WEBVTT - What If Earth Had Rings? 0:00:01.890 --> 0:00:07.930 Welcome to BrainStuff, a production of iHeartRadio. Hey BrainStuff, Lauren 0:00:07.950 --> 0:00:13.030 Vogelbaum here. Earth's moon feels like an ever-present feature in 0:00:13.090 --> 0:00:15.960 our skies, even if it's really only visible from any 0:00:16.020 --> 0:00:19.920 given point on Earth about half the time. But what 0:00:20.040 --> 0:00:22.960 if you looked skyward and saw not a moon, but 0:00:23.000 --> 0:00:26.200 a ring, much like the ones that encircle our solar 0:00:26.239 --> 0:00:30.870 system's gas giants? Saturn in particular is known for its 0:00:30.990 --> 0:00:35.670 brilliant ring system, the most extensive we know of. But Jupiter, Uranus, 0:00:35.729 --> 0:00:40.629 and Neptune have rings too. Today, let's talk about planetary rings, 0:00:40.900 --> 0:00:43.600 and what it would be like if Earth boasted its own. 0:00:45.620 --> 0:00:48.920 Scientists believe Earth did have a ring once, albeit a 0:00:48.960 --> 0:00:52.769 few billion years ago. This ring would have appeared early 0:00:52.830 --> 0:00:57.120 in the formation of Earth's moon. Our best hypothesis for 0:00:57.160 --> 0:01:00.810 how the moon formed is what's called the giant impact hypothesis. 0:01:01.790 --> 0:01:04.070 The idea is that about four and a half billion 0:01:04.110 --> 0:01:06.350 years ago, while the Earth itself was still forming, a 0:01:06.910 --> 0:01:10.850 large object or fellow proto-planet about the size of Mars 0:01:11.170 --> 0:01:15.370 hit Earth at an angle. The impact threw debris into 0:01:15.450 --> 0:01:20.020 space from Earth's crust and mantle. The impactor itself, which 0:01:20.060 --> 0:01:25.500 we've named Theia, melted and merged with Earth's interior. Meanwhile, 0:01:25.819 --> 0:01:28.640 some of the hot debris got caught in Earth's orbit 0:01:29.040 --> 0:01:33.860 and eventually cooled and coalesced to form the moon. The 0:01:33.920 --> 0:01:37.140 giant impact hypothesis would explain why moon rocks have a 0:01:37.180 --> 0:01:40.410 composition similar to Earth's mantle and why they seem to 0:01:40.450 --> 0:01:44.270 have been baked, and why the moon has no iron core, 0:01:44.590 --> 0:01:48.050 because the iron in Earth's core and Theia's core remained 0:01:48.210 --> 0:01:52.780 on Earth. But while the moon was coming together... all 0:01:52.800 --> 0:01:55.180 of that debris would have been hovering in a ring 0:01:55.260 --> 0:02:00.730 in Earth's orbit. Now, planetary rings are temporary structures. We 0:02:00.770 --> 0:02:03.030 talked about this a while ago on the show, when, 0:02:03.110 --> 0:02:07.950 back in 2018, researchers found that Saturn's glorious rings have 0:02:08.110 --> 0:02:11.590 only been around for about 100 million years, and that 0:02:11.610 --> 0:02:15.180 they'll be gone, having fallen into the gassy planet, and 0:02:15.180 --> 0:02:19.780 100 million more. So, no matter what, this early ring 0:02:19.820 --> 0:02:24.269 of Earth's wouldn't have lasted until today. But the reason 0:02:24.330 --> 0:02:26.850 that this debris became a moon and not a ring 0:02:27.340 --> 0:02:31.079 is that it existed outside of what's called the Roche limit. 0:02:32.440 --> 0:02:36.260 The Roche limit is named for the French mathematician Edouard Roche, who, 0:02:36.620 --> 0:02:41.049 in 1848, figured out that any given planet's gravitational pull 0:02:41.150 --> 0:02:44.330 on a moon will be unequal across the surface of 0:02:44.350 --> 0:02:49.070 that moon. That a planet exerts a greater gravitational force 0:02:49.210 --> 0:02:51.600 on the side of the moon closest to the planet. 0:02:51.930 --> 0:02:54.829 and a lesser gravitational force on the side facing away. 0:02:56.230 --> 0:02:58.990 This means that if a moon or other object that 0:02:59.130 --> 0:03:02.170 wanders into a planet's orbit is too close to the planet, 0:03:02.669 --> 0:03:07.840 the unequal pull of the planet's gravity could tear it apart. Essentially, 0:03:07.860 --> 0:03:11.140 the Roche limit is the minimum distance an object can 0:03:11.220 --> 0:03:14.200 be from a planet and still hold itself together by 0:03:14.260 --> 0:03:18.700 its own gravity. Inside the Roche Limit, any debris from 0:03:18.740 --> 0:03:22.380 a giant impact, or any object that the planet attracts 0:03:22.419 --> 0:03:26.589 with its gravitational pull, say smaller moons or asteroids, will 0:03:26.600 --> 0:03:31.990 get torn apart again and again, eventually ground down to water, ice, 0:03:32.050 --> 0:03:36.390 and dust particles, traveling along the planet's gravitational orbit like 0:03:36.790 --> 0:03:42.210 water running down a drain, very slowly. Researchers estimate that 0:03:42.230 --> 0:03:45.920 around Saturn, Ring material, to the amount of some 10 0:03:45.920 --> 0:03:50.720 tons or 9,000 kilos, is falling into the planet every second. 0:03:51.720 --> 0:03:54.520 Part of why our gas giants all have rings, but 0:03:54.640 --> 0:03:57.660 our rocky inner planets don't, is that the outer planets 0:03:57.800 --> 0:04:01.700 have masses large enough to attract ring material, and they 0:04:01.780 --> 0:04:04.400 orbit far away enough from the sun for water ice 0:04:04.560 --> 0:04:07.860 to stay frozen. Part of how we figured out that 0:04:07.900 --> 0:04:10.880 Saturn's rings are so young is that they're predominantly made 0:04:10.920 --> 0:04:13.890 of ice. If they were older, that ice would have 0:04:13.910 --> 0:04:18.310 gotten contaminated over time with interplanetary debris, making them dull. 0:04:18.830 --> 0:04:23.940 But they're still beautifully bright. Saturn has seven main rings, 0:04:24.180 --> 0:04:28.700 each composed of thousands of tiny ringlets. They're massively wide, 0:04:28.779 --> 0:04:31.080 extending up to 175,000 miles, or 280,000 kilometers, out into space. 0:04:31.140 --> 0:04:33.020 But they're proportionally very thin, only about 30 feet or 0:04:33.020 --> 0:04:42.450 10 meters thick. ranging up to a little over half 0:04:42.470 --> 0:04:46.150 a mile or a kilometer at the thickest. They're made 0:04:46.190 --> 0:04:49.270 up of chunks of water ice, rock, and other materials, 0:04:49.529 --> 0:04:54.130 varying in size from specks to enormous house-sized pieces that 0:04:54.420 --> 0:04:59.839 collide constantly, shattering the larger chunks. Scientists think the rings 0:04:59.940 --> 0:05:03.440 formed when comets or asteroids collided with one or more 0:05:03.480 --> 0:05:07.539 of the planet's moons. The fragments from the collisions spread 0:05:07.600 --> 0:05:12.150 out around Saturn within the Roche limit. Saturn's two innermost 0:05:12.230 --> 0:05:15.630 rings are very transparent. The next two out are the 0:05:15.730 --> 0:05:19.349 brightest and largest. The fifth ring is very narrow and 0:05:19.410 --> 0:05:23.060 held together by two moons, Pandora and Prometheus, that sit 0:05:23.150 --> 0:05:26.620 on either side of the ring. The final two are 0:05:26.660 --> 0:05:31.140 farther out, with the farthest made up of near-microscopic ice particles, 0:05:31.160 --> 0:05:34.800 thought to have been ejected from the moon Enceladus, sprayed 0:05:34.860 --> 0:05:39.430 out of volcanic geysers near its south pole. Saturn's rings 0:05:39.490 --> 0:05:41.880 are named after the first seven letters of the alphabet, 0:05:42.060 --> 0:05:44.880 in the order that they were discovered. So, from innermost 0:05:45.000 --> 0:05:49.890 to outermost, that's D, C, B, A, F, G, and E. 0:05:51.339 --> 0:05:54.349 The rings aren't perfect circles, but instead have bends in 0:05:54.390 --> 0:05:57.469 them caused by the pull of gravity from nearby moons. 0:05:58.470 --> 0:06:01.890 There's also a mysterious phenomenon among the rings, referred to 0:06:01.950 --> 0:06:06.080 as spokes. These are features that rotate along with the rings, 0:06:06.339 --> 0:06:09.700 but appear and disappear in ways that we haven't entirely 0:06:09.779 --> 0:06:13.380 been able to explain yet. They look like spokes on 0:06:13.420 --> 0:06:16.430 the wheels of the rings, and researchers think that they 0:06:16.470 --> 0:06:20.490 may be formed by seasonal interactions between solar wind and 0:06:20.529 --> 0:06:25.410 Saturn's magnetic field, creating some kind of static electricity that 0:06:25.490 --> 0:06:30.290 pulls fine dust particles into different shapes. Saturn's rings are 0:06:30.330 --> 0:06:34.049 bright enough that Galileo observed them way back in 1610, 0:06:34.050 --> 0:06:36.810 though he didn't know what he was looking at. Their 0:06:36.890 --> 0:06:39.969 extension from the sides of Saturn reminded him of ears, 0:06:40.250 --> 0:06:43.250 and he wrote about them being two smaller stars, or 0:06:43.410 --> 0:06:48.060 perhaps two large moons. It wasn't until 1655 that Dutch 0:06:48.120 --> 0:06:53.800 scientist Christian Huygens identified them as rings. The other gas giants' 0:06:53.860 --> 0:06:58.820 rings went undetected for over 300 years. Uranuses were the 0:06:58.880 --> 0:07:03.370 first to be discovered in 1977. They run parallel to 0:07:03.410 --> 0:07:06.210 its tilted equator, which is nearly at a right angle 0:07:06.250 --> 0:07:08.729 to its orbit, so the rings appear to go up 0:07:08.850 --> 0:07:12.870 and over the planet. It has two sets, nine inner 0:07:12.910 --> 0:07:16.140 rings that are narrow and gray, and then two outer rings, 0:07:16.460 --> 0:07:21.040 one reddish and one blue. Jupiter's rings weren't discovered until 0:07:21.080 --> 0:07:26.110 Voyager 1's initial flyby in 1979. They're very faint. and 0:07:26.130 --> 0:07:28.960 they're thought to have been created by meteoroid impacts on 0:07:29.060 --> 0:07:33.780 small nearby moons. They have four components, an inner halo 0:07:33.820 --> 0:07:38.060 of dust, a bright, thin main ring, and then two wide, 0:07:38.220 --> 0:07:43.400 dim outer rings called the gossamer rings. Neptune's rings weren't 0:07:43.480 --> 0:07:48.210 definitively detected until 1989, when Voyager 2 captured images of 0:07:48.250 --> 0:07:51.950 them on its flyby. It has five main rings and 0:07:52.050 --> 0:07:55.650 four prominent ring arcs, which are smaller rings that are 0:07:55.710 --> 0:08:00.710 formed by faint, thin collections of micrometer-sized dust that's shepherded 0:08:00.830 --> 0:08:05.440 around the ring system by Neptune's four small moons. But 0:08:06.070 --> 0:08:09.780 back to Earth. It's unlikely that our planet will form 0:08:09.800 --> 0:08:13.420 its own ring system anytime soon. In order to break 0:08:13.480 --> 0:08:16.800 apart properly, an asteroid or a bunch of space rubble 0:08:17.190 --> 0:08:20.730 would need to enter our orbit at around 9,000 kilometers, 0:08:21.170 --> 0:08:26.160 which is in low-to-mid-medium Earth orbit. But what would it 0:08:26.180 --> 0:08:29.940 be like if Earth did have rings? Okay, any rings 0:08:30.040 --> 0:08:33.260 would most likely form parallel to the equator, and thus 0:08:33.280 --> 0:08:37.040 would arc across the sky from east to west. And 0:08:37.160 --> 0:08:39.720 your view of them would depend on your latitude away 0:08:39.760 --> 0:08:43.390 from the equator. Near the equator, the rings would be 0:08:43.450 --> 0:08:46.980 like thin slices of light erupting from the distant horizons 0:08:47.050 --> 0:08:49.320 and stretching up into the sky as far as the 0:08:49.380 --> 0:08:52.660 eye could see. The farther north or south you were, 0:08:53.020 --> 0:08:56.040 the more the appearance of the rings would change. They'd 0:08:56.059 --> 0:08:59.339 become markedly wider and more visible, and would, from some 0:08:59.380 --> 0:09:02.620 vantage points, appear close enough to the horizon to reach 0:09:02.679 --> 0:09:06.900 out and touch. Just as the moon currently does, the 0:09:06.940 --> 0:09:10.240 rings would reflect sunlight back to Earth and appear to glow, 0:09:10.559 --> 0:09:14.130 especially at night. Depending on exactly what they were made of, 0:09:14.150 --> 0:09:17.450 the rings could reflect so much sunlight that the planet 0:09:17.510 --> 0:09:20.709 would never fully plunge into darkness, but remain in a 0:09:20.750 --> 0:09:24.750 gentle twilight, even in the depth of night. Even daylight 0:09:24.790 --> 0:09:28.670 might be brighter because of them. Rings around Earth would 0:09:28.710 --> 0:09:33.850 have significant climatic implications. These vast sheets of debris could 0:09:34.010 --> 0:09:37.449 act as a shield in some regions, potentially preventing some 0:09:37.490 --> 0:09:40.819 of the sun's rays from reaching Earth's surface. This could 0:09:40.860 --> 0:09:44.429 lead to cooler temperatures in some areas, especially those beneath 0:09:44.490 --> 0:09:49.210 the densest parts of the ring. Conversely, the reflected sunlight 0:09:49.230 --> 0:09:52.069 from the rings could cause a warming effect in other regions. 0:09:52.890 --> 0:09:55.700 Climate models would need to account for these new variables, 0:09:56.020 --> 0:09:59.140 making our understanding of global weather patterns even more complex. 0:10:00.630 --> 0:10:04.940 Planetary rings would also pose challenges to our current satellite infrastructure. 0:10:05.780 --> 0:10:08.660 After all, we have stuff in our medium Earth orbit. 0:10:09.780 --> 0:10:11.820 Just a bit farther out than a ring would sit, 0:10:12.220 --> 0:10:16.020 we've placed a lot of telecommunications and GPS equipment, and 0:10:16.240 --> 0:10:20.260 above that, a lot of weather platforms. rings could interfere 0:10:20.300 --> 0:10:24.120 with the trajectories of nearby platforms or with communication from 0:10:24.160 --> 0:10:28.120 the ground to anything orbiting above them. The presence of 0:10:28.160 --> 0:10:31.530 a dense ring could also present navigational hazards for space 0:10:31.570 --> 0:10:36.450 missions leaving or entering Earth's atmosphere. If material from the 0:10:36.510 --> 0:10:39.090 rings should rain down onto the planet the way that 0:10:39.190 --> 0:10:42.250 Saturn's ring material does, it could also pose a hazard 0:10:42.290 --> 0:10:45.290 to the equipment in low Earth orbit, like the International 0:10:45.350 --> 0:10:50.319 Space Station. Space agencies and other satellite constructors would need 0:10:50.360 --> 0:10:55.160 to recalibrate and perhaps even redesign spacecraft to safely navigate 0:10:55.300 --> 0:10:59.340 in or through such an environment. On the flip side, 0:10:59.820 --> 0:11:05.090 falling ring material might create some spectacular meteor showers. And 0:11:05.450 --> 0:11:07.250 just think of all the new sayings we'd have to 0:11:07.290 --> 0:11:10.270 come up with. Perhaps we'd no longer shoot for the moon, 0:11:10.670 --> 0:11:15.500 but aim for the rings instead. It's not completely out 0:11:15.520 --> 0:11:19.290 of the realm of possibility. We're still learning about planetary rings. 0:11:20.610 --> 0:11:24.069 Just in 2023, an international team of astronomers published a 0:11:24.090 --> 0:11:26.929 study in the journal Nature about a new ring system 0:11:26.970 --> 0:11:29.650 they discovered in the far reaches of our solar system. 0:11:30.550 --> 0:11:34.070 The rings are around Quawar, a dwarf planet that's about 0:11:34.110 --> 0:11:38.120 as wide as Texas and orbits beyond Neptune. The rings 0:11:38.160 --> 0:11:40.960 are too faint to see directly from Earth, the team 0:11:40.980 --> 0:11:44.920 discovered them by observing an oculation, meaning that they watched 0:11:44.940 --> 0:11:48.100 the light from a background star, as Quawar blocked it 0:11:48.200 --> 0:11:51.310 by passing between us and the star during its orbit. 0:11:52.610 --> 0:11:55.830 What makes this ring system especially interesting is that it's 0:11:55.950 --> 0:11:58.250 twice as far out from the surface of the dwarf 0:11:58.309 --> 0:12:02.130 planet as scientists previously thought was possible according to the 0:12:02.170 --> 0:12:06.580 Roche limit. So who knows? Maybe rings are in Earth's 0:12:06.640 --> 0:12:14.260 future after all. Today's episode is based on the articles 0:12:14.440 --> 0:12:17.200 Does Earth Have Rings? by Laurie L. Dove and The 0:12:17.220 --> 0:12:20.250 Four Planets with Rings Might Surprise You by Mitch Ryan, 0:12:20.490 --> 0:12:24.670 both on HowStuffWorks.com. BrainStuff is a production of iHeartRadio in 0:12:24.710 --> 0:12:28.709 partnership with HowStuffWorks.com and is produced by Tyler Klang. For 0:12:28.730 --> 0:12:32.679 more shows from iHeart Podcasts, visit the iHeartRadio app, Apple Podcasts, 0:12:32.840 --> 0:12:34.700 or wherever you listen to your favorite shows.