WEBVTT 00:00:07.529 --> 00:00:10.330 Howdy Star Gazers and welcome to this episode 00:00:10.330 --> 00:00:13.669 of Star Trails. My name is Drew, and I'll be 00:00:13.669 --> 00:00:16.410 your guide to the night sky for the week of March 00:00:16.410 --> 00:00:21.250 29th through April 4th. This week we leave the 00:00:21.250 --> 00:00:23.989 familiar planets behind and journey into the 00:00:23.989 --> 00:00:27.309 farthest reaches of our solar system. where the 00:00:27.309 --> 00:00:30.210 sun's influence begins to fade and the boundaries 00:00:30.210 --> 00:00:34.170 of our cosmic neighborhood grow uncertain. We'll 00:00:34.170 --> 00:00:38.649 explore the Kuiper Belt, a vast disk of icy remnants 00:00:38.649 --> 00:00:42.310 from planetary formation, and venture even farther 00:00:42.310 --> 00:00:47.369 into the mysterious unseen Oort Cloud, a distant 00:00:47.369 --> 00:00:50.770 spherical halo that may stretch halfway to the 00:00:50.770 --> 00:00:54.009 nearest stars. Later in the show, we'll take 00:00:54.009 --> 00:00:56.450 a look at what you can expect to see in this 00:00:56.450 --> 00:00:59.509 week's night sky. Whether you're tuning in from 00:00:59.509 --> 00:01:01.969 the backyard or the balcony, I'm glad you're 00:01:01.969 --> 00:01:04.790 here. So grab a comfortable spot under the night 00:01:04.790 --> 00:01:10.109 sky and let's get started. Over the past several 00:01:10.109 --> 00:01:12.849 weeks, we've taken a journey through our solar 00:01:12.849 --> 00:01:15.890 system. We've stood on the scorched surface of 00:01:15.890 --> 00:01:18.890 Mercury. drifted through the thick clouds of 00:01:18.890 --> 00:01:22.310 Venus and looked back at our fragile home from 00:01:22.310 --> 00:01:25.989 orbit. We've explored the red deserts of Mars, 00:01:26.609 --> 00:01:29.670 crossed the asteroid belt, and marveled at the 00:01:29.670 --> 00:01:33.150 immense presence of Jupiter and Saturn. We reached 00:01:33.150 --> 00:01:35.950 the outermost planets and we've looked at some 00:01:35.950 --> 00:01:39.510 of the strange moons that orbit them. For much 00:01:39.510 --> 00:01:42.370 of human history, that's where the story ended. 00:01:42.700 --> 00:01:46.879 When Johann Gottfried Gall first observed Neptune 00:01:46.879 --> 00:01:51.159 in 1846, it marked the boundary of the known 00:01:51.159 --> 00:01:55.079 solar system. Even after Clyde Tombaugh discovered 00:01:55.079 --> 00:01:59.079 Pluto in 1930, astronomers still thought in terms 00:01:59.079 --> 00:02:03.079 of planets. Isolated worlds spaced out across 00:02:03.079 --> 00:02:07.060 an otherwise empty void. But tonight we're going 00:02:07.060 --> 00:02:11.180 beyond that idea. Because the solar system doesn't 00:02:11.180 --> 00:02:14.590 end with Neptune. In many ways, that's just where 00:02:14.590 --> 00:02:18.969 it begins to get strange. Just beyond Neptune's 00:02:18.969 --> 00:02:22.430 orbit lies a vast and dimly lit region known 00:02:22.430 --> 00:02:26.250 as the Kuiper Belt. This is not a place of dominant 00:02:26.250 --> 00:02:30.490 planets, but a wide, flattened disk of icy debris 00:02:30.490 --> 00:02:34.530 stretching from about 30 to 50 astronomical units 00:02:34.530 --> 00:02:39.129 from the sun. Out here, sunlight is faint. Temperatures 00:02:39.129 --> 00:02:42.360 hover just above absolute zero. and the pace 00:02:42.360 --> 00:02:46.080 of motion slows to something almost imperceptible. 00:02:46.659 --> 00:02:49.379 Every now and then, it sends us a short period 00:02:49.379 --> 00:02:53.340 comet, like Halley's Comet for instance. These 00:02:53.340 --> 00:02:56.159 distant regions are not random collections of 00:02:56.159 --> 00:02:59.740 objects. They're time capsules. When the planets 00:02:59.740 --> 00:03:03.000 formed billions of years ago, gravity gathered 00:03:03.000 --> 00:03:06.300 material into worlds like Earth and Jupiter. 00:03:06.840 --> 00:03:10.460 But not everything was used. What remained was 00:03:10.460 --> 00:03:13.400 scattered outward, pushed into distant orbits 00:03:13.400 --> 00:03:17.080 by the giant planets, where it's remained largely 00:03:17.080 --> 00:03:21.020 unchanged ever since. The Kuiper Belt is not 00:03:21.020 --> 00:03:23.919 just a region, it's actually a preserved record 00:03:23.919 --> 00:03:27.860 of the solar system's formation. A construction 00:03:27.860 --> 00:03:31.840 site that was never finished. The idea of such 00:03:31.840 --> 00:03:36.759 a region didn't always exist. In 1951, astronomer 00:03:36.759 --> 00:03:40.460 Gerard Kuyper proposed that leftover debris might 00:03:40.460 --> 00:03:43.919 exist beyond Neptune, though he believed it may 00:03:43.919 --> 00:03:47.599 have dissipated over time. For decades, the idea 00:03:47.599 --> 00:03:51.699 remained theoretical. It wasn't until 1992 that 00:03:51.699 --> 00:03:54.960 astronomers finally confirmed this distant region 00:03:54.960 --> 00:03:58.520 was real. Working at the University of Hawaii, 00:03:59.120 --> 00:04:02.930 David Jewett and Jane Lu spent years patiently 00:04:02.930 --> 00:04:06.409 scanning the sky, searching for something incredibly 00:04:06.409 --> 00:04:09.930 difficult to detect. These objects are small, 00:04:10.250 --> 00:04:13.629 dark, and move very slowly against the background 00:04:13.629 --> 00:04:17.310 stars. Night after night, they compared images 00:04:17.310 --> 00:04:20.610 looking for a faint point of light that shifted 00:04:20.610 --> 00:04:24.250 just enough to reveal itself. And then they found 00:04:24.250 --> 00:04:31.259 it. A tiny object now known as 1992 QB1. It wasn't 00:04:31.259 --> 00:04:34.680 a planet and it wasn't a comet. It was something 00:04:34.680 --> 00:04:38.319 new. The first confirmed member of what we now 00:04:38.319 --> 00:04:42.120 call the Kuiper Belt. That discovery changed 00:04:42.120 --> 00:04:46.240 everything. It meant that Pluto was not an outlier. 00:04:46.800 --> 00:04:50.500 It was part of a vast population of distant worlds. 00:04:50.949 --> 00:04:53.970 In the years that followed, astronomers discovered 00:04:53.970 --> 00:04:56.850 more and more of these objects, until it became 00:04:56.850 --> 00:04:59.769 clear that the outer solar system was not empty 00:04:59.769 --> 00:05:03.730 at all. It was crowded. Among the astronomers 00:05:03.730 --> 00:05:07.129 leading that exploration was Mike Pluto Killer 00:05:07.129 --> 00:05:10.930 Brown. In the early 2000s, Brown and his team 00:05:10.930 --> 00:05:13.670 began discovering large objects in the Kuiper 00:05:13.670 --> 00:05:18.129 Belt, worlds that rivaled Pluto in size. Then, 00:05:18.310 --> 00:05:22.189 in 2005, they found something even more provocative. 00:05:22.889 --> 00:05:27.089 Eris. Eris is slightly more massive than Pluto, 00:05:27.490 --> 00:05:30.490 and travels in a distant, elongated orbit that 00:05:30.490 --> 00:05:34.449 carries it far beyond Pluto's path. At times, 00:05:34.769 --> 00:05:37.550 it's more than twice as far from the sun as Pluto. 00:05:38.370 --> 00:05:41.430 And its discovery raised a difficult question. 00:05:41.769 --> 00:05:45.189 If Pluto was a planet, Then what is Eris? Another 00:05:45.189 --> 00:05:48.129 planet? The tenth? Or, had we misunderstood, 00:05:48.550 --> 00:05:52.029 Pluto all along? What followed was one of the 00:05:52.029 --> 00:05:56.589 most public debates in modern astronomy. In 2006, 00:05:56.870 --> 00:05:59.689 the definition of a planet was formally revised, 00:06:00.069 --> 00:06:03.110 and Pluto was reclassified as a dwarf planet. 00:06:03.810 --> 00:06:06.750 Mike Brown took the fall as the so -called man 00:06:06.750 --> 00:06:10.230 who killed Pluto, but in reality, he didn't take 00:06:10.230 --> 00:06:13.439 anything away. He revealed something larger. 00:06:13.920 --> 00:06:16.399 The solar system didn't really lose a planet. 00:06:16.680 --> 00:06:21.120 It gained an entire new region of worlds. But 00:06:21.120 --> 00:06:24.980 even the Kuiper Belt is not the edge. The idea 00:06:24.980 --> 00:06:28.040 of something even farther out came from a different 00:06:28.040 --> 00:06:33.500 mystery. In 1950, Dutch astronomer Jan Oort studied 00:06:33.500 --> 00:06:37.759 the paths of long period comets. These rare visitors 00:06:37.759 --> 00:06:41.050 that appear suddenly and may not return for thousands 00:06:41.050 --> 00:06:44.990 of years. Their orbits didn't make sense. They 00:06:44.990 --> 00:06:48.250 weren't confined to the mostly flat plane of 00:06:48.250 --> 00:06:51.430 the solar system. Instead, they approached from 00:06:51.430 --> 00:06:55.430 every direction, above, below, and at every angle 00:06:55.430 --> 00:07:00.509 imaginable. Oort realized these comets must originate 00:07:00.509 --> 00:07:03.689 from a spherical distribution of objects, not 00:07:03.689 --> 00:07:07.379 a disk. He proposed the existence of a vast, 00:07:07.500 --> 00:07:10.800 distant cloud of icy bodies surrounding the sun 00:07:10.800 --> 00:07:15.120 in all directions. So far away that they're only 00:07:15.120 --> 00:07:18.699 loosely bound by its gravity. A passing star 00:07:18.699 --> 00:07:21.839 or even the gentle tidal forces of the Milky 00:07:21.839 --> 00:07:24.920 Way could disturb one of these objects and send 00:07:24.920 --> 00:07:27.860 it falling inward where we would briefly see 00:07:27.860 --> 00:07:31.480 it as a comet. We have never directly observed 00:07:31.480 --> 00:07:35.180 this cloud. No telescope has imaged it. and yet 00:07:35.180 --> 00:07:38.680 every long period comet we see points back to 00:07:38.680 --> 00:07:42.879 its existence. Today we call it the Oort cloud. 00:07:43.740 --> 00:07:46.319 Some astronomers believe there may even be a 00:07:46.319 --> 00:07:49.279 dense inner region, sometimes called the Hills 00:07:49.279 --> 00:07:53.500 cloud, hidden within the larger structure. Taken 00:07:53.500 --> 00:07:56.899 together, this region may extend tens of thousands 00:07:56.899 --> 00:08:00.680 of astronomical units from the Sun, perhaps even 00:08:00.680 --> 00:08:04.170 approaching halfway to the nearest star. At that 00:08:04.170 --> 00:08:07.850 distance, our sun is no longer a dominant presence. 00:08:08.170 --> 00:08:10.930 It becomes just another point of light in the 00:08:10.930 --> 00:08:14.769 sky. When we see a comet from Earth, we're seeing 00:08:14.769 --> 00:08:18.089 something ancient, a fragment of the early solar 00:08:18.089 --> 00:08:21.250 system, preserved in deep freeze for billions 00:08:21.250 --> 00:08:24.810 of years, now briefly illuminated by the sun 00:08:24.810 --> 00:08:28.339 before returning to the darkness. When I first 00:08:28.339 --> 00:08:31.699 began this series, I specifically wanted to highlight 00:08:31.699 --> 00:08:34.879 places that humanity has physically explored. 00:08:35.480 --> 00:08:38.039 And believe it or not, space probes are in the 00:08:38.039 --> 00:08:41.620 Oort cloud right now. Of course, I'm talking 00:08:41.620 --> 00:08:46.240 about the two spacecraft launched in 1977, Voyager 00:08:46.240 --> 00:08:50.759 1 and Voyager 2. These are the most distant objects 00:08:50.759 --> 00:08:54.679 ever created by human hands. They pass the planets, 00:08:54.899 --> 00:08:58.000 cross the Kuiper Belt, and entered interstellar 00:08:58.000 --> 00:09:02.200 space, moving beyond the Sun's heliosphere. That's 00:09:02.200 --> 00:09:06.480 the region dominated by the solar wind. Now nearly 00:09:06.480 --> 00:09:10.399 one light day away, they're deep within the broader 00:09:10.399 --> 00:09:14.539 domain of the Oort cloud. Out there in the darkness, 00:09:14.779 --> 00:09:17.480 the Voyagers are not just drifting silently, 00:09:17.559 --> 00:09:21.179 they're still working. Both spacecraft continue 00:09:21.179 --> 00:09:23.940 to send back data about the environment beyond 00:09:23.940 --> 00:09:27.820 the heliosphere. measuring cosmic rays, magnetic 00:09:27.820 --> 00:09:31.240 fields, and the faint plasma that exists between 00:09:31.240 --> 00:09:34.460 the stars. If the distance from the Earth to 00:09:34.460 --> 00:09:37.960 the Sun were reduced to a single inch, the outer 00:09:37.960 --> 00:09:41.240 edge of the Oort cloud would lie nearly a mile 00:09:41.240 --> 00:09:44.559 away. By that scale, the Voyagers have barely 00:09:44.559 --> 00:09:47.559 begun the journey. They've left the Sun's bubble, 00:09:47.720 --> 00:09:51.700 but not the Sun's backyard. Even out here, this 00:09:51.700 --> 00:09:55.350 story is not complete. Astronomers have found 00:09:55.350 --> 00:09:58.049 hints that something else may be lurking in the 00:09:58.049 --> 00:10:02.870 outer solar system. Planet 9 is a proposed world, 00:10:03.409 --> 00:10:06.029 inferred from the unusual clustering of orbits 00:10:06.029 --> 00:10:09.850 among distant Kuiper belt objects. If it exists, 00:10:10.049 --> 00:10:12.549 it could be several times the mass of Earth, 00:10:13.129 --> 00:10:15.950 orbiting hundreds of astronomical units from 00:10:15.950 --> 00:10:19.669 the Sun, taking tens of thousands of years to 00:10:19.669 --> 00:10:23.269 complete a single orbit. It's never been seen. 00:10:23.419 --> 00:10:26.580 Its existence is only written in the motions 00:10:26.580 --> 00:10:29.740 of other objects. But the search for this hidden 00:10:29.740 --> 00:10:33.279 world is happening right now. Astronomers are 00:10:33.279 --> 00:10:36.419 actively looking. New observatories like the 00:10:36.419 --> 00:10:40.000 Vera C. Rubin Observatory in Chile are beginning 00:10:40.000 --> 00:10:42.919 to scan the sky with unprecedented depth and 00:10:42.919 --> 00:10:46.059 precision, searching for faint objects that drift 00:10:46.059 --> 00:10:49.860 slowly against the stars. At the same time, scientists 00:10:49.860 --> 00:10:52.850 are combing through infrared data looking for 00:10:52.850 --> 00:10:55.710 the faint heat signature of a distant unseen 00:10:55.710 --> 00:11:00.009 planet. Others are refining the mathematics itself, 00:11:00.470 --> 00:11:03.029 tracking distant Kuiper belt objects and asking 00:11:03.029 --> 00:11:06.190 whether their strange orbits truly point to something 00:11:06.190 --> 00:11:09.690 massive, or whether we're being misled by the 00:11:09.690 --> 00:11:13.610 limits of our observations. And then there are 00:11:13.610 --> 00:11:18.000 the visitors, one of them two -eye Borisov made 00:11:18.000 --> 00:11:21.419 waves in the news last year as the first confirmed 00:11:21.419 --> 00:11:25.679 interstellar comet. Borisov and another visitor, 00:11:26.259 --> 00:11:30.980 One Eye Umauamaua, discovered in 2017, are objects 00:11:30.980 --> 00:11:34.279 that do not belong to our solar system at all. 00:11:34.799 --> 00:11:37.879 They arrived from elsewhere, passing briefly 00:11:37.879 --> 00:11:40.580 through our neighborhood before continuing their 00:11:40.580 --> 00:11:43.240 journey through the galaxy. They don't orbit 00:11:43.240 --> 00:11:46.580 the sun, they arrive, pass through, and then 00:11:46.580 --> 00:11:50.220 they vanish. If we can detect fragments from 00:11:50.220 --> 00:11:53.179 other star systems drifting through ours, then 00:11:53.179 --> 00:11:55.980 somewhere out there, other systems may be doing 00:11:55.980 --> 00:11:59.200 the same. Watching a chunk of our solar system 00:11:59.200 --> 00:12:02.899 drift through their domain. At some point out 00:12:02.899 --> 00:12:05.200 there, it becomes difficult to say where the 00:12:05.200 --> 00:12:08.360 solar system ends and where interstellar space 00:12:08.360 --> 00:12:12.490 truly begins. The boundary isn't a sharp line, 00:12:12.570 --> 00:12:16.250 but a gradual fading, a transition from the sun's 00:12:16.250 --> 00:12:18.909 influence to the wider gravitational currents 00:12:18.909 --> 00:12:22.649 of the Milky Way. So as we close out this journey, 00:12:22.909 --> 00:12:25.230 it's worth remembering that the solar system 00:12:25.230 --> 00:12:29.090 is not a fixed map of planets. It's a vast and 00:12:29.090 --> 00:12:32.769 evolving structure, shaped by gravity, time, 00:12:33.110 --> 00:12:36.450 and chance. For centuries we believed the planets 00:12:36.450 --> 00:12:39.320 were the whole story. Then we discovered the 00:12:39.320 --> 00:12:43.080 Kuiper Belt. Then we inferred the Oort Cloud. 00:12:43.620 --> 00:12:47.159 And now we continue searching for worlds we cannot 00:12:47.159 --> 00:13:06.480 yet see. After a quick break, we'll be back to 00:13:06.480 --> 00:13:22.659 cover this week's night sky. Stay with us. Welcome 00:13:22.659 --> 00:13:25.840 back. We're entering this week under a bright 00:13:25.840 --> 00:13:29.559 and increasingly dominant moon. After reaching 00:13:29.559 --> 00:13:32.879 first quarter back on March 25th, The moon is 00:13:32.879 --> 00:13:36.080 now waxing toward fullness, culminating in a 00:13:36.080 --> 00:13:39.659 full moon on April the 1st. This week's full 00:13:39.659 --> 00:13:43.139 moon is known as the pink moon, not for its color, 00:13:43.379 --> 00:13:46.519 but for the flowers that bloom beneath it, marking 00:13:46.519 --> 00:13:49.940 the quiet return of spring. It's also known as 00:13:49.940 --> 00:13:53.379 the egg moon, as it's linked to fertility and 00:13:53.379 --> 00:13:56.340 renewal. Early in the week, you'll still have 00:13:56.340 --> 00:13:59.940 some decent dark sky windows after sunset, but 00:13:59.940 --> 00:14:03.039 as we move closer to midweek, Moonlight will 00:14:03.039 --> 00:14:06.259 begin to wash out fainter objects, so if you're 00:14:06.259 --> 00:14:08.860 planning any deep sky observing, earlier in the 00:14:08.860 --> 00:14:12.879 week is your best bet. Tonight, March 29th, the 00:14:12.879 --> 00:14:16.700 moon passes extremely close to Regulus, the heart 00:14:16.700 --> 00:14:19.940 of the constellation Leo. In some parts of the 00:14:19.940 --> 00:14:23.039 world, like Europe, observers will even see an 00:14:23.039 --> 00:14:26.120 occultation where the moon passes directly in 00:14:26.120 --> 00:14:28.860 front of the star, causing it to disappear and 00:14:28.860 --> 00:14:32.220 reappear abruptly. Here in North America, we 00:14:32.220 --> 00:14:35.139 won't witness the occultation itself, but it's 00:14:35.139 --> 00:14:37.639 still a nice pairing that's easy to spot shortly 00:14:37.639 --> 00:14:41.399 after sunset in the western sky. A bright moon 00:14:41.399 --> 00:14:44.299 sitting right next to one of the spring sky's 00:14:44.299 --> 00:14:48.500 most recognizable stars. Planet -wise, we've 00:14:48.500 --> 00:14:51.440 got a few good targets this week. Jupiter is 00:14:51.440 --> 00:14:54.720 still the star of the show. It's bright, unmistakable, 00:14:54.960 --> 00:14:58.289 and well placed in the evening sky. sitting high 00:14:58.289 --> 00:15:02.210 after sunset and lingering for hours. Venus is 00:15:02.210 --> 00:15:05.190 visible low in the western sky just after sunset. 00:15:05.710 --> 00:15:08.169 It's brilliant, but it doesn't stick around long, 00:15:08.350 --> 00:15:11.330 so you'll want a clear horizon and good timing. 00:15:12.129 --> 00:15:14.950 Uranus is still technically visible in Taurus, 00:15:15.029 --> 00:15:17.649 though you'll need binoculars or a small telescope 00:15:17.649 --> 00:15:21.350 to pick it out. Mercury and Mars are mostly lost 00:15:21.350 --> 00:15:24.149 in the Sun's glare this week, making them difficult 00:15:24.149 --> 00:15:27.549 to observe. With the full moon this week, a lot 00:15:27.549 --> 00:15:30.529 of deep sky objects may be off the table. So 00:15:30.529 --> 00:15:32.929 let's look at some that punch through the bright 00:15:32.929 --> 00:15:37.029 moonlight. Globular clusters are fantastic in 00:15:37.029 --> 00:15:39.909 moonlight because they're dense and bright. Seek 00:15:39.909 --> 00:15:43.990 out Messier 3 and Canes Venetici. It's one of 00:15:43.990 --> 00:15:46.710 the brightest globulars in the northern sky and 00:15:46.710 --> 00:15:49.990 resolves into stars in small scopes. It will 00:15:49.990 --> 00:15:52.690 be high enough for comfortable observation this 00:15:52.690 --> 00:15:57.139 week. Messier 35 is a bright open cluster near 00:15:57.139 --> 00:16:00.519 the foot of Gemini. It looks good in binoculars 00:16:00.519 --> 00:16:04.759 and it's visible in the early evening. Open clusters 00:16:04.759 --> 00:16:08.240 like the beehive cluster in Cancer remain beautiful 00:16:08.240 --> 00:16:11.759 even under a bright sky, appearing as a soft 00:16:11.759 --> 00:16:15.519 scattering of stars in binoculars. And if you 00:16:15.519 --> 00:16:18.539 look west early in the evening, the Orion Nebula 00:16:18.539 --> 00:16:21.779 is still visible, glowing faintly in the Sword 00:16:21.779 --> 00:16:25.309 of Orion. Even with the moon nearby, it remains 00:16:25.309 --> 00:16:28.350 one of the most rewarding objects you can observe. 00:16:35.289 --> 00:16:38.690 We're in the home stretch in our book club selection. 00:16:38.970 --> 00:16:41.870 Next week we're going to wrap up the final chapters 00:16:41.870 --> 00:16:45.509 in Nightwatch. And looking deeper into April, 00:16:45.629 --> 00:16:48.309 we're going to get a little meta and turn away 00:16:48.309 --> 00:16:51.190 from the objects in the sky to the processes 00:16:51.190 --> 00:16:54.529 and tools scientists actually use to study them. 00:16:55.110 --> 00:16:57.809 We're going to talk about observatories, the 00:16:57.809 --> 00:17:01.210 scientific method, how data is collected, used, 00:17:01.610 --> 00:17:05.170 and analyzed, and in general, peel back the curtain 00:17:05.170 --> 00:17:13.650 on the machinery behind the study of space. That's 00:17:13.650 --> 00:17:15.910 going to do it for this week. If you found this 00:17:15.910 --> 00:17:18.329 episode interesting, please share it with a friend 00:17:18.329 --> 00:17:21.210 who might enjoy it. The easiest way to do that 00:17:21.210 --> 00:17:24.549 is by sending folks to our website StarTrails 00:17:24.549 --> 00:17:27.809 .Show. And if you'd like to support the show, 00:17:27.930 --> 00:17:30.250 use the link on the site to buy me a coffee. 00:17:30.630 --> 00:17:33.950 That really helps. Be sure to follow Star Trails 00:17:33.950 --> 00:17:37.130 on Blue Sky and YouTube. Links are in the show 00:17:37.130 --> 00:17:40.130 notes. Until we meet again beneath the stars, 00:17:40.710 --> 00:17:41.829 clear skies everyone!