.690 --> 00:03:34.650 together and study them to make life easier. 93 00:03:35.530 --> 00:03:37.050 And we talked about that, of course, in the 94 00:03:37.050 --> 00:03:39.330 context of Pluto, with the whole thing of 95 00:03:39.330 --> 00:03:41.050 when is a planet not a planet, when it's a 96 00:03:41.050 --> 00:03:43.290 dwarf planet, and why all that happened. 97 00:03:43.290 --> 00:03:45.130 That's exactly the same kind of thing. In my 98 00:03:45.130 --> 00:03:46.970 kind of contextualization, that was the right 99 00:03:46.970 --> 00:03:48.570 decision. That's a hill I'll quite happily 100 00:03:48.570 --> 00:03:50.810 plant my flag on. But 101 00:03:51.050 --> 00:03:53.130 Pluto's like the gangly teenager. From a 102 00:03:53.130 --> 00:03:54.690 distance, it looks big and like a serious 103 00:03:54.690 --> 00:03:56.050 adult, but it's still not very good at 104 00:03:56.050 --> 00:03:57.730 tidying its room up. That's the kind of 105 00:03:57.730 --> 00:04:00.630 analogy you there. This 106 00:04:00.630 --> 00:04:02.990 whole storey is another one of those same 107 00:04:02.990 --> 00:04:04.710 things. If we had been talking 108 00:04:05.430 --> 00:04:08.070 300 years ago, people would have been 109 00:04:08.070 --> 00:04:09.870 familiar with comets, at least the bright 110 00:04:09.870 --> 00:04:11.390 ones. You know, things that get bright enough 111 00:04:11.390 --> 00:04:13.230 to see with the naked eye that have a glowy 112 00:04:13.230 --> 00:04:15.710 coma and a tail. They appear briefly, then 113 00:04:15.710 --> 00:04:18.070 vanish forever. And we had great comets a 114 00:04:18.070 --> 00:04:20.590 couple of times in the last few years, on 115 00:04:20.590 --> 00:04:22.430 average one per decade. But it's a bit hit 116 00:04:22.430 --> 00:04:24.670 and miss. And the idea is, with modern 117 00:04:24.670 --> 00:04:27.390 scientific knowledge, what you're seeing when 118 00:04:27.390 --> 00:04:29.470 you get that phenomenon is a big dirty 119 00:04:29.470 --> 00:04:31.770 snowball or a snowy dirt ball that's whizzing 120 00:04:31.770 --> 00:04:33.610 around the sun on this hugely elongated 121 00:04:33.610 --> 00:04:36.210 orbit. When it's far from the sun and it's 122 00:04:36.210 --> 00:04:38.290 nice and cold, we just don't see it. You'd 123 00:04:38.290 --> 00:04:39.810 need the biggest telescopes on the world 124 00:04:39.810 --> 00:04:41.570 because you've just got this little thing 125 00:04:41.570 --> 00:04:44.130 reflecting a bit of sunlight. But when it 126 00:04:44.130 --> 00:04:46.770 comes near to the sun, its surface gets hot. 127 00:04:47.410 --> 00:04:50.210 The volatile material on it gets too hot to 128 00:04:50.210 --> 00:04:53.210 still be solid, so turns into gas. And 129 00:04:53.210 --> 00:04:55.530 that gas erupts from the surface, carrying 130 00:04:55.530 --> 00:04:57.970 with it dust, shrouds that snowball 131 00:04:58.420 --> 00:05:00.420 in what's called a coma, a big spherical 132 00:05:00.660 --> 00:05:03.420 cloud of gas. And then the solar wind pushes 133 00:05:03.420 --> 00:05:04.980 the gas and dust away from the sun and you 134 00:05:04.980 --> 00:05:07.940 get the tails. And so a comet, as we see 135 00:05:07.940 --> 00:05:10.860 it, is pretty big, can be millions or 136 00:05:10.860 --> 00:05:12.540 tens of kilometres, tens of millions of 137 00:05:12.540 --> 00:05:15.540 kilometres across, which is this huge amount 138 00:05:15.540 --> 00:05:17.180 of gas and dust floating around in the solar 139 00:05:17.180 --> 00:05:19.780 system, all given off by an icy, 140 00:05:19.780 --> 00:05:22.460 rocky, rubbly object only a few kilometres 141 00:05:22.460 --> 00:05:25.100 across in the head. And that's a comet. So 142 00:05:25.100 --> 00:05:27.760 it's basically something that has activity 143 00:05:27.760 --> 00:05:29.720 that out gases as it goes around the sun. 144 00:05:29.880 --> 00:05:30.440 Andrew Dunkley: Yep. 145 00:05:31.320 --> 00:05:33.960 Jonti Horner: 19. In 1801, sorry came along 146 00:05:34.200 --> 00:05:37.160 and Giuseppe Piazzi found Ceres, which 147 00:05:37.160 --> 00:05:39.040 was an object between the orbits of Mars and 148 00:05:39.040 --> 00:05:41.960 Jupiter. And he found it because they were 149 00:05:41.960 --> 00:05:43.800 looking for a planet, because people had 150 00:05:43.800 --> 00:05:46.120 suggested that might just be that there's a 151 00:05:46.120 --> 00:05:47.640 planet between Mars and Jupiter. So the 152 00:05:47.640 --> 00:05:50.280 celestial police were looking, but Piazzi got 153 00:05:50.280 --> 00:05:51.960 there first and that was the first of the 154 00:05:51.960 --> 00:05:54.960 asteroids. And over the decades, and 155 00:05:54.960 --> 00:05:56.640 the couple of centuries that followed, one 156 00:05:56.640 --> 00:05:59.380 object became four, became tens, 157 00:05:59.380 --> 00:06:02.020 became hundreds, became thousands, and 158 00:06:02.020 --> 00:06:04.980 nowadays it's over a million. And if we 159 00:06:04.980 --> 00:06:07.900 were talking kind of 30 or 40 years ago, we'd 160 00:06:07.900 --> 00:06:09.740 have had a very clear idea of what an 161 00:06:09.740 --> 00:06:12.340 asteroid is and that an asteroid is very 162 00:06:12.340 --> 00:06:14.340 different to a comet. So an asteroid is a 163 00:06:14.340 --> 00:06:17.140 rocky or metallic object that 164 00:06:17.140 --> 00:06:19.100 even when it gets near the sun, just stays as 165 00:06:19.100 --> 00:06:21.860 a rocky metallic object. No gas comes off it, 166 00:06:21.940 --> 00:06:23.820 just a lump of rock or rubble going around 167 00:06:23.820 --> 00:06:26.240 the sun. So 168 00:06:26.480 --> 00:06:28.800 rocky, rubbly object, icy object with loads 169 00:06:28.800 --> 00:06:30.680 of gas. You've got a comet, you've got an 170 00:06:30.680 --> 00:06:32.720 asteroid, very distinct. 171 00:06:33.600 --> 00:06:36.600 Now, water's got a bit more muddied for 172 00:06:36.600 --> 00:06:38.480 a few reasons over the last few decades. 173 00:06:38.480 --> 00:06:41.440 Firstly, you had objects called the 174 00:06:41.520 --> 00:06:44.280 Centaurs, which I studied for my PhD, that 175 00:06:44.280 --> 00:06:46.240 are big icy objects that are too far away 176 00:06:46.240 --> 00:06:49.120 from the sun most of the time to outgas. So 177 00:06:49.120 --> 00:06:51.600 got kind of asteroidal classifications and a 178 00:06:51.600 --> 00:06:53.080 couple of them got a bit nearer in and 179 00:06:53.080 --> 00:06:55.920 started out gassing, so got a dual classific. 180 00:06:57.020 --> 00:06:59.220 Chiron is the most famous. Chiron has both an 181 00:06:59.220 --> 00:07:01.580 asteroidal classification and, um, a cometary 182 00:07:01.580 --> 00:07:03.660 classification. Cause sometimes it looks like 183 00:07:03.660 --> 00:07:05.660 an asteroid, sometimes it looks like a comet. 184 00:07:06.220 --> 00:07:08.420 You then have things like the Geminid meteor 185 00:07:08.420 --> 00:07:10.660 shower every December, which is our best 186 00:07:10.660 --> 00:07:13.180 meteor shower. I love it dearly. Almost 187 00:07:13.420 --> 00:07:15.340 all of the meteor showers are produced by 188 00:07:15.340 --> 00:07:17.300 comets and we get them when we go through the 189 00:07:17.300 --> 00:07:18.900 dust that has been left behind by the 190 00:07:18.900 --> 00:07:20.420 activity of the comet when it was out 191 00:07:20.420 --> 00:07:22.940 gassing. But when they found the parent of 192 00:07:22.940 --> 00:07:25.590 the Geminids, it doesn't look like a comet, 193 00:07:25.590 --> 00:07:28.030 it's an asteroid. So the idea became that 194 00:07:28.030 --> 00:07:29.910 maybe it's a rock comet and it's getting so 195 00:07:29.910 --> 00:07:32.510 close to the sun it's shedding dust and we 196 00:07:32.510 --> 00:07:35.430 get the meteor shower. Then there were 197 00:07:35.430 --> 00:07:38.030 a couple of comets that were lost. And then 198 00:07:38.030 --> 00:07:40.710 many, many decades later, an asteroid was 199 00:07:40.710 --> 00:07:42.230 found that looked to be moving on the same 200 00:07:42.230 --> 00:07:44.430 orbit as a comet. And so maybe they're the 201 00:07:44.430 --> 00:07:47.030 same object and the comet has turned off. And 202 00:07:47.030 --> 00:07:48.710 when the comet has turned off and stopped 203 00:07:48.710 --> 00:07:51.100 making any gas, maybe it looks like an 204 00:07:51.100 --> 00:07:53.940 asteroid. So there's this blurring going on. 205 00:07:55.220 --> 00:07:57.540 In reality, what you've got is a 206 00:07:57.540 --> 00:08:00.140 continuum from rocky and metallic and nothing 207 00:08:00.140 --> 00:08:02.220 else on one end to incredibly icy on the 208 00:08:02.220 --> 00:08:04.820 other, and everything in between where you 209 00:08:04.820 --> 00:08:07.300 have more rock, less ice, more ice, less rock 210 00:08:07.620 --> 00:08:10.460 blurring together. That's a 211 00:08:10.460 --> 00:08:12.300 hell of a lengthy introduction, hell of a lot 212 00:08:12.300 --> 00:08:14.780 of background to give the context for this 213 00:08:14.780 --> 00:08:17.300 storey. So, in light of all that, back in 214 00:08:17.460 --> 00:08:20.300 1998 there was this near Earth 215 00:08:20.300 --> 00:08:22.850 asteroid discovered. It goes by the of 1998 216 00:08:23.030 --> 00:08:25.960 SH2 and it looks like a lump of rock. 217 00:08:25.960 --> 00:08:27.760 It goes around the sun every four or five 218 00:08:27.760 --> 00:08:30.240 years, whizzing around. It's been seen at a 219 00:08:30.240 --> 00:08:33.080 few apparitions since. And, um, that's all 220 00:08:33.080 --> 00:08:35.680 well and good. We know a few thousand Near 221 00:08:35.680 --> 00:08:37.760 Earth asteroids now and we're finding more 222 00:08:37.760 --> 00:08:39.400 and more of them all the time. And people are 223 00:08:39.400 --> 00:08:40.800 particularly interested because, of course, 224 00:08:40.800 --> 00:08:42.960 if they come near the Earth, there's a 225 00:08:42.960 --> 00:08:44.560 possibility that eventually one of them will 226 00:08:44.560 --> 00:08:46.720 come too near the Earth and will hit us and 227 00:08:46.720 --> 00:08:49.400 we'll have issues. And ask the dinosaurs 228 00:08:49.400 --> 00:08:50.680 about that. We can come back to that a little 229 00:08:50.680 --> 00:08:52.800 bit later on. So there's a lot of interest in 230 00:08:53.660 --> 00:08:56.140 learning more about near Earth asteroids and 231 00:08:56.140 --> 00:08:57.940 following them because the longer you observe 232 00:08:57.940 --> 00:08:59.700 them, the more accurately you know how 233 00:08:59.700 --> 00:09:01.980 they're moving. So the better you can predict 234 00:09:01.980 --> 00:09:04.500 into the future where they'll be and 235 00:09:04.500 --> 00:09:06.740 therefore rule out the chance of that object 236 00:09:06.740 --> 00:09:09.139 hitting the Earth. Uh, may also, of course, 237 00:09:09.139 --> 00:09:10.660 be interesting to people who want to mine 238 00:09:10.660 --> 00:09:12.300 that object in the future with off Earth 239 00:09:12.300 --> 00:09:14.500 mining that if you want to go mine it, you 240 00:09:14.500 --> 00:09:17.180 need to know where it is. Yeah, so 241 00:09:17.740 --> 00:09:20.070 that's this object. Brilliant. We found an 242 00:09:20.070 --> 00:09:20.990 Earth asteroid. 243 00:09:21.550 --> 00:09:24.270 Where it gets interesting for this storey 244 00:09:24.590 --> 00:09:26.830 is that, uh, back in August 2025, 245 00:09:27.470 --> 00:09:29.870 which is what, 27 years after this thing was 246 00:09:29.870 --> 00:09:32.710 discovered it had another close approach 247 00:09:32.710 --> 00:09:35.510 to Earth. Now, this wasn't like the 248 00:09:35.510 --> 00:09:37.110 forthcoming approach for the asteroid 249 00:09:37.110 --> 00:09:39.470 Apophis, which is going to come closer to us 250 00:09:39.470 --> 00:09:42.350 than geostationary satellites. This was close 251 00:09:42.350 --> 00:09:44.390 to astronomers and distant to everybody else. 252 00:09:44.390 --> 00:09:46.110 You're talking about the thing coming about 3 253 00:09:46.110 --> 00:09:48.570 million kilometres away at its closest 254 00:09:48.570 --> 00:09:51.530 approach. Now, that's relatively close, but 255 00:09:51.530 --> 00:09:53.130 it's not something to get particularly 256 00:09:53.130 --> 00:09:55.650 panicked about. That's nearly 10 times as far 257 00:09:55.650 --> 00:09:57.410 away as the moon is, about 8 times as far 258 00:09:57.410 --> 00:10:00.170 away as the Moon is. But it's near enough 259 00:10:00.330 --> 00:10:01.810 that if you want to learn more about the 260 00:10:01.810 --> 00:10:03.530 asteroid, what you can do is you can get the 261 00:10:03.530 --> 00:10:06.410 planetary radar, uh, that they used to beam 262 00:10:06.410 --> 00:10:08.370 radar, uh, out into space and bounce it off 263 00:10:08.370 --> 00:10:10.850 things and get it back. Yeah, to try and 264 00:10:10.850 --> 00:10:13.130 bounce radar, uh, off this asteroid 265 00:10:13.710 --> 00:10:15.750 to get an image of what its shape is, to 266 00:10:15.750 --> 00:10:17.670 learn about its rotation and figure out how 267 00:10:17.670 --> 00:10:20.350 big it is. Because even with the biggest 268 00:10:20.350 --> 00:10:23.030 telescopes on the planet, something like this 269 00:10:23.030 --> 00:10:26.030 is always just a single pixel. You can't zoom 270 00:10:26.030 --> 00:10:28.870 in. So what they did was they got the 271 00:10:28.870 --> 00:10:31.270 planetary radar, uh, sent radar out to this 272 00:10:31.270 --> 00:10:32.350 object and missed 273 00:10:34.350 --> 00:10:37.150 a little bit. Embarrassing as you do, it 274 00:10:37.150 --> 00:10:39.470 wasn't quite where it was supposed to be. 275 00:10:40.340 --> 00:10:41.700 So based on all those historical 276 00:10:41.700 --> 00:10:44.020 observations, you can predict into the future 277 00:10:44.820 --> 00:10:47.820 where the asteroid will be based purely on 278 00:10:47.820 --> 00:10:49.460 the gravity of all the planets. It's getting 279 00:10:49.460 --> 00:10:51.500 pulled around by the Earth, uh, and Venus, 280 00:10:51.500 --> 00:10:53.620 Jupiter, everything's pulling and tugging on 281 00:10:53.620 --> 00:10:56.060 it. And you can in a very prescriptive way 282 00:10:56.060 --> 00:10:57.900 run its orbit forward in time and say where 283 00:10:57.900 --> 00:11:00.660 it will be in the future if the only thing 284 00:11:00.820 --> 00:11:02.740 acting on it is gravity. 285 00:11:03.700 --> 00:11:06.420 But it wasn't where it should be. Uh, the 286 00:11:06.420 --> 00:11:08.700 fact it wasn't where it should be says 287 00:11:08.700 --> 00:11:10.340 something else is happening as well. 288 00:11:10.340 --> 00:11:12.300 Something else is happening to push it around 289 00:11:12.540 --> 00:11:14.980 now. So at this point, sometimes that we get 290 00:11:14.980 --> 00:11:17.100 the, oh, well, it must be an alien spaceship 291 00:11:17.100 --> 00:11:19.980 thing happening. That's exactly what's 292 00:11:19.980 --> 00:11:21.540 happened in the past with people suggesting 293 00:11:21.540 --> 00:11:24.340 there's maybe something more going on that 294 00:11:24.340 --> 00:11:26.060 actually hasn't happened with this one, which 295 00:11:26.060 --> 00:11:28.380 is really nice to see. But what 296 00:11:28.940 --> 00:11:31.660 that being out of position tells you is that 297 00:11:31.660 --> 00:11:33.860 there are non gravitational forces acting on 298 00:11:33.860 --> 00:11:36.500 this thing. Something other than gravity is 299 00:11:36.500 --> 00:11:38.440 happening to push it around a little bit. 300 00:11:39.000 --> 00:11:41.200 Now, M. If we rewind to comets for a little 301 00:11:41.200 --> 00:11:43.640 bit. I remember when I was a teenager back in 302 00:11:43.640 --> 00:11:46.160 the early 1990s, we had Comet Swift Tuttle 303 00:11:46.160 --> 00:11:48.520 came past and, um, Comet Swift Tuttle's a 304 00:11:48.520 --> 00:11:51.040 parent of the Perseid shower. And, um, that 305 00:11:51.040 --> 00:11:52.600 was kind of a relief because at, uh, Its 306 00:11:52.600 --> 00:11:54.720 previous apparition, Comet Swift Tuttle, had 307 00:11:54.720 --> 00:11:57.720 been seen widely observed and had been 308 00:11:57.880 --> 00:11:59.320 predicted that it would come back in about 309 00:11:59.320 --> 00:12:01.400 120 years. It would come back in the early 310 00:12:01.400 --> 00:12:03.880 1980s and it didn't show up. 311 00:12:04.420 --> 00:12:06.240 M which was a bit weird because this is a 312 00:12:06.240 --> 00:12:08.160 bigger and more active comet than Comet 313 00:12:08.160 --> 00:12:10.280 Hallie. It's probably the biggest of the 314 00:12:10.280 --> 00:12:12.280 comets with a period less than 200 years. 315 00:12:12.360 --> 00:12:15.280 Pretty epic object. And it came back 10 316 00:12:15.280 --> 00:12:17.000 years later. Now, by the time it came back, 317 00:12:17.000 --> 00:12:18.720 people had figured out kind of what was going 318 00:12:18.720 --> 00:12:21.280 on, had realised that it was going to be 319 00:12:21.280 --> 00:12:23.560 late. But part of the complexity there 320 00:12:24.280 --> 00:12:25.920 was that, uh, because this is quite an active 321 00:12:25.920 --> 00:12:28.560 comet, when it's ejecting gas and dust to 322 00:12:28.560 --> 00:12:31.280 space, that process acts like a 323 00:12:31.280 --> 00:12:33.900 rocket engine that pushes it around. So it's 324 00:12:33.900 --> 00:12:36.140 ejecting gas in one direction and that exerts 325 00:12:36.140 --> 00:12:37.940 a force pushing the nucleus in another. 326 00:12:38.980 --> 00:12:41.980 And that is not a predictable thing in 327 00:12:41.980 --> 00:12:44.500 that every time a comet comes around the sun, 328 00:12:44.660 --> 00:12:46.660 its rotation will be a bit different. Some 329 00:12:46.660 --> 00:12:48.580 active areas will turn off and some will turn 330 00:12:48.580 --> 00:12:51.420 on. So while you can get a general trend and 331 00:12:51.420 --> 00:12:53.340 you can make loose predictions, there's 332 00:12:53.340 --> 00:12:55.500 always going to be a bit of uncertainty in 333 00:12:55.500 --> 00:12:57.340 where a comet will be in the future because 334 00:12:57.340 --> 00:12:59.420 it's got these forces pushing and nudging it 335 00:12:59.420 --> 00:13:02.340 around. You know, it's a bit like, I don't 336 00:13:02.340 --> 00:13:04.320 know if you could strap a few fireworks to a 337 00:13:04.320 --> 00:13:05.760 snowball and throw it up in the air. That's 338 00:13:05.760 --> 00:13:07.480 probably not very healthy to do. But you get 339 00:13:07.480 --> 00:13:08.880 the same kind of thing, they go off at 340 00:13:08.880 --> 00:13:11.120 different times and be pushed around all over 341 00:13:11.120 --> 00:13:13.840 the place. Um, interestingly, Comet Encke, 342 00:13:13.840 --> 00:13:15.480 which is a comet with the shortest non 343 00:13:15.480 --> 00:13:18.200 orbital period, has been seen every three and 344 00:13:18.200 --> 00:13:20.640 a half years, 3.3 years for more than 200 345 00:13:20.640 --> 00:13:22.880 years. And we've actually seen its orbital 346 00:13:22.880 --> 00:13:24.800 period get shorter and then get longer again 347 00:13:24.960 --> 00:13:26.800 as a direct result of the jets on its 348 00:13:26.800 --> 00:13:29.400 surface, uh, pushing it around and those jets 349 00:13:29.400 --> 00:13:31.680 changing the rotation direction of the 350 00:13:32.050 --> 00:13:34.850 comet. Loads of cool stuff there. 351 00:13:36.130 --> 00:13:39.090 So with that knowledge, you can look at this 352 00:13:39.090 --> 00:13:41.410 object, 1998 SH2. 353 00:13:41.890 --> 00:13:44.250 It's not where it's supposed to be. So that 354 00:13:44.250 --> 00:13:45.690 suggests that there's non gravitational 355 00:13:45.690 --> 00:13:48.050 forces happening. But whenever people have 356 00:13:48.050 --> 00:13:50.280 observed it in the past, it has looked inert. 357 00:13:50.280 --> 00:13:52.770 Uh, it's looked like an asteroid. 358 00:13:53.650 --> 00:13:56.490 What that suggests is that it is active. 359 00:13:56.490 --> 00:13:58.410 It's got some outgassing happening, but at 360 00:13:58.410 --> 00:14:01.250 such low levels that it wasn't possible to 361 00:14:01.250 --> 00:14:04.180 detect them before. So that was a clue 362 00:14:04.660 --> 00:14:06.340 that seems a really likely storey. 363 00:14:06.500 --> 00:14:08.940 So scientists go away and they do a couple of 364 00:14:08.940 --> 00:14:11.660 things. Firstly, they look for pre discovery 365 00:14:11.660 --> 00:14:13.900 observations of this, you know, times when 366 00:14:13.900 --> 00:14:16.060 there was a photographic plate made 50 years 367 00:14:16.060 --> 00:14:17.820 ago that just happened to have the object in 368 00:14:17.820 --> 00:14:20.220 the field of view so you can get a longer 369 00:14:20.220 --> 00:14:22.020 period of knowledge of how it's moved. 370 00:14:22.100 --> 00:14:22.580 Andrew Dunkley: Yeah. 371 00:14:23.380 --> 00:14:25.140 Jonti Horner: And um, with these really accurate 372 00:14:25.140 --> 00:14:27.980 observations, you can tell that it has been 373 00:14:27.980 --> 00:14:29.540 misbehaving for a long time. It's getting 374 00:14:29.540 --> 00:14:32.300 pushed and nudged around. What then 375 00:14:32.300 --> 00:14:34.380 happened was they used some of the really 376 00:14:34.380 --> 00:14:36.860 biggest telescopes in the world to take a 377 00:14:36.860 --> 00:14:39.580 look at it and detect just a tiny hint of gas 378 00:14:39.580 --> 00:14:42.060 being emitted, tiny little wisp. 379 00:14:42.380 --> 00:14:44.780 And so you put all that together and um, this 380 00:14:44.780 --> 00:14:46.980 thing is probably, of all the comets we know 381 00:14:46.980 --> 00:14:49.380 in the solar system, the least active that we 382 00:14:49.380 --> 00:14:51.740 currently know of. But it is exhibiting 383 00:14:51.740 --> 00:14:54.220 cometary behaviour. So it's another object 384 00:14:54.220 --> 00:14:56.900 really straddling the boundary. And it's 385 00:14:56.900 --> 00:14:58.860 fascinating. It'll be wonderful to learn more 386 00:14:58.860 --> 00:15:01.600 about it. But it's fascinating too, 387 00:15:02.160 --> 00:15:04.280 because here's the thing that looks like an 388 00:15:04.280 --> 00:15:06.160 asteroid, sounds like an asteroid. It does 389 00:15:06.160 --> 00:15:07.920 everything you'd expect an asteroid to do, 390 00:15:08.320 --> 00:15:10.480 except it's wibbling and misbehaving a bit. 391 00:15:10.480 --> 00:15:13.080 Now, if you're finding hundreds and thousands 392 00:15:13.080 --> 00:15:14.960 of near Earth asteroids and you want to know 393 00:15:14.960 --> 00:15:17.960 whether the Earth's safe, well, if you see 394 00:15:17.960 --> 00:15:19.720 something that's an asteroid, you can predict 395 00:15:19.720 --> 00:15:22.280 where it is with gravity going forward, the 396 00:15:22.280 --> 00:15:24.800 Earth's safe. What this is telling you is 397 00:15:24.800 --> 00:15:27.200 that, uh, gravity may not be enough. So you 398 00:15:27.200 --> 00:15:28.840 can't just say, well, it looks like it'll be 399 00:15:28.840 --> 00:15:31.000 safe, we'll stop looking. Because if this 400 00:15:31.000 --> 00:15:33.400 object's unpredictable, what about all the 401 00:15:33.400 --> 00:15:34.680 other ones we're finding too? 402 00:15:34.760 --> 00:15:36.880 Andrew Dunkley: I was about to bring that up. There's got to 403 00:15:36.880 --> 00:15:37.720 be more than one. 404 00:15:38.280 --> 00:15:40.760 Jonti Horner: Oh, absolutely. Um, we found 405 00:15:41.320 --> 00:15:43.400 quite a few of these over the years now in 406 00:15:43.400 --> 00:15:45.480 various circumstances. My favourite 407 00:15:46.280 --> 00:15:48.680 really is the Taurid stream of debris. We get 408 00:15:48.680 --> 00:15:50.400 the Taurid meteor shower every year from 409 00:15:50.400 --> 00:15:52.320 about September to December. We've got the 410 00:15:52.320 --> 00:15:54.920 northern and southern Taurids. We also get a 411 00:15:54.920 --> 00:15:57.000 daytime meteor shower in June called the Beta 412 00:15:57.000 --> 00:15:59.630 Taurids. Result is we spend about 413 00:15:59.710 --> 00:16:02.510 four months of every 12 passing 414 00:16:02.510 --> 00:16:05.230 through this enormous broad swath of debris 415 00:16:05.630 --> 00:16:07.630 where on any given night, when the meteor 416 00:16:07.630 --> 00:16:09.510 shower is active even at its peak ulcely, 417 00:16:09.510 --> 00:16:12.190 four or five meteors an hour, the debris is 418 00:16:12.190 --> 00:16:14.830 very spread out. But because the Earth spends 419 00:16:14.830 --> 00:16:16.750 so long going through it, we get more debris 420 00:16:16.750 --> 00:16:18.630 from that stream than all other meteor 421 00:16:18.630 --> 00:16:21.070 showers combined over the course of a year. 422 00:16:22.190 --> 00:16:25.070 At the core of that is Comet Encke, which is 423 00:16:25.070 --> 00:16:27.950 that comet with a 3.3 year period, but 424 00:16:27.950 --> 00:16:30.370 also a huge amount of other rubble and 425 00:16:30.370 --> 00:16:33.370 debris. There's lots and lots of asteroids or 426 00:16:33.370 --> 00:16:35.130 things that behave like asteroids moving 427 00:16:35.130 --> 00:16:37.770 around in the storage stream. And the idea is 428 00:16:37.770 --> 00:16:40.410 that this was a, uh, mega comet 20 or 429 00:16:40.410 --> 00:16:43.290 30,000 years ago that fell apart, 430 00:16:43.770 --> 00:16:46.249 giving us this stream of debris. Comet Encke 431 00:16:46.650 --> 00:16:48.930 was probably behaving like an asteroid if 432 00:16:48.930 --> 00:16:50.650 he'd found it a thousand years ago. But 433 00:16:50.650 --> 00:16:53.330 something happened 250 years ago to wake it 434 00:16:53.330 --> 00:16:55.850 up and it started behaving like a comet and 435 00:16:55.850 --> 00:16:58.430 we see it as a comet. And the other asteroids 436 00:16:58.590 --> 00:17:01.430 in that stream are currently dormant and 437 00:17:01.430 --> 00:17:03.750 there's a load of them. So it's likely in the 438 00:17:03.750 --> 00:17:06.070 inner solar system that even just in the 439 00:17:06.070 --> 00:17:08.150 Taurid Stream, you're going to have hundreds, 440 00:17:08.150 --> 00:17:10.790 if not thousands of objects just like 441 00:17:10.790 --> 00:17:13.750 1998 SH2 that straddle 442 00:17:13.750 --> 00:17:15.390 that boundary between the comet and the 443 00:17:15.390 --> 00:17:16.030 asteroid. 444 00:17:18.190 --> 00:17:20.510 Andrew Dunkley: Fair enough. And, uh, as a consequence of 445 00:17:20.510 --> 00:17:21.790 that, they've had to rename it. 446 00:17:23.880 --> 00:17:26.520 Jonti Horner: Yep. So it now has a cometary classification 447 00:17:26.520 --> 00:17:29.400 as well. What happens with comets is you 448 00:17:29.400 --> 00:17:32.120 get. When people find a comet, 449 00:17:32.570 --> 00:17:35.570 um, it's C, slash, then the year, 450 00:17:35.570 --> 00:17:37.400 ah, and then a catalogue number. So basically 451 00:17:37.400 --> 00:17:39.680 every comet gets a unique identifier. So we 452 00:17:39.680 --> 00:17:42.040 remember Chuchinshan Atlas, which, 453 00:17:42.570 --> 00:17:45.040 um. I'm trying to remember the correct ID for 454 00:17:45.040 --> 00:17:47.581 it, but it was, I think it was like 2023 455 00:17:47.719 --> 00:17:50.560 A, ah, 1 or something like that, A3. So 456 00:17:50.560 --> 00:17:52.520 the A means that it's discovered in the first 457 00:17:52.520 --> 00:17:54.900 fortnight of the year. 3 is the third object 458 00:17:54.900 --> 00:17:56.420 found in the first fortnight of the year. 459 00:17:56.900 --> 00:17:59.900 That tells you about the comet and then 460 00:17:59.900 --> 00:18:01.940 it's named after the discoverer in brackets. 461 00:18:02.580 --> 00:18:04.540 If the comet is seen at more than one 462 00:18:04.540 --> 00:18:06.780 apparition, the C gets changed to a P to show 463 00:18:06.780 --> 00:18:09.580 that it's periodic. In this 464 00:18:09.580 --> 00:18:12.020 case, because this already has 465 00:18:12.500 --> 00:18:15.340 an asteroidal name by which 466 00:18:15.340 --> 00:18:17.540 it's known, it's kept that, but they've added 467 00:18:17.540 --> 00:18:19.580 a P in front of it. So it's gone from being 468 00:18:19.580 --> 00:18:22.350 1998 SH2 to being 469 00:18:22.350 --> 00:18:25.150 P. 1998 SH2, 470 00:18:25.500 --> 00:18:28.030 um, will be interesting to see whether down 471 00:18:28.030 --> 00:18:29.910 the line they add the name of the discovery 472 00:18:29.910 --> 00:18:32.630 facility to it. Um, that wouldn't surprise 473 00:18:32.630 --> 00:18:34.670 me. That's been done for previous occasions 474 00:18:34.670 --> 00:18:36.390 where we've had an asteroid that became a 475 00:18:36.390 --> 00:18:38.710 comet. But it'll be interesting to see. But 476 00:18:38.710 --> 00:18:41.590 it's. I guess what I love about this is 477 00:18:41.590 --> 00:18:43.350 you get into the nitty gritty of it, but it's 478 00:18:43.350 --> 00:18:45.630 that reminder of the beautiful complexity 479 00:18:45.630 --> 00:18:47.710 we've got. There's so much more to learn. 480 00:18:48.510 --> 00:18:50.750 Andrew Dunkley: Absolutely, yes. Uh, it's a really good 481 00:18:50.750 --> 00:18:53.070 storey and, um, one worth reading up. You can 482 00:18:53.070 --> 00:18:55.790 do that@space.com or you can 483 00:18:55.790 --> 00:18:58.350 read the published findings in the journal 484 00:18:58.430 --> 00:19:01.310 Nature Astronomy. This is Space Nuts with 485 00:19:01.310 --> 00:19:03.790 Andrew Dunkley and Professor John T Horner. 486 00:19:06.350 --> 00:19:09.150 Jonti Horner: The crew of Artemis 2 now bound for the moon. 487 00:19:09.390 --> 00:19:11.790 Generic: Humanity's next great voyage begins. 488 00:19:12.510 --> 00:19:13.860 Jonti Horner: Space note Nuts. 489 00:19:13.940 --> 00:19:16.940 Andrew Dunkley: Let's move from a comet flying through 490 00:19:16.940 --> 00:19:19.900 space to a comet, uh, or an asteroid in this 491 00:19:19.900 --> 00:19:22.500 case, that stopped, uh, flying through space 492 00:19:22.500 --> 00:19:24.820 because a big planet called Earth got in the 493 00:19:24.820 --> 00:19:27.500 way. And the one 494 00:19:27.500 --> 00:19:29.850 that, um, is referred to as, uh, 495 00:19:30.740 --> 00:19:32.900 or creating the Chicxulub crater 496 00:19:33.380 --> 00:19:35.820 in what is now known, uh, as the Gulf of 497 00:19:35.820 --> 00:19:38.780 Mexico. Uh, and we even know the 498 00:19:38.780 --> 00:19:40.620 exact impact point because they've been down 499 00:19:40.620 --> 00:19:43.180 there and taken samples, uh, which was a very 500 00:19:43.180 --> 00:19:45.210 exciting storey when we covered that sometime 501 00:19:45.440 --> 00:19:47.960 back. But now they've taken another look at 502 00:19:47.960 --> 00:19:50.840 this, uh, and gone back to the very moment of 503 00:19:50.840 --> 00:19:53.720 impact and the few hours afterwards and 504 00:19:53.720 --> 00:19:56.640 decided by the look of it that this thing was 505 00:19:56.640 --> 00:19:58.320 much more brutal than 506 00:19:59.360 --> 00:20:00.560 we first envisaged. 507 00:20:02.320 --> 00:20:04.840 Jonti Horner: Absolutely. And this kind of ties in with the 508 00:20:04.840 --> 00:20:06.720 storeys that were told again. Back when I was 509 00:20:06.720 --> 00:20:09.280 a teenager, I remember hearing about the 510 00:20:10.080 --> 00:20:12.400 impact that killed the dinosaurs and storeys 511 00:20:12.400 --> 00:20:14.420 about what would have happened on the other 512 00:20:14.420 --> 00:20:17.220 side of the planet and the idea of firestorms 513 00:20:17.220 --> 00:20:18.820 and, you know, it was a hellish experience 514 00:20:18.980 --> 00:20:21.100 worldwide. But the way you'd normally hear 515 00:20:21.100 --> 00:20:23.740 this storey relatively recently is you had 516 00:20:23.740 --> 00:20:26.340 the impact. Things were bad in the vicinity 517 00:20:26.340 --> 00:20:28.460 of the impact. Shockwaves went out, tsunamis 518 00:20:28.460 --> 00:20:30.540 went out. So over a very large area, it was 519 00:20:30.540 --> 00:20:33.420 immediately fairly devastating. But 520 00:20:33.420 --> 00:20:35.420 there was a huge amount of dust and debris 521 00:20:35.420 --> 00:20:38.180 flung into the Earth's atmosphere, which led 522 00:20:38.180 --> 00:20:40.660 to this prolonged nuclear winter type event. 523 00:20:40.660 --> 00:20:42.580 You know, it blocked the sun, got really 524 00:20:42.580 --> 00:20:45.440 cold, the plants died, the animals died. Then 525 00:20:45.440 --> 00:20:47.360 when the clouds cleared, it got really, 526 00:20:47.360 --> 00:20:49.040 really nasty because you got this period of 527 00:20:49.040 --> 00:20:51.520 runaway global warming and hideous acid rain 528 00:20:51.760 --> 00:20:53.680 because the impact had hit rocks that were 529 00:20:53.920 --> 00:20:56.320 packed with carbon and sulphur 530 00:20:56.400 --> 00:20:58.670 carbonate and sulphate rocks, which led to, 531 00:20:58.670 --> 00:21:01.280 uh, carbonic and sulfuric acid 532 00:21:01.280 --> 00:21:04.000 rain. It led to an atmosphere super loaded 533 00:21:04.000 --> 00:21:06.880 with greenhouse gases. So it basically 534 00:21:06.880 --> 00:21:09.520 made the planet fairly hellish for a few tens 535 00:21:09.520 --> 00:21:11.600 of thousands of years, from one stage to the 536 00:21:11.600 --> 00:21:14.300 next to the next. But when I was 537 00:21:14.460 --> 00:21:16.420 younger, there were these storeys about while 538 00:21:16.420 --> 00:21:18.420 there were probably global firestorms. The 539 00:21:18.420 --> 00:21:20.700 idea that an impact halfway around the world 540 00:21:21.100 --> 00:21:23.580 could set fire to forests elsewhere. 541 00:21:24.300 --> 00:21:27.180 And in recent years I've not heard 542 00:21:27.180 --> 00:21:29.299 that storey told so much. It's kind of fallen 543 00:21:29.299 --> 00:21:31.740 a little bit out of fashion. But the new 544 00:21:31.740 --> 00:21:34.500 research that's been done here is kind of 545 00:21:34.500 --> 00:21:36.860 bringing that idea back into the picture. 546 00:21:37.500 --> 00:21:39.980 Now, the idea here is that you get this 547 00:21:40.140 --> 00:21:41.620 impactor that was probably about 10 548 00:21:41.620 --> 00:21:44.220 kilometres across, smacking into the Yukon 549 00:21:44.220 --> 00:21:47.020 Peninsula, creating a crater that was 550 00:21:47.020 --> 00:21:49.260 two to 300 kilometres in diameter. 551 00:21:50.060 --> 00:21:51.860 In doing that, it would have flung a huge 552 00:21:51.860 --> 00:21:54.780 amount of rocky material, vaporised material, 553 00:21:55.180 --> 00:21:57.460 out of the atmosphere. And a lot of that 554 00:21:57.460 --> 00:21:59.380 material would have travelled at speeds 555 00:21:59.380 --> 00:22:01.060 slower than the Earth's escape velocity to 556 00:22:01.060 --> 00:22:03.580 rain back down into the atmosphere. And when 557 00:22:03.580 --> 00:22:05.380 that material falls back into the atmosphere, 558 00:22:05.380 --> 00:22:07.300 it's travelling at speeds of kilometres per 559 00:22:07.300 --> 00:22:10.190 second, so it ablates like a 560 00:22:10.190 --> 00:22:11.750 fireball that we see in the sky, like a 561 00:22:11.750 --> 00:22:13.550 meteor. But you're not seeing one or two, 562 00:22:13.550 --> 00:22:15.630 you're seeing a huge deluge of material 563 00:22:15.630 --> 00:22:17.590 raining down all across the planet. 564 00:22:18.310 --> 00:22:21.230 Now, when these bits of material hit 565 00:22:21.230 --> 00:22:23.470 the atmosphere and ablate, what they're doing 566 00:22:23.470 --> 00:22:25.390 is they're taking the kinetic energy of their 567 00:22:25.390 --> 00:22:28.110 Martian and emitting, turning it into heat 568 00:22:28.110 --> 00:22:30.830 and light, which, you know, if you get a 569 00:22:30.830 --> 00:22:32.830 single small meteor, you're not gonna get 570 00:22:32.830 --> 00:22:35.070 sunburn from it. If you get something the 571 00:22:35.070 --> 00:22:36.710 size of the Chelyabinsk impact, people 572 00:22:36.710 --> 00:22:38.670 actually did get sunburn, um, from that, from 573 00:22:38.670 --> 00:22:41.290 the brightness of the flash. Now imagine, 574 00:22:41.290 --> 00:22:43.130 instead of having one Chelyabinsk impact, 575 00:22:43.130 --> 00:22:45.490 having this rain of material falling into the 576 00:22:45.490 --> 00:22:48.290 atmosphere all across the planet, creating 577 00:22:48.290 --> 00:22:50.450 this, what's described as a thermal pulse 578 00:22:51.410 --> 00:22:53.970 that has been discussed and 579 00:22:54.130 --> 00:22:55.970 previous models, things that have come out, 580 00:22:56.050 --> 00:22:58.130 suggested that that effect would have been 581 00:22:58.130 --> 00:23:01.010 like putting a grill on. It would have been 582 00:23:01.010 --> 00:23:03.050 really quite unpleasant for thin skinned 583 00:23:03.050 --> 00:23:04.770 animals that were exposed to it. You'd have 584 00:23:04.770 --> 00:23:07.170 got burned, you might even have got killed. 585 00:23:07.880 --> 00:23:09.920 But if you were, uh, underground or you were 586 00:23:09.920 --> 00:23:12.200 underwater, you'd have been able to live 587 00:23:12.200 --> 00:23:14.880 through it. I mean, you'd have lived to see 588 00:23:14.880 --> 00:23:16.200 all the other horrors that were coming from 589 00:23:16.200 --> 00:23:17.920 the impacts. It wasn't really a good news, 590 00:23:17.920 --> 00:23:19.640 Storey, but you'd have probably survived it. 591 00:23:20.200 --> 00:23:22.720 But the argument had been that that thermal 592 00:23:22.720 --> 00:23:24.440 pulse from that material coming into the 593 00:23:24.440 --> 00:23:26.920 atmosphere would not have got things hot 594 00:23:26.920 --> 00:23:29.480 enough to ignite things like grasses. You 595 00:23:29.480 --> 00:23:32.200 know, the tinder that you get that can start 596 00:23:32.200 --> 00:23:34.640 forest fires and things like this, which I 597 00:23:34.640 --> 00:23:36.240 think is why that idea of the global 598 00:23:36.240 --> 00:23:39.210 firestorms had gone away. What 599 00:23:39.210 --> 00:23:41.730 the new research has done is looking at 600 00:23:41.730 --> 00:23:43.930 fossil sites in North America, which must be 601 00:23:43.930 --> 00:23:45.570 remembered, was quite close to the impact, 602 00:23:46.130 --> 00:23:48.970 relatively speaking, on a global sense. They 603 00:23:48.970 --> 00:23:51.690 found this layer of spherules of material, 604 00:23:51.690 --> 00:23:53.530 which is a debris that rained back down to 605 00:23:53.530 --> 00:23:56.370 Earth, uh, in the fossil record and above it 606 00:23:56.370 --> 00:23:59.090 there's this very thin layer of silicate 607 00:23:59.090 --> 00:24:01.930 dust which must have fallen out at about the 608 00:24:01.930 --> 00:24:04.540 same time. Now the 609 00:24:04.540 --> 00:24:06.860 idea is that that silicate dust 610 00:24:07.340 --> 00:24:09.420 would have effectively acted like a bit of a 611 00:24:09.420 --> 00:24:11.860 doona with that raining down and that in the 612 00:24:11.860 --> 00:24:14.780 atmosphere. The fact that it's fallen in the 613 00:24:14.780 --> 00:24:17.740 fossil record above the spherules 614 00:24:17.740 --> 00:24:19.620 means the spherules got to the ground before 615 00:24:19.620 --> 00:24:22.500 the dust got to the ground, effectively. So 616 00:24:22.500 --> 00:24:24.020 the researchers have said, well, what would 617 00:24:24.020 --> 00:24:25.700 happen if you had all this dust, all this 618 00:24:25.700 --> 00:24:28.420 silicate dust in the atmosphere and you had 619 00:24:28.420 --> 00:24:30.860 these ferrules running through, giving off 620 00:24:30.860 --> 00:24:33.780 all this heat? And it's effectively like that 621 00:24:33.780 --> 00:24:36.060 dust in the atmosphere would have acted a bit 622 00:24:36.060 --> 00:24:38.020 like a reflecting, uh, blanket or something 623 00:24:38.020 --> 00:24:40.220 like that. It would have trapped even more of 624 00:24:40.220 --> 00:24:42.300 the heat in the atmosphere and reflected it 625 00:24:42.300 --> 00:24:44.300 back down at the ground. And, um, the 626 00:24:44.300 --> 00:24:47.300 calculations that they've made suggest that 627 00:24:47.300 --> 00:24:49.860 that extra energy, because of the energy 628 00:24:49.860 --> 00:24:51.620 being re radiated back down to the ground, 629 00:24:51.620 --> 00:24:54.420 rather than escaping to space, would have 630 00:24:54.420 --> 00:24:56.220 made things hot enough for grass to catch 631 00:24:56.220 --> 00:24:58.860 fire, for pine cones to catch fire. Not 632 00:24:58.860 --> 00:25:01.240 enough not for an entire tree to burst into 633 00:25:01.240 --> 00:25:03.600 flames, but for all the tinder that was lying 634 00:25:03.600 --> 00:25:06.280 on the ground to be called a flame. 635 00:25:06.920 --> 00:25:08.800 And if that happens, what you do is you 636 00:25:08.800 --> 00:25:11.800 trigger global firestorms. So you 637 00:25:11.800 --> 00:25:13.960 turn a situation and you make it much, much 638 00:25:13.960 --> 00:25:16.720 worse. Now, what should be said 639 00:25:16.720 --> 00:25:19.080 here is this, uh, work is looking at North 640 00:25:19.080 --> 00:25:22.000 America and it strikes me that further 641 00:25:22.000 --> 00:25:23.640 away from the impact site, you probably 642 00:25:23.640 --> 00:25:25.040 wouldn't have got the impact dust. So it 643 00:25:25.040 --> 00:25:26.640 might well be that you actually had a 644 00:25:26.640 --> 00:25:29.120 gradiated kind of level of nastiness from the 645 00:25:29.120 --> 00:25:31.620 impact. So nearby it brutal. And 646 00:25:32.100 --> 00:25:33.900 then you had the tsunamis and stuff washing 647 00:25:33.900 --> 00:25:36.220 out on the far side of the planet. You 648 00:25:36.220 --> 00:25:38.060 probably didn't get the silicate dust, so you 649 00:25:38.060 --> 00:25:40.100 just got the normal level of hellishness 650 00:25:40.500 --> 00:25:42.620 where you didn't set off firestorms, but 651 00:25:42.620 --> 00:25:44.700 things were nasty. But there was probably 652 00:25:44.700 --> 00:25:47.460 this sweet spot like the ultimately bad 653 00:25:47.460 --> 00:25:49.860 porridge in the Cinderella Storey, where 654 00:25:49.860 --> 00:25:52.500 things were ultimately worse, ultimately 655 00:25:52.820 --> 00:25:55.540 as bad as they could be, where the impact 656 00:25:55.620 --> 00:25:57.700 way over the horizon, way in the distance, 657 00:25:58.200 --> 00:26:00.440 was enough to trigger forests to burst into 658 00:26:00.440 --> 00:26:02.840 flame because of igniting the tinder enough 659 00:26:02.840 --> 00:26:05.840 to cook animals alive as they were on the 660 00:26:05.840 --> 00:26:08.600 surface. Uh, really kind of brutal and 661 00:26:08.600 --> 00:26:10.920 remarkably horrific imagery. 662 00:26:11.480 --> 00:26:14.239 But it's fascinating work and m it's another 663 00:26:14.239 --> 00:26:16.360 insight into just how bad impacts like this 664 00:26:16.360 --> 00:26:18.520 could be. It's that whole thing that we're 665 00:26:18.520 --> 00:26:21.400 playing with a detective storey that is 66 666 00:26:21.400 --> 00:26:23.880 million years old and we're trying to piece 667 00:26:23.880 --> 00:26:26.240 together the narrative of what happened and 668 00:26:26.240 --> 00:26:27.800 every bit of information we get like this 669 00:26:27.800 --> 00:26:29.560 just seems to make a more and more horrific 670 00:26:29.560 --> 00:26:30.260 piece picture. 671 00:26:30.580 --> 00:26:33.220 Andrew Dunkley: Yeah, I mean, the original consensus was 672 00:26:33.300 --> 00:26:35.940 the, um, asteroid hit 673 00:26:36.660 --> 00:26:39.060 the planet and, uh, it 674 00:26:39.060 --> 00:26:41.380 created, um, tsunamis that went around the 675 00:26:41.380 --> 00:26:43.780 world, um, three, four times, something like 676 00:26:43.780 --> 00:26:46.420 that. Um, and uh, created 677 00:26:47.220 --> 00:26:49.780 the equivalent of a nuclear winter and 678 00:26:49.860 --> 00:26:52.820 everything died and there was no food and, 679 00:26:52.850 --> 00:26:55.260 uh, the creatures died along with it over a 680 00:26:55.260 --> 00:26:58.260 period of time. But this is suggesting that a 681 00:26:58.260 --> 00:27:00.420 lot of, um, the initial death, 682 00:27:01.290 --> 00:27:03.630 uh, due to these firestorms happened in a few 683 00:27:03.790 --> 00:27:06.390 mere hours. Um, it's a 684 00:27:06.390 --> 00:27:07.310 horrifying thought. 685 00:27:08.110 --> 00:27:10.390 Jonti Horner: It is. And I mean, you start getting to that 686 00:27:10.390 --> 00:27:12.550 kind of philosophical side of thing is does 687 00:27:12.550 --> 00:27:14.510 this make it better or does it make it worse? 688 00:27:14.510 --> 00:27:15.910 You know, if you were there at the time, 689 00:27:15.910 --> 00:27:17.910 would you rather be broiled and baked and 690 00:27:17.910 --> 00:27:20.830 cooked quickly or left to starve slowly in 691 00:27:20.830 --> 00:27:23.350 the cold that followed it? Yeah, I mean it's 692 00:27:23.350 --> 00:27:25.750 all fairly bleak, but it is also that 693 00:27:25.750 --> 00:27:27.230 reminder drawing just a bit like we were 694 00:27:27.230 --> 00:27:28.630 talking about in the previous storey. We are 695 00:27:28.630 --> 00:27:30.510 in the crosshairs. This will happen again. 696 00:27:30.830 --> 00:27:32.670 It's not like the Earth has been hit for the 697 00:27:32.670 --> 00:27:35.430 last time unless we do something about 698 00:27:35.430 --> 00:27:38.070 it. And it's great that we have the capacity 699 00:27:38.070 --> 00:27:40.870 to discover objects further and further 700 00:27:40.870 --> 00:27:42.549 from the Earth with a greater and greater 701 00:27:42.549 --> 00:27:44.310 lead time before they come close to us. It's 702 00:27:44.310 --> 00:27:46.790 great that we're learning the capacity to 703 00:27:46.790 --> 00:27:49.110 deflect them. But it's sometimes hard to 704 00:27:49.110 --> 00:27:51.150 justify to people why people are doing this 705 00:27:51.150 --> 00:27:53.390 kind of research. And it's one of the 706 00:27:53.390 --> 00:27:55.070 arguments we have, for example, against the 707 00:27:55.070 --> 00:27:57.230 satellite megalithic constellations, because 708 00:27:57.230 --> 00:27:59.330 we're finally a spec that can look out at the 709 00:27:59.330 --> 00:28:02.010 cosmos and detect threats. And what we're 710 00:28:02.010 --> 00:28:04.130 doing is we're throwing tinsel in the way and 711 00:28:04.130 --> 00:28:04.970 hiding the view. 712 00:28:06.330 --> 00:28:08.570 Andrew Dunkley: And that is a bit of a worry. Well, it's a 713 00:28:08.570 --> 00:28:10.770 big worry and it's not getting any better. In 714 00:28:10.770 --> 00:28:13.470 fact, it's going to get worse. We'll um, 715 00:28:13.470 --> 00:28:15.530 probably discuss that more in our next 716 00:28:15.530 --> 00:28:15.930 episode. 717 00:28:15.930 --> 00:28:18.650 But, um, I did notice 718 00:28:18.650 --> 00:28:21.130 in sort of looking at this storey that, uh, 719 00:28:21.130 --> 00:28:24.130 some papers or some websites refer to 720 00:28:24.130 --> 00:28:26.330 it as a meteorite impact rather than an 721 00:28:26.330 --> 00:28:28.430 asteroid. Why would they do that? 722 00:28:28.910 --> 00:28:31.790 Jonti Horner: This is interesting with terminology and 723 00:28:31.950 --> 00:28:34.030 I'm less uncomfortable with the idea of 724 00:28:34.270 --> 00:28:37.070 meteorite impact, asteroid impact being 725 00:28:37.070 --> 00:28:39.990 a conflation. The terminology of 726 00:28:39.990 --> 00:28:42.590 objects is a weird one and 727 00:28:42.989 --> 00:28:45.550 astronomers have very specific terminology 728 00:28:46.350 --> 00:28:48.310 that then gets a little bit confused when you 729 00:28:48.310 --> 00:28:50.470 see popular science and you see the news and 730 00:28:50.470 --> 00:28:53.270 all the rest of it when something's floating 731 00:28:53.270 --> 00:28:56.210 around in space nowhere near the Earth, 732 00:28:56.690 --> 00:28:59.570 we refer to it as a meteoroid 733 00:28:59.570 --> 00:29:01.810 or an asteroid or comet, basically. 734 00:29:02.560 --> 00:29:04.170 Um, and we talked about asteroids and comets 735 00:29:04.170 --> 00:29:05.890 earlier on and where the line blurs there. 736 00:29:07.090 --> 00:29:09.890 The typical boundary between 737 00:29:09.890 --> 00:29:12.850 calling a meteoroid and an asteroid is 738 00:29:12.850 --> 00:29:15.130 often taken as being about one metre in size, 739 00:29:15.130 --> 00:29:16.610 but that's just fairly arbitrary. 740 00:29:18.130 --> 00:29:21.040 When something enters the atmosphere and it's 741 00:29:21.040 --> 00:29:22.320 pushing the air in front of it and it's 742 00:29:22.320 --> 00:29:25.320 glowing in the sky, that phenomenon we call 743 00:29:25.320 --> 00:29:28.200 a meteor, if it's really bright, we call it 744 00:29:28.200 --> 00:29:30.160 a fireball. And that boundary is set roughly 745 00:29:30.160 --> 00:29:32.680 as bright as a planet Venus. If we see an 746 00:29:32.680 --> 00:29:34.800 explosion at the end, we call it a bolide. 747 00:29:34.800 --> 00:29:36.480 And that just means exploding fireball, 748 00:29:36.640 --> 00:29:39.440 basically. So meteor, bolide, 749 00:29:39.600 --> 00:29:42.080 fireball are uh, atmospheric phenomena. 750 00:29:42.320 --> 00:29:43.880 You're not actually seeing the thing coming 751 00:29:43.880 --> 00:29:46.080 through the atmosphere, you're seeing the gas 752 00:29:46.080 --> 00:29:48.550 that it's heated up and excited in the 753 00:29:48.550 --> 00:29:50.310 atmosphere. That's what you're seeing as a 754 00:29:50.310 --> 00:29:53.190 glow. When it reaches the ground and hits the 755 00:29:53.190 --> 00:29:55.750 ground, you call it a meteorite. That's the 756 00:29:55.750 --> 00:29:58.630 physical object on the ground or hitting the 757 00:29:58.630 --> 00:30:01.590 ground. Now, whether 758 00:30:01.590 --> 00:30:04.110 you call something like this a meteorite 759 00:30:04.110 --> 00:30:05.950 impact or an asteroid impact, I think it's 760 00:30:05.950 --> 00:30:08.870 probably both. You know, technically the 761 00:30:08.870 --> 00:30:11.870 asteroid hits the ground, um, you 762 00:30:11.870 --> 00:30:13.910 could call it a meteorite. But maybe what you 763 00:30:13.910 --> 00:30:15.670 should do is have that idea in your head of 764 00:30:15.670 --> 00:30:17.830 if it's less than a metre across, you could 765 00:30:17.830 --> 00:30:19.930 call it a meteorite. Bigger than that, you'd 766 00:30:19.930 --> 00:30:21.210 call it an asteroid. I've never seen 767 00:30:21.210 --> 00:30:24.130 clarification on where that 768 00:30:24.130 --> 00:30:26.290 boundary comes because terms are used in 769 00:30:26.290 --> 00:30:29.130 different sensors kind of thing. So for me, 770 00:30:29.290 --> 00:30:31.090 I don't think it's unreasonable to say 771 00:30:31.090 --> 00:30:32.890 meteorite impact here, although you're 772 00:30:32.890 --> 00:30:35.450 probably pushing the size definition. 773 00:30:36.010 --> 00:30:38.330 Call it an asteroid or comet impact is 774 00:30:38.330 --> 00:30:40.130 probably more reasonable. And it might be 775 00:30:40.130 --> 00:30:42.050 that if you dug into the physics of it and 776 00:30:42.050 --> 00:30:44.930 you were to do an IAU resolution a bit like 777 00:30:44.930 --> 00:30:47.930 we did with Pluto, maybe what you do is look 778 00:30:47.930 --> 00:30:49.610 at it in terms of the effect of the 779 00:30:49.610 --> 00:30:52.330 atmosphere on the object coming in. So 780 00:30:52.330 --> 00:30:54.770 things that create fireballs and bolides in 781 00:30:54.770 --> 00:30:57.370 day to day life, the atmosphere is much 782 00:30:57.370 --> 00:31:00.210 bigger in size than the object coming in, 783 00:31:00.370 --> 00:31:02.330 which means wind resistance will eventually 784 00:31:02.330 --> 00:31:05.130 slow it down. So the meteorite that we talked 785 00:31:05.130 --> 00:31:06.650 about a few months ago that landed on 786 00:31:06.650 --> 00:31:09.330 someone's driveway in Canada was travelling 787 00:31:09.330 --> 00:31:11.490 at about the same speed that a rock dropped 788 00:31:11.490 --> 00:31:12.970 out of an aircraft would have done. It was at 789 00:31:12.970 --> 00:31:15.810 terminal velocity. Its speed was 790 00:31:15.810 --> 00:31:18.330 governed by the atmosphere. Whereas with 791 00:31:18.330 --> 00:31:20.950 things that are kilometre scale, the 792 00:31:20.950 --> 00:31:22.710 Atmosphere is essentially not there. It's not 793 00:31:22.710 --> 00:31:25.270 going to slow them down. And so I wonder 794 00:31:25.270 --> 00:31:26.990 whether there is an argument that you could 795 00:31:26.990 --> 00:31:29.590 set up a definition that said if it's 796 00:31:29.590 --> 00:31:31.870 travelling at uh, speed less than 797 00:31:31.870 --> 00:31:34.710 supersonic, you'd call it a meteorite impact. 798 00:31:34.710 --> 00:31:36.309 If it's travelling faster than that, maybe 799 00:31:36.309 --> 00:31:38.990 you'd call it an asteroid impact. But I don't 800 00:31:38.990 --> 00:31:40.910 think that there's any official delineation 801 00:31:40.990 --> 00:31:43.350 like that. That's just kind of how I think 802 00:31:43.350 --> 00:31:44.590 about things in my own head. 803 00:31:44.670 --> 00:31:46.760 Andrew Dunkley: No, I like that that works. Well, well, 804 00:31:46.760 --> 00:31:48.560 that's probably a good way to think about it. 805 00:31:49.420 --> 00:31:52.000 Um, another interesting storey that uh, the 806 00:31:52.000 --> 00:31:54.960 asteroid impact uh, that killed the dinosaurs 807 00:31:55.280 --> 00:31:57.720 was a lot more damaging in the early stages 808 00:31:57.720 --> 00:32:00.240 than we first thought by the look of. But uh, 809 00:32:00.240 --> 00:32:02.400 plenty of, plenty of websites and news 810 00:32:02.640 --> 00:32:04.360 platforms have picked this one up, not 811 00:32:04.360 --> 00:32:06.720 surprisingly. Uh, but you can read 812 00:32:07.760 --> 00:32:10.280 at uh, the Science 813 00:32:10.280 --> 00:32:13.160 Advances, uh, website published in 814 00:32:13.160 --> 00:32:15.600 Science Advances. Uh, this is Space Nuts 815 00:32:15.600 --> 00:32:17.440 Andrew Dunkley here with Johnty Horner. 816 00:32:20.220 --> 00:32:22.140 Jonti Horner: 0G and I feel fine. 817 00:32:22.140 --> 00:32:24.940 Andrew Dunkley: Space Nuts, the storey. Jonty 818 00:32:25.020 --> 00:32:27.740 takes us to Canadia and 819 00:32:27.900 --> 00:32:30.620 this is a storey, uh, about a 820 00:32:30.620 --> 00:32:33.620 Canadian amateur astronomer who 821 00:32:33.620 --> 00:32:36.140 decided to plan a holiday using online maps. 822 00:32:36.140 --> 00:32:36.620 It is. 823 00:32:36.620 --> 00:32:38.380 Jonti Horner: This is lovely. I think we've all done this 824 00:32:38.380 --> 00:32:41.140 to some degree. You planning your holiday, 825 00:32:41.140 --> 00:32:42.700 planning your road trip. I just had a lovely 826 00:32:42.700 --> 00:32:45.230 holiday with the in laws. And you look at uh, 827 00:32:45.230 --> 00:32:47.140 the online maps of your choice that typically 828 00:32:47.140 --> 00:32:49.140 have really nice satellite images of the 829 00:32:49.140 --> 00:32:52.110 places you're um, and you try and figure out 830 00:32:52.110 --> 00:32:53.230 what you're going to see, what you're going 831 00:32:53.230 --> 00:32:55.990 to go there. And to some degree you sat 832 00:32:55.990 --> 00:32:57.510 browsing around thinking, I wonder if I can 833 00:32:57.510 --> 00:32:59.230 see anything unusual, what's it like around 834 00:32:59.230 --> 00:33:02.030 there? And that's what happened 835 00:33:02.030 --> 00:33:05.030 here. We've got this amateur astronomer going 836 00:33:05.030 --> 00:33:08.030 by the name of Joel Lapointe who back in 837 00:33:08.030 --> 00:33:10.990 2024 was planning his hiking and 838 00:33:10.990 --> 00:33:13.830 camping trip. And I think it's in northern 839 00:33:13.830 --> 00:33:16.350 Quebec. It's near a place called Lake Mars. 840 00:33:17.620 --> 00:33:20.340 And he found this unusual looking 841 00:33:20.820 --> 00:33:23.220 feature next to that lake. Looks a bit odd 842 00:33:23.620 --> 00:33:26.420 on the maps on the satellite imaging. Now 843 00:33:26.420 --> 00:33:29.300 there is a university in Canada that has a 844 00:33:29.300 --> 00:33:31.820 website called Impact Earth that allows 845 00:33:31.820 --> 00:33:34.020 people to, as a kind of popular 846 00:33:34.570 --> 00:33:36.500 um, collaborative endeavour for 847 00:33:36.980 --> 00:33:39.060 citizen science is the word I'm looking for 848 00:33:39.460 --> 00:33:42.260 to log things where people think they've 849 00:33:42.260 --> 00:33:45.250 found impact features. So being an 850 00:33:45.250 --> 00:33:46.930 amateur astronomer being aware of this, he 851 00:33:46.930 --> 00:33:49.690 logged it. I think I found a crater. About 852 00:33:49.690 --> 00:33:52.410 a year later, um, the site 853 00:33:52.490 --> 00:33:54.970 as a result of this report was 854 00:33:55.210 --> 00:33:57.730 explored, visited by a planetary geologist 855 00:33:57.730 --> 00:34:00.250 from the university called Gordon Ozinski. 856 00:34:00.810 --> 00:34:03.050 Who went there, took a lot of samples, 857 00:34:03.290 --> 00:34:06.130 explored around and confirmed that 858 00:34:06.130 --> 00:34:07.890 this really is an impact feature. It's an 859 00:34:07.890 --> 00:34:09.780 impact crater about 860 00:34:10.020 --> 00:34:12.900 390 million years old, 861 00:34:12.980 --> 00:34:14.940 so way older than the impact that killed the 862 00:34:14.940 --> 00:34:17.780 dinosaurs. About 25 kilometres 863 00:34:17.780 --> 00:34:20.580 across, which includes a load of 864 00:34:20.580 --> 00:34:23.460 incredibly well preserved features in terms 865 00:34:23.460 --> 00:34:26.260 of glassy hardened volcanic type rocks from 866 00:34:26.260 --> 00:34:29.180 the impact that he himself has said he's 867 00:34:29.180 --> 00:34:30.860 surprised at that well preserved, given how 868 00:34:30.860 --> 00:34:33.420 old it is and how far north this is, how cold 869 00:34:33.420 --> 00:34:36.140 the weather gets in the winter and stuff. Now 870 00:34:36.140 --> 00:34:38.260 this makes it the biggest crater found on 871 00:34:38.260 --> 00:34:40.740 Earth since 2018, when there was a crater 872 00:34:40.960 --> 00:34:43.480 discovered under the Greenland ice sheet. But 873 00:34:43.480 --> 00:34:45.120 the difference is that the one under the 874 00:34:45.120 --> 00:34:47.400 Greenland ice sheet is below a kilometre's 875 00:34:47.400 --> 00:34:50.040 depth of ice. So it isn't like we can get 876 00:34:50.040 --> 00:34:51.800 there and learn much more about it. That's 877 00:34:51.800 --> 00:34:53.360 still quite a mysterious spot. 878 00:34:54.320 --> 00:34:56.880 Whereas this is open and exposed and 879 00:34:56.880 --> 00:34:59.600 accessible, so people are able to go there 880 00:34:59.600 --> 00:35:02.280 and explore it, learn a lot about it. There's 881 00:35:02.280 --> 00:35:04.720 some really nice imagery out there on the 882 00:35:05.040 --> 00:35:07.800 Internet about this. From the maps, images 883 00:35:07.800 --> 00:35:10.540 where it was found to images of 884 00:35:10.540 --> 00:35:12.740 features called shatter cones, which are the 885 00:35:12.740 --> 00:35:15.060 kind of thing created that are very typical 886 00:35:15.060 --> 00:35:17.780 of an impact crater formed under very high 887 00:35:17.780 --> 00:35:20.580 pressure, very high temperature molten rock. 888 00:35:20.580 --> 00:35:23.020 So it is absolutely amazing. 889 00:35:23.420 --> 00:35:26.140 But it's also to me kind of breathtaking that 890 00:35:26.140 --> 00:35:29.020 here is a feature 25 kilometres in diameter 891 00:35:29.980 --> 00:35:32.500 in the middle of a built up, well, not that 892 00:35:32.500 --> 00:35:34.660 built up country, but in the middle of a 893 00:35:34.660 --> 00:35:37.640 country near a famous lake, there is an 894 00:35:37.640 --> 00:35:39.800 impact crater that had never been identified 895 00:35:39.800 --> 00:35:42.360 until now. You know, we're still discovering 896 00:35:43.000 --> 00:35:45.320 kilometres, tens of kilometre scale features 897 00:35:45.320 --> 00:35:47.120 on the Earth. I mean, that's just 898 00:35:47.120 --> 00:35:47.960 astonishing. 899 00:35:50.460 --> 00:35:53.440 Andrew Dunkley: Uh, yeah, it is. And um, I 900 00:35:53.440 --> 00:35:56.000 think we've talked about it in the past that 901 00:35:56.000 --> 00:35:58.040 one of the problems with finding these things 902 00:35:58.040 --> 00:36:00.880 on Earth is the fact that the Earth's kind 903 00:36:00.880 --> 00:36:03.330 of covered up with vegetation and uh, 904 00:36:03.800 --> 00:36:06.180 you know, lots of, um, weather, uh, 905 00:36:06.520 --> 00:36:08.700 activity which has caused erosion and then 906 00:36:08.700 --> 00:36:10.220 we've got earthquakes that have caused 907 00:36:10.220 --> 00:36:12.500 mountain ranges to pop up here and there. And 908 00:36:12.500 --> 00:36:15.380 so a lot of these impact points get uh, 909 00:36:15.540 --> 00:36:18.260 disturbed or are hidden. Not uncommon 910 00:36:18.260 --> 00:36:18.580 now. 911 00:36:20.100 --> 00:36:22.380 Jonti Horner: Absolutely. And I mean 70% of the Earth's 912 00:36:22.380 --> 00:36:25.260 surface is water and you need to be a bigger 913 00:36:25.260 --> 00:36:27.140 impacter than the depth of the ocean to leave 914 00:36:27.140 --> 00:36:29.860 a scar on the ocean floor. So the 915 00:36:30.260 --> 00:36:32.820 history of impacts on the Earth is very much 916 00:36:32.820 --> 00:36:35.160 muddied by all of these different 917 00:36:35.240 --> 00:36:37.560 processes. The Ice Ages have scoured the 918 00:36:37.560 --> 00:36:39.080 surface of the Earth clean. We've got 919 00:36:39.080 --> 00:36:41.400 weathering, we've got forests, the Earth's 920 00:36:41.400 --> 00:36:43.480 surface is actually an incredibly dynamic 921 00:36:43.480 --> 00:36:46.280 place compared to the Moon. If you look at 922 00:36:46.280 --> 00:36:48.000 the Moon, there are many craters of this kind 923 00:36:48.000 --> 00:36:50.000 of size. And one of the things that is 924 00:36:50.000 --> 00:36:51.600 actually discussed in the articles online 925 00:36:51.600 --> 00:36:54.160 about this is whether this could be a venue 926 00:36:54.160 --> 00:36:56.320 for people to learn more in preparation for 927 00:36:56.320 --> 00:36:58.600 visits to the Moon where we can go to craters 928 00:36:58.680 --> 00:37:00.720 or vice versa. Whether we could learn more 929 00:37:00.720 --> 00:37:02.680 about craters like this by going to the ones 930 00:37:02.680 --> 00:37:04.240 on the Moon that are the same size but are 931 00:37:04.240 --> 00:37:06.840 pristine because we're at a similar 932 00:37:06.840 --> 00:37:08.960 location with similar targets in the shooting 933 00:37:08.960 --> 00:37:11.440 gallery. But on the Earth everything gets 934 00:37:11.440 --> 00:37:13.400 worn away fairly effectively, whereas on the 935 00:37:13.400 --> 00:37:16.200 Moon it stays pretty pristine until something 936 00:37:16.200 --> 00:37:18.360 else hits it and weathers it away. The only 937 00:37:18.360 --> 00:37:19.880 real way you're going to weather lunar 938 00:37:19.880 --> 00:37:22.680 craters, um, with a few exceptions, is 939 00:37:22.680 --> 00:37:24.720 by other things hitting them and muddying the 940 00:37:24.720 --> 00:37:27.600 water. There is going to be a lot more to 941 00:37:27.600 --> 00:37:30.560 learn about this. It is still relatively new 942 00:37:30.560 --> 00:37:32.770 news. The geologists involved 943 00:37:33.170 --> 00:37:35.050 won't be going there year round because it 944 00:37:35.050 --> 00:37:36.890 gets really, really cold and really 945 00:37:36.890 --> 00:37:38.410 unpleasant in the winter. So there'll be 946 00:37:38.410 --> 00:37:40.170 summer expeditions going there, trying to 947 00:37:40.170 --> 00:37:42.810 learn more about it, getting more and more 948 00:37:42.810 --> 00:37:44.530 samples of it. Because we don't know many 949 00:37:44.530 --> 00:37:46.210 craters that are that old on the Earth. 950 00:37:46.290 --> 00:37:49.050 Andrew Dunkley: No, this is 390 million 951 00:37:49.050 --> 00:37:51.890 years. That's a long time back, isn't 952 00:37:51.890 --> 00:37:54.730 it? That's over 300 million years beyond the 953 00:37:54.730 --> 00:37:55.730 dinosaur impact. 954 00:37:56.930 --> 00:37:59.290 Jonti Horner: Absolutely pretty impressive. It's far from 955 00:37:59.290 --> 00:38:01.010 the oldest crater on the Earth, but I would 956 00:38:01.330 --> 00:38:04.050 argue that we know far more younger craters 957 00:38:04.290 --> 00:38:06.410 than this than. We know older craters than 958 00:38:06.410 --> 00:38:06.690 this. 959 00:38:06.690 --> 00:38:09.570 Andrew Dunkley: Yeah. Didn't they recently say they found 960 00:38:09.570 --> 00:38:12.050 the oldest one in Western Australia? Was it? 961 00:38:12.930 --> 00:38:15.050 Jonti Horner: Yeah. Then I think that was a little bit 962 00:38:15.050 --> 00:38:16.810 controversial, but there was a lot of talk 963 00:38:16.810 --> 00:38:18.850 about shattercons with that one as well. 964 00:38:18.850 --> 00:38:20.690 Andrew Dunkley: Yes, there was, Yeah, I remember that. 965 00:38:21.090 --> 00:38:23.450 Jonti Horner: You know, these are, uh, we're finding 966 00:38:23.450 --> 00:38:25.210 craters more and more and they tell us about 967 00:38:25.210 --> 00:38:27.790 the history of the Earth and the heritage of 968 00:38:27.790 --> 00:38:30.710 it. With the really old craters, there's even 969 00:38:30.710 --> 00:38:33.310 some arguments that the, ah, largest impacts 970 00:38:33.310 --> 00:38:35.190 that happened very early on in the Earth's 971 00:38:35.190 --> 00:38:38.110 history were actually the seeds of the 972 00:38:38.110 --> 00:38:40.150 continents to some degree. There was some 973 00:38:40.390 --> 00:38:43.270 amazing work. This is probably actually best 974 00:38:43.270 --> 00:38:45.110 part of a decade ago now. But there was great 975 00:38:45.110 --> 00:38:47.070 work by Craig o' Neill and his team that were 976 00:38:47.070 --> 00:38:50.030 looking at trying to model the initiation of 977 00:38:50.030 --> 00:38:51.630 plate tectonics on the Earth. So how did 978 00:38:51.630 --> 00:38:53.750 plate tectonics get going? And, um, these 979 00:38:53.750 --> 00:38:55.870 incredibly talented geophysicists here in 980 00:38:55.870 --> 00:38:58.820 Australia were running models where 981 00:38:58.820 --> 00:39:00.860 you start the Earth with no plate tectonics, 982 00:39:00.860 --> 00:39:02.540 looking at the interior, looking at how hot 983 00:39:02.540 --> 00:39:04.940 it was back then. And if you started the 984 00:39:04.940 --> 00:39:06.420 Earth without plate tectonics, plate 985 00:39:06.420 --> 00:39:08.900 tectonics didn't happen. And uh, what they 986 00:39:08.900 --> 00:39:11.380 thought could be the smoking gun was that you 987 00:39:11.380 --> 00:39:14.340 had impacts that caused a big impulse of 988 00:39:14.340 --> 00:39:16.860 energy and motion in the mantle 989 00:39:17.180 --> 00:39:19.700 that triggered a downwelling which would then 990 00:39:19.700 --> 00:39:21.340 trigger an upwelling and you could get impact 991 00:39:21.580 --> 00:39:24.300 induced plate tectonics which would then 992 00:39:24.300 --> 00:39:26.340 cause these things to maybe even give you the 993 00:39:26.340 --> 00:39:28.100 seeds of the continents of the earliest 994 00:39:28.100 --> 00:39:31.040 continents. And that's an 995 00:39:31.040 --> 00:39:32.960 awesome storey. The videos that they made of 996 00:39:32.960 --> 00:39:35.620 their simulations were fabulous. And 997 00:39:35.620 --> 00:39:37.520 um, yeah, it's amazing what more there is 998 00:39:37.520 --> 00:39:38.520 still to learn, I guess. 999 00:39:38.680 --> 00:39:41.120 Andrew Dunkley: Yeah, absolutely true. And this is another 1000 00:39:41.120 --> 00:39:43.880 storey that's been picked up by Orlin Sundry. 1001 00:39:44.420 --> 00:39:46.640 Uh, so, um, yeah, you shouldn't have any 1002 00:39:46.640 --> 00:39:48.720 trouble finding it if you do, um, a search 1003 00:39:48.720 --> 00:39:51.040 for the Canadian amateur astronomer who was 1004 00:39:51.040 --> 00:39:53.800 planning his holiday. And uh, the storey will 1005 00:39:53.800 --> 00:39:56.080 pop up just about everywhere. Space.com, the 1006 00:39:56.080 --> 00:39:58.280 Smithsonian magazine, et cetera, et cetera. 1007 00:39:58.600 --> 00:40:01.540 Uh, and uh, by, by now, 1008 00:40:01.620 --> 00:40:04.460 when you hear this episode or very close to 1009 00:40:04.460 --> 00:40:07.220 this point in time, uh, the team 1010 00:40:07.220 --> 00:40:09.020 that uh, made the discovery will be 1011 00:40:09.020 --> 00:40:11.780 presenting their work at the 88th Annual 1012 00:40:11.780 --> 00:40:14.280 Meeting of the Meteor. Uh, 1013 00:40:14.280 --> 00:40:17.100 meteoritis. I can't say 1014 00:40:17.100 --> 00:40:20.060 it, uh, Meteorocital 1015 00:40:20.060 --> 00:40:22.780 Society in Germany, I think. That's right. I 1016 00:40:22.780 --> 00:40:25.380 don't know. Anyway, yeah, look it up. It's a 1017 00:40:25.380 --> 00:40:25.900 great yarn. 1018 00:40:25.900 --> 00:40:28.660 Uh, we've had a very rocky programme today. 1019 00:40:29.300 --> 00:40:32.260 Um, Jonty, it's been fascinating the 1020 00:40:32.260 --> 00:40:34.540 way those storeys all dovetailed into each 1021 00:40:34.540 --> 00:40:36.980 other. Uh, and we're at the end. Thank you 1022 00:40:36.980 --> 00:40:38.540 very much. Nice to see you again. 1023 00:40:39.200 --> 00:40:40.500 Jonti Horner: Uh, it's good to be back. Thank you for 1024 00:40:40.500 --> 00:40:41.260 having me and hope 1025 00:40:41.260 --> 00:40:43.260 Andrew Dunkley: Fred Watson's enjoying his jaunt 1026 00:40:44.220 --> 00:40:45.860 chasing a, uh, solar eclipse. 1027 00:40:45.860 --> 00:40:48.340 Jonti Horner: Yes, yes, it's a hard life but somebody's got 1028 00:40:48.340 --> 00:40:48.860 to do it. 1029 00:40:48.940 --> 00:40:50.860 Andrew Dunkley: Absolutely true. I'm waiting for one to come 1030 00:40:50.860 --> 00:40:52.620 to me. I only have to wait two more years. 1031 00:40:52.700 --> 00:40:53.500 Jonti Horner: Two more years. 1032 00:40:54.300 --> 00:40:54.700 Andrew Dunkley: Thanks. 1033 00:40:54.700 --> 00:40:56.220 Jonti Horner: And it'll be cloudy. You know it's going to 1034 00:40:56.220 --> 00:40:56.540 be cloudy. 1035 00:40:56.540 --> 00:40:57.780 Andrew Dunkley: Oh yeah, it's probably going to be raining 1036 00:40:57.850 --> 00:41:00.530 training and I'm m giving up a game of golf 1037 00:41:00.530 --> 00:41:02.970 for it too. All right, thanks Jonty. We'll 1038 00:41:02.970 --> 00:41:05.010 see you soon. Yeah, It's a pleasure, 1039 00:41:05.010 --> 00:41:06.690 Professor Jonty Horner, professor of 1040 00:41:06.690 --> 00:41:08.850 Astrophysics at the University of Southern 1041 00:41:08.850 --> 00:41:11.130 Queensland. Don't forget, uh, to visit us 1042 00:41:11.130 --> 00:41:13.530 online while uh, you are, ah, waiting for the 1043 00:41:13.530 --> 00:41:14.290 next episode, 1044 00:41:14.290 --> 00:41:16.650 spacenutspodcast.com 1045 00:41:17.370 --> 00:41:18.810 and have a look around while you're there. 1046 00:41:18.810 --> 00:41:21.450 Visit the shop, etc etc and thanks to Huw in 1047 00:41:21.450 --> 00:41:23.730 the studio couldn't be with us today. Um, put 1048 00:41:23.730 --> 00:41:25.490 his home address in Google Maps. We haven't 1049 00:41:25.490 --> 00:41:27.810 seen him since. And from me, Andrew Dunkley. 1050 00:41:27.810 --> 00:41:29.610 Thanks for your company. We'll see you on the 1051 00:41:29.610 --> 00:41:31.830 next next episode of Space Nuts. Bye. Bye. 1052 00:41:33.030 --> 00:41:35.230 Jonti Horner: You've been listening to the Space Nuts 1053 00:41:35.230 --> 00:41:38.190 podcast, available at 1054 00:41:38.190 --> 00:41:40.150 Apple Podcasts, Spotify, 1055 00:41:40.390 --> 00:41:43.150 iHeartRadio or your favourite podcast 1056 00:41:43.150 --> 00:41:44.830 player. You can also stream on 1057 00:41:44.830 --> 00:41:46.470 demand@bytes.com M. 1058 00:41:46.870 --> 00:41:48.950 Andrew Dunkley: This has been another quality podcast 1059 00:41:48.950 --> 00:41:51.030 production from bytes.com.