1 00:00:00,000 --> 00:00:11,200 Howdy Star Gazers and welcome to this episode of Star Trails. 2 00:00:11,200 --> 00:00:17,080 I'm Drew and I'll be your guide to the night sky for the week starting October 13th to 3 00:00:17,080 --> 00:00:18,760 19th. 4 00:00:18,760 --> 00:00:23,480 This week brings a full moon and the possibility of a shimmering comet. 5 00:00:23,480 --> 00:00:29,200 We'll take a look at a minor constellation with a lonely star, and later in the episode 6 00:00:29,200 --> 00:00:35,960 we'll explore the orbital patterns that shape our planetary system, the gravitational interactions 7 00:00:35,960 --> 00:00:40,520 that create predictable patterns known as resonances. 8 00:00:40,520 --> 00:00:47,120 So grab a comfortable spot under the night sky and let's get started. 9 00:00:47,120 --> 00:00:51,840 First off, I hope many of you were able to catch the northern lights in some of the lower 10 00:00:51,840 --> 00:00:54,160 48 states this week. 11 00:00:54,160 --> 00:01:00,400 Following a massive geomagnetic storm in the wake of a coronal mass ejection, the skies 12 00:01:00,400 --> 00:01:05,720 lit up with aurora as far south as Mexico on October 11th. 13 00:01:05,720 --> 00:01:12,320 I know folks around my area saw and managed to photograph the aurora, but I wasn't so 14 00:01:12,320 --> 00:01:13,560 lucky. 15 00:01:13,560 --> 00:01:18,800 I thought I could spot some high altitude red or pink bands earlier in the evening from 16 00:01:18,800 --> 00:01:25,400 a photo taken in my backyard, so I ventured out into the countryside around 9pm and found 17 00:01:25,400 --> 00:01:28,360 a vast north-facing field. 18 00:01:28,360 --> 00:01:35,360 In the near total darkness, I saw absolutely nothing, so I suspect whatever folks saw in 19 00:01:35,360 --> 00:01:38,800 my area dissipated quickly. 20 00:01:38,800 --> 00:01:43,880 Since May, many states in lower latitudes have been fortunate to see the northern lights 21 00:01:43,880 --> 00:01:50,160 thanks to a very active solar cycle. While a solar storm can kill radio communications 22 00:01:50,160 --> 00:01:56,280 on some bands, overall, this solar cycle has been a boon for ham radio operators for the 23 00:01:56,280 --> 00:01:58,120 past year or more. 24 00:01:58,120 --> 00:02:04,440 A few years ago, solar activity, which plays a role in the propagation of radio waves, 25 00:02:04,440 --> 00:02:10,880 was at an all-time minimum, so operations in certain bands, like 10 meters, were very 26 00:02:10,880 --> 00:02:12,200 hit or miss. 27 00:02:12,200 --> 00:02:18,320 Anyway, space weather and amateur radio are topics for a future show, so let's get on 28 00:02:18,320 --> 00:02:28,520 with this week's exploration of the night sky. 29 00:02:28,520 --> 00:02:34,480 October 17th marks the full hunter's moon, which will also be the biggest and brightest 30 00:02:34,480 --> 00:02:37,480 supermoon of 2024. 31 00:02:37,480 --> 00:02:42,880 This supermoon will appear larger than usual due to the moon being at its closest point 32 00:02:42,880 --> 00:02:48,400 to Earth. You can start observing it on the evening of October 16th, and it will shine 33 00:02:48,400 --> 00:02:51,280 in the constellation Pisces. 34 00:02:51,280 --> 00:02:57,440 The hunter's moon has a rich lore rooted in the rhythms of rural life. The name originated 35 00:02:57,440 --> 00:03:01,360 from Native American and European traditions. 36 00:03:01,360 --> 00:03:05,840 After farmers brought in their crops under the bright harvest moon, which is the full 37 00:03:05,840 --> 00:03:11,920 moon nearest the autumnal equinox, the hunter's moon provided additional light for hunting 38 00:03:11,920 --> 00:03:15,280 game, which was then stored for winter. 39 00:03:15,280 --> 00:03:20,440 The bright moonlight allowed hunters to track animals at night, especially deer and other 40 00:03:20,440 --> 00:03:21,760 creatures. 41 00:03:21,760 --> 00:03:27,160 The hunter's moon is known for rising just after sunset, with the moonlight lasting throughout 42 00:03:27,160 --> 00:03:32,600 the night. This is because of the moon's shallow angle relative to the horizon during 43 00:03:32,600 --> 00:03:38,160 this time of year, which causes it to rise sooner than at other times. 44 00:03:38,160 --> 00:03:43,840 This creates an effect where the moonlight appears brighter and lasts longer in the sky, 45 00:03:43,840 --> 00:03:47,120 adding to its importance in ancient times. 46 00:03:47,120 --> 00:03:51,920 In modern times, the hunter's moon is also celebrated for its beauty, often appearing 47 00:03:51,920 --> 00:03:57,880 larger and more orange as it rises due to the atmospheric conditions when it's closer 48 00:03:57,880 --> 00:04:05,760 to the horizon. 49 00:04:05,760 --> 00:04:10,800 Elsewhere in the solar system, Saturn will be visible in the southeastern sky just after 50 00:04:10,800 --> 00:04:17,240 sunset and remain up for most of the night. On October 14th, it will be near the waxing 51 00:04:17,240 --> 00:04:20,960 gibbous moon, creating a striking conjunction. 52 00:04:20,960 --> 00:04:27,040 Jupiter will rise after 10pm, and in the early morning of October 19th, it will appear near 53 00:04:27,040 --> 00:04:32,440 the nearly full moon in the constellation Taurus. Look for Jupiter's bright presence 54 00:04:32,440 --> 00:04:36,320 in the eastern sky, especially after midnight. 55 00:04:36,320 --> 00:04:42,480 Mars rises near midnight. Its reddish hue will be noticeable in the pre-dawn hours as it 56 00:04:42,480 --> 00:04:49,280 climbs higher in the sky. Venus will be visible low in the west just after sunset. Although 57 00:04:49,280 --> 00:04:55,960 it sets soon after, you can catch it shining brightly early in the evening right now. 58 00:04:55,960 --> 00:05:05,080 And I've saved the best for last. From October 14th until the end of the month, Comet C2023A3 59 00:05:05,080 --> 00:05:10,560 should make a stunning appearance low on the western horizon after sunset. 60 00:05:10,560 --> 00:05:16,960 The best viewing window for this comet is from October 14th to the 24th, and is predicted 61 00:05:16,960 --> 00:05:23,200 to have a magnitude around zero. That means it's about the same brightness as Mars and 62 00:05:23,200 --> 00:05:29,600 will be easily visible to the naked eye. This comet has a long, curved tail, and images 63 00:05:29,600 --> 00:05:34,800 already captured of it have been stunning. Hopefully, you'll get a chance to see this 64 00:05:34,800 --> 00:05:41,560 icy visitor. The last time it visited Earth may have been around 80,000 years ago, in 65 00:05:41,560 --> 00:05:49,880 the era of the Neanderthals. 66 00:05:49,880 --> 00:05:54,680 For those of you looking to spot something a little off the beaten path this October, 67 00:05:54,680 --> 00:06:01,160 take a look at Pisces Austrinus, the southern fish. It's a lesser known but still interesting 68 00:06:01,160 --> 00:06:07,880 constellation that rises in the southern sky during the fall. While it may not be as famous 69 00:06:07,880 --> 00:06:13,760 as some of its neighboring constellations, such as Aquarius, Pisces Austrinus holds a 70 00:06:13,760 --> 00:06:19,400 special place in the sky. In fact, it's home to one of the brightest stars you can see 71 00:06:19,400 --> 00:06:28,280 this time of year, Fomalot. Fomalot shines at magnitude 1.16, making it one of the brightest 72 00:06:28,280 --> 00:06:34,520 stars in the night sky, and the brightest star in its immediate region. It's often 73 00:06:34,520 --> 00:06:41,480 called the Lonely Star, because it stands alone in a relatively empty patch of sky, away 74 00:06:41,480 --> 00:06:47,360 from other bright stars. You'll notice its clear, solitary presence in the southern 75 00:06:47,360 --> 00:06:56,440 sky, especially on dark autumn nights. Fomalot also has some modern significance. Astronomers 76 00:06:56,440 --> 00:07:04,400 have discovered an exoplanet orbiting this star, known as Fomalot B, or Dagon. This makes 77 00:07:04,400 --> 00:07:10,240 Pisces Austrinus an exciting target for those interested in the ongoing search for planets 78 00:07:10,240 --> 00:07:16,840 beyond our solar system. In ancient Greek stories, Pisces Austrinus represents the great 79 00:07:16,840 --> 00:07:23,160 fish that swallowed water from the floods sent by Zeus. Some myths also associate it 80 00:07:23,160 --> 00:07:28,840 with the fish that saved Aphrodite and her son Eros when they were transformed to escape 81 00:07:28,840 --> 00:07:36,280 the monstrous Typhon. This tale is also tied to the neighboring constellation Pisces, representing 82 00:07:36,280 --> 00:07:47,600 two fish swimming together. Today, we're going to explore one of the 83 00:07:47,600 --> 00:07:54,840 more fascinating aspects of orbital dynamics in our solar system, resonances. These are 84 00:07:54,840 --> 00:08:00,360 relationships between orbiting bodies where their gravitational interactions cause them 85 00:08:00,360 --> 00:08:07,000 to establish predictable, repeating patterns. In simple terms, a resonance occurs when two 86 00:08:07,000 --> 00:08:14,240 or more orbiting objects exert a regular periodic gravitational influence on each other, usually 87 00:08:14,240 --> 00:08:21,320 because their orbital periods are a similar ratio. For example, if one planet takes exactly 88 00:08:21,320 --> 00:08:28,480 twice as long to orbit the sun as another, we call that a 2 to 1 resonance. Resonances 89 00:08:28,480 --> 00:08:34,840 can occur between planets, moons, or even small objects like asteroids, and these orbital 90 00:08:34,840 --> 00:08:41,640 relationships play a key role in the stability of our solar system. Our understanding of 91 00:08:41,640 --> 00:08:47,880 orbital resonances goes back centuries to the early days of celestial mechanics. One 92 00:08:47,880 --> 00:08:53,160 of the key figures in this field was the French mathematician and physicist Pierre Simon 93 00:08:53,160 --> 00:09:00,080 Laplace. In the late 18th century, Laplace developed a mathematical framework for understanding 94 00:09:00,080 --> 00:09:06,740 how gravitational forces shape the motion of celestial bodies. His work extended and 95 00:09:06,740 --> 00:09:12,800 built upon the laws of motion first formulated by Isaac Newton, and he laid the foundation 96 00:09:12,800 --> 00:09:19,960 for modern orbital mechanics. Laplace was the first to describe the Laplace resonance, 97 00:09:19,960 --> 00:09:26,800 a three-body orbital resonance that we observe today among the moons of Jupiter, Io, Europa, 98 00:09:26,800 --> 00:09:34,520 and Ganymede. These moons follow a 1 to 2 to 4 resonance, meaning for every four orbits 99 00:09:34,520 --> 00:09:42,080 Io makes around Jupiter, Europa makes 2, and Ganymede makes 1. This resonance affects 100 00:09:42,080 --> 00:09:48,880 the physical conditions of these moons, particularly Io. The constant gravitational tug from the 101 00:09:48,880 --> 00:09:55,200 other moons causes significant tidal forces, which heat Io's interior, leading to the 102 00:09:55,200 --> 00:10:02,440 extreme volcanic activity we observe there. In the centuries following Laplace, astronomers 103 00:10:02,440 --> 00:10:09,120 began to realize that these resonant patterns weren't just an abstract mathematical curiosity, 104 00:10:09,120 --> 00:10:15,560 they were a key to unlocking new discoveries. For instance, the discovery of Neptune was 105 00:10:15,560 --> 00:10:21,240 the result of the study of resonances. In the early 19th century, astronomers noticed 106 00:10:21,240 --> 00:10:27,960 that Uranus wasn't moving as expected. Its orbit showed small deviations, suggesting 107 00:10:27,960 --> 00:10:34,080 that another planet was influencing it through gravitational interactions, likely a resonance 108 00:10:34,080 --> 00:10:38,800 effect. Using these discrepancies, French mathematician 109 00:10:38,800 --> 00:10:45,880 Urbain Le Verrier and British astronomer John Couch Adams independently calculated the position 110 00:10:45,880 --> 00:10:52,840 of this unseen planet. In 1846, astronomers pointed their telescopes to the predicted 111 00:10:52,840 --> 00:10:59,280 coordinates and Neptune was found, exactly where the calculations had indicated. This 112 00:10:59,280 --> 00:11:05,400 marked the first time a planet was discovered through mathematical prediction, an extraordinary 113 00:11:05,400 --> 00:11:10,160 triumph for celestial mechanics and gravitational theory. 114 00:11:10,160 --> 00:11:16,080 And speaking of Neptune, let's explore the resonance between it and Pluto. Despite the 115 00:11:16,080 --> 00:11:22,040 fact that Pluto's orbit crosses inside Neptune's, the two will never collide because they're 116 00:11:22,040 --> 00:11:29,000 locked in a 3-2 resonance. This means that for every 3 orbits Neptune completes around 117 00:11:29,000 --> 00:11:35,200 the Sun, Pluto completes 2. This resonance ensures that they're never at the same point 118 00:11:35,200 --> 00:11:42,760 in their orbits at the same time, which stabilizes their otherwise intersecting paths. 119 00:11:42,760 --> 00:11:48,400 Saturn's moons and rings provide several examples of resonance-driven dynamics. One 120 00:11:48,400 --> 00:11:55,880 prominent case involves the moons Mimas and Tethys, which are in a 2-1 resonance. Each 121 00:11:55,880 --> 00:12:02,760 time Tethys completes one orbit around Saturn, Mimas completes two. This interaction has 122 00:12:02,760 --> 00:12:09,000 played a role in shaping Saturn's rings, particularly the Cassini division, a gap in 123 00:12:09,000 --> 00:12:15,160 the rings. Mimas exerts gravitational forces on the particles and the rings, preventing 124 00:12:15,160 --> 00:12:18,200 material from accumulating in this region. 125 00:12:18,200 --> 00:12:25,360 There's also a fascinating resonance between the Earth and the Moon. This is a 1-1 spin 126 00:12:25,360 --> 00:12:31,880 orbit resonance, more commonly referred to as synchronous rotation. It means that the 127 00:12:31,880 --> 00:12:37,400 Moon rotates on its axis in the same amount of time it takes to orbit the Earth, about 128 00:12:37,400 --> 00:12:45,760 27.3 days. As a result, the same side of the Moon is always facing Earth. That's why we 129 00:12:45,760 --> 00:12:50,440 never see the far side of the Moon from our vantage point. 130 00:12:50,440 --> 00:12:56,240 This synchronous rotation is the result of tidal forces between the Earth and the Moon. 131 00:12:56,240 --> 00:13:02,680 In the early history of our planet, the Moon rotated faster. Over millions of years, Earth's 132 00:13:02,680 --> 00:13:08,520 gravitational pull created tidal friction on the Moon, gradually slowing its rotation 133 00:13:08,520 --> 00:13:14,600 until it became locked in this resonance. Now, the Moon's spin is perfectly matched 134 00:13:14,600 --> 00:13:20,040 to its orbital period, and it's been that way for a very long time. 135 00:13:20,040 --> 00:13:26,880 There is a reciprocal effect to this interaction. The Moon, of course, exerts tidal forces here 136 00:13:26,880 --> 00:13:32,800 on Earth, which is why we experience tides in the oceans. Over time, these forces are 137 00:13:32,800 --> 00:13:40,840 also slowing Earth's rotation. Every century, Earth's day gets a tiny bit longer, about 138 00:13:40,840 --> 00:13:48,960 1.7 milliseconds per century. As Earth's rotation slows, the Moon is gradually moving farther 139 00:13:48,960 --> 00:13:56,720 away from us, by about 3.8 centimeters per year. This means the resonance between Earth 140 00:13:56,720 --> 00:14:01,480 and the Moon will continue to evolve over millions of years. 141 00:14:01,480 --> 00:14:07,600 You may recall in our last episode, I mentioned that Earth recently captured a new Moon, a 142 00:14:07,600 --> 00:14:14,760 small asteroid about the size of a school bus. This isn't the first time this has happened. 143 00:14:14,760 --> 00:14:24,160 Here Earth asteroid 3753 Crueenye has in the past been called Earth's second Moon. Crueenye 144 00:14:24,160 --> 00:14:29,600 isn't a true Moon but shares a one-to-one resonance with Earth. Instead of orbiting 145 00:14:29,600 --> 00:14:36,080 Earth directly, Crueenye follows a unique, horseshoe-shaped path around the Sun that 146 00:14:36,080 --> 00:14:41,960 keeps it in sync with Earth. This resonance prevents Crueenye from ever coming too close 147 00:14:41,960 --> 00:14:48,200 to Earth while keeping it in a gravitational dance with our planet. 148 00:14:48,200 --> 00:14:52,440 Resonances are not limited to just these major moons and planets. There are several 149 00:14:52,440 --> 00:14:56,640 other interesting examples throughout our solar system. 150 00:14:56,640 --> 00:15:02,560 Jupiter plays a key role in shaping the asteroid belt through a series of resonances. These 151 00:15:02,560 --> 00:15:08,840 are called Kirkwood gaps, named after astronomer Daniel Kirkwood, who discovered them in the 152 00:15:08,840 --> 00:15:15,160 19th century. The Kirkwood gaps are regions in the asteroid belt where there are fewer 153 00:15:15,160 --> 00:15:20,960 asteroids because their orbital periods would have been in resonance with Jupiter, causing 154 00:15:20,960 --> 00:15:26,960 gravitational disturbances that ejected the asteroids from these orbits. For instance, 155 00:15:26,960 --> 00:15:32,560 there's a three-to-one resonance gap where an asteroid would orbit the Sun three times 156 00:15:32,560 --> 00:15:39,240 for every one orbit of Jupiter. Over time, these resonances either push asteroids into 157 00:15:39,240 --> 00:15:44,800 new orbits or eject them from the belt altogether. 158 00:15:44,800 --> 00:15:50,200 Resonances also occur in the distant Kuiper Belt, where objects like Pluto and its fellow 159 00:15:50,200 --> 00:15:57,960 dwarf planets preside. Many Kuiper Belt objects are in resonance with Neptune. For instance, 160 00:15:57,960 --> 00:16:03,960 there are KBOs in two to three resonances with Neptune, meaning that for every two orbits 161 00:16:03,960 --> 00:16:10,560 Neptune makes around the Sun, these objects complete three orbits. This stabilizes the 162 00:16:10,560 --> 00:16:16,760 orbits of these small bodies despite their proximity to Neptune's much stronger gravitational 163 00:16:16,760 --> 00:16:18,680 influence. 164 00:16:18,680 --> 00:16:23,520 While not part of our solar system, it's worth noting that resonances are observed in 165 00:16:23,520 --> 00:16:30,880 exoplanetary systems as well. Several multi-planet systems discovered by astronomers show planets 166 00:16:30,880 --> 00:16:37,160 in tight, resonant orbits, providing evidence that resonance is a common feature in planetary 167 00:16:37,160 --> 00:16:40,720 systems across the galaxy. 168 00:16:40,720 --> 00:16:45,600 Resonances are important because they help maintain the stability of our solar system 169 00:16:45,600 --> 00:16:52,960 over long timescales. By preventing chaotic interactions between orbiting bodies, resonances 170 00:16:52,960 --> 00:17:00,640 help keep their orbits predictable and stable. In some cases, resonances can also destabilize 171 00:17:00,640 --> 00:17:07,080 certain orbits as we see with asteroids in the Kirkwood gaps. The existence of resonances 172 00:17:07,080 --> 00:17:12,920 suggests that the solar system has undergone a delicate process of gravitational balancing 173 00:17:12,920 --> 00:17:15,800 that has shaped its current structure. 174 00:17:15,800 --> 00:17:22,560 That's it for today's episode of Star Trails. If you found this episode informative or 175 00:17:22,560 --> 00:17:27,800 entertaining, please share it with a friend. The easiest way to do that is by visiting 176 00:17:27,800 --> 00:17:35,240 our website, startrails.show, where you can find all of our episodes including transcripts, 177 00:17:35,240 --> 00:17:37,800 night sky maps, and more. 178 00:17:37,800 --> 00:17:53,600 Until next time, keep looking up and exploring the night sky. Clear skies, everyone!