WEBVTT 0 00:00:00.400 --> 00:00:02.960 Avery: Welcome, listeners, to Astronomy Daily, the 1 00:00:02.960 --> 00:00:05.520 podcast that brings the cosmos down to Earth. 2 00:00:05.680 --> 00:00:06.720 I'm Avery. 3 00:00:06.800 --> 00:00:09.560 Anna: And I'm Anna. We have a fantastic 4 00:00:09.560 --> 00:00:12.000 show for you today, packed with news from our 5 00:00:12.000 --> 00:00:14.160 celestial neighborhood and the farthest 6 00:00:14.160 --> 00:00:15.440 reaches of the universe. 7 00:00:15.840 --> 00:00:17.600 Avery: That's right, we'll be looking up at the 8 00:00:17.600 --> 00:00:20.000 biggest supermoon of 2025, 9 00:00:20.320 --> 00:00:22.840 tracking an interstellar visitor as it zips 10 00:00:22.840 --> 00:00:25.360 past the sun and uncovering a strange 11 00:00:25.360 --> 00:00:27.440 atmospheric mystery on Mars. 12 00:00:27.680 --> 00:00:30.360 Anna: And to cap it all off, we'll be exploring a 13 00:00:30.360 --> 00:00:33.100 mind bending new the that asks, what if 14 00:00:33.100 --> 00:00:35.180 dark matter doesn't exist at all? 15 00:00:35.660 --> 00:00:37.660 Avery: It's going to be a, um, big one. 16 00:00:37.900 --> 00:00:40.140 Let's get started with a sight we can all 17 00:00:40.140 --> 00:00:42.300 look forward to in our own night sky. 18 00:00:42.460 --> 00:00:45.380 Anna: Indeed, after a year of seeing the Moon 19 00:00:45.380 --> 00:00:47.780 looking a bit smaller than usual, we're in 20 00:00:47.780 --> 00:00:49.100 for a treat next week. 21 00:00:49.580 --> 00:00:52.540 11:48pm Eastern Time on 22 00:00:52.540 --> 00:00:55.340 October 6, to be precise, which, 23 00:00:55.420 --> 00:00:57.420 if I've done my math correctly, 24 00:00:57.740 --> 00:00:59.980 corresponds to 3:48 25 00:01:00.220 --> 00:01:02.860 UTC on October 7th 26 00:01:03.380 --> 00:01:05.860 will see the biggest and brightest supermoon 27 00:01:05.860 --> 00:01:07.060 of 2025. 28 00:01:07.380 --> 00:01:10.300 Avery: I'm already marking my calendar. So for 29 00:01:10.300 --> 00:01:13.020 our listeners who might be new to this, what 30 00:01:13.020 --> 00:01:15.380 exactly makes a full moon a, uh, 31 00:01:15.380 --> 00:01:16.180 supermoon? 32 00:01:16.340 --> 00:01:19.219 Anna: It's all about the moon's orbit. It's not a 33 00:01:19.219 --> 00:01:21.900 perfect circle, it's an ellipse. So 34 00:01:21.900 --> 00:01:24.180 sometimes the Moon is at its farthest point 35 00:01:24.180 --> 00:01:26.780 from Earth, which we call apogee. And 36 00:01:26.780 --> 00:01:28.980 sometimes it's at its closest point, or 37 00:01:28.980 --> 00:01:31.710 perigee. A supermoon happens when a full 38 00:01:31.710 --> 00:01:33.830 moon coincides with its perigee. 39 00:01:33.910 --> 00:01:35.910 Avery: And that makes it look bigger and brighter in 40 00:01:35.910 --> 00:01:38.630 the sky. Right. I read it can appear up to 41 00:01:38.630 --> 00:01:41.590 14% larger and 30% brighter than a 42 00:01:41.590 --> 00:01:43.470 micro moon, which is when the full moon 43 00:01:43.470 --> 00:01:44.710 happens at apogee. 44 00:01:44.950 --> 00:01:47.510 Anna: Exactly. And we've just come through a period 45 00:01:47.510 --> 00:01:49.550 of micro moons, so the difference will be 46 00:01:49.550 --> 00:01:52.350 quite noticeable. This particular supermoon 47 00:01:52.350 --> 00:01:54.630 is also the Harvest Moon, which is the full 48 00:01:54.630 --> 00:01:57.190 moon closest to the autumnal equinox. 49 00:01:57.660 --> 00:01:59.740 Avery: The harvest Moon. That's the one that 50 00:01:59.740 --> 00:02:01.660 historically helped farmers bring in their 51 00:02:01.660 --> 00:02:04.380 crops. Because it rises so close to sunset, 52 00:02:04.380 --> 00:02:07.060 giving them extra light to work by, it often 53 00:02:07.060 --> 00:02:09.420 looks huge and orange on the horizon. 54 00:02:09.580 --> 00:02:12.180 Anna: That's the one. The orange color is due to 55 00:02:12.180 --> 00:02:14.740 the same effect that makes sunsets red. The 56 00:02:14.740 --> 00:02:16.660 light is passing through more of Earth's 57 00:02:16.660 --> 00:02:19.580 atmosphere. So next week we get a combination 58 00:02:19.580 --> 00:02:22.060 of things. The closest full moon of the year 59 00:02:22.220 --> 00:02:24.860 and the beautiful effect of the harvest moon, 60 00:02:25.020 --> 00:02:27.740 all making for a spectacular celestial event. 61 00:02:28.270 --> 00:02:30.510 Avery: From something we can see with our own eyes 62 00:02:30.590 --> 00:02:32.590 to something that requires a fleet of 63 00:02:32.590 --> 00:02:34.270 interplanetary spacecraft. 64 00:02:34.590 --> 00:02:37.430 Let's get an update on the interstellar comet 65 00:02:37.430 --> 00:02:38.750 3i Atlas. 66 00:02:38.990 --> 00:02:41.070 Anna: This is incredibly exciting. 67 00:02:41.470 --> 00:02:43.870 3i Atlas is only the third 68 00:02:43.949 --> 00:02:46.350 interstellar object we've ever detected 69 00:02:46.590 --> 00:02:48.870 passing through our solar system. The first 70 00:02:48.870 --> 00:02:51.590 was Oumuamua and The second was 71 00:02:51.590 --> 00:02:54.350 2i Borisov. These objects are 72 00:02:54.350 --> 00:02:56.990 cosmic messengers from other star systems. 73 00:02:57.340 --> 00:02:59.940 Avery: And the European Space Agency is pulling out 74 00:02:59.940 --> 00:03:02.620 all the stops to study this one. From now 75 00:03:02.620 --> 00:03:04.900 until early November, they're planning to use 76 00:03:04.900 --> 00:03:07.620 a trio of their spacecraft, the Mars 77 00:03:07.620 --> 00:03:10.540 Express and ExoMars Trace Gas Orbiter, 78 00:03:10.700 --> 00:03:13.500 which are both orbiting Mars, and the JUICE 79 00:03:13.500 --> 00:03:15.740 spacecraft, which is on its way to Jupiter. 80 00:03:16.060 --> 00:03:18.540 Anna: The reason this is such a unique opportunity 81 00:03:18.780 --> 00:03:21.500 is because of the comet's trajectory. As it 82 00:03:21.500 --> 00:03:24.020 makes its closest approach to the sun, it's 83 00:03:24.020 --> 00:03:26.550 going to heat up dramatically. This heating 84 00:03:26.550 --> 00:03:29.030 causes ices on its surface to sublimate, 85 00:03:29.270 --> 00:03:32.150 turn directly into gas, releasing dust 86 00:03:32.150 --> 00:03:34.750 and revealing the chemical composition of the 87 00:03:34.750 --> 00:03:35.750 comet's nucleus. 88 00:03:36.070 --> 00:03:38.390 Avery: So it's like unwrapping a gift from another 89 00:03:38.390 --> 00:03:41.310 star. And using three different spacecraft 90 00:03:41.310 --> 00:03:43.350 gives them a huge advantage, doesn't it? 91 00:03:43.350 --> 00:03:46.190 Anna: It certainly does. Each spacecraft has 92 00:03:46.190 --> 00:03:48.190 different instruments and will see the comet 93 00:03:48.190 --> 00:03:50.150 from a different vantage point. This 94 00:03:50.150 --> 00:03:53.110 triangulation allows scientists to build a 95 00:03:53.110 --> 00:03:56.110 much more complete 3D picture of the comet's 96 00:03:56.110 --> 00:03:59.090 activity and the mater its shedding. By 97 00:03:59.090 --> 00:04:01.130 studying the composition of this gas and 98 00:04:01.130 --> 00:04:03.730 dust, we can learn about the building blocks 99 00:04:03.730 --> 00:04:06.210 of planets in whatever distant star system 100 00:04:06.210 --> 00:04:07.410 this comet came from. 101 00:04:07.650 --> 00:04:09.930 Avery: It's a reminder of how interconnected the 102 00:04:09.930 --> 00:04:12.930 galaxy is. A piece of another solar system 103 00:04:13.010 --> 00:04:15.010 just passing through for a quick visit. 104 00:04:15.330 --> 00:04:16.130 Incredible. 105 00:04:17.250 --> 00:04:18.210 Anna: Absolutely. 106 00:04:19.090 --> 00:04:21.970 Now let's bring our focus a little closer to 107 00:04:21.970 --> 00:04:24.450 home, to our planetary neighborhood, 108 00:04:24.760 --> 00:04:27.760 Mars. Scientists have been puzzled 109 00:04:27.760 --> 00:04:30.440 by a mysterious surge in ozone 110 00:04:30.600 --> 00:04:33.360 that appears over its north pole during the 111 00:04:33.360 --> 00:04:33.720 winter. 112 00:04:33.740 --> 00:04:36.640 Avery: M ozone on Mars. I, uh, usually 113 00:04:36.640 --> 00:04:39.080 associate ozone with Earth's protective 114 00:04:39.080 --> 00:04:41.000 layer. Is it the same thing? 115 00:04:41.320 --> 00:04:43.960 Anna: It's the same molecule. Three 116 00:04:43.960 --> 00:04:46.920 oxygen atoms bonded together. But 117 00:04:46.920 --> 00:04:49.800 on Mars, its behavior is very different. 118 00:04:50.940 --> 00:04:53.500 Using the ExoMars Trace Gas Orbiter. 119 00:04:53.820 --> 00:04:55.740 The same one. Watching the comet, 120 00:04:56.140 --> 00:04:58.420 scientists noticed that ozone 121 00:04:58.420 --> 00:05:00.940 concentrations in the middle atmosphere 122 00:05:01.260 --> 00:05:03.900 spike during the winter inside the 123 00:05:03.900 --> 00:05:04.860 polar vortex. 124 00:05:05.260 --> 00:05:08.260 Avery: A, uh, polar vortex. We have those on 125 00:05:08.260 --> 00:05:11.060 Earth too. Basically a giant spinning cyclone 126 00:05:11.060 --> 00:05:12.140 of frigid air, right? 127 00:05:12.380 --> 00:05:15.180 Anna: Precisely. And on Mars, it 128 00:05:15.180 --> 00:05:17.740 gets incredibly cold inside this 129 00:05:17.740 --> 00:05:20.380 vortex, dropping below minus 130 00:05:20.380 --> 00:05:22.380 1, 130 degrees Celsius. 131 00:05:23.100 --> 00:05:25.580 This cold is the key to the mystery. 132 00:05:26.300 --> 00:05:29.060 Normally, water vapor in the atmosphere 133 00:05:29.060 --> 00:05:31.700 reacts with other chemicals to destroy 134 00:05:31.700 --> 00:05:32.300 ozone. 135 00:05:33.020 --> 00:05:35.580 Avery: But when it gets that cold, the water vapor 136 00:05:35.580 --> 00:05:38.220 freezes out, forming ice clouds. 137 00:05:38.540 --> 00:05:41.020 So with the water vapor gone, the. 138 00:05:41.020 --> 00:05:43.820 Anna: Ozone destroying chemical reactions Stop. 139 00:05:44.220 --> 00:05:46.900 And the ozone is allowed to build up to 140 00:05:46.900 --> 00:05:49.500 much higher concentrations than seen 141 00:05:49.500 --> 00:05:51.100 anywhere else on the planet. 142 00:05:52.160 --> 00:05:53.960 Avery: That's a clever piece of atmospheric 143 00:05:53.960 --> 00:05:56.360 detective work. What does this tell us about 144 00:05:56.360 --> 00:05:56.880 Mars? 145 00:05:57.200 --> 00:05:59.720 Anna: It gives us a new way to trace the 146 00:05:59.720 --> 00:06:02.040 circulation of gases in the Martian 147 00:06:02.040 --> 00:06:04.880 atmosphere. And more importantly, 148 00:06:05.120 --> 00:06:07.880 it helps us understand the history of water 149 00:06:07.880 --> 00:06:10.680 on Mars. By tracking where and 150 00:06:10.680 --> 00:06:13.560 when water vapor is present, we can build 151 00:06:13.560 --> 00:06:16.560 better models of Mars past climate and 152 00:06:16.560 --> 00:06:19.360 figure out where all its ancient water went. 153 00:06:20.270 --> 00:06:22.790 Avery: From a mystery on Mars to the biggest 154 00:06:22.790 --> 00:06:25.790 mystery in the entire cosmos. Ana, uh, we 155 00:06:25.790 --> 00:06:27.590 have to talk about this new theory that 156 00:06:27.590 --> 00:06:30.030 challenges the very existence of dark matter 157 00:06:30.030 --> 00:06:31.150 and dark energy. 158 00:06:31.710 --> 00:06:34.350 Anna: This is one of those ideas that could either 159 00:06:34.350 --> 00:06:36.950 be a dead end or completely 160 00:06:36.950 --> 00:06:39.910 revolutionized cosmology. The standard 161 00:06:39.910 --> 00:06:42.350 model of the universe called Lambda 162 00:06:42.350 --> 00:06:44.430 CDM tells us that about 163 00:06:44.510 --> 00:06:47.470 95% of the universe is made of 164 00:06:47.470 --> 00:06:50.270 two invisible components, dark 165 00:06:50.270 --> 00:06:51.830 matter and dark energy. 166 00:06:52.310 --> 00:06:54.670 Avery: Right. Dark matter provides the extra gravity 167 00:06:54.670 --> 00:06:57.390 needed to hold galaxies together. And dark 168 00:06:57.390 --> 00:06:59.150 energy is, ah, a force that's causing the 169 00:06:59.150 --> 00:07:02.110 universe's expansion to accelerate. We can't 170 00:07:02.110 --> 00:07:04.190 see them, but we infer their existence from 171 00:07:04.190 --> 00:07:04.950 their effects. 172 00:07:05.190 --> 00:07:08.070 Anna: Exactly. But physicist Rajendra 173 00:07:08.070 --> 00:07:11.030 Gupta, uh, from the University of Ottawa, has 174 00:07:11.030 --> 00:07:13.830 proposed a new model that gets rid of both. 175 00:07:14.310 --> 00:07:17.270 His idea is based on a combination of 176 00:07:17.270 --> 00:07:20.230 other theories, including one about tired 177 00:07:20.230 --> 00:07:23.010 light and another covariing 178 00:07:23.010 --> 00:07:24.370 coupling constants. 179 00:07:25.010 --> 00:07:27.490 Avery: Whoa, those are some heavy terms. Let's break 180 00:07:27.490 --> 00:07:30.050 that down. Covariing coupling 181 00:07:30.130 --> 00:07:32.130 constants. What does that mean? 182 00:07:32.450 --> 00:07:34.690 Anna: In simple terms? It means that the 183 00:07:34.690 --> 00:07:37.570 fundamental constants of nature, things like 184 00:07:37.570 --> 00:07:39.570 the strength of gravity or the 185 00:07:39.570 --> 00:07:42.370 electromagnetic force, might not actually 186 00:07:42.450 --> 00:07:45.450 be constant. They could be changing very, 187 00:07:45.450 --> 00:07:48.330 very slowly as the universe ages and 188 00:07:48.330 --> 00:07:49.010 expands. 189 00:07:49.900 --> 00:07:52.140 Avery: So if the strength of these forces changed 190 00:07:52.140 --> 00:07:54.620 over billions of years, how would that 191 00:07:54.620 --> 00:07:55.740 replace dark matter? 192 00:07:56.300 --> 00:07:58.700 Anna: Gupta's model suggests that these 193 00:07:58.780 --> 00:08:01.700 changing constants could create effects that 194 00:08:01.700 --> 00:08:04.380 we currently misinterpret as dark matter. 195 00:08:04.780 --> 00:08:07.660 For example, the way galaxies rotate 196 00:08:07.660 --> 00:08:10.260 much faster than they should, which is, uh, a 197 00:08:10.260 --> 00:08:12.740 key piece of evidence for Dark matter could 198 00:08:12.740 --> 00:08:15.260 be explained by these evolving physical 199 00:08:15.260 --> 00:08:17.980 laws instead of an unseen particle. 200 00:08:18.540 --> 00:08:21.300 The model also accounts for the accelerated 201 00:08:21.300 --> 00:08:24.020 expansion of the universe without needing 202 00:08:24.020 --> 00:08:24.700 dark energy. 203 00:08:25.660 --> 00:08:28.060 Avery: So we might not be living in a universe 204 00:08:28.140 --> 00:08:31.060 filled with mysterious dark stuff, but in a 205 00:08:31.060 --> 00:08:33.700 universe where the fundamental rules are 206 00:08:33.700 --> 00:08:36.620 slowly changing. That's a profound thought. 207 00:08:37.020 --> 00:08:39.900 Anna: It is. It's important to stress that 208 00:08:39.900 --> 00:08:42.220 this is still a very new and 209 00:08:42.300 --> 00:08:45.010 untested hypothesis. The vast 210 00:08:45.010 --> 00:08:47.890 majority of evidence still points towards the 211 00:08:47.890 --> 00:08:50.650 standard lambda CDM model. But 212 00:08:50.650 --> 00:08:53.410 it's a fascinating alternative that reminds 213 00:08:53.410 --> 00:08:55.530 us to keep questioning our assumptions. 214 00:08:56.090 --> 00:08:58.650 It shows that there are still huge 215 00:08:58.890 --> 00:09:01.890 fundamental questions about our universe left 216 00:09:01.890 --> 00:09:02.570 to answer. 217 00:09:02.810 --> 00:09:04.730 Avery: And that is a perfect place to wrap up for 218 00:09:04.730 --> 00:09:05.050 today. 219 00:09:05.130 --> 00:09:07.250 From a supermoon in our backyard to an 220 00:09:07.250 --> 00:09:09.490 interstellar comet, a Martian weather 221 00:09:09.490 --> 00:09:11.730 mystery, and a whole new way to think about 222 00:09:11.730 --> 00:09:14.540 the universe itself, it's been a. 223 00:09:14.540 --> 00:09:17.460 Anna: Whirlwind tour of the cosmos. Thank you so 224 00:09:17.460 --> 00:09:19.980 much for joining us on Astronomy Daily. If 225 00:09:19.980 --> 00:09:21.700 you'd like to see more details on these 226 00:09:21.700 --> 00:09:23.820 stories and more, please visit our 227 00:09:23.820 --> 00:09:26.780 website@astronomydaily.IO 228 00:09:26.860 --> 00:09:28.939 and check out our continually updated 229 00:09:28.939 --> 00:09:31.860 newsfeed. And while there, you may like to 230 00:09:31.860 --> 00:09:34.100 sign up for our free daily newsletter as 231 00:09:34.100 --> 00:09:34.380 well. 232 00:09:34.860 --> 00:09:37.060 Avery: Join us again tomorrow as we continue to 233 00:09:37.060 --> 00:09:39.460 explore the wonders of the universe. Clear 234 00:09:39.460 --> 00:09:41.740 skies, everyone. And remember to keep looking 235 00:09:41.740 --> 00:09:43.650 up, especially this week.