WEBVTT 00:00:07.520 --> 00:00:11.000 Howdy Star Gazers and welcome to Star Trails. 00:00:11.220 --> 00:00:13.919 I'm Drew and I'll be your guide to the night 00:00:13.919 --> 00:00:17.820 sky for the week of October 5th to the 11th. 00:00:18.120 --> 00:00:21.320 This week the bright harvest supermoon takes 00:00:21.320 --> 00:00:24.940 center stage, Saturn continues its evening rain, 00:00:25.460 --> 00:00:28.559 and autumn constellations emerge in full force. 00:00:28.910 --> 00:00:32.549 Later in the show we'll examine some truly weird 00:00:32.549 --> 00:00:38.270 stuff five unsolved mysteries of the cosmos Whether 00:00:38.270 --> 00:00:41.009 you're tuning in from the backyard the balcony 00:00:41.009 --> 00:00:44.189 or just your imagination I'm glad you're here. 00:00:44.409 --> 00:00:47.890 So find a cozy spot Let your eyes adjust and 00:00:47.890 --> 00:00:52.670 let's see what the sky holds for us this week 00:00:52.670 --> 00:00:56.130 Folks again, let me apologize for the lack of 00:00:56.130 --> 00:00:59.490 shows in September In addition to it being a 00:00:59.490 --> 00:01:02.990 very busy period at my day job, I had a birthday 00:01:02.990 --> 00:01:06.090 last month, and it's one of the ones that no 00:01:06.090 --> 00:01:11.030 one looks forward to. Age 50. And to be honest, 00:01:11.209 --> 00:01:14.049 this one put me in a bad place for a week or 00:01:14.049 --> 00:01:18.250 so. As I tried to stave off the imminent collapse 00:01:18.250 --> 00:01:21.590 of my own wave function, I looked to quantum 00:01:21.590 --> 00:01:25.150 physics for answers to life's questions. And 00:01:25.150 --> 00:01:28.719 here's what I landed on. 50 isn't a gateway to 00:01:28.719 --> 00:01:33.280 old age. It's proof of improbable survival against 00:01:33.280 --> 00:01:37.239 entropy, against chance, and against the noise 00:01:37.239 --> 00:01:40.620 of the universe. I like to think that the fact 00:01:40.620 --> 00:01:44.500 that I'm still here is a superposition of sorts. 00:01:45.140 --> 00:01:47.359 At least that's what I've been telling myself 00:01:47.359 --> 00:01:51.519 to stay sane. I'm also happy to report the weather 00:01:51.519 --> 00:01:54.500 here in the south has finally cooled off a little, 00:01:54.819 --> 00:01:57.000 and we're seeing clear skies in the evenings 00:01:57.000 --> 00:02:00.299 again. Hopefully that's been the case for you 00:02:00.299 --> 00:02:04.120 as well. Fall officially arrived last month, 00:02:04.280 --> 00:02:06.939 and that means it's time to dust off the binoculars 00:02:06.939 --> 00:02:10.580 and scopes as we enjoy longer, cooler nights. 00:02:11.919 --> 00:02:14.719 Your first target for observation this week is 00:02:14.719 --> 00:02:18.340 likely going to be the moon. The full moon arrives 00:02:18.340 --> 00:02:21.280 Monday night, and this is not only the harvest 00:02:21.280 --> 00:02:24.360 moon, but a supermoon, meaning it's slightly 00:02:24.360 --> 00:02:27.340 closer to Earth than usual and will look just 00:02:27.340 --> 00:02:30.800 a bit larger and brighter. For most of the week, 00:02:31.000 --> 00:02:34.159 the bright moon will wash out fainter deep sky 00:02:34.159 --> 00:02:37.340 objects, but it also gives us some spectacular 00:02:37.340 --> 00:02:40.520 lunar conjunctions with planets and star clusters. 00:02:41.219 --> 00:02:44.409 More on those in a moment. Now, last week in 00:02:44.409 --> 00:02:48.849 my brief update episode, I mistakenly said September's 00:02:48.849 --> 00:02:52.430 full moon was the Harvest Moon. That was an oversight 00:02:52.430 --> 00:02:56.490 on my part. The Harvest Moon can occur in either 00:02:56.490 --> 00:03:00.490 September or October. It's simply the full moon 00:03:00.490 --> 00:03:05.430 closest to the autumnal equinox. This year, October's 00:03:05.430 --> 00:03:09.280 full moon has that honor. The name of the Harvest 00:03:09.280 --> 00:03:12.000 Moon dates back to when farmers used to rely 00:03:12.000 --> 00:03:14.919 on this extra moonlight to bring in the last 00:03:14.919 --> 00:03:19.439 of the harvest after sunset. So what was September's 00:03:19.439 --> 00:03:23.139 full moon called? That was the corn or barley 00:03:23.139 --> 00:03:27.500 moon. Looking further out, Saturn continues to 00:03:27.500 --> 00:03:30.360 dominate the evening sky. It reached opposition 00:03:30.360 --> 00:03:32.960 just a couple weeks ago and it's still bright 00:03:32.960 --> 00:03:36.419 and well placed for observation. Step outside 00:03:36.419 --> 00:03:39.319 after sunset and look toward the southeast to 00:03:39.319 --> 00:03:43.680 find it. Tonight the moon slides close to Saturn 00:03:43.680 --> 00:03:47.139 making for a lovely pairing. Binoculars show 00:03:47.139 --> 00:03:50.280 them beautifully together and a moderately powered 00:03:50.280 --> 00:03:53.439 telescope will reveal Saturn's rings, although 00:03:53.439 --> 00:03:56.259 they may look a little thinner than expected. 00:03:57.500 --> 00:04:00.819 Saturn's thin rings this year aren't an illusion. 00:04:01.000 --> 00:04:03.680 They're a matter of Earth's changing vantage 00:04:03.680 --> 00:04:07.199 point. The planet's ring system is tilted about 00:04:07.199 --> 00:04:11.259 27 degrees relative to its orbit, and as Saturn 00:04:11.259 --> 00:04:14.340 moves around the Sun, we see that tilt from different 00:04:14.340 --> 00:04:19.360 angles. Roughly every 14 to 15 years, Earth passes 00:04:19.360 --> 00:04:22.160 through the plane of Saturn's rings, an event 00:04:22.160 --> 00:04:26.459 called a ring -plane crossing. Around these times, 00:04:26.639 --> 00:04:29.639 the rings appear edge -on and seem to disappear 00:04:29.639 --> 00:04:32.970 in small telescopes. They don't actually vanish, 00:04:33.110 --> 00:04:36.290 the rings are just extraordinarily thin, so they 00:04:36.290 --> 00:04:39.569 present almost no reflective surface when seen 00:04:39.569 --> 00:04:44.189 edge on. Fun side note, ring plane crossings 00:04:44.189 --> 00:04:47.449 often allow astronomers to spot some of Saturn's 00:04:47.449 --> 00:04:50.089 smaller moons that are normally lost in the ring's 00:04:50.089 --> 00:04:54.029 glare. So these periods are scientifically valuable, 00:04:54.170 --> 00:04:58.100 even if the visual show dims a bit. Later at 00:04:58.100 --> 00:05:01.300 night, Jupiter rises dazzling in the pre -dawn 00:05:01.300 --> 00:05:05.199 sky. It's a brilliant beacon currently in Gemini. 00:05:06.100 --> 00:05:08.839 Venus is also in the morning sky, hugging the 00:05:08.839 --> 00:05:12.459 eastern horizon before sunrise. If you have a 00:05:12.459 --> 00:05:14.839 flat view toward the east, you can't miss it. 00:05:15.160 --> 00:05:17.540 It's the brightest object in the sky after the 00:05:17.540 --> 00:05:21.339 moon. Mars and Mercury are too close to the Sun 00:05:21.339 --> 00:05:25.959 to observe this week. From October the 6th through 00:05:25.959 --> 00:05:29.019 the 10th, we get a visit from the draconid meteor 00:05:29.019 --> 00:05:32.079 shower. The predicted peak is the evening of 00:05:32.079 --> 00:05:36.180 Wednesday, October the 8th. This is an unusual 00:05:36.180 --> 00:05:38.699 shower because the best time to watch it is right 00:05:38.699 --> 00:05:42.279 after nightfall, not before dawn. The radiant 00:05:42.279 --> 00:05:45.620 is high in the northwest after sunset, so grab 00:05:45.620 --> 00:05:49.100 a chair, face away from the moon, and scan the 00:05:49.100 --> 00:05:52.920 sky during twilight's fade. The waning gibbous 00:05:52.920 --> 00:05:55.680 moon will drown out many of the fainter meteors, 00:05:55.959 --> 00:05:59.980 so expect just a handful per hour. But the draconids 00:05:59.980 --> 00:06:03.180 are famous for surprise outbursts, so it's worth 00:06:03.180 --> 00:06:07.139 a look. On the nights of October 9th and 10th, 00:06:07.339 --> 00:06:10.639 the moon passes very close to the Pleiades star 00:06:10.639 --> 00:06:14.560 cluster, also known as the Seven Sisters. For 00:06:14.560 --> 00:06:17.279 some observers in North America, the moon will 00:06:17.279 --> 00:06:20.899 actually occult or pass in front of several of 00:06:20.899 --> 00:06:23.959 the brighter stars in the cluster. If you have 00:06:23.959 --> 00:06:27.060 binoculars or a small telescope, this is a magical 00:06:27.060 --> 00:06:30.879 sight. Watch stars disappear behind the moon's 00:06:30.879 --> 00:06:34.360 bright limb and reappear on the dark side. As 00:06:34.360 --> 00:06:38.319 always, refer to a stargazing app like Sky Safari 00:06:38.319 --> 00:06:41.759 or Stellarium to see if this phenomenon is visible 00:06:41.759 --> 00:06:46.079 in your area. Summer's constellations are on 00:06:46.079 --> 00:06:49.439 their way out. By mid -evening, Pegasus stands 00:06:49.439 --> 00:06:52.279 tall in the east, marked by the Great Square. 00:06:52.899 --> 00:06:55.959 Trace a line from the Great Square into Andromeda, 00:06:56.279 --> 00:07:01.040 and you can find M31, the Andromeda galaxy. Visible 00:07:01.040 --> 00:07:05.560 in binoculars, even from suburban skies. Above 00:07:05.560 --> 00:07:09.920 Pegasus, Cassiopeia forms her distinctive W shape, 00:07:10.199 --> 00:07:13.759 which is a reliable signpost to M31 as well. 00:07:14.379 --> 00:07:17.480 The larger point of the W seems to form an arrow 00:07:17.480 --> 00:07:21.160 that points the way to M31. This is how I've 00:07:21.160 --> 00:07:25.600 always located the Andromeda galaxy. Meanwhile, 00:07:25.959 --> 00:07:29.000 Perseus and the double cluster rise in the northeast, 00:07:29.339 --> 00:07:32.980 a binocular favorite. To the south, the bright 00:07:32.980 --> 00:07:36.980 star Fomalot shines alone, low on the horizon, 00:07:37.399 --> 00:07:39.920 while the summer triangle still lingers in the 00:07:39.920 --> 00:07:43.060 west, slowly giving way to the stars of autumn. 00:07:50.500 --> 00:07:53.180 There's been another giant comet in the news. 00:07:53.439 --> 00:08:00.500 Comet 3I Atlas, also known as C2025N1, is the 00:08:00.500 --> 00:08:03.860 third confirmed interstellar object to enter 00:08:03.860 --> 00:08:08.360 our solar system, after Oumuamua and Borisov. 00:08:08.879 --> 00:08:11.899 Despite breathless headlines recently, this is 00:08:11.899 --> 00:08:15.379 not a naked eye spectacle. This week, it's actually 00:08:15.379 --> 00:08:18.439 too close to the sun in the evening sky to observe 00:08:18.439 --> 00:08:22.379 safely. The comet will reach perihelion on October 00:08:22.379 --> 00:08:25.579 29, then gradually reappear in the pre -dawn 00:08:25.579 --> 00:08:29.459 sky in December, mostly for large telescopes. 00:08:30.680 --> 00:08:34.080 Early Hubble data suggests a nucleus no larger 00:08:34.080 --> 00:08:38.340 than about 5 km, and its peak brightness is expected 00:08:38.340 --> 00:08:43.000 around magnitude 11 to 12. Faint, but scientifically 00:08:43.000 --> 00:08:49.399 thrilling. It's interstellar, after all. It's 00:08:49.399 --> 00:08:52.419 October, so that means it's time for some eerie 00:08:52.419 --> 00:08:56.480 topics. Imagine a smoke machine running, Robert 00:08:56.480 --> 00:09:00.019 Stack in his trench coat, and that creepy, synth 00:09:00.019 --> 00:09:03.320 -heavy theme whispering into the void. We're 00:09:03.320 --> 00:09:07.240 about to explore some unsolved mysteries of the 00:09:07.240 --> 00:09:10.620 cosmos. That's coming up after the break. Stay 00:09:10.620 --> 00:09:29.879 with us. Welcome back. The universe, vast, silent, 00:09:30.480 --> 00:09:34.139 filled with mysteries beyond imagination. Everywhere 00:09:34.139 --> 00:09:37.899 we look the cosmos is brimming with enigmas, 00:09:38.320 --> 00:09:41.720 riddles that defy our laws of physics and confound 00:09:41.720 --> 00:09:45.639 even the sharpest minds. They are the cold cases 00:09:45.639 --> 00:09:50.000 of astronomy, the unsolved puzzles of astrophysics. 00:09:50.799 --> 00:09:54.929 Tonight we open the cosmic case file, Five mysteries, 00:09:55.409 --> 00:09:59.450 each as unsettling as it is profound. These are 00:09:59.450 --> 00:10:02.690 the questions that haunt the night sky, waiting 00:10:02.690 --> 00:10:05.429 for answers that may change everything we think 00:10:05.429 --> 00:10:09.049 and know. Let's dim the lights and step into 00:10:09.049 --> 00:10:24.129 the shadows of the universe. the dark sector, 00:10:24.549 --> 00:10:29.789 matter and energy we cannot see. It begins with 00:10:29.789 --> 00:10:33.509 a crime of omission, a hidden force at work. 00:10:34.110 --> 00:10:37.590 Galaxies, those magnificent pinwheels of stars, 00:10:38.129 --> 00:10:41.809 are not behaving as they should. According to 00:10:41.809 --> 00:10:45.269 Newton, according to Einstein, stars at the edges 00:10:45.269 --> 00:10:48.450 should drift lazily, moving slower than those 00:10:48.450 --> 00:10:51.929 near the core. Instead, they whirl around at 00:10:51.929 --> 00:10:55.529 the same breakneck speed, as if an invisible 00:10:55.529 --> 00:11:00.129 hand is holding the galaxy together. That invisible 00:11:00.129 --> 00:11:04.210 hand is called dark matter. We can't see it, 00:11:04.210 --> 00:11:07.629 we can't touch it, but the evidence is overwhelming. 00:11:08.509 --> 00:11:12.009 Dark matter doesn't glow, reflect, or even absorb 00:11:12.009 --> 00:11:16.269 light, yet it outweighs the visible stars 5 to 00:11:16.269 --> 00:11:20.029 1, like a shadowy suspect. it makes its presence 00:11:20.029 --> 00:11:24.570 known only through its gravitational pull. And 00:11:24.570 --> 00:11:27.870 then there's its partner in mystery, dark energy. 00:11:33.870 --> 00:11:37.730 In 1998, astronomers studying distant exploding 00:11:37.730 --> 00:11:41.190 stars, supernova, noticed something shocking. 00:11:41.769 --> 00:11:45.539 The universe isn't just expanding. It's accelerating, 00:11:46.000 --> 00:11:49.440 as if some unseen energy is stretching the fabric 00:11:49.440 --> 00:11:53.460 of space itself. Dark matter and dark energy 00:11:53.460 --> 00:11:57.419 together make up about 95 % of the universe. 00:11:59.019 --> 00:12:03.259 95%. That means everything we see, stars, planets, 00:12:03.740 --> 00:12:07.899 gas clouds, even ourselves, amounts to a cosmic 00:12:07.899 --> 00:12:17.059 rounding error. Theories abound. Perhaps exotic 00:12:17.059 --> 00:12:20.039 particles are hiding in plain sight. Perhaps 00:12:20.039 --> 00:12:23.019 there are unseen dimensions warping the rules, 00:12:23.600 --> 00:12:26.639 or maybe the very laws of gravity need rewriting. 00:12:27.179 --> 00:12:30.659 But no experiment has yet revealed the culprit. 00:12:45.419 --> 00:12:49.059 Let's rewind the clock to the first second of 00:12:49.059 --> 00:12:52.600 the universe. The Big Bang should have created 00:12:52.600 --> 00:12:56.720 equal amounts of matter and antimatter. For every 00:12:56.720 --> 00:13:00.240 proton, an anti -proton. For every electron, 00:13:00.559 --> 00:13:04.360 a positron. Matter and antimatter are mirror 00:13:04.360 --> 00:13:08.299 images. Same mass, but with an opposite charge. 00:13:09.019 --> 00:13:11.960 When they meet, they annihilate, vanishing in 00:13:11.960 --> 00:13:19.320 a burst of light. By that logic, the universe 00:13:19.320 --> 00:13:22.440 should have destroyed itself almost instantly, 00:13:22.700 --> 00:13:26.679 yet it didn't. Somehow matter gained the upper 00:13:26.679 --> 00:13:30.759 hand, and antimatter vanished, and we are the 00:13:30.759 --> 00:13:35.940 survivors of that imbalance. But why? Physicists 00:13:35.940 --> 00:13:40.240 call this puzzle baryon asymmetry. The smoking 00:13:40.240 --> 00:13:43.799 gun lies in something known as CP violation. 00:13:44.169 --> 00:13:47.570 And here's the translation. C stands for charge 00:13:47.570 --> 00:13:51.750 conjugation. Swap a particle for its antiparticle. 00:13:52.590 --> 00:13:56.509 P stands for parity. Flip the universe like a 00:13:56.509 --> 00:14:01.450 mirror image. If the laws of physics were fair, 00:14:01.750 --> 00:14:04.690 a process should look the same under both flips, 00:14:04.870 --> 00:14:07.909 but experiments show that's not always true. 00:14:08.830 --> 00:14:11.669 In the 1960s, researchers found that certain 00:14:11.669 --> 00:14:15.399 subatomic particles Kions decayed differently 00:14:15.399 --> 00:14:18.919 than their antimatter twins. Nature had shown 00:14:18.919 --> 00:14:24.000 a preference. This CP violation is the universe's 00:14:24.000 --> 00:14:27.500 tiny cheat code favoring matter ever so slightly 00:14:27.500 --> 00:14:30.679 over antimatter. But here's the problem. The 00:14:30.679 --> 00:14:33.580 CP violation we've measured isn't strong enough 00:14:33.580 --> 00:14:36.240 to explain why the universe is filled with matter 00:14:36.240 --> 00:14:39.879 instead of just light. That's why physicists 00:14:39.879 --> 00:14:43.679 are chasing neutrinos. These ghostly particles 00:14:43.679 --> 00:14:46.940 able to slip through a trillion miles of lead 00:14:46.940 --> 00:14:51.740 unhindered may hold the answer. Neutrinos oscillate 00:14:51.740 --> 00:14:55.659 between different flavors, electron, muon, tau, 00:14:55.899 --> 00:14:59.519 and in doing so, they might break CP symmetry 00:14:59.519 --> 00:15:03.980 in ways far more dramatic than quarks do. If 00:15:03.980 --> 00:15:07.080 so, we'll finally know why matter won. Until 00:15:07.080 --> 00:15:13.509 then, the trail is cold. Case three black holes 00:15:13.509 --> 00:15:26.149 and the information paradox There is no greater 00:15:26.149 --> 00:15:30.210 locked room in the cosmos than a black hole Cross 00:15:30.210 --> 00:15:33.690 its boundary the event horizon and escape is 00:15:33.690 --> 00:15:38.149 impossible Gravity there is absolute light itself 00:15:38.149 --> 00:15:42.700 cannot flee Einstein's equations tell us matter 00:15:42.700 --> 00:15:46.539 falls inward, collapsing to a singularity, a 00:15:46.539 --> 00:15:50.539 point of infinite density. But infinities are 00:15:50.539 --> 00:15:54.460 the mathematician's red flag, a sign that our 00:15:54.460 --> 00:15:58.440 theories might be broken. What happens to the 00:15:58.440 --> 00:16:01.340 information carried by particles that fall in? 00:16:01.740 --> 00:16:05.059 Quantum mechanics says information can never 00:16:05.059 --> 00:16:09.299 be destroyed, yet black holes seem to erase it 00:16:09.299 --> 00:16:12.440 completely. This contradiction is called the 00:16:12.440 --> 00:16:17.379 information paradox. Stephen Hawking offered 00:16:17.379 --> 00:16:21.080 a clue. Black holes aren't perfectly black. They 00:16:21.080 --> 00:16:24.460 radiate faint amounts of energy, now called Hawking 00:16:24.460 --> 00:16:29.049 radiation, and slowly evaporate. If they vanish 00:16:29.049 --> 00:16:31.830 completely, what becomes of the information they 00:16:31.830 --> 00:16:35.549 devoured? Does it escape scrambled in the radiation? 00:16:36.169 --> 00:16:38.870 Is it somehow preserved on the surface of the 00:16:38.870 --> 00:16:43.570 event horizon like a cosmic hologram? Some theories 00:16:43.570 --> 00:16:47.690 suggest firewalls of energy at the event horizon, 00:16:48.429 --> 00:16:51.549 violent boundaries that incinerate matter instantly. 00:16:51.879 --> 00:16:55.620 Others propose that our universe itself may be 00:16:55.620 --> 00:16:59.759 holographic, and black holes are the proof. The 00:16:59.759 --> 00:17:03.000 Event Horizon Telescope gave us our first images 00:17:03.000 --> 00:17:06.420 of these beasts, shadows of darkness against 00:17:06.420 --> 00:17:10.299 glowing disks of gas. But their inner secrets 00:17:10.299 --> 00:17:27.740 remain sealed. Ultra High Energy Cosmic Rays 00:17:27.740 --> 00:17:35.740 Every second Earth is bombarded by cosmic rays, 00:17:36.079 --> 00:17:39.299 charged particles hurled through space at near 00:17:39.299 --> 00:17:43.799 light speed. Most are modest in energy, spawned 00:17:43.799 --> 00:17:48.390 by exploding stars. But sometimes a monster arrives, 00:17:48.849 --> 00:17:52.289 a cosmic ray with energies so vast it staggers 00:17:52.289 --> 00:17:57.890 belief. In 1991, one such particle hit a detector 00:17:57.890 --> 00:18:02.190 in Utah. Its energy was so extreme, more than 00:18:02.190 --> 00:18:06.549 10 to the 20th power, electron volts, that physicists 00:18:06.549 --> 00:18:10.730 nicknamed it the Oh My God particle. Packed into 00:18:10.730 --> 00:18:13.890 a single proton it carried as much energy as 00:18:13.890 --> 00:18:17.710 a baseball traveling at 90 kilometers per hour 00:18:17.710 --> 00:18:21.150 Imagine something that tiny carrying that much 00:18:21.150 --> 00:18:26.029 punch But here's the paradox physics says such 00:18:26.029 --> 00:18:28.769 particles shouldn't reach us on their journey 00:18:28.769 --> 00:18:31.230 They should collide with the faint glow of the 00:18:31.230 --> 00:18:34.769 cosmic microwave background That's the afterglow 00:18:34.769 --> 00:18:38.750 of the Big Bang and lose energy in the process 00:18:42.480 --> 00:18:46.980 This predicted cutoff is known as the GZK limit, 00:18:47.180 --> 00:18:51.299 and yet they arrive anyway. Where do they come 00:18:51.299 --> 00:18:55.940 from? Some point to active galactic nuclei, jets 00:18:55.940 --> 00:18:59.680 from supermassive black holes. Others suggest 00:18:59.680 --> 00:19:02.799 gamma ray bursts, the most violent explosions 00:19:02.799 --> 00:19:06.880 known. A few even whisper about exotic physics, 00:19:07.279 --> 00:19:10.079 remnants of the Big Bang itself decaying into 00:19:10.079 --> 00:19:14.859 cosmic bullets. Detectors like the Pierre Auger 00:19:14.859 --> 00:19:18.960 Observatory in Argentina and IceCube in Antarctica 00:19:18.960 --> 00:19:22.680 are on the case, scanning the skies. But the 00:19:22.680 --> 00:19:29.380 source remains unidentified. Case 5. The Hubble 00:19:29.380 --> 00:19:36.660 tension. At the heart of cosmology lies a deceptively 00:19:36.660 --> 00:19:40.390 simple number, the Hubble constant. the rate 00:19:40.390 --> 00:19:44.309 at which the universe expands. Measure it carefully 00:19:44.309 --> 00:19:48.250 and you know the age, size, and fate of the cosmos. 00:19:49.509 --> 00:19:52.930 But here the case takes a strange turn. Using 00:19:52.930 --> 00:19:56.809 the cosmic distance ladder, measuring Cepheid 00:19:56.809 --> 00:20:00.269 variable stars in certain supernova, astronomers 00:20:00.269 --> 00:20:03.930 get a value of about 73 kilometers per second 00:20:03.930 --> 00:20:08.000 per megaparsec. But when they measure the same 00:20:08.000 --> 00:20:10.619 expansion through the ancient light of the cosmic 00:20:10.619 --> 00:20:15.779 microwave background, they get 67. Two methods, 00:20:16.059 --> 00:20:21.880 two results, and they refuse to agree. This disagreement 00:20:21.880 --> 00:20:25.240 is known as the Hubble tension, and it's no minor 00:20:25.240 --> 00:20:29.319 discrepancy. The gap is now statistically significant, 00:20:29.539 --> 00:20:32.059 suggesting something fundamental is missing in 00:20:32.059 --> 00:20:42.359 our picture of the universe. Could there be new 00:20:42.359 --> 00:20:45.259 physics in the early universe, a hidden form 00:20:45.259 --> 00:20:48.819 of energy, early dark energy that vanished long 00:20:48.819 --> 00:20:52.220 ago, or subtle interactions between dark matter 00:20:52.220 --> 00:20:56.160 and neutrinos? If the tension holds, it means 00:20:56.160 --> 00:20:59.720 our standard cosmological model, the proud achievement 00:20:59.720 --> 00:21:03.759 of 20th century science, may be incomplete. The 00:21:03.759 --> 00:21:14.119 universe may still have surprises waiting. Five 00:21:14.119 --> 00:21:18.519 mysteries, five case files still open. The dark 00:21:18.519 --> 00:21:23.000 sector that hides 95 % of reality. The disappearance 00:21:23.000 --> 00:21:26.460 of antimatter, cheated out of existence by subtle 00:21:26.460 --> 00:21:30.839 violations of symmetry. Black holes, the cosmic 00:21:30.839 --> 00:21:34.430 vaults where information may vanish. Ultra -high 00:21:34.430 --> 00:21:37.990 -energy cosmic rays, impossible bullets from 00:21:37.990 --> 00:21:41.930 nowhere, and the Hubble tension, a crack in our 00:21:41.930 --> 00:21:45.750 cosmic foundation. Each of these is a shadow 00:21:45.750 --> 00:21:49.549 in the night sky, each a locked door daring us 00:21:49.549 --> 00:21:53.230 to find the key. With each new telescope, each 00:21:53.230 --> 00:21:56.029 detector buried in ice or lofted into orbit, 00:21:56.410 --> 00:21:59.630 the case grows warmer. And maybe one day, one 00:21:59.630 --> 00:22:03.309 of these mysteries will be solved. But for now, 00:22:03.490 --> 00:22:07.309 they remain the unsolved mysteries of the cosmos. 00:22:12.450 --> 00:22:14.849 If the stars spoke to you this week, or if a 00:22:14.849 --> 00:22:17.009 question's been on your mind, I'd love to hear 00:22:17.009 --> 00:22:20.589 it. Visit our website StarTrails .Show where 00:22:20.589 --> 00:22:23.950 you can contact me and explore past episodes. 00:22:24.410 --> 00:22:27.250 Be sure to follow us on Blue Sky and YouTube. 00:22:27.690 --> 00:22:30.529 Links are in the show notes. Until we meet again 00:22:30.529 --> 00:22:33.099 beneath the stars, Clear skies everyone.