WEBVTT 0 00:00:00.400 --> 00:00:02.800 Anna: Somewhere above your head right now, about 1 00:00:02.880 --> 00:00:05.440 36,000 km up, 2 00:00:05.840 --> 00:00:08.160 there is a graveyard shift going on. 3 00:00:08.640 --> 00:00:11.040 Hundreds of satellites still working, 4 00:00:11.440 --> 00:00:14.400 still useful, and slowly running out of 5 00:00:14.400 --> 00:00:14.880 fuel. 6 00:00:15.280 --> 00:00:17.800 Avery: And as of last night, there is finally a 7 00:00:17.800 --> 00:00:18.880 mechanic on the way. 8 00:00:19.200 --> 00:00:22.160 Anna: Good evening and welcome to Astronomy Daily. 9 00:00:22.400 --> 00:00:23.360 I'm Anna. 10 00:00:23.440 --> 00:00:26.400 Avery: And I'm Avery. Coming up, a spacecraft 11 00:00:26.400 --> 00:00:28.840 with arms launches on a mission to keep other 12 00:00:28.840 --> 00:00:31.800 spacecraft alive. A rocket stage is two 13 00:00:31.800 --> 00:00:33.480 weeks out from hitting the moon and 14 00:00:33.480 --> 00:00:35.880 astronomers have just put out a call to arms 15 00:00:35.880 --> 00:00:36.360 about it. 16 00:00:36.680 --> 00:00:39.160 Anna: We've got two stars that were born together, 17 00:00:39.560 --> 00:00:42.520 lived together and then died in sequence, 18 00:00:42.680 --> 00:00:44.960 leaving behind the first pair of 19 00:00:44.960 --> 00:00:47.840 supernova remnants ever traced back to 20 00:00:47.840 --> 00:00:49.080 a single binary. 21 00:00:49.560 --> 00:00:52.320 Avery: The first complete magnetic map of a galaxy 22 00:00:52.320 --> 00:00:54.720 cluster, an asteroid breakup that may have 23 00:00:54.720 --> 00:00:57.120 bombarded three worlds and helped freeze our 24 00:00:57.120 --> 00:00:57.400 own. 25 00:00:58.060 --> 00:01:00.780 Anna: And a sky watching window that is closing 26 00:01:00.860 --> 00:01:02.220 faster than you'd like. 27 00:01:02.780 --> 00:01:03.740 Avery: Let's get into it. 28 00:01:04.140 --> 00:01:07.100 Anna: So Avery, here's a problem that has quietly 29 00:01:07.100 --> 00:01:09.580 bothered the satellite industry for about 30 00:01:09.820 --> 00:01:12.780 60 years. You build a satellite, you 31 00:01:12.780 --> 00:01:15.180 spend hundreds of millions of dollars on it. 32 00:01:15.340 --> 00:01:17.740 You put it in geostationary orbit 33 00:01:17.980 --> 00:01:19.456 35,786 34 00:01:19.784 --> 00:01:22.660 km up where it hovers 35 00:01:22.660 --> 00:01:25.630 over the same patch of ground forever. And 36 00:01:25.630 --> 00:01:28.070 it works beautifully for 15 years 37 00:01:28.550 --> 00:01:30.550 and then it runs out of fuel. 38 00:01:30.950 --> 00:01:33.110 Avery: And um, that's, uh, it. The hardware is fine. 39 00:01:33.430 --> 00:01:36.230 Anna: The hardware is often perfectly fine. The 40 00:01:36.230 --> 00:01:38.910 cameras work, the transponders work, the 41 00:01:38.910 --> 00:01:41.670 solar panels work. But without propellant, 42 00:01:41.670 --> 00:01:44.430 it can't hold its position. So it drifts 43 00:01:44.430 --> 00:01:47.430 and it becomes junk. You throw away a 44 00:01:47.430 --> 00:01:50.310 working satellite because the tank is empty. 45 00:01:51.040 --> 00:01:53.440 Avery: That is a spectacularly wasteful way to run 46 00:01:53.440 --> 00:01:53.920 an industry. 47 00:01:54.480 --> 00:01:57.000 Anna: It is. And last night, Northrop 48 00:01:57.000 --> 00:01:59.960 Grumman launched the most serious attempt yet 49 00:01:59.960 --> 00:02:02.600 to fix it. At 05:15 in the 50 00:02:02.600 --> 00:02:05.448 evening Eastern Time on Tuesday 21st 51 00:02:05.592 --> 00:02:08.400 July, the Falcon 9 lifted 52 00:02:08.400 --> 00:02:11.360 off from Space Launch Complex 40 at 53 00:02:11.360 --> 00:02:14.240 Cape Canaveral carrying the Mission Robotic 54 00:02:14.240 --> 00:02:17.000 Vehicle plus three Mission Extension 55 00:02:17.000 --> 00:02:17.440 pods. 56 00:02:18.220 --> 00:02:20.540 Avery: Mission robotic vehicle. What does it 57 00:02:20.540 --> 00:02:21.420 actually look like? 58 00:02:21.900 --> 00:02:24.460 Anna: Picture a satellite bus with two 59 00:02:24.460 --> 00:02:27.140 arms, two robotic arms, each 60 00:02:27.140 --> 00:02:28.540 about 3 meters long, 61 00:02:29.900 --> 00:02:32.460 built by the United States Naval Research 62 00:02:32.540 --> 00:02:35.420 Laboratory and supplied through DARPA's 63 00:02:35.420 --> 00:02:37.940 Robotic Servicing of Geostationary 64 00:02:37.940 --> 00:02:38.860 Satellite program. 65 00:02:39.500 --> 00:02:42.340 Avery: So this is a genuinely dexterous machine, not 66 00:02:42.340 --> 00:02:43.900 just the tug that bolt on. 67 00:02:44.580 --> 00:02:47.300 Anna: That's the distinction that matters. The MRV 68 00:02:47.300 --> 00:02:50.260 can inspect, it can relocate, it can 69 00:02:50.260 --> 00:02:52.980 repair, it can upgrade. And its 70 00:02:52.980 --> 00:02:55.580 headline job on this mission is to pick up 71 00:02:55.580 --> 00:02:58.300 those three mission extension pods and 72 00:02:58.300 --> 00:03:00.780 install them on client satellites that are 73 00:03:00.780 --> 00:03:02.260 running low on propellant. 74 00:03:02.740 --> 00:03:05.460 Avery: So the pods are the actual fuel solution. 75 00:03:06.020 --> 00:03:08.900 Anna: Think of them as jetpacks. Each pod 76 00:03:08.900 --> 00:03:11.740 clamps onto a satellite and takes over orbit 77 00:03:11.740 --> 00:03:14.100 control and momentum management. Using 78 00:03:14.100 --> 00:03:17.100 electric propulsion, each one can handle a 79 00:03:17.100 --> 00:03:19.780 satellite of about 2,000kg. 80 00:03:19.940 --> 00:03:22.900 That's a typical big geostationary bird 81 00:03:22.980 --> 00:03:25.700 and give it up to eight more years of life. 82 00:03:26.260 --> 00:03:28.700 Avery: Eight years on a satellite that was 83 00:03:28.700 --> 00:03:29.940 otherwise finished. 84 00:03:30.500 --> 00:03:33.300 Anna: Eight years. And the MRV M itself 85 00:03:33.380 --> 00:03:35.300 carries something called a ah, Passive 86 00:03:35.300 --> 00:03:37.780 Refueling Interface, which is the first 87 00:03:37.860 --> 00:03:40.500 refueling interface approved by the US 88 00:03:40.580 --> 00:03:43.080 Space Force. So the servicer is 89 00:03:43.080 --> 00:03:45.600 itself designed to be refueled later. 90 00:03:46.160 --> 00:03:48.480 Avery: Now, Northrub have done a version of this 91 00:03:48.480 --> 00:03:49.440 before, haven't they? 92 00:03:49.760 --> 00:03:52.360 Anna: They have, and this is why they're the ones 93 00:03:52.360 --> 00:03:55.280 doing it. Mission extension vehicle 1 94 00:03:55.360 --> 00:03:58.120 launched in October 2019, the 95 00:03:58.120 --> 00:04:00.400 first commercial satellite servicing 96 00:04:00.400 --> 00:04:03.360 spacecraft ever. And four months later, it 97 00:04:03.360 --> 00:04:05.440 docked with communications satellite 98 00:04:05.600 --> 00:04:08.480 Intelsat 901 in geostationary 99 00:04:08.480 --> 00:04:11.170 orbit. MEV 2 followed in 100 00:04:11.170 --> 00:04:12.290 August 2020. 101 00:04:12.850 --> 00:04:14.450 Avery: So what's different this time? 102 00:04:14.690 --> 00:04:17.570 Anna: Those earlier vehicles were one to one. 103 00:04:17.810 --> 00:04:20.770 One servicer went to one satellite, docked 104 00:04:20.770 --> 00:04:22.770 with it, and stayed there doing the work 105 00:04:22.770 --> 00:04:25.490 itself. The MRV is one to 106 00:04:25.490 --> 00:04:28.290 many. It carries pods, installs them, 107 00:04:28.290 --> 00:04:31.050 and moves on. It's the difference between a 108 00:04:31.050 --> 00:04:33.570 tow truck that has to stay attached to your 109 00:04:33.570 --> 00:04:36.570 car forever and. And a mechanic who fits a 110 00:04:36.570 --> 00:04:39.010 new part and drives off to the next job. 111 00:04:39.330 --> 00:04:40.290 Avery: That scales. 112 00:04:40.450 --> 00:04:43.450 Anna: That scales. And there's a nice detail on 113 00:04:43.450 --> 00:04:46.410 the launch itself. The Falcon 9 booster 114 00:04:46.410 --> 00:04:49.050 B1069 was flying its 115 00:04:49.050 --> 00:04:51.570 32nd mission and it was 116 00:04:51.570 --> 00:04:53.970 deliberately expended. No landing. 117 00:04:54.210 --> 00:04:56.850 Avery: Why give up a booster with 31 flights on it? 118 00:04:57.010 --> 00:04:59.730 Anna: Because geostationary transfer orbit is 119 00:04:59.730 --> 00:05:02.490 demanding. Getting that much mass that 120 00:05:02.490 --> 00:05:05.210 high needed every bit of performance the 121 00:05:05.210 --> 00:05:07.850 rocket had, and there wasn't propellant left 122 00:05:07.850 --> 00:05:10.490 for a landing burn. SpaceX made the trade. 123 00:05:10.890 --> 00:05:12.970 Avery: So when does the actual servicing start? 124 00:05:13.130 --> 00:05:15.970 Anna: Not for a while. The MRV and the three 125 00:05:15.970 --> 00:05:18.570 pods each separate and then climb to 126 00:05:18.570 --> 00:05:21.210 geostationary orbit under their own 127 00:05:21.210 --> 00:05:23.810 solar electric propulsion. And that 128 00:05:23.810 --> 00:05:26.490 climb takes up to a year. Servicing 129 00:05:26.490 --> 00:05:28.690 operations are expected to begin in 130 00:05:28.690 --> 00:05:31.610 2027. After the initial checkouts, 131 00:05:31.610 --> 00:05:34.450 the RSGS program gets handed over to 132 00:05:34.450 --> 00:05:35.770 the US Space Force. 133 00:05:36.200 --> 00:05:38.960 Avery: A year of just going up slowly 134 00:05:38.960 --> 00:05:40.040 and efficiently. 135 00:05:40.360 --> 00:05:43.360 Anna: Electric propulsion is patient. And at the 136 00:05:43.360 --> 00:05:45.680 end of it, for the first time, there's a 137 00:05:45.680 --> 00:05:48.560 repair capability parked permanently in 138 00:05:48.560 --> 00:05:51.040 the most valuable orbital real estate we 139 00:05:51.040 --> 00:05:51.320 have. 140 00:05:51.720 --> 00:05:53.960 Avery: Right from a machine built to preserve 141 00:05:53.960 --> 00:05:56.520 spacecraft to a spacecraft that is about to 142 00:05:56.520 --> 00:05:58.200 be very thoroughly destroyed. 143 00:05:58.520 --> 00:06:00.040 Anna: This is one we've been tracking. 144 00:06:00.280 --> 00:06:02.760 Avery: It is, and I want to be upfront about that. 145 00:06:02.920 --> 00:06:05.440 We covered this back in June in episode 146 00:06:05.440 --> 00:06:08.370 125. But there is a genuine reason 147 00:06:08.370 --> 00:06:10.410 to come back to it, because the science 148 00:06:10.410 --> 00:06:12.530 community has just done something about it. 149 00:06:12.690 --> 00:06:15.130 The short version for anyone joining us 150 00:06:15.130 --> 00:06:17.810 since. In January 2025, 151 00:06:17.970 --> 00:06:20.690 a Falcon 9 launched two commercial 152 00:06:20.690 --> 00:06:23.570 lunar landers, Firefly's Blue Ghost 153 00:06:23.570 --> 00:06:26.490 and ispace's Hakuto R mission 154 00:06:26.490 --> 00:06:29.490 2. It did its job, but the upper 155 00:06:29.490 --> 00:06:31.170 stage, cataloged as 156 00:06:31.170 --> 00:06:34.130 2025010 d 157 00:06:34.610 --> 00:06:37.600 never came home. Instead of burning up in our 158 00:06:37.600 --> 00:06:40.440 atmosphere, it ended up in a long looping 159 00:06:40.440 --> 00:06:43.200 orbit through the Earth Moon system. And 160 00:06:43.200 --> 00:06:44.160 somebody noticed. 161 00:06:44.480 --> 00:06:47.200 Anna: The independent astronomer Bill Gray, who 162 00:06:47.200 --> 00:06:49.960 runs Project Pluto and tracks this sort of 163 00:06:49.960 --> 00:06:52.960 high orbit debris. His software flagged an 164 00:06:52.960 --> 00:06:55.600 impact on the 5th of August. This year 165 00:06:55.840 --> 00:06:57.760 that stage hits the Moon. 166 00:06:58.160 --> 00:07:01.160 Avery: So what's new? Three things. First, a 167 00:07:01.160 --> 00:07:04.040 new preprint has just gone up on Arxiv and it 168 00:07:04.040 --> 00:07:07.000 is signed by 23 astronomers. It is 169 00:07:07.000 --> 00:07:09.960 essentially a call to arms. They're asking 170 00:07:09.960 --> 00:07:12.400 the scientific community, professional and 171 00:07:12.400 --> 00:07:15.280 amateur, to point everything they've got at 172 00:07:15.280 --> 00:07:16.840 the moon on the 5th of August. 173 00:07:17.160 --> 00:07:19.480 Anna: Because this is a rare thing, because 174 00:07:19.480 --> 00:07:22.360 Avery: we almost never get this. We get natural 175 00:07:22.360 --> 00:07:24.720 impacts on the Moon all the time, but we 176 00:07:24.720 --> 00:07:27.280 don't know when they're coming here. We know 177 00:07:27.280 --> 00:07:30.040 the object, we know its mass, we know its 178 00:07:30.040 --> 00:07:32.720 structure, we know its velocity and we know 179 00:07:32.720 --> 00:07:35.710 the time to within about a second. That is an 180 00:07:35.710 --> 00:07:38.350 artificial impact experiment we didn't have 181 00:07:38.350 --> 00:07:39.310 to pay to set up. 182 00:07:39.550 --> 00:07:42.030 Anna: And the timing has been tightened, hasn't it? 183 00:07:42.110 --> 00:07:44.390 Avery: That's a second u, uh, thing. Gray's latest 184 00:07:44.390 --> 00:07:47.310 published calculation, dated the 17th of July 185 00:07:47.790 --> 00:07:50.350 puts the impact at 6, 34 and 186 00:07:50.350 --> 00:07:53.350 32 seconds UTC. Earlier coverage 187 00:07:53.350 --> 00:07:55.870 back in May was quoting 644. 188 00:07:56.270 --> 00:07:58.430 So if you've got the old number written down, 189 00:07:58.430 --> 00:08:01.400 update it am the third. The third is 190 00:08:01.400 --> 00:08:04.200 the actual physics prediction and this is the 191 00:08:04.200 --> 00:08:07.160 part I find genuinely interesting. The paper 192 00:08:07.160 --> 00:08:10.080 models what happens on contact. This thing 193 00:08:10.080 --> 00:08:12.640 is roughly 12 meters long and about 194 00:08:12.640 --> 00:08:15.480 4,000 kilograms and crucially, it's 195 00:08:15.480 --> 00:08:17.920 hollow. It's a tank. So the 196 00:08:17.920 --> 00:08:20.320 prediction is that it crushes rather than 197 00:08:20.320 --> 00:08:22.320 punching deep like a can 198 00:08:22.400 --> 00:08:23.440 Anna: rather than a bullet. 199 00:08:23.920 --> 00:08:26.760 Avery: Exactly like a can. And the result of 200 00:08:26.760 --> 00:08:29.560 that is a relatively shallow crater. They're 201 00:08:29.560 --> 00:08:32.390 estimating 20 to 30 meters across, but a 202 00:08:32.540 --> 00:08:34.540 a very large ejecta plume, 203 00:08:34.860 --> 00:08:37.140 kilometers of debris thrown up off the 204 00:08:37.140 --> 00:08:37.580 surface. 205 00:08:38.060 --> 00:08:39.980 Anna: So the plume might be the visible part. 206 00:08:40.460 --> 00:08:42.740 Avery: That's the hope, and it's a subtle bit of 207 00:08:42.740 --> 00:08:45.460 reasoning. The impact site is near the crater 208 00:08:45.460 --> 00:08:48.220 Einstein right on the moon's western limb, 209 00:08:48.380 --> 00:08:50.540 about the 10 o' clock position on the disk. 210 00:08:50.540 --> 00:08:53.300 As you look at it now, that's awkward because 211 00:08:53.300 --> 00:08:56.300 it's on the sunlit part of the surface and no 212 00:08:56.380 --> 00:08:58.780 impact Flash, artificial or natural, 213 00:08:59.020 --> 00:09:01.580 has ever been recorded on the lit face of the 214 00:09:01.580 --> 00:09:01.900 Moon. 215 00:09:02.310 --> 00:09:05.110 Anna: The glare defeats you, but being on the limb 216 00:09:05.110 --> 00:09:05.510 helps. 217 00:09:05.910 --> 00:09:08.270 Avery: Being on the limb might save it, because 218 00:09:08.270 --> 00:09:10.670 rocks thrown up from a site that close to the 219 00:09:10.670 --> 00:09:13.550 edge rise off the Moon entirely. And 220 00:09:13.550 --> 00:09:14.990 once they're off the limb, they're 221 00:09:14.990 --> 00:09:17.350 silhouetted against black sky, catching 222 00:09:17.350 --> 00:09:20.030 sunlight. So you might not see the flash, but 223 00:09:20.030 --> 00:09:21.430 you might see the plume. 224 00:09:21.590 --> 00:09:22.710 Anna: Who else is watching? 225 00:09:23.110 --> 00:09:25.310 Avery: NASA's Lunar Reconnaissance Orbiter will 226 00:09:25.310 --> 00:09:28.270 image the site before and after, which gives 227 00:09:28.270 --> 00:09:30.740 a clean comparison. And South Korea's 228 00:09:30.740 --> 00:09:32.820 Pathfinder Lunar Orbiter is going to attempt 229 00:09:32.820 --> 00:09:35.380 to observe as well. There's precedent for the 230 00:09:35.380 --> 00:09:38.140 afterimage too. When a Chinese rocket stage 231 00:09:38.140 --> 00:09:40.940 hit the far side in 2022, LRO 232 00:09:41.020 --> 00:09:43.180 found the site and it had made not one 233 00:09:43.180 --> 00:09:44.300 crater, but two. 234 00:09:44.700 --> 00:09:46.700 Anna: And there's a longer term payoff to 235 00:09:46.700 --> 00:09:49.460 Avery: all this, and this is why the paper matters. 236 00:09:49.460 --> 00:09:52.020 Beyond the spectacle, they want to test a 237 00:09:52.020 --> 00:09:54.340 method for pinpointing exactly where an 238 00:09:54.340 --> 00:09:56.020 object strikes the Moon using the 239 00:09:56.020 --> 00:09:58.480 observations. If you can nail that down 240 00:09:58.480 --> 00:10:01.240 against a known impact, you've validated a 241 00:10:01.240 --> 00:10:03.680 technique. And that feeds directly into 242 00:10:03.680 --> 00:10:05.960 planning seismic experiments on the lunar 243 00:10:05.960 --> 00:10:07.280 surface for future missions. 244 00:10:07.840 --> 00:10:10.520 Anna: Now the practical question, who actually gets 245 00:10:10.520 --> 00:10:11.120 to see this? 246 00:10:11.520 --> 00:10:13.360 Avery: And, um, this is where our North American 247 00:10:13.440 --> 00:10:16.000 listeners want to pay attention, because this 248 00:10:16.000 --> 00:10:17.680 one is squarely yours. 249 00:10:18.240 --> 00:10:20.880 6:34 UTC on the 5th of August 250 00:10:20.880 --> 00:10:23.760 is 29 minutes past 2 in the morning, Eastern 251 00:10:23.760 --> 00:10:25.750 Time. 1:34 Central, 252 00:10:26.310 --> 00:10:29.070 12:34 Mountain. And on the west coast 253 00:10:29.070 --> 00:10:31.870 it's still the night before. 11:34 in the 254 00:10:31.870 --> 00:10:33.110 evening on the 4th, 255 00:10:33.510 --> 00:10:35.910 Anna: middle of the night, but the Moon is well up. 256 00:10:36.150 --> 00:10:38.390 Avery: The Moon is well placed across the continent, 257 00:10:38.390 --> 00:10:40.629 and the paper specifically identifies 258 00:10:40.629 --> 00:10:43.510 observers in the Americas as the ideal group. 259 00:10:43.830 --> 00:10:45.910 If you have a telescope and you've ever 260 00:10:45.910 --> 00:10:48.390 wanted to contribute to something real, this 261 00:10:48.390 --> 00:10:51.110 is the night they are explicitly asking 262 00:10:51.110 --> 00:10:52.230 amateurs to take part. 263 00:10:52.730 --> 00:10:55.050 Anna: And for those of us further around the globe, 264 00:10:55.450 --> 00:10:56.170 less kind. 265 00:10:56.170 --> 00:10:58.450 Avery: And I'll be straight about it. For us In 266 00:10:58.450 --> 00:11:01.130 Australia, that's 4:34 in the afternoon, 267 00:11:01.210 --> 00:11:04.170 broad daylight, New Zealand early evening, 268 00:11:04.250 --> 00:11:07.250 no good either. The UK and Europe get half 269 00:11:07.250 --> 00:11:09.210 past seven in the morning, which is also 270 00:11:09.210 --> 00:11:11.890 daylight. So the live event belongs to the 271 00:11:11.890 --> 00:11:14.570 Anna: Americas, but the aftermath belongs to 272 00:11:14.570 --> 00:11:14.890 everyone. 273 00:11:15.290 --> 00:11:17.850 Avery: The aftermath belongs to everyone. The 274 00:11:17.850 --> 00:11:20.530 LRO before and after imagery, the crater 275 00:11:20.530 --> 00:11:23.090 measurements, the analysis of how well the 276 00:11:23.090 --> 00:11:25.400 predictions held up, and frankly, the 277 00:11:25.400 --> 00:11:27.400 question sitting underneath all of this is 278 00:11:27.400 --> 00:11:29.760 global. We are about to start putting people 279 00:11:29.760 --> 00:11:32.600 back on the Moon and we are currently hitting 280 00:11:32.600 --> 00:11:35.360 it with our own rubbish by accident, without 281 00:11:35.360 --> 00:11:35.840 warning. 282 00:11:36.000 --> 00:11:38.960 Anna: Alright, Avery, moving on to our next story. 283 00:11:39.600 --> 00:11:42.440 More than Half of all stars are in multiple 284 00:11:42.440 --> 00:11:45.440 systems, two or more suns orbiting each 285 00:11:45.440 --> 00:11:48.360 other. And for the really massive stars, the 286 00:11:48.360 --> 00:11:51.320 ones destined to explode, that fraction is 287 00:11:51.320 --> 00:11:52.080 even higher. 288 00:11:53.000 --> 00:11:55.240 Avery: So most supernovae should have had a sibling. 289 00:11:55.640 --> 00:11:58.280 Anna: That is exactly the implication. And yet, 290 00:11:58.360 --> 00:12:01.320 until this week, astronomers had never found 291 00:12:01.320 --> 00:12:03.960 a single case where both stars in a binary 292 00:12:03.960 --> 00:12:06.960 exploded and both left behind remnants we 293 00:12:06.960 --> 00:12:07.640 can still see 294 00:12:08.040 --> 00:12:09.960 Avery: not one out of how many. 295 00:12:10.280 --> 00:12:13.000 Anna: We've cataloged around 300 supernova 296 00:12:13.000 --> 00:12:15.760 remnants in our galaxy. Not one confirmed 297 00:12:15.760 --> 00:12:18.120 sibling pair. And the reason is a bit 298 00:12:18.120 --> 00:12:20.420 embarrassing, actually. One of them was 299 00:12:20.420 --> 00:12:22.580 probably sitting in plain sight the whole 300 00:12:22.580 --> 00:12:22.860 time. 301 00:12:23.180 --> 00:12:23.820 Avery: Go on. 302 00:12:24.060 --> 00:12:25.740 Anna: The Jellyfish Nebula 303 00:12:25.820 --> 00:12:28.220 IC443 in the 304 00:12:28.220 --> 00:12:30.940 constellation Gemini, about 6,000 305 00:12:30.940 --> 00:12:33.420 light years away. It is one of the best 306 00:12:33.500 --> 00:12:36.380 studied supernova remnants in the sky and 307 00:12:36.380 --> 00:12:38.700 one of the brightest gamma ray sources of its 308 00:12:38.700 --> 00:12:41.540 kind. If you could see it with your eye, it 309 00:12:41.540 --> 00:12:43.500 would look bigger than the full Moon. 310 00:12:43.900 --> 00:12:46.300 Avery: And, um, something was hiding behind it. 311 00:12:46.740 --> 00:12:49.300 Anna: Next to it, there's a much fainter object 312 00:12:49.380 --> 00:12:51.553 called G189 6 313 00:12:51.740 --> 00:12:54.460 3. It was first picked up in 314 00:12:54.460 --> 00:12:57.100 1994 by the German ROSAT 315 00:12:57.100 --> 00:12:59.700 satellite as a faint X ray glow. 316 00:12:59.860 --> 00:13:02.300 And later the Russian German spectrum 317 00:13:02.300 --> 00:13:05.260 Rontgen Gamma Observatory saw shell like 318 00:13:05.260 --> 00:13:07.780 structures in it, which suggested it was also 319 00:13:07.860 --> 00:13:10.820 a supernova remnant. But it sits right 320 00:13:10.820 --> 00:13:13.460 up against the glare of the jellyfish, and 321 00:13:13.460 --> 00:13:14.980 that glare drowns it. 322 00:13:15.530 --> 00:13:17.610 Avery: So how did they finally separate them? 323 00:13:18.010 --> 00:13:20.970 Anna: 16 years of data from NASA's Fermi 324 00:13:20.970 --> 00:13:23.810 Gamma Ray Space Telescope. The team led 325 00:13:23.810 --> 00:13:26.130 by Miltiades Michaelides, a 326 00:13:26.130 --> 00:13:29.010 postdoctoral fellow at Stanford, essentially 327 00:13:29.010 --> 00:13:31.850 subtracted the jellyfish out, isolated 328 00:13:31.850 --> 00:13:34.410 its gamma ray emission and looked at what was 329 00:13:34.410 --> 00:13:35.210 left underneath. 330 00:13:35.770 --> 00:13:37.210 Avery: And, um, there was something left. 331 00:13:37.370 --> 00:13:38.770 Anna: There was G 332 00:13:38.770 --> 00:13:41.610 189.63 is 333 00:13:41.610 --> 00:13:44.210 independently producing gamma rays. Which 334 00:13:44.210 --> 00:13:47.040 matters enormously because gamma rays mean 335 00:13:47.270 --> 00:13:49.430 particle acceleration, and particle 336 00:13:49.430 --> 00:13:51.910 acceleration is what a supernova remnant 337 00:13:51.910 --> 00:13:54.390 does. It's the shock wave doing work. 338 00:13:54.550 --> 00:13:56.950 Avery: Mikhail Adiz had a nice way of putting that, 339 00:13:56.950 --> 00:13:57.510 didn't he? 340 00:13:57.590 --> 00:14:00.470 Anna: He compared it to a drop of water falling on 341 00:14:00.470 --> 00:14:03.390 a still lake. The ripples spread out from 342 00:14:03.390 --> 00:14:06.070 the point of contact. A supernova remnant 343 00:14:06.070 --> 00:14:08.750 does exactly the same thing. And if you can 344 00:14:08.750 --> 00:14:11.350 see the ripples, you know, something dropped. 345 00:14:11.750 --> 00:14:14.310 Avery: So we have two remnants next to each other. 346 00:14:14.670 --> 00:14:16.430 How do we know they're related rather than 347 00:14:16.430 --> 00:14:18.190 just an accident of line of sight? 348 00:14:18.430 --> 00:14:21.270 Anna: This is the elegant part. There's a filament 349 00:14:21.270 --> 00:14:23.750 of gas arcing between them. And that 350 00:14:23.750 --> 00:14:25.750 filament is where the shock wave from 351 00:14:25.750 --> 00:14:28.350 G189.6 3 352 00:14:28.590 --> 00:14:31.230 has slammed into the same molecular cloud 353 00:14:31.310 --> 00:14:33.230 that the jellyfish is pushing against. 354 00:14:33.870 --> 00:14:36.790 Avery: Same cloud so same distance, same 355 00:14:36.790 --> 00:14:37.230 cloud. 356 00:14:37.310 --> 00:14:40.230 Anna: Same distance, same neighborhood. They're not 357 00:14:40.230 --> 00:14:43.030 one in front of the other. They're genuinely 358 00:14:43.030 --> 00:14:45.330 next door to each other. And that's what 359 00:14:45.330 --> 00:14:47.610 makes the shared origin story credible. 360 00:14:48.010 --> 00:14:49.650 Avery: So walk me through the story they're 361 00:14:49.650 --> 00:14:50.170 proposing. 362 00:14:50.410 --> 00:14:52.890 Anna: A tale of two massive stars 363 00:14:52.970 --> 00:14:55.450 born together, gravitationally bound, 364 00:14:55.690 --> 00:14:58.570 orbiting extremely closely, perhaps 365 00:14:58.570 --> 00:15:01.290 only a few times the Earth's sun distance 366 00:15:01.290 --> 00:15:04.250 apart. Close enough that material was likely 367 00:15:04.250 --> 00:15:07.010 flowing from one to the other. And then the 368 00:15:07.010 --> 00:15:09.610 bigger one runs out of fuel and detonates. 369 00:15:09.930 --> 00:15:11.850 Avery: And, um. The explosion breaks the 370 00:15:11.850 --> 00:15:12.490 partnership. 371 00:15:12.920 --> 00:15:15.400 Anna: The explosion breaks the partnership. The 372 00:15:15.400 --> 00:15:17.960 binary is disrupted and the surviving 373 00:15:17.960 --> 00:15:20.840 companion is essentially kicked flung 374 00:15:20.840 --> 00:15:23.680 off through the galaxy on its own. It keeps 375 00:15:23.680 --> 00:15:26.040 traveling, and tens of thousands of years 376 00:15:26.040 --> 00:15:27.960 later, it explodes too. 377 00:15:28.200 --> 00:15:29.800 Avery: How far apart did they end up? 378 00:15:30.120 --> 00:15:32.960 Anna: The centers of the two explosions are now 379 00:15:32.960 --> 00:15:35.640 somewhere between 30 and 50 light years 380 00:15:35.640 --> 00:15:38.480 apart. Two stars that were once close enough 381 00:15:38.480 --> 00:15:41.410 to be exchanging material, now separated 382 00:15:41.410 --> 00:15:44.250 by that gap. And each marked by its own 383 00:15:44.250 --> 00:15:45.490 expanding shell. 384 00:15:45.730 --> 00:15:46.530 Avery: What were they? 385 00:15:46.690 --> 00:15:49.290 Anna: The jellyfish's progenitor is thought to have 386 00:15:49.290 --> 00:15:52.170 been something like 15 to 25 times 387 00:15:52.170 --> 00:15:55.010 the mass of the Sun. Its companion at 388 00:15:55.010 --> 00:15:57.850 least 20. Both were probably tens 389 00:15:57.850 --> 00:16:00.250 of thousands times more luminous than the 390 00:16:00.250 --> 00:16:02.850 sun. And both may now be neutron 391 00:16:02.850 --> 00:16:03.330 stars. 392 00:16:03.570 --> 00:16:05.770 Avery: And, um, publication status because I know 393 00:16:05.770 --> 00:16:07.250 this was previewed at a conference. 394 00:16:07.760 --> 00:16:10.560 Anna: Good flag. Miltiais presented the results at 395 00:16:10.560 --> 00:16:13.080 the American Astronomical Society meeting in 396 00:16:13.080 --> 00:16:15.840 Pasadena back in June. What's happened this 397 00:16:15.840 --> 00:16:18.200 week is the peer reviewed paper. It's in 398 00:16:18.200 --> 00:16:20.440 Nature communications with the Stanford 399 00:16:20.440 --> 00:16:22.840 release. And wider coverage landing on the 400 00:16:22.840 --> 00:16:23.360 21st. 401 00:16:23.920 --> 00:16:26.440 Avery: And one for our listeners. Can we go and look 402 00:16:26.440 --> 00:16:27.200 at any of this? 403 00:16:27.600 --> 00:16:30.480 Anna: Not this month. Wherever you are. Gemini 404 00:16:30.480 --> 00:16:33.040 is close to the sun at the moment. So it's 405 00:16:33.040 --> 00:16:35.800 lost in the glare globally. But it comes 406 00:16:35.800 --> 00:16:38.160 back. And this is one where Northern 407 00:16:38.160 --> 00:16:40.080 hemisphere listeners get the better deal. 408 00:16:40.480 --> 00:16:43.120 From North America and Europe, Gemini 409 00:16:43.120 --> 00:16:45.360 rides high overhead through winter 410 00:16:45.680 --> 00:16:48.360 December into March. And the jellyfish 411 00:16:48.360 --> 00:16:51.320 sits. Beautifully placed for a telescope or a 412 00:16:51.320 --> 00:16:52.240 long exposure. 413 00:16:52.640 --> 00:16:55.000 Avery: And from down here we still get it. 414 00:16:55.000 --> 00:16:57.920 Anna: Just lower from Australia and New Zealand, 415 00:16:57.920 --> 00:17:00.400 Gemini comes up in the northern sky through 416 00:17:00.400 --> 00:17:02.850 our summer. Visible, worth hunting, 417 00:17:03.010 --> 00:17:06.010 but closer to the horizon. Either way, put 418 00:17:06.010 --> 00:17:08.010 it on the list for the end of the year. And 419 00:17:08.010 --> 00:17:10.890 bear in mind the jellyfish is faint. It would 420 00:17:10.890 --> 00:17:12.930 be bigger than the full moon if your eye 421 00:17:12.930 --> 00:17:15.370 could pick it up. But it needs photography or 422 00:17:15.370 --> 00:17:17.250 a decent aperture to show itself. 423 00:17:17.730 --> 00:17:20.170 Avery: Anna, uh, here's something we know exists but 424 00:17:20.170 --> 00:17:22.050 have never actually been able to draw. 425 00:17:22.690 --> 00:17:24.850 Galaxy clusters. The largest 426 00:17:24.850 --> 00:17:27.050 gravitationally bound structures in the 427 00:17:27.050 --> 00:17:29.660 universe. Hundreds or thousands of 428 00:17:29.660 --> 00:17:32.540 galaxies plus enormous clouds of hot gas, 429 00:17:32.620 --> 00:17:35.300 plus dark matter Are threaded through 430 00:17:35.300 --> 00:17:36.780 with magnetic fields. 431 00:17:37.180 --> 00:17:38.860 Anna: We've known that for decades. 432 00:17:39.180 --> 00:17:41.900 Avery: What we have never done is map the shape of 433 00:17:41.900 --> 00:17:44.580 one across an entire cluster from the 434 00:17:44.580 --> 00:17:46.060 middle right out to the edge. 435 00:17:46.300 --> 00:17:47.820 Anna: And now somebody has. 436 00:17:48.140 --> 00:17:50.940 Avery: A team led by Andrea, uh, Boton at innaf, 437 00:17:51.020 --> 00:17:53.820 Italy's National Astrophysics institute, Has 438 00:17:53.820 --> 00:17:56.380 reconstructed the magnetic field of Galaxy 439 00:17:56.380 --> 00:17:59.320 cluster Abell 2255. And I 440 00:17:59.320 --> 00:18:01.600 want to be precise about that name because at 441 00:18:01.600 --> 00:18:03.880 least one outlet has got it wrong this week 442 00:18:03.880 --> 00:18:06.440 and called it Abell 2142. 443 00:18:06.760 --> 00:18:09.240 It is Abell 2255, 444 00:18:09.560 --> 00:18:11.240 about a billion light years away. 445 00:18:11.720 --> 00:18:12.920 Anna: Why that cluster? 446 00:18:13.160 --> 00:18:15.400 Avery: Because it's famously messy in radio. 447 00:18:15.720 --> 00:18:18.600 Abell 2255 has long been known for 448 00:18:18.600 --> 00:18:21.360 its complexity. It's full of strange, diffuse 449 00:18:21.360 --> 00:18:24.280 radio structures, Halos and filaments, which 450 00:18:24.280 --> 00:18:26.240 is exactly what you want if you're trying to 451 00:18:26.240 --> 00:18:28.470 trace magnetic fields, because those 452 00:18:28.470 --> 00:18:31.030 structures are made by energetic electrons 453 00:18:31.030 --> 00:18:32.990 spiraling along magnetic lines. 454 00:18:33.310 --> 00:18:35.470 Anna: So the radio emission is the field 455 00:18:35.630 --> 00:18:37.070 effectively made visible. 456 00:18:37.390 --> 00:18:40.310 Avery: It's the tracer. Electrons corkscrewing 457 00:18:40.310 --> 00:18:42.990 along magnetic lines give off radio waves. 458 00:18:43.230 --> 00:18:45.470 So if you can see the emission finely enough, 459 00:18:45.550 --> 00:18:48.110 you can work backwards to the field. The 460 00:18:48.110 --> 00:18:50.230 problem has always been that these signals 461 00:18:50.230 --> 00:18:52.110 are extraordinarily faint. 462 00:18:52.350 --> 00:18:55.020 Anna: What did they observe with lofar, the 463 00:18:55.020 --> 00:18:57.580 Avery: low frequency array, the European radial 464 00:18:57.580 --> 00:19:00.300 telescope spread across a continent. And 465 00:19:00.300 --> 00:19:02.820 these are the deepest radio observations ever 466 00:19:02.820 --> 00:19:05.660 made of a galaxy cluster that was combined 467 00:19:05.660 --> 00:19:07.660 with a new data analysis technique. And 468 00:19:07.660 --> 00:19:09.540 between them, that's what cracked it. 469 00:19:09.780 --> 00:19:11.140 Anna: And what does the map show? 470 00:19:11.540 --> 00:19:14.300 Avery: This is defining in some regions of the 471 00:19:14.300 --> 00:19:16.580 cluster, the magnetic field lines are 472 00:19:16.580 --> 00:19:19.140 strikingly coherent. They follow very 473 00:19:19.140 --> 00:19:21.620 specific directions stretching radially 474 00:19:21.620 --> 00:19:24.020 outward along the extended radial structures. 475 00:19:24.390 --> 00:19:26.790 Anna: They're not random, which tells you something 476 00:19:26.870 --> 00:19:28.990 made them that way, which tells you 477 00:19:28.990 --> 00:19:31.630 Avery: something is organizing them. And Boton's 478 00:19:31.630 --> 00:19:33.870 conclusion is that the shape of the field is 479 00:19:33.870 --> 00:19:36.270 intimately linked to the motion of the gas it 480 00:19:36.270 --> 00:19:38.790 sits in. The field gets stretched and 481 00:19:38.790 --> 00:19:41.150 compressed by the movements associated with 482 00:19:41.150 --> 00:19:42.710 the cluster's own formation. 483 00:19:43.110 --> 00:19:45.750 Anna: So the cluster assembling itself is what 484 00:19:45.750 --> 00:19:46.950 shapes the magnetism? 485 00:19:47.350 --> 00:19:49.230 Avery: That's the argument, and it's the first 486 00:19:49.230 --> 00:19:51.570 observational evidence of it. The same 487 00:19:51.570 --> 00:19:54.410 violent process that builds a galaxy cluster, 488 00:19:54.570 --> 00:19:57.530 Gas falling in, sloshing, colliding, 489 00:19:57.530 --> 00:20:00.210 merging, is the process that combs the 490 00:20:00.210 --> 00:20:02.650 magnetic field into the pattern we now see. 491 00:20:02.970 --> 00:20:05.610 Anna: And that ties into the radio halos question. 492 00:20:05.930 --> 00:20:08.530 Avery: It does. Bolton says they believe the 493 00:20:08.530 --> 00:20:10.930 mechanism that switches on these gigantic 494 00:20:10.930 --> 00:20:13.610 radio emissions is linked to the formation 495 00:20:13.610 --> 00:20:16.210 process of the clusters themselves. So the 496 00:20:16.210 --> 00:20:18.450 map isn't just a pretty picture. It's the 497 00:20:18.450 --> 00:20:19.770 evidence for the engine. 498 00:20:19.790 --> 00:20:22.460 Anna: The. It's a lovely Example of the thing radio 499 00:20:22.460 --> 00:20:25.180 astronomy does best, showing you a 500 00:20:25.180 --> 00:20:28.060 Avery: structure that is completely invisible, is a 501 00:20:28.060 --> 00:20:30.460 billion light years away, is bigger than 502 00:20:30.460 --> 00:20:32.540 anything else in the universe, and has been 503 00:20:32.540 --> 00:20:35.490 sitting there the entire time. Published in, 504 00:20:35.490 --> 00:20:37.140 uh, Astronomy and Astrophysics. 505 00:20:37.380 --> 00:20:40.140 Anna: Every if you want to know what has hit the 506 00:20:40.140 --> 00:20:41.460 Earth, don't look at 507 00:20:41.460 --> 00:20:43.940 Avery: the Earth because the Earth keeps erasing it 508 00:20:44.180 --> 00:20:44.900 constantly. 509 00:20:45.060 --> 00:20:47.540 Anna: Plate tectonics, volcanism, weather, 510 00:20:47.700 --> 00:20:50.610 water, erosion. Craters get buried, 511 00:20:50.610 --> 00:20:53.530 distorted, subducted, destroyed. The 512 00:20:53.530 --> 00:20:55.730 practical consequence is that geological 513 00:20:55.730 --> 00:20:57.890 evidence for impacts older than about 514 00:20:57.970 --> 00:21:00.410 650 million years is 515 00:21:00.410 --> 00:21:01.810 extremely scarce here. 516 00:21:02.050 --> 00:21:03.810 Avery: And the Moon doesn't do any of that. 517 00:21:03.970 --> 00:21:06.970 Anna: No plate tectonics, no flowing water, no 518 00:21:06.970 --> 00:21:09.650 meaningful atmosphere. The Moon just keeps 519 00:21:09.650 --> 00:21:11.570 the receipts. And when you read those 520 00:21:11.570 --> 00:21:14.010 receipts carefully, there's a spike. When, 521 00:21:14.010 --> 00:21:16.690 uh, around 800 million years ago, 522 00:21:17.100 --> 00:21:19.500 there's a surge in large lunar impacts. And 523 00:21:19.500 --> 00:21:22.460 it shows up in two independent ways. One 524 00:21:22.460 --> 00:21:25.020 is the estimated ages of big craters, 525 00:21:25.020 --> 00:21:27.580 including copernicus, which is 93 526 00:21:27.580 --> 00:21:30.300 kilometers across. The other is impact 527 00:21:30.380 --> 00:21:30.940 glass. 528 00:21:31.340 --> 00:21:33.100 Avery: Explain impact glass. 529 00:21:33.580 --> 00:21:35.900 Anna: When something hits hard enough, the heat 530 00:21:35.900 --> 00:21:38.500 melts. Rock that melt cools into 531 00:21:38.500 --> 00:21:41.340 glass, and the glass locks in a, uh, chemical 532 00:21:41.340 --> 00:21:44.020 timestamp. The Apollo missions brought a lot 533 00:21:44.020 --> 00:21:46.160 of it home. And when you look at the age 534 00:21:46.160 --> 00:21:48.680 distribution of that glass, you see the same 535 00:21:48.680 --> 00:21:50.840 spike at 800 million years. 536 00:21:51.480 --> 00:21:53.840 Avery: So two different methods agree that something 537 00:21:53.840 --> 00:21:55.720 happened, but nobody knew what. 538 00:21:55.960 --> 00:21:58.280 Anna: Nobody knew what. That's the puzzle that's 539 00:21:58.280 --> 00:22:00.480 been sitting there for decades. And a new 540 00:22:00.480 --> 00:22:03.040 paper led by Dr. William Bakke at the 541 00:22:03.040 --> 00:22:05.240 Southwest Research Institute in Boulder 542 00:22:05.400 --> 00:22:08.280 proposes a specific culprit, which is 543 00:22:08.520 --> 00:22:11.320 an asteroid called Eulalia, or rather 544 00:22:11.320 --> 00:22:13.760 the parent body of the family of asteroids we 545 00:22:13.760 --> 00:22:16.520 now call Eulalia. Uh, because the object, its 546 00:22:17.060 --> 00:22:19.780 no longer exists. It was catastrophically 547 00:22:19.780 --> 00:22:22.260 broken apart in a collision in the main belt. 548 00:22:22.500 --> 00:22:24.820 Avery: And the location of that breakup matters. 549 00:22:25.060 --> 00:22:27.900 Anna: The location is everything. It happened right 550 00:22:27.900 --> 00:22:30.700 next to what's called the J3 to one resonance 551 00:22:30.700 --> 00:22:33.019 with Jupiter. And a resonance like that is 552 00:22:33.019 --> 00:22:35.380 essentially a gravitational trapdoor. 553 00:22:35.540 --> 00:22:37.700 Material that wanders into it, gets its 554 00:22:37.700 --> 00:22:40.340 orbit, pumped up by Jupiter and flung into 555 00:22:40.340 --> 00:22:41.460 the inner solar system. 556 00:22:41.940 --> 00:22:44.460 Avery: So the shrapnel had a delivery mechanism 557 00:22:44.460 --> 00:22:45.460 waiting right there. 558 00:22:45.790 --> 00:22:48.390 Anna: It had an open door right next to it. And the 559 00:22:48.390 --> 00:22:51.070 simulations show what happened in two phases. 560 00:22:51.390 --> 00:22:53.230 Half the fragments reached the resonance 561 00:22:53.230 --> 00:22:55.430 almost immediately. That's the prompt 562 00:22:55.430 --> 00:22:58.230 bombardment Planetary shrapnel sprayed across 563 00:22:58.230 --> 00:22:59.310 the inner solar system. 564 00:22:59.710 --> 00:23:01.470 Avery: And, um, the other half, over the 565 00:23:01.470 --> 00:23:04.110 Anna: following 100 to 150 million 566 00:23:04.110 --> 00:23:06.350 years, another quarter of the fragments 567 00:23:06.350 --> 00:23:08.670 drifted into the resonance more slowly, 568 00:23:08.830 --> 00:23:11.110 pushed by something called the Yarkovsky 569 00:23:11.110 --> 00:23:14.100 effect, which is what, in plain terms it's 570 00:23:14.100 --> 00:23:16.940 sunlight doing work. A rotating asteroid 571 00:23:16.940 --> 00:23:19.100 absorbs sunlight on one side and 572 00:23:19.100 --> 00:23:21.980 reradiates that heat as it turns. That 573 00:23:21.980 --> 00:23:24.780 reradiation gives an incredibly gentle 574 00:23:24.780 --> 00:23:27.779 push. On a human scale, it's nothing. Over 575 00:23:27.779 --> 00:23:30.140 a hundred million years, it can move an 576 00:23:30.140 --> 00:23:32.620 asteroid's orbit enough to drop it into a 577 00:23:32.620 --> 00:23:33.340 trapdoor. 578 00:23:33.580 --> 00:23:36.300 Avery: So this wasn't one bad afternoon. This was a 579 00:23:36.300 --> 00:23:37.100 long siege. 580 00:23:37.500 --> 00:23:39.740 Anna: That's the reframing, I think, is genuinely 581 00:23:39.740 --> 00:23:42.700 important here. Not an event, an episode, 582 00:23:42.780 --> 00:23:45.300 a bombardment that opened suddenly and then 583 00:23:45.300 --> 00:23:48.220 kept going for well over 100 million years. 584 00:23:48.700 --> 00:23:50.220 Avery: And what does that mean for Earth? 585 00:23:50.380 --> 00:23:52.580 Anna: Here's the number that changes the scale of 586 00:23:52.580 --> 00:23:55.260 it. For every large impact recorded on the 587 00:23:55.260 --> 00:23:58.060 moon, roughly 20 similar or larger 588 00:23:58.060 --> 00:24:00.500 impacts hit the Earth, where a bigger target 589 00:24:00.500 --> 00:24:01.820 with stronger gravity. 590 00:24:02.140 --> 00:24:03.368 Avery: 20 to 1. 591 00:24:03.481 --> 00:24:06.350 Anna: 20 to 1. So a spike on the Moon 592 00:24:06.350 --> 00:24:09.350 means a barrage down here. And now look 593 00:24:09.350 --> 00:24:11.950 at what else was happening around 800 million 594 00:24:11.950 --> 00:24:14.790 years ago. That is the run up to one of the 595 00:24:14.790 --> 00:24:16.990 most dramatic climate episodes in our 596 00:24:16.990 --> 00:24:19.550 planet's history. Widespread global 597 00:24:19.630 --> 00:24:22.430 cooling and major shifts in the biosphere. 598 00:24:22.830 --> 00:24:24.910 Avery: Is he climbing a causal link? 599 00:24:25.310 --> 00:24:27.950 Anna: He's careful. And I want to be careful too. 600 00:24:28.270 --> 00:24:30.830 Bakke's phrasing is that given the peak of 601 00:24:30.830 --> 00:24:33.390 this barrage coincides with a period of 602 00:24:33.390 --> 00:24:35.970 widespread cooling and major shifts in our 603 00:24:35.970 --> 00:24:38.810 biosphere, it is tempting to suggest the 604 00:24:38.810 --> 00:24:41.490 former produced the latter. That is a 605 00:24:41.490 --> 00:24:44.450 hypothesis flagged as tempting, not a 606 00:24:44.450 --> 00:24:45.050 conclusion. 607 00:24:45.450 --> 00:24:48.330 Avery: Because so far, only one impact has ever 608 00:24:48.330 --> 00:24:51.050 been firmly tied to a biological outcome. 609 00:24:51.369 --> 00:24:54.330 Anna: Pictxulub, 66 million years ago. 610 00:24:54.490 --> 00:24:57.050 The end of the dinosaurs. That's the one. 611 00:24:57.290 --> 00:24:58.890 Everything else is inference. 612 00:24:59.370 --> 00:25:01.290 Avery: So how would you ever test this? 613 00:25:02.040 --> 00:25:04.560 Anna: This is my favorite part of the paper. And 614 00:25:04.560 --> 00:25:06.760 it's the reason to keep an eye on this story. 615 00:25:07.080 --> 00:25:10.040 We have asteroid samples on Earth right now. 616 00:25:10.120 --> 00:25:12.520 Hayabusa2 brought material back from 617 00:25:12.520 --> 00:25:15.520 Ryugu in December 2020. Osiris 618 00:25:15.520 --> 00:25:17.866 Rex brought Bennu back in September 619 00:25:18.014 --> 00:25:20.760 2023. Both are under analysis. 620 00:25:21.240 --> 00:25:23.720 Avery: And if they carry the Eulalia fingerprint, 621 00:25:24.120 --> 00:25:26.880 Anna: if the mineralogy matches the Eulalia 622 00:25:26.880 --> 00:25:29.880 family, then we are holding in a laboratory 623 00:25:30.280 --> 00:25:32.760 physical samples of the material that rained 624 00:25:32.760 --> 00:25:35.700 on solar system 800 million 625 00:25:35.780 --> 00:25:38.620 years ago. That would turn a dynamical 626 00:25:38.620 --> 00:25:41.380 model into a direct compositional record. 627 00:25:41.940 --> 00:25:44.700 Avery: That's a remarkable thought. Brains in a lab 628 00:25:44.700 --> 00:25:47.620 in Japan and Texas. That might be pieces of 629 00:25:47.620 --> 00:25:50.020 the thing that helped freeze the Earth. 630 00:25:50.500 --> 00:25:53.100 Anna: Published in the Planetary Science Journal by 631 00:25:53.100 --> 00:25:55.740 Botke, with Volkerlitsky, Dykhuis and 632 00:25:55.740 --> 00:25:56.260 Zellner. 633 00:25:56.340 --> 00:25:56.740 Avery: Great. 634 00:25:56.740 --> 00:25:58.780 And our next story comes with a deadline. 635 00:25:58.780 --> 00:26:00.340 Wherever in the world you're listening. 636 00:26:00.760 --> 00:26:01.640 Anna: What's the urgency? 637 00:26:01.960 --> 00:26:04.760 Avery: The moon first quarter was yesterday, 638 00:26:04.760 --> 00:26:07.720 the 21st. Tonight it's a waxing 639 00:26:07.720 --> 00:26:10.120 gibbous. And every night from here it gets 640 00:26:10.120 --> 00:26:12.920 brighter and stays up longer, building to the 641 00:26:12.920 --> 00:26:15.800 buck. Moon full at 4:36 in the afternoon 642 00:26:15.880 --> 00:26:18.360 UTC on Wednesday the 29th. 643 00:26:18.680 --> 00:26:21.320 That's 10:36 in the morning Eastern time in 644 00:26:21.320 --> 00:26:23.880 the States and 12:36 on Thursday 645 00:26:23.960 --> 00:26:25.240 morning for us in Australia. 646 00:26:25.960 --> 00:26:28.200 Anna: And that matters because of what's peaking. 647 00:26:28.880 --> 00:26:31.840 Avery: The southern Delta Aquariates peak falls 648 00:26:31.840 --> 00:26:34.440 on the 30th, effectively the same night as 649 00:26:34.440 --> 00:26:36.760 the full moon. So the peak is going to be 650 00:26:36.760 --> 00:26:39.360 washed out, which means the practical advice 651 00:26:39.360 --> 00:26:41.720 is the same for everybody. Don't wait for 652 00:26:41.720 --> 00:26:44.559 peak night. This week is your window in the 653 00:26:44.559 --> 00:26:46.760 small hours while the moon still sets and 654 00:26:46.760 --> 00:26:48.800 leaves you real darkness before dawn. 655 00:26:49.200 --> 00:26:51.360 Anna: And this is a shower that favors us. 656 00:26:51.680 --> 00:26:54.680 Avery: It does. From Australia, New Zealand and 657 00:26:54.680 --> 00:26:57.660 southern Africa, the radiant sits high close 658 00:26:57.660 --> 00:27:00.060 to overhead, which is why the shower gets 659 00:27:00.060 --> 00:27:02.860 underrated. In the north, under genuinely 660 00:27:02.860 --> 00:27:05.780 dark skies, you might see 15 to 20 661 00:27:05.780 --> 00:27:08.780 an hour. And they're lovely meteors. Long, 662 00:27:08.780 --> 00:27:11.340 graceful streaks rather than quick flashes, 663 00:27:11.340 --> 00:27:13.860 and known for persistent trains, those 664 00:27:13.860 --> 00:27:16.100 glowing trails that hang in the air for a 665 00:27:16.100 --> 00:27:17.260 second or two afterwards. 666 00:27:17.740 --> 00:27:19.860 Anna: And northern listeners aren't shut out of 667 00:27:19.860 --> 00:27:22.340 Avery: this one, not at all. And I want to be clear 668 00:27:22.340 --> 00:27:24.420 about that, because this shower gets written 669 00:27:24.420 --> 00:27:27.130 off in the north too readily. If you're in 670 00:27:27.130 --> 00:27:29.530 North America, particularly the southern 671 00:27:29.530 --> 00:27:32.410 states, Texas, Florida, Arizona, the 672 00:27:32.410 --> 00:27:35.130 Gulf coast, the Delta Aquarids are a 673 00:27:35.130 --> 00:27:37.810 genuinely worthwhile watch. The radiance 674 00:27:37.810 --> 00:27:39.970 sits low in your southern sky rather than 675 00:27:39.970 --> 00:27:42.730 overhead, so you'll see fewer of them. But 676 00:27:42.730 --> 00:27:45.210 the ones you do catch travel long paths 677 00:27:45.210 --> 00:27:47.650 across the sky, and they can be spectacular. 678 00:27:47.970 --> 00:27:50.450 Best time is after midnight through to dawn. 679 00:27:50.770 --> 00:27:52.930 Southern Europe, the Mediterranean, North 680 00:27:52.930 --> 00:27:54.210 Africa. Same deal. 681 00:27:54.770 --> 00:27:55.890 Anna: And where do people look? 682 00:27:56.370 --> 00:27:58.850 Avery: The radiant is in Aquarius, near the star 683 00:27:58.850 --> 00:28:01.770 Delta Aquarii. Use Fomalhaut to find 684 00:28:01.770 --> 00:28:04.690 the region. But honestly, don't stare at 685 00:28:04.690 --> 00:28:07.690 the radiant. Lie back, take in as much sky as 686 00:28:07.690 --> 00:28:10.649 you can and let them come to you. Parent body 687 00:28:10.649 --> 00:28:12.330 is suspected to be Comet 688 00:28:12.330 --> 00:28:15.330 96PMachholz. There are also 689 00:28:15.330 --> 00:28:18.050 the Alpha Capricornids building to the 30th 690 00:28:18.050 --> 00:28:20.930 and 31st. Far fewer meteors, but 691 00:28:20.930 --> 00:28:23.710 few famous for slow, brilliant fireballs that 692 00:28:23.710 --> 00:28:25.590 can punch straight through moonlight. 693 00:28:25.910 --> 00:28:27.670 Anna: And for the north, there's something 694 00:28:27.750 --> 00:28:29.190 considerably bigger coming. 695 00:28:29.830 --> 00:28:32.190 Avery: There is, and if you're listening in North 696 00:28:32.190 --> 00:28:34.510 America or Europe, you should be planning for 697 00:28:34.510 --> 00:28:37.269 this. Now, two things land together on the 698 00:28:37.269 --> 00:28:40.190 12th of August 1st, the Perseids Peak. 699 00:28:40.190 --> 00:28:42.830 And this year the moon is new that same day, 700 00:28:42.830 --> 00:28:45.670 which means A properly dark sky that 701 00:28:45.670 --> 00:28:48.650 is the best Perseid year in some time. And 702 00:28:48.650 --> 00:28:51.130 the second, a, uh, total solar 703 00:28:51.130 --> 00:28:53.850 eclipse, the first on mainland Europe 704 00:28:53.930 --> 00:28:56.890 since 1999 and the first in Spain 705 00:28:56.890 --> 00:28:59.890 since 1905. Totality sweeps 706 00:28:59.890 --> 00:29:02.610 across the Arctic, Greenland, Iceland and 707 00:29:02.610 --> 00:29:05.210 northern Spain. And in Spain, it happens 708 00:29:05.210 --> 00:29:07.730 close to sunset, with the sun only a few 709 00:29:07.730 --> 00:29:10.130 degrees above the horizon, which could be 710 00:29:10.130 --> 00:29:11.050 extraordinary. 711 00:29:11.610 --> 00:29:14.250 Anna: North America doesn't get totality this time. 712 00:29:15.090 --> 00:29:18.090 Avery: No, and I won't oversell it, but there is a 713 00:29:18.090 --> 00:29:20.490 real partial eclipse across much of the 714 00:29:20.490 --> 00:29:23.330 continent. Alaska gets the deepest view 715 00:29:23.330 --> 00:29:26.010 near sunrise. Atlantic Canada gets 716 00:29:26.010 --> 00:29:28.450 roughly half the sun covered at maximum in 717 00:29:28.450 --> 00:29:30.649 the afternoon. New England and the 718 00:29:30.649 --> 00:29:32.970 northeastern states get a smaller bite. And 719 00:29:32.970 --> 00:29:35.010 there's some coverage visible right across 720 00:29:35.090 --> 00:29:37.570 every Canadian province and the northern 721 00:29:37.570 --> 00:29:39.530 contiguous states, though. 722 00:29:39.530 --> 00:29:40.610 Anna: Dig out the glasses. 723 00:29:41.080 --> 00:29:43.800 Avery: Dig out the eclipse glasses from 2024 and 724 00:29:43.800 --> 00:29:45.180 check their ISO 1, uh, 725 00:29:45.440 --> 00:29:48.200 23122 certified. 726 00:29:48.680 --> 00:29:51.240 It will not get dark even with 50% 727 00:29:51.240 --> 00:29:53.880 coverage. The remaining sun is blindingly 728 00:29:53.880 --> 00:29:56.080 bright, so there is never a safe moment to 729 00:29:56.080 --> 00:29:58.520 look without protection and the lovely 730 00:29:58.520 --> 00:30:00.520 detail. If you're standing in the path of 731 00:30:00.520 --> 00:30:03.120 totality in Spain or Iceland, there's a 732 00:30:03.120 --> 00:30:05.800 genuine chance of a Perseid streaking pass 733 00:30:05.800 --> 00:30:07.000 during those two minutes. 734 00:30:07.660 --> 00:30:10.500 Anna: And tonight for everyone, the Milky 735 00:30:10.500 --> 00:30:10.860 Way 736 00:30:11.100 --> 00:30:13.180 Avery: from the Southern Hemisphere, the galactic 737 00:30:13.180 --> 00:30:16.100 core is riding high overhead right now. One 738 00:30:16.100 --> 00:30:18.340 of the real privileges of our winter, and 739 00:30:18.340 --> 00:30:20.500 it's at its best. From the Northern 740 00:30:20.500 --> 00:30:22.820 Hemisphere, it's lower in the south towards 741 00:30:22.820 --> 00:30:25.580 Sagittarius. But on a dark night, it's still 742 00:30:25.580 --> 00:30:28.540 magnificent. And before dawn, Saturn and 743 00:30:28.540 --> 00:30:30.540 Mars are in the eastern sky for both 744 00:30:30.540 --> 00:30:31.260 hemispheres. 745 00:30:31.740 --> 00:30:33.260 Anna: One more thing before we go. 746 00:30:33.720 --> 00:30:36.680 Avery: The launchers SpaceX is targeting Thursday 747 00:30:36.840 --> 00:30:39.400 the 23rd for Starship Flight 13. 748 00:30:39.960 --> 00:30:42.720 Window opening at 6:45 in the evening 749 00:30:42.720 --> 00:30:45.400 Eastern Time. That's 5:45 Central, 750 00:30:45.640 --> 00:30:48.440 3:45 Pacific and Friday morning, 751 00:30:48.600 --> 00:30:51.440 quarter to nine for us in Australia. 20 752 00:30:51.440 --> 00:30:54.240 Starlink V3 satellites aboard. Second 753 00:30:54.240 --> 00:30:57.080 flight of the V3 vehicle dead and alarm. 754 00:30:57.320 --> 00:30:59.920 And as always with starship, check before you 755 00:30:59.920 --> 00:31:02.440 commit the date has already moved twice. 756 00:31:03.000 --> 00:31:06.000 Anna: That's Astronomy daily for Wednesday 22 757 00:31:06.000 --> 00:31:08.160 July, a mechanic on its way to 758 00:31:08.160 --> 00:31:10.960 geostationary orbit, a rocket stage 759 00:31:10.960 --> 00:31:13.960 two, two weeks from making a new crater, and 760 00:31:13.960 --> 00:31:16.680 23 astronomers asking the world to watch 761 00:31:17.240 --> 00:31:17.600 two 762 00:31:17.600 --> 00:31:20.000 Avery: stars that died in sequence and left their 763 00:31:20.000 --> 00:31:22.920 remnants side by side. The first magnetic 764 00:31:22.920 --> 00:31:25.480 map of a galaxy cluster and an asteroid 765 00:31:25.480 --> 00:31:27.640 breakup that may have been raining down on us 766 00:31:27.640 --> 00:31:28.840 while the Earth froze. 767 00:31:29.540 --> 00:31:31.620 Anna: Donotes sources and links are all at 768 00:31:31.620 --> 00:31:34.500 astronomydaily IO and you can find us 769 00:31:34.500 --> 00:31:37.140 at astrodaily Pod across the socials. 770 00:31:37.460 --> 00:31:39.460 Avery: If you enjoy the show, a, uh, rating or 771 00:31:39.460 --> 00:31:41.860 review genuinely helps other people find us. 772 00:31:42.100 --> 00:31:44.580 Astronomy Daily is part of the bytes.com 773 00:31:44.580 --> 00:31:45.540 podcast network. 774 00:31:45.860 --> 00:31:46.740 Anna: I'm Anna. 775 00:31:46.900 --> 00:31:49.340 Avery: And I'm, um, Avery. Get outside this week. It 776 00:31:49.340 --> 00:31:50.340 won't be dark for long. 777 00:31:50.740 --> 00:31:51.620 Anna: Clear skies.