WEBVTT 00:00:07.200 --> 00:00:09.839 Howdy Star Gazers and welcome to this episode 00:00:09.839 --> 00:00:13.359 of Star Trails. My name is Drew and I'll be your 00:00:13.359 --> 00:00:15.779 guide to the night sky for the week of March 00:00:15.779 --> 00:00:19.379 the 1st through the 7th. Believe it or not, this 00:00:19.379 --> 00:00:23.320 is our 100th episode and over the past few months 00:00:23.320 --> 00:00:26.359 we've traveled far. We've talked about stars 00:00:26.359 --> 00:00:29.059 that will outlive our species. We've wandered 00:00:29.059 --> 00:00:32.079 through globular clusters and nebula. We've stood 00:00:32.079 --> 00:00:34.920 at the edge of galaxies and contemplated black 00:00:34.920 --> 00:00:38.859 holes. but this month we're coming home. Every 00:00:38.859 --> 00:00:41.979 object we'll discuss in March is right here in 00:00:41.979 --> 00:00:46.100 our own solar system, not light years away. These 00:00:46.100 --> 00:00:49.240 are worlds we can see with our own eyes, and 00:00:49.240 --> 00:00:52.000 more than that, these are worlds we have visited. 00:00:52.719 --> 00:00:55.140 Later in the show, we'll check in with this week's 00:00:55.140 --> 00:00:58.359 sky, which features the only total lunar eclipse 00:00:58.359 --> 00:01:01.780 of the year, and we'll take a quick look at electric 00:01:01.780 --> 00:01:04.900 cars in space. Whether you're tuning in from 00:01:04.900 --> 00:01:07.420 the backyard or the balcony, I'm glad you're 00:01:07.420 --> 00:01:10.060 here. So grab a comfortable spot under the night 00:01:10.060 --> 00:01:14.379 sky and let's get started. This month we're taking 00:01:14.379 --> 00:01:17.560 a closer look at our solar system. We'll start 00:01:17.560 --> 00:01:21.060 with the inner planets and move outward. Later 00:01:21.060 --> 00:01:23.480 in the month we'll explore some of the wildest 00:01:23.480 --> 00:01:26.480 moons of our system, venture into the mysterious 00:01:26.480 --> 00:01:29.579 area beyond the outer planets, and we'll take 00:01:29.579 --> 00:01:33.200 a special detour over to Pluto, the planet that 00:01:33.200 --> 00:01:36.939 went on trial and lost. What I love about this 00:01:36.939 --> 00:01:40.200 month's series is that humanity has orbited, 00:01:40.599 --> 00:01:44.780 landed on, driven across, drifted into, and photographed 00:01:44.780 --> 00:01:48.420 every planet we'll talk about this month. That's 00:01:48.420 --> 00:01:51.189 stunning if you stop and think about it. So this 00:01:51.189 --> 00:01:54.510 week we begin with the inner planets, Mercury, 00:01:54.890 --> 00:01:59.430 Venus, Earth, and Mars. Four rocky worlds with 00:01:59.430 --> 00:02:08.990 very different outcomes. Mercury is often overlooked. 00:02:09.409 --> 00:02:12.949 It's tiny, it hugs the Sun, it never strays far 00:02:12.949 --> 00:02:16.330 from the horizon, and it's notoriously difficult 00:02:16.330 --> 00:02:20.280 to observe. But Mercury played a pivotal role 00:02:20.280 --> 00:02:22.780 in one of the greatest scientific revolutions 00:02:22.780 --> 00:02:26.759 in history. For decades in the 19th century, 00:02:27.379 --> 00:02:30.080 astronomers noticed something odd about Mercury's 00:02:30.080 --> 00:02:33.580 orbit. The point of closest approach to the Sun, 00:02:33.840 --> 00:02:37.219 its perihelion, slowly shifted over time in a 00:02:37.219 --> 00:02:40.060 way that Newton's laws couldn't fully explain. 00:02:40.439 --> 00:02:44.439 The discrepancy was small, just 43 arc seconds 00:02:44.439 --> 00:02:47.919 per century. Some astronomers proposed that an 00:02:47.919 --> 00:02:51.620 unseen planet inside Mercury's orbit was tugging 00:02:51.620 --> 00:02:55.159 on it gravitationally. They even gave this hypothetical 00:02:55.159 --> 00:02:59.539 world a name, Vulcan. Searches were conducted, 00:03:00.099 --> 00:03:03.099 observations were claimed, Vulcan sightings were 00:03:03.099 --> 00:03:06.060 reported near the Sun's glare during eclipses, 00:03:06.439 --> 00:03:11.780 but Vulcan didn't exist. Instead, in 1915 Albert 00:03:11.780 --> 00:03:15.120 Einstein showed that Mercury's strange orbital 00:03:15.120 --> 00:03:18.580 precession wasn't caused by an invisible planet. 00:03:19.060 --> 00:03:21.759 It was caused by the curvature of space -time 00:03:21.759 --> 00:03:25.719 itself. According to general relativity, massive 00:03:25.719 --> 00:03:28.860 objects like the Sun warp the fabric of space 00:03:28.860 --> 00:03:32.639 -time. Mercury, being so close to the Sun, moves 00:03:32.639 --> 00:03:36.159 through that warped geometry. Its orbit isn't 00:03:36.159 --> 00:03:39.860 simply a Newtonian ellipse, it's an ellipse slowly 00:03:39.860 --> 00:03:43.979 turning within curved space -time. Mercury helped 00:03:43.979 --> 00:03:47.419 prove that gravity isn't just a force, but rather 00:03:47.419 --> 00:03:50.740 geometry. That's an extraordinary legacy for 00:03:50.740 --> 00:03:53.259 a little planet most people struggle to find 00:03:53.259 --> 00:03:57.060 in the twilight. But Mercury is weird in other 00:03:57.060 --> 00:04:01.020 ways too. A year on Mercury, that's the time 00:04:01.020 --> 00:04:04.539 it takes to orbit the sun, is 88 Earth days. 00:04:04.830 --> 00:04:08.270 But a single solar day, from one sunrise to the 00:04:08.270 --> 00:04:14.789 next, lasts 176 Earth days. If you stood on Mercury's 00:04:14.789 --> 00:04:17.810 surface, you would watch the sun rise, pause, 00:04:18.149 --> 00:04:20.990 reverse direction slightly, then continue its 00:04:20.990 --> 00:04:25.490 path across the sky. The planet's 3 to 2 spin 00:04:25.490 --> 00:04:28.410 orbit resonance creates one of the strangest 00:04:28.410 --> 00:04:32.459 day -night cycles in the solar system. And despite 00:04:32.459 --> 00:04:35.240 being the closest planet to the Sun, Mercury 00:04:35.240 --> 00:04:39.319 has water ice. Not oceans, of course, but water 00:04:39.319 --> 00:04:42.319 ice trapped in permanently shadowed craters near 00:04:42.319 --> 00:04:46.680 its poles, where sunlight never reaches. So the 00:04:46.680 --> 00:04:49.620 hottest world in the solar system harbors ice 00:04:49.620 --> 00:04:53.680 in eternal darkness. As for exploration, Mercury 00:04:53.680 --> 00:04:56.819 has only been visited by a handful of spacecraft. 00:04:57.680 --> 00:05:02.639 NASA's Mariner 10 flew by in the 1970s. Decades 00:05:02.639 --> 00:05:05.579 later, the MESSENGER mission orbited Mercury 00:05:05.579 --> 00:05:10.040 from 2011 to 2015, mapping its surface in detail 00:05:10.040 --> 00:05:12.939 and confirming the presence of that polar ice. 00:05:14.160 --> 00:05:17.060 From Mercury, we venture out to Earth's twin, 00:05:17.579 --> 00:05:20.699 Venus. Well, maybe it's more of a fraternal twin 00:05:20.699 --> 00:05:24.540 than identical. Venus is nearly the same size 00:05:24.540 --> 00:05:27.560 and mass as Earth. It's a rocky world wrapped 00:05:27.560 --> 00:05:31.199 in clouds. For much of the 20th century, science 00:05:31.199 --> 00:05:34.060 fiction writers imagined steaming jungles beneath 00:05:34.060 --> 00:05:38.360 those clouds, swamps, oceans, maybe even life. 00:05:39.379 --> 00:05:42.180 Instead, Venus turned out to be something far 00:05:42.180 --> 00:05:46.100 more unsettling. It's a runaway greenhouse world. 00:05:46.819 --> 00:05:49.920 Its thick atmosphere is composed mostly of carbon 00:05:49.920 --> 00:05:53.750 dioxide. with surface pressures about 90 times 00:05:53.750 --> 00:05:57.050 that of Earth. That's like being nearly a mile 00:05:57.050 --> 00:06:00.649 underwater. The surface temperature hovers around 00:06:00.649 --> 00:06:04.389 900 degrees Fahrenheit, and that's hot enough 00:06:04.389 --> 00:06:08.050 to melt lead. As for those clouds, well, they're 00:06:08.050 --> 00:06:12.529 made of sulfuric acid. Venus has a weird orbital 00:06:12.529 --> 00:06:15.800 quirk in that it rotates backwards. While most 00:06:15.800 --> 00:06:18.339 planets spin in the same direction they orbit 00:06:18.339 --> 00:06:22.480 the Sun, Venus spins retrograde. That means on 00:06:22.480 --> 00:06:25.519 Venus the Sun rises in the West and sets in the 00:06:25.519 --> 00:06:30.680 East. Also, it rotates extremely slowly. A single 00:06:30.680 --> 00:06:34.720 rotation of Venus takes about 243 Earth days. 00:06:35.199 --> 00:06:39.019 That's longer than its year, which is about 225 00:06:39.019 --> 00:06:42.819 Earth days. If you stood on its surface, ignoring 00:06:42.819 --> 00:06:45.500 the fact that you'd be crushed and incinerated 00:06:45.500 --> 00:06:47.939 almost instantly, you would experience one of 00:06:47.939 --> 00:06:52.319 the strangest celestial rhythms imaginable. And 00:06:52.319 --> 00:06:56.120 we've been there. The Soviet Union's Venera program 00:06:56.120 --> 00:06:58.620 achieved one of the most remarkable feats in 00:06:58.620 --> 00:07:02.959 planetary exploration. In the 1970s and early 00:07:02.959 --> 00:07:06.259 80s, several Venera landers successfully reached 00:07:06.259 --> 00:07:09.459 the surface of Venus. They transmitted data, 00:07:09.819 --> 00:07:13.040 and in some cases images, before succumbing quickly 00:07:13.040 --> 00:07:16.379 to the heat and pressure. The images they returned 00:07:16.379 --> 00:07:20.920 are eerie. A flat, rock -strewn landscape beneath 00:07:20.920 --> 00:07:24.540 a yellowish sky. The light filtered and distorted 00:07:24.540 --> 00:07:29.180 by thick atmosphere. A suffocating alien stillness. 00:07:29.879 --> 00:07:32.699 More recently, orbiters like NASA's Magellan 00:07:32.699 --> 00:07:36.269 mission mapped Venus using radar. since visible 00:07:36.269 --> 00:07:40.410 light can't penetrate the cloud deck. Radar revealed 00:07:40.410 --> 00:07:44.430 a world shaped by volcanism, vast lava plains, 00:07:44.810 --> 00:07:49.529 pancake domes, massive shield volcanoes. We're 00:07:49.529 --> 00:07:52.589 still not entirely sure if Venus is volcanically 00:07:52.589 --> 00:07:56.290 active today, but there have been hints. Sulfur 00:07:56.290 --> 00:08:00.149 dioxide fluctuations, possible thermal anomalies. 00:08:00.529 --> 00:08:03.730 Venus may still be reshaping itself beneath those 00:08:03.730 --> 00:08:07.560 clouds. Scientists see Venus as a cautionary 00:08:07.560 --> 00:08:11.439 tale for Earth. Two rocky planets born from the 00:08:11.439 --> 00:08:15.480 same solar nebula, similar in size and composition, 00:08:15.879 --> 00:08:19.560 and yet they diverged dramatically. One became 00:08:19.560 --> 00:08:22.300 a world of oceans and life, the other became 00:08:22.300 --> 00:08:25.819 a greenhouse gas furnace wrapped in acid clouds. 00:08:26.839 --> 00:08:30.399 And yet, in our twilight sky, Venus remains the 00:08:30.399 --> 00:08:33.750 brightest planet of all. Serene and beautiful 00:08:33.750 --> 00:08:38.230 from a distance. Now we arrive at a planet we 00:08:38.230 --> 00:08:41.789 think we know very well, Earth. But let's do 00:08:41.789 --> 00:08:44.629 something unusual. Let's imagine we're not standing 00:08:44.629 --> 00:08:47.929 on it. Let's imagine we're alien astronomers 00:08:47.929 --> 00:08:51.370 observing this small blue world from dozens of 00:08:51.370 --> 00:08:55.559 light years away. What would we see? First, we'd 00:08:55.559 --> 00:08:58.740 notice the color. Earth is strikingly blue because 00:08:58.740 --> 00:09:02.000 liquid water covers about 70 % of the surface. 00:09:03.019 --> 00:09:06.639 That water absorbs red wavelengths and scatters 00:09:06.639 --> 00:09:09.899 blue back into space. To a distant observer, 00:09:10.179 --> 00:09:12.720 Earth's spectrum would show strong signatures 00:09:12.720 --> 00:09:16.220 of water vapor in the atmosphere. That alone 00:09:16.220 --> 00:09:20.120 would be interesting. But then the alien spectroscopist 00:09:20.120 --> 00:09:23.240 would notice something even stranger. Oxygen. 00:09:23.600 --> 00:09:27.600 Earth's atmosphere contains about 21 % molecular 00:09:27.600 --> 00:09:31.200 oxygen, which is highly reactive. It doesn't 00:09:31.200 --> 00:09:34.159 like to remain free in an atmosphere for long. 00:09:34.559 --> 00:09:38.059 It bonds, oxidizes, and disappears into rocks. 00:09:38.960 --> 00:09:41.360 For an atmosphere to maintain that much free 00:09:41.360 --> 00:09:44.799 oxygen, something must be replenishing it continuously. 00:09:45.519 --> 00:09:49.019 From a purely chemical perspective, Earth's atmosphere 00:09:49.019 --> 00:09:52.840 is in disequilibrium. An alien observer might 00:09:52.840 --> 00:09:57.269 detect methane alongside oxygen. Those two gases 00:09:57.269 --> 00:10:00.230 should rapidly react and cancel each other out, 00:10:00.509 --> 00:10:04.309 yet on Earth both persist. Of course, here on 00:10:04.309 --> 00:10:08.870 Earth we know the explanation is biology. Photosynthesis 00:10:08.870 --> 00:10:12.389 splits water molecules and releases oxygen as 00:10:12.389 --> 00:10:16.529 waste. Microbes, plants, forests, and plankton 00:10:16.529 --> 00:10:19.669 are all quietly altering the chemistry of an 00:10:19.669 --> 00:10:23.220 entire planet. Then there's the reflectivity 00:10:23.220 --> 00:10:27.360 problem. As Earth rotates, its brightness changes. 00:10:27.740 --> 00:10:31.480 Oceans reflect differently than continents. Cloud 00:10:31.480 --> 00:10:35.679 cover shifts. Seasonal variations alter albedo. 00:10:35.960 --> 00:10:39.980 Ice caps grow and shrink. An alien observer tracking 00:10:39.980 --> 00:10:43.419 the light curve might infer continents, weather 00:10:43.419 --> 00:10:47.240 systems, polar ice caps. They'd even detect our 00:10:47.240 --> 00:10:51.799 moon. Earth's unusually large moon stabilizes 00:10:51.799 --> 00:10:55.940 the planet's axial tilt. That stabilizes climate 00:10:55.940 --> 00:10:59.940 over long periods. From afar, the gravitational 00:10:59.940 --> 00:11:03.039 dance between Earth and Moon would reveal itself 00:11:03.039 --> 00:11:07.000 in subtle wobbles. And then there are the unnatural 00:11:07.000 --> 00:11:10.519 signatures. Over the past century, Earth has 00:11:10.519 --> 00:11:14.299 begun leaking radio signals into space, television 00:11:14.299 --> 00:11:18.620 broadcasts, radar pulses, communications. a faint 00:11:18.620 --> 00:11:22.460 expanding shell of electromagnetic noise roughly 00:11:22.460 --> 00:11:26.779 100 light years in radius. And Earth has begun 00:11:26.779 --> 00:11:30.000 sending objects away from itself. We've placed 00:11:30.000 --> 00:11:33.100 satellites in orbit. We've sent probes to other 00:11:33.100 --> 00:11:35.940 planets. We've launched spacecraft that have 00:11:35.940 --> 00:11:39.299 exited the solar system entirely. And while an 00:11:39.299 --> 00:11:42.340 alien astronomer wouldn't know about our culture, 00:11:42.860 --> 00:11:46.480 our music, literature, or lifestyles, They'd 00:11:46.480 --> 00:11:49.860 still see spectral lines, and if they're conducting 00:11:49.860 --> 00:11:52.620 their own search for extraterrestrial intelligence, 00:11:52.879 --> 00:11:56.419 maybe they'd hear our radio waves. The alien 00:11:56.419 --> 00:12:00.399 observers would certainly notice our moon. Among 00:12:00.399 --> 00:12:02.879 the inner planets, Earth is the only one with 00:12:02.879 --> 00:12:06.500 a truly large, gravitationally significant moon. 00:12:07.419 --> 00:12:11.200 Mars has two small, irregular moons, Phobos and 00:12:11.200 --> 00:12:14.279 Deimos, which are likely captured asteroids. 00:12:14.840 --> 00:12:18.419 But Earth's moon is enormous relative to its 00:12:18.419 --> 00:12:21.320 planet. It's about one -quarter the diameter 00:12:21.320 --> 00:12:25.480 of Earth and more than 1 % of Earth's mass. That 00:12:25.480 --> 00:12:28.440 might not sound like much, but in planetary terms, 00:12:28.759 --> 00:12:32.539 it's huge. In fact, some astronomers even describe 00:12:32.539 --> 00:12:36.820 the Earth -Moon system as a double planet. The 00:12:36.820 --> 00:12:39.919 barycenter, the shared center of mass around 00:12:39.919 --> 00:12:42.870 which both Earth and the moon orbit, doesn't 00:12:42.870 --> 00:12:45.929 sit at the exact center of Earth. It lies about 00:12:45.929 --> 00:12:49.970 1700 kilometers beneath Earth's surface. Earth 00:12:49.970 --> 00:12:53.129 itself wobbles around this point as the moon 00:12:53.129 --> 00:12:56.970 orbits. Earth itself also does something subtle 00:12:56.970 --> 00:13:00.389 but important. It spins once every 24 hours. 00:13:01.250 --> 00:13:04.110 That rapid rotation helps generate a magnetic 00:13:04.110 --> 00:13:07.169 field through the motion of molten iron at its 00:13:07.169 --> 00:13:11.250 core. That magnetic field shields the atmosphere 00:13:11.250 --> 00:13:13.990 from the solar wind, preventing it from being 00:13:13.990 --> 00:13:17.309 stripped away over billions of years. And that 00:13:17.309 --> 00:13:20.629 brings us to Mars, the red planet that wasn't 00:13:20.629 --> 00:13:23.590 as lucky as Earth in regards to its atmosphere. 00:13:24.629 --> 00:13:27.509 From a distance, Mars looks almost like Earth. 00:13:27.809 --> 00:13:32.649 It has polar caps, seasons, a 24 .6 hour day, 00:13:33.110 --> 00:13:36.850 remarkably close to our own. A tilted axis produces 00:13:36.850 --> 00:13:39.870 familiar rhythms of spring, summer, autumn, and 00:13:39.870 --> 00:13:43.710 winter. Mars is a world that seems to have started 00:13:43.710 --> 00:13:46.730 with potential. We see ancient river valleys 00:13:46.730 --> 00:13:50.269 carved into its surface. Delta formations where 00:13:50.269 --> 00:13:53.090 sediment once fanned outward into standing bodies 00:13:53.090 --> 00:13:56.610 of water. Minerals that form only in the presence 00:13:56.610 --> 00:14:00.429 of liquid water. Billions of years ago, Mars 00:14:00.429 --> 00:14:03.830 almost certainly had flowing water on its surface. 00:14:04.120 --> 00:14:07.340 It had a thicker atmosphere, a warmer climate, 00:14:07.740 --> 00:14:11.100 and then something changed. Mars is only about 00:14:11.100 --> 00:14:14.679 half the diameter of Earth. Smaller planets cool 00:14:14.679 --> 00:14:18.779 faster. As its interior cooled, Mars likely lost 00:14:18.779 --> 00:14:21.919 the dynamo effect that once generated a global 00:14:21.919 --> 00:14:25.360 magnetic field. Without that magnetic shield, 00:14:25.679 --> 00:14:28.399 the solar wind gradually stripped away much of 00:14:28.399 --> 00:14:32.190 its atmosphere. The water didn't simply vanish, 00:14:32.429 --> 00:14:35.909 some escaped to space, some froze underground, 00:14:36.389 --> 00:14:40.070 and some remains locked in polar ice. What we're 00:14:40.070 --> 00:14:43.529 left with today is a thin, cold atmosphere, less 00:14:43.529 --> 00:14:46.809 than 1 % the pressure of Earth's, and a landscape 00:14:46.809 --> 00:14:50.929 sculpted by wind and dust. Mars may be the most 00:14:50.929 --> 00:14:55.029 explored inner planet after Earth. NASA's Spirit 00:14:55.029 --> 00:14:58.450 and Opportunity rovers, solar -powered explorers, 00:14:58.600 --> 00:15:03.120 lasted far beyond their expected lifetimes. Opportunity 00:15:03.120 --> 00:15:07.799 operated for nearly 15 years. Curiosity and perseverance, 00:15:08.320 --> 00:15:10.960 nuclear -powered rovers, continue to traverse 00:15:10.960 --> 00:15:14.419 ancient lake beds and deltas, drilling into rocks 00:15:14.419 --> 00:15:17.980 that may preserve chemical traces of past habitability. 00:15:18.639 --> 00:15:22.159 We've flown a helicopter, ingenuity, in the thin 00:15:22.159 --> 00:15:26.059 Martian air. That alone sounds like science fiction. 00:15:26.440 --> 00:15:29.419 We haven't sent humans to Mars, but we're trying 00:15:29.419 --> 00:15:33.220 to, and maybe one day we will. There's one more 00:15:33.220 --> 00:15:36.059 reason Mars continues to grip our imagination, 00:15:36.559 --> 00:15:40.379 the possibility that it once hosted life. We 00:15:40.379 --> 00:15:43.519 know that early Mars had liquid water, and for 00:15:43.519 --> 00:15:46.740 a period billions of years ago, Mars was likely 00:15:46.740 --> 00:15:51.019 warmer and wetter. On Earth, life appears very 00:15:51.019 --> 00:15:54.779 early in our geological record. almost as soon 00:15:54.779 --> 00:15:58.279 as conditions allowed it. So scientists ask a 00:15:58.279 --> 00:16:01.200 simple question. If life arose quickly here, 00:16:01.340 --> 00:16:04.720 could it have arisen there? We haven't found 00:16:04.720 --> 00:16:09.820 proof, but we found hints. In 1996, a meteorite 00:16:09.820 --> 00:16:16.200 from Mars known as ALH84001 made headlines around 00:16:16.200 --> 00:16:19.620 the world. Scientists announced that it contained 00:16:19.620 --> 00:16:23.019 tiny structures resembling fossilized microbes. 00:16:23.259 --> 00:16:26.279 along with chemical signatures suggestive of 00:16:26.279 --> 00:16:29.659 biological activity. For a brief moment it seemed 00:16:29.659 --> 00:16:32.679 possible that we had found evidence of past Martian 00:16:32.679 --> 00:16:36.360 life. But over the following years further analysis 00:16:36.360 --> 00:16:38.559 showed that those structures could be explained 00:16:38.559 --> 00:16:43.059 by non -biological processes. The consensus today 00:16:43.059 --> 00:16:46.500 is that the meteorite does not provide convincing 00:16:46.500 --> 00:16:50.820 evidence of life. Since then, rovers have detected 00:16:50.820 --> 00:16:54.960 organic molecules in Martian rocks. But organic 00:16:54.960 --> 00:16:59.059 chemistry is not the same thing as biology. Methane 00:16:59.059 --> 00:17:01.460 has also been detected in trace amounts in the 00:17:01.460 --> 00:17:05.619 Martian atmosphere. Intriguing, but still inconclusive. 00:17:07.480 --> 00:17:10.480 All four of these worlds formed from the same 00:17:10.480 --> 00:17:13.759 protoplanetary disk four and a half billion years 00:17:13.759 --> 00:17:18.559 ago. Same star, similar materials. But over billions 00:17:18.559 --> 00:17:22.839 of years, tiny differences compounded. The inner 00:17:22.839 --> 00:17:26.240 solar system is not a random assortment of rocks. 00:17:26.460 --> 00:17:29.980 It's a long running experiment in planetary evolution. 00:17:30.660 --> 00:17:34.759 Four test cases, one sun, and four very different 00:17:34.759 --> 00:17:38.339 outcomes. If you want to understand how fragile 00:17:38.339 --> 00:17:41.220 habitability is, you don't need to travel light 00:17:41.220 --> 00:17:44.420 years away. You only need to look next door. 00:18:02.440 --> 00:18:05.039 After a quick break, we'll be back with this 00:18:05.039 --> 00:18:09.220 week's Night Sky Report and more. Stay with us. 00:18:21.519 --> 00:18:25.140 Welcome back. I hope you don't mind if I take 00:18:25.140 --> 00:18:29.079 a moment to meander and maybe nerd out a bit. 00:18:29.609 --> 00:18:33.650 The last time I bought a car was almost 15 years 00:18:33.650 --> 00:18:36.809 ago, and the hot tech of that era was built -in 00:18:36.809 --> 00:18:40.670 GPS navigation, backup cameras, and Bluetooth. 00:18:41.730 --> 00:18:44.390 These are things we just expect a new car to 00:18:44.390 --> 00:18:48.430 have nowadays. My little economy hatchback had 00:18:48.430 --> 00:18:51.549 none of that, although I did pack a few amateur 00:18:51.549 --> 00:18:54.630 radio transceivers into it, earning it the nickname 00:18:54.630 --> 00:18:59.150 The Hamster among my friends. Just as the universe 00:18:59.150 --> 00:19:02.609 is fumbling toward entropy, so is my old car. 00:19:03.190 --> 00:19:06.529 With many systems failing, I finally had to retire 00:19:06.529 --> 00:19:10.269 it last week. In the 15 years since the hamster 00:19:10.269 --> 00:19:13.049 rolled off the assembly line, a lot has changed. 00:19:13.950 --> 00:19:17.210 In 2011, there were maybe three consumer electric 00:19:17.210 --> 00:19:21.609 cars, and only society's elite or extreme early 00:19:21.609 --> 00:19:24.549 adopters drove them. Now they're everywhere, 00:19:25.009 --> 00:19:27.569 and charging points are peppered throughout cities 00:19:27.569 --> 00:19:31.309 and along highways. Electric is just another 00:19:31.309 --> 00:19:34.630 choice in the sea of automobiles. In recent years, 00:19:34.730 --> 00:19:37.329 they've become surprisingly affordable, particularly 00:19:37.329 --> 00:19:40.309 in the used market, where they currently represent 00:19:40.309 --> 00:19:43.390 some of the best value in the industry. So I 00:19:43.390 --> 00:19:47.230 decided my next ride would be powered by electrons, 00:19:47.529 --> 00:19:50.670 and I've been in full -on geek mode ever since. 00:19:50.970 --> 00:19:54.410 For my new car, I chose a color similar to Neil 00:19:54.410 --> 00:19:58.349 Armstrong's Marina Blue Corvette Stingray, and 00:19:58.349 --> 00:20:02.529 yes, that was absolutely on purpose. My new hatchback 00:20:02.529 --> 00:20:06.029 on steroids is fun to drive, but because a large 00:20:06.029 --> 00:20:08.910 part of the car is a high -voltage battery, you 00:20:08.910 --> 00:20:11.710 can also do some very practical things with it, 00:20:11.890 --> 00:20:15.490 like power equipment. Imagine being at a dark 00:20:15.490 --> 00:20:18.450 sky site with your imaging rig plugged straight 00:20:18.450 --> 00:20:21.730 into your electric car. Maybe it gets cold, so 00:20:21.730 --> 00:20:24.710 you plug in a small space heater. Maybe you get 00:20:24.710 --> 00:20:28.230 sleepy, so you power up a coffee maker. Meanwhile, 00:20:28.470 --> 00:20:32.289 a laptop hums quietly, guiding a telescope that's 00:20:32.289 --> 00:20:34.970 tracking a galaxy millions of light years away. 00:20:35.569 --> 00:20:38.910 No marine batteries, power inverters, or noisy 00:20:38.910 --> 00:20:43.130 generators. Just stored energy in silence. This 00:20:43.130 --> 00:20:47.150 is my Observatory on Wheels. And it dawned on 00:20:47.150 --> 00:20:49.750 me that electric cars have been part of space 00:20:49.750 --> 00:20:53.009 travel for more than half a century. The first 00:20:53.009 --> 00:20:56.349 vehicles humans ever drove on another world were 00:20:56.349 --> 00:20:59.470 electric. During the Apollo missions beginning 00:20:59.470 --> 00:21:05.369 with Apollo 15 in 1971, astronauts unfolded the 00:21:05.369 --> 00:21:08.269 lunar roving vehicle from the side of the lunar 00:21:08.269 --> 00:21:12.359 module like some kind of cosmic origami. It ran 00:21:12.359 --> 00:21:15.599 on non -rechargeable silver -zinc -potassium 00:21:15.599 --> 00:21:19.319 -hydroxide batteries with four independent electric 00:21:19.319 --> 00:21:23.700 motors, one in each wheel. Top speed? 8 miles 00:21:23.700 --> 00:21:27.500 per hour. In this case, electricity was required 00:21:27.500 --> 00:21:29.720 because it couldn't have burned fuel even if 00:21:29.720 --> 00:21:32.619 it wanted to. There's no oxygen on the moon. 00:21:33.480 --> 00:21:36.720 Lunar astronauts logged nearly 60 miles on the 00:21:36.720 --> 00:21:39.380 lunar surface with their rovers. They collected 00:21:39.380 --> 00:21:42.619 samples, explored craters, and dramatically increased 00:21:42.619 --> 00:21:45.880 the scientific return of the missions. And when 00:21:45.880 --> 00:21:48.740 they left, they parked the rovers there. There 00:21:48.740 --> 00:21:52.180 are still three electric vehicles sitting quietly 00:21:52.180 --> 00:21:55.740 on the moon. Then there are the Mars rovers, 00:21:55.819 --> 00:21:57.799 which we've already mentioned earlier in this 00:21:57.799 --> 00:22:00.599 episode. While they weren't made to carry humans, 00:22:00.680 --> 00:22:04.000 they are, in every meaningful way, electric cars 00:22:04.000 --> 00:22:07.799 operating on a different planet. And, of course, 00:22:07.900 --> 00:22:11.140 there's the slightly absurd case of the Tesla 00:22:11.140 --> 00:22:14.680 Roadster launched into space in 2018, during 00:22:14.680 --> 00:22:18.039 the first flight of SpaceX's Falcon Heavy rocket. 00:22:18.619 --> 00:22:21.619 Instead of a dummy payload, they bolted a production 00:22:21.619 --> 00:22:24.759 electric sports car to the upper stage and sent 00:22:24.759 --> 00:22:28.400 it into orbit around the sun. On the dashboard, 00:22:28.619 --> 00:22:32.200 a sign read, don't panic, a nod to writer Douglas 00:22:32.200 --> 00:22:36.220 Adams. David Bowie's Space Oddity blasted through 00:22:36.220 --> 00:22:39.400 the speakers on a loop into the soundless vacuum 00:22:39.400 --> 00:22:42.920 of the cosmos. There's a mannequin in a space 00:22:42.920 --> 00:22:45.799 suit in the driver's seat, nicknamed Starman, 00:22:46.119 --> 00:22:49.079 and the roadster is still orbiting the sun to 00:22:49.079 --> 00:22:52.039 this day. You can track its location on websites 00:22:52.039 --> 00:22:55.500 like Heavens Above, and it may wander the inner 00:22:55.500 --> 00:22:58.720 solar system for millions of years. That means 00:22:58.720 --> 00:23:02.019 the first production car to leave Earth was electric. 00:23:02.759 --> 00:23:05.700 EVs may or may not be the future depending on 00:23:05.700 --> 00:23:08.420 who you ask, but the truth is they were humanity's 00:23:08.420 --> 00:23:11.599 first off -world transportation dating back to 00:23:11.599 --> 00:23:15.700 the Apollo era. And so here I am driving what 00:23:15.700 --> 00:23:18.559 feels like a spaceship on pavement during a week 00:23:18.559 --> 00:23:21.960 when the moon takes center stage. So let's get 00:23:21.960 --> 00:23:25.500 into it. This month kicks off with a headline 00:23:25.500 --> 00:23:29.559 event, a total lunar eclipse. The moon begins 00:23:29.559 --> 00:23:32.519 the week waxing toward full. By the night of 00:23:32.519 --> 00:23:35.940 March 2, into the early hours of March 3, it 00:23:35.940 --> 00:23:38.920 reaches full moon, traditionally known as the 00:23:38.920 --> 00:23:42.039 worm moon, named for the time of year when the 00:23:42.039 --> 00:23:44.900 ground softens and life begins to stir beneath 00:23:44.900 --> 00:23:48.299 the surface. But this year that full moon won't 00:23:48.299 --> 00:23:51.599 stay bright for long. In the early morning hours 00:23:51.599 --> 00:23:54.640 of March 3, the earth will move directly between 00:23:54.640 --> 00:23:57.440 the sun and the moon, casting its shadow across 00:23:57.440 --> 00:24:01.359 the lunar surface. This is a total lunar eclipse, 00:24:01.619 --> 00:24:05.039 and it's the only one in 2026 visible to much 00:24:05.039 --> 00:24:08.700 of North America and the Pacific region. A lunar 00:24:08.700 --> 00:24:12.339 eclipse unfolds gradually. First, the moon slips 00:24:12.339 --> 00:24:15.619 into the Earth's penumbra, a subtle shading that 00:24:15.619 --> 00:24:18.720 many observers won't even notice. Then comes 00:24:18.720 --> 00:24:22.440 the umbra, the darker central shadow, and you'll 00:24:22.440 --> 00:24:25.279 begin to see a distinct bite taken from the lunar 00:24:25.279 --> 00:24:28.170 disk. Over the course of a couple hours, that 00:24:28.170 --> 00:24:31.490 bite grows until the moon is fully engulfed. 00:24:31.769 --> 00:24:35.549 Totality lasts just under an hour, about 58 minutes. 00:24:35.950 --> 00:24:38.809 Instead of disappearing, the moon turns coppery 00:24:38.809 --> 00:24:42.109 red. This effect is caused by a sunlight passing 00:24:42.109 --> 00:24:44.769 through Earth's atmosphere, where it gets filtered 00:24:44.769 --> 00:24:48.289 and bent. Blue light scatters away, while the 00:24:48.289 --> 00:24:51.869 longer red wavelengths continue on, curving into 00:24:51.869 --> 00:24:55.150 Earth's shadow and softly illuminating the moon. 00:24:55.519 --> 00:24:59.819 The exact shade of red can vary. If Earth's atmosphere 00:24:59.819 --> 00:25:03.039 is especially dusty, perhaps from volcanic eruptions 00:25:03.039 --> 00:25:05.880 or heavy pollution, the moon can appear darker, 00:25:06.200 --> 00:25:09.779 even brick red. On a particularly clear year, 00:25:09.960 --> 00:25:13.200 it may glow more orange or copper. You won't 00:25:13.200 --> 00:25:16.079 need a telescope. In fact, lunar eclipses are 00:25:16.079 --> 00:25:19.779 best enjoyed with your own eyes. Binoculars can 00:25:19.779 --> 00:25:22.660 enhance the color contrast, but this is a naked 00:25:22.660 --> 00:25:26.200 eye event. Once this eclipse passes, we won't 00:25:26.200 --> 00:25:28.900 see another total lunar eclipse in North America 00:25:28.900 --> 00:25:34.200 until late 2028 or early 2029. So if skies are 00:25:34.200 --> 00:25:36.880 clear, this is one to check out. You'll want 00:25:36.880 --> 00:25:39.200 to use an app like Stellarium to track where 00:25:39.200 --> 00:25:42.299 the eclipse occurs in your area. Here in the 00:25:42.299 --> 00:25:44.940 southeast U .S., where I'm located, the eclipse 00:25:44.940 --> 00:25:48.640 begins around 5 a .m. on the morning of the 3rd. 00:25:48.680 --> 00:25:51.859 Very low on the western horizon, so it's going 00:25:51.859 --> 00:25:54.839 to be a tough one for some of us to spot. Now 00:25:54.839 --> 00:25:57.200 while the moon steals the spotlight this week, 00:25:57.279 --> 00:25:59.480 the planets are still putting on their quiet 00:25:59.480 --> 00:26:02.640 show. Jupiter shines brightly in the evening 00:26:02.640 --> 00:26:05.660 sky, still positioned among the stars of Gemini. 00:26:06.240 --> 00:26:08.480 It's one of the brightest objects overhead after 00:26:08.480 --> 00:26:13.400 sunset, outshining nearby stars Castor and Pollux. 00:26:13.640 --> 00:26:16.640 Low in the western twilight, Mercury lingers, 00:26:16.700 --> 00:26:20.059 but it's a fleeting target. Around March 7th, 00:26:20.059 --> 00:26:23.119 it reaches inferior conjunction, passing between 00:26:23.119 --> 00:26:26.480 Earth and the Sun, which means it will be extremely 00:26:26.480 --> 00:26:29.359 difficult to see by week's end. Catch it early 00:26:29.359 --> 00:26:31.759 in the week if you have a very clear western 00:26:31.759 --> 00:26:36.019 horizon. Venus also glows in the dusk. Near the 00:26:36.019 --> 00:26:38.519 end of the week it draws close to Neptune in 00:26:38.519 --> 00:26:41.880 a conjunction, though Neptune itself will require 00:26:41.880 --> 00:26:45.259 binoculars and very steady skies to glimpse. 00:26:46.200 --> 00:26:48.839 I'd plan to get into the next two chapters of 00:26:48.839 --> 00:26:51.359 Night Watch in this episode, but let's hold off 00:26:51.359 --> 00:26:54.079 on that discussion until next week. We'll be 00:26:54.079 --> 00:26:56.599 discussing the outer planets in the next episode, 00:26:56.740 --> 00:26:59.700 so the chapter about the planets should fit nicely 00:26:59.700 --> 00:27:05.440 into our discussion. That's going to do it for 00:27:05.440 --> 00:27:07.859 this week. If you found this episode interesting, 00:27:08.059 --> 00:27:10.019 please share it with a friend who might enjoy 00:27:10.019 --> 00:27:12.640 it. The easiest way to do that is by sending 00:27:12.640 --> 00:27:16.740 folks to our website, StarTrails .Show. And if 00:27:16.740 --> 00:27:18.960 you want to support the show, use the link on 00:27:18.960 --> 00:27:21.680 the site to buy me a coffee. That really helps. 00:27:22.359 --> 00:27:25.240 Be sure to follow Star Trails on Blue Sky and 00:27:25.240 --> 00:27:28.460 YouTube. Links are in the show notes. Until we 00:27:28.460 --> 00:27:31.440 meet again beneath the stars, clear skies everyone.