WEBVTT 00:00:07.499 --> 00:00:10.519 Howdy Star Gazers and welcome to Star Trails. 00:00:10.759 --> 00:00:13.439 I'm Drew and I'll be your guide to the night 00:00:13.439 --> 00:00:16.879 sky for the week of Sunday, August the 24th to 00:00:16.879 --> 00:00:20.719 the 30th. This is a week that begins in darkness 00:00:20.719 --> 00:00:24.100 and ends with a silver lantern in the sky, thanks 00:00:24.100 --> 00:00:27.420 to a waxing moon. We'll take a look at what else 00:00:27.420 --> 00:00:30.100 is up this week and in the second half of the 00:00:30.100 --> 00:00:33.710 show, We journey out to Uranus where a tiny new 00:00:33.710 --> 00:00:36.969 moon has just been discovered. More importantly, 00:00:37.270 --> 00:00:40.130 we wonder, what would it be like to walk around 00:00:40.130 --> 00:00:43.570 this tiny moon? Whether you're tuning in from 00:00:43.570 --> 00:00:46.770 the backyard, the balcony, or just your imagination, 00:00:47.149 --> 00:00:50.549 I'm glad you're here. So find a cozy spot, let 00:00:50.549 --> 00:00:53.289 your eyes adjust, and let's see what the sky 00:00:53.289 --> 00:00:57.890 holds for us this week. The new moon slipped 00:00:57.890 --> 00:01:01.570 past us on August the 23rd, which means the first 00:01:01.570 --> 00:01:04.629 half of this week belongs to deep -sky hunters, 00:01:05.170 --> 00:01:08.450 galaxies, clusters, and nebula without the lunar 00:01:08.450 --> 00:01:11.890 washout. But each evening, the waxing crescent 00:01:11.890 --> 00:01:14.829 grows larger, rising higher in the west until 00:01:14.829 --> 00:01:17.689 it becomes a bright beacon by Saturday night. 00:01:18.390 --> 00:01:21.090 Try for the razor -thin crescent earlier in the 00:01:21.090 --> 00:01:25.129 week low in the west 20 to 45 minutes after sunset. 00:01:25.549 --> 00:01:28.189 By the week's end, the crescent is high enough 00:01:28.189 --> 00:01:30.909 to sketch shadows along the terminator when viewed 00:01:30.909 --> 00:01:34.750 with binoculars. Saturn is the planetary star 00:01:34.750 --> 00:01:37.709 of the show this week. It lifts itself into the 00:01:37.709 --> 00:01:41.569 southeastern sky by mid -evening. Its rings tilted 00:01:41.569 --> 00:01:44.810 just enough to remind us why Galileo once called 00:01:44.810 --> 00:01:48.590 them ears. A small telescope will reveal Titan 00:01:48.590 --> 00:01:52.420 as a tiny golden companion. and with larger optics 00:01:52.420 --> 00:01:55.439 you'll spot multiple moons strung like faint 00:01:55.439 --> 00:01:59.400 pearls nearby. Look east before dawn and you'll 00:01:59.400 --> 00:02:02.739 find a brighter spectacle, Venus blazing like 00:02:02.739 --> 00:02:06.260 a spotlight with Jupiter tagging along. They've 00:02:06.260 --> 00:02:08.900 been in conjunction recently, but even as they 00:02:08.900 --> 00:02:11.699 drift apart they still share binocular fields 00:02:11.699 --> 00:02:14.699 like two bright exclamation points in the morning 00:02:14.699 --> 00:02:18.539 twilight. In the evening, Mars is hanging low 00:02:18.539 --> 00:02:22.280 in the western twilight for about 45 -60 minutes 00:02:22.280 --> 00:02:25.939 after sunset. It's small and faint now, so we 00:02:25.939 --> 00:02:29.080 can treat it as a goodbye glance object this 00:02:29.080 --> 00:02:33.219 week. Uranus rises around midnight, high before 00:02:33.219 --> 00:02:36.340 dawn, in Taurus, drifting beneath the Pleiades 00:02:36.340 --> 00:02:39.400 this month, which makes it an easy star -hop 00:02:39.400 --> 00:02:44.180 target for 50 -70mm binoculars under dark skies. 00:02:45.069 --> 00:02:48.430 Telescopes will reveal a tiny greenish disc. 00:02:49.150 --> 00:02:52.129 Another meteor shower, the Aurigids, arrives 00:02:52.129 --> 00:02:55.569 this week, active from August 28th into early 00:02:55.569 --> 00:02:59.250 September. They're usually modest, maybe 10 streaks 00:02:59.250 --> 00:03:02.629 per hour at their best, but they're quirky. The 00:03:02.629 --> 00:03:05.449 shower is known for sharp, unpredictable bursts. 00:03:06.250 --> 00:03:09.509 Their radiant lies in Auriga, climbing high before 00:03:09.509 --> 00:03:12.750 dawn. So the best time to watch is the final 00:03:12.750 --> 00:03:15.870 hours of darkness on Friday and Saturday morning. 00:03:16.210 --> 00:03:19.550 With only a slim crescent moon, the sky is yours. 00:03:20.469 --> 00:03:23.389 Now let's wander away from the summer triangle 00:03:23.389 --> 00:03:26.610 and dip into some lesser traveled constellations 00:03:26.610 --> 00:03:30.430 you can see this month. Lacerda the lizard is 00:03:30.430 --> 00:03:34.490 a faint zigzag north of Cygnus, often overlooked. 00:03:35.090 --> 00:03:37.909 Its pattern is delicate, more a whisper than 00:03:37.909 --> 00:03:41.479 a shout. But sweep binoculars through and you'll 00:03:41.479 --> 00:03:47.139 stumble across the open cluster NGC 7243, a loose 00:03:47.139 --> 00:03:49.759 scattering of stars that looks like a spilled 00:03:49.759 --> 00:03:54.099 box of jewels. Lacerda was only added to the 00:03:54.099 --> 00:03:57.979 official sky maps in the 17th century, a relative 00:03:57.979 --> 00:04:02.159 newcomer compared to the ancient Greek constellations. 00:04:02.879 --> 00:04:05.740 Aquarius, the water bearer, sits lower in the 00:04:05.740 --> 00:04:09.650 south, sprawling and hard to trace. In mythology, 00:04:09.909 --> 00:04:12.969 Aquarius pours the life -giving waters onto the 00:04:12.969 --> 00:04:16.250 Earth, but for observers it hides treasures of 00:04:16.250 --> 00:04:19.529 a different sort. Look for the globular cluster 00:04:19.529 --> 00:04:24.589 M2, a dense ball of stars about 37 ,000 light 00:04:24.589 --> 00:04:28.129 -years away, so bright that even small telescopes 00:04:28.129 --> 00:04:32.389 can resolve its grainy edges. The ancients saw 00:04:32.389 --> 00:04:35.709 Aquarius as a bringer of floods. Astronomers 00:04:35.709 --> 00:04:40.050 see him as a keeper of starry vaults. And then 00:04:40.050 --> 00:04:43.350 there's Capricornus, the sea goat, straddling 00:04:43.350 --> 00:04:47.170 myth's line between land and water. To the eye, 00:04:47.290 --> 00:04:50.089 it's a pair of shallow triangles, almost like 00:04:50.089 --> 00:04:54.810 a sideways smile, low in the southern sky. In 00:04:54.810 --> 00:04:58.300 lore, the sea goat is tied to Pan. who leapt 00:04:58.300 --> 00:05:01.579 into the Nile to escape a monster, half transformed 00:05:01.579 --> 00:05:05.680 into a fish. Through the eyepiece, Capricornus 00:05:05.680 --> 00:05:09.220 is a playground of doubles and patterns, a geometry 00:05:09.220 --> 00:05:13.279 lesson written in stars. Scan slowly and you'll 00:05:13.279 --> 00:05:15.939 find the planet Saturn parked here this season, 00:05:16.399 --> 00:05:19.600 the mythic goat, sharing the stage with the Lord 00:05:19.600 --> 00:05:23.709 of the Rings. These constellations may not command 00:05:23.709 --> 00:05:27.230 the same fame as Orion or Scorpius, but they 00:05:27.230 --> 00:05:31.250 reward patient eyes with quiet wonders. You may 00:05:31.250 --> 00:05:33.790 have heard last week that a new moon has been 00:05:33.790 --> 00:05:37.730 discovered around Uranus, thanks to careful observations 00:05:37.730 --> 00:05:41.389 by the James Webb Space Telescope. This moon 00:05:41.389 --> 00:05:45.350 is only about six miles across, which made me 00:05:45.350 --> 00:05:49.050 wonder, is it possible to walk around it? That's 00:05:49.050 --> 00:06:03.019 coming up after the break. Stay with us. Welcome 00:06:03.019 --> 00:06:06.779 back! Astronomers have just added another body 00:06:06.779 --> 00:06:11.040 to Uranus's family tree, a tiny moon barely 6 00:06:11.040 --> 00:06:14.060 miles across whirling around the planet in less 00:06:14.060 --> 00:06:18.540 than 10 hours per orbit. That bumps the official 00:06:18.540 --> 00:06:22.519 moon count for Uranus to 29. The little moon 00:06:22.519 --> 00:06:25.800 is currently only known by its placeholder name, 00:06:26.399 --> 00:06:31.899 S -2025U1. But in keeping with tradition, it'll 00:06:31.899 --> 00:06:35.120 possibly be given a literary name, perhaps a 00:06:35.120 --> 00:06:37.879 character from Shakespeare or Alexander Pope. 00:06:38.959 --> 00:06:42.100 The discovery was made with the James Webb Space 00:06:42.100 --> 00:06:44.660 Telescope with its jaw -dropping sensitivity 00:06:44.660 --> 00:06:48.680 and ability to view the near -infrared. The new 00:06:48.680 --> 00:06:51.639 moon was spotted tucked within Uranus's inner 00:06:51.639 --> 00:06:55.420 ring system, a region previously blind to Voyager 00:06:55.420 --> 00:06:59.220 2 and Hubble. It's kind of like spotting a pebble 00:06:59.220 --> 00:07:03.600 from a hundred miles away. Uranus already has 00:07:03.600 --> 00:07:07.389 a wonderfully eccentric entourage. There are 00:07:07.389 --> 00:07:11.350 the five big rounded moons, Titania, Oberon, 00:07:11.709 --> 00:07:15.889 Ariel, Umbriel, and Miranda. These are strange 00:07:15.889 --> 00:07:19.389 places carved by canyons, cliffs, and perhaps 00:07:19.389 --> 00:07:23.389 hiding briny underground seas. Then there's a 00:07:23.389 --> 00:07:26.129 swarm of smaller inner moons that shepherd the 00:07:26.129 --> 00:07:29.129 planet's delicate rings, and even more distant 00:07:29.129 --> 00:07:32.329 irregular satellites looping in eccentric orbits. 00:07:33.320 --> 00:07:36.720 Voyager 2 gave us our first and only close -up 00:07:36.720 --> 00:07:40.600 look back in 1986, discovering many of these 00:07:40.600 --> 00:07:44.459 worlds in a single flyby. Since then, telescopes 00:07:44.459 --> 00:07:48.060 have slowly filled in the roster. But this new 00:07:48.060 --> 00:07:52.379 web find fascinates me because of its size. Normally, 00:07:52.540 --> 00:07:54.879 when we're talking about topics in astronomy, 00:07:55.120 --> 00:07:57.879 we're measuring objects that are incomprehensible 00:07:57.879 --> 00:08:01.689 in size and scale. We often need to resort to 00:08:01.689 --> 00:08:05.870 exponents, 10 to some power, to describe distances, 00:08:06.370 --> 00:08:10.189 mass, and so on. For example, something gigantic, 00:08:10.449 --> 00:08:13.670 like the Milky Way galaxy, has a diameter around 00:08:13.670 --> 00:08:18.329 10 to the 24th power in meters. That's a 1 followed 00:08:18.329 --> 00:08:22.829 by 24 zeros, a nearly incomprehensible number. 00:08:23.529 --> 00:08:26.389 But this newly discovered moon is really tiny 00:08:26.389 --> 00:08:29.490 in a way that makes it relatable. Some of you 00:08:29.490 --> 00:08:31.990 may know that I'm a walker. I try to get out 00:08:31.990 --> 00:08:34.789 and walk every day if possible, and, in fact, 00:08:34.990 --> 00:08:37.970 one of these late -night Constitutionals planted 00:08:37.970 --> 00:08:42.269 the seed that resulted in this podcast. At just 00:08:42.269 --> 00:08:45.870 10 kilometers across, this new moon is so small 00:08:45.870 --> 00:08:48.590 you could, in theory, walk all the way around 00:08:48.590 --> 00:08:53.309 it in a few hours. The idea intrigues me, a hiker's 00:08:53.309 --> 00:08:57.200 circuit of an entire moon before lunch. The catch 00:08:57.200 --> 00:09:00.759 is, of course, gravity. Does an object this small 00:09:00.759 --> 00:09:03.600 produce enough gravity to keep an average human 00:09:03.600 --> 00:09:08.279 rooted on its surface? So we did the math, and 00:09:08.279 --> 00:09:11.799 the numbers are fascinating. Let's take a look 00:09:11.799 --> 00:09:14.779 at some figures, and just know these are estimates. 00:09:15.620 --> 00:09:18.559 The new moon is only about 10 kilometers across, 00:09:18.759 --> 00:09:22.720 or roughly 6 miles. That means a radius of around 00:09:22.720 --> 00:09:27.259 5 ,000 meters. If it's made of dark, icy or rocky 00:09:27.259 --> 00:09:31.000 material like Uranus's other inner moons, perhaps 00:09:31.000 --> 00:09:35.179 we can estimate the density around 1200 to 1800 00:09:35.179 --> 00:09:40.360 kg per cubic meter. That means its surface gravity 00:09:40.360 --> 00:09:46.980 works out to roughly 0 .00017 or thereabouts 00:09:46.980 --> 00:09:53.889 to 0 .00026 g. That's around 4 ,000 to 6 ,000 00:09:53.889 --> 00:09:57.870 times weaker than Earth's gravity. On Earth, 00:09:58.309 --> 00:10:03.929 gravity is a firm tug. On S -2025U1, it's practically 00:10:03.929 --> 00:10:07.870 a whisper. Surface gravity would be about 2 ten 00:10:07.870 --> 00:10:10.850 -thousandths of Earth's. Put another way, if 00:10:10.850 --> 00:10:14.830 you weigh 180 pounds here, you'd weigh less than 00:10:14.830 --> 00:10:18.779 an ounce there. The escape velocity, that's the 00:10:18.779 --> 00:10:21.840 speed you need to break free entirely, is only 00:10:21.840 --> 00:10:25.440 around 10 miles per hour. That's a hard jog. 00:10:26.019 --> 00:10:28.960 Trip and shove off too forcefully, and you wouldn't 00:10:28.960 --> 00:10:31.820 come down, you'd be in orbit for a moment and 00:10:31.820 --> 00:10:36.720 likely drifting away into space. So, would walking 00:10:36.720 --> 00:10:39.899 even work? Well, not in the traditional sense. 00:10:40.590 --> 00:10:43.289 Each step would act more like a little launch. 00:10:43.470 --> 00:10:46.389 You'd move in slow arcs, spending most of your 00:10:46.389 --> 00:10:49.210 time hovering above the surface before settling 00:10:49.210 --> 00:10:53.330 back down. To stay grounded, you'd need a tether, 00:10:53.590 --> 00:10:55.990 or something you can use to stay connected to 00:10:55.990 --> 00:10:58.769 the ground, kind of like an ice climber using 00:10:58.769 --> 00:11:02.909 a pick on a slippery slope. With care, you could 00:11:02.909 --> 00:11:05.710 shuffle around, but it would feel like spelunking 00:11:05.710 --> 00:11:09.600 on a giant trampoline in slow motion. Like the 00:11:09.600 --> 00:11:12.799 Earth's moon, the new Uranian moon is tidally 00:11:12.799 --> 00:11:16.440 locked, so it spins only once every time it orbits 00:11:16.440 --> 00:11:21.799 Uranus, about every 9 .6 hours. So at the equator, 00:11:22.159 --> 00:11:25.259 the ground slides under you at around 2 miles 00:11:25.259 --> 00:11:29.039 per hour. That slightly reduces effective gravity 00:11:29.039 --> 00:11:33.120 and escape speed at the equator by 5 to 10 percent. 00:11:33.470 --> 00:11:37.190 For comparison, Mars's tiny moon, Deimos, which 00:11:37.190 --> 00:11:40.090 is a bit larger than this object, has an escape 00:11:40.090 --> 00:11:43.309 speed around jogging pace. People often point 00:11:43.309 --> 00:11:46.769 out you can almost jump to orbit. This new moon 00:11:46.769 --> 00:11:50.350 is in that same ballpark. There's another factor 00:11:50.350 --> 00:11:53.529 at play here, and that's the tidal forces of 00:11:53.529 --> 00:11:56.779 Uranus itself. If you're trying to walk on the 00:11:56.779 --> 00:11:59.159 side of the moon facing Uranus, things get a 00:11:59.159 --> 00:12:02.179 little ticklish. You'd be even floatier, thanks 00:12:02.179 --> 00:12:05.100 to the massive influence of Uranus, which steals 00:12:05.100 --> 00:12:07.639 about a quarter of your already light weight. 00:12:08.379 --> 00:12:10.879 You won't be yanked into space while you're standing 00:12:10.879 --> 00:12:13.779 still, but a gentle hop could send you flying. 00:12:14.860 --> 00:12:17.220 I hope you enjoyed this little thought experiment, 00:12:17.299 --> 00:12:20.360 or daydream, really. There's something beautifully 00:12:20.360 --> 00:12:24.019 peculiar about Uranus. It's a sideways spinning 00:12:24.019 --> 00:12:27.639 planet. hiding possible oceans and ring moon 00:12:27.639 --> 00:12:32.240 chaos that defies typical orbits. Now Webb has 00:12:32.240 --> 00:12:35.220 shown us that Uranus contains even more secrets 00:12:35.220 --> 00:12:37.980 and reminds us that the solar system is a lot 00:12:37.980 --> 00:12:45.659 less static than we sometimes think. If the stars 00:12:45.659 --> 00:12:48.100 spoke to you this week or if a question's been 00:12:48.100 --> 00:12:50.659 on your mind, I'd love to hear it. Visit our 00:12:50.659 --> 00:12:54.240 website, StarTrails .Show, where you can contact 00:12:54.240 --> 00:12:57.899 me and explore past episodes. Be sure to follow 00:12:57.899 --> 00:13:01.080 us on Blue Sky and YouTube. Links are in the 00:13:01.080 --> 00:13:04.220 show notes. Until we meet again beneath the stars, 00:13:04.759 --> 00:13:05.759 clear skies everyone.