WEBVTT 00:00:07.690 --> 00:00:10.429 Howdy Star Gazers and welcome to this episode 00:00:10.429 --> 00:00:13.849 of Star Trails. I'm Drew and I'll be your guide 00:00:13.849 --> 00:00:16.350 to the night sky for the week starting May the 00:00:16.350 --> 00:00:20.230 4th through the 10th. This week the moon brightens, 00:00:20.449 --> 00:00:23.050 some familiar planets are still hanging around, 00:00:23.350 --> 00:00:26.210 and we have a unique opportunity to potentially 00:00:26.210 --> 00:00:29.870 view an asteroid. Later in the show we'll take 00:00:29.870 --> 00:00:32.469 a look at one of the most exciting fields in 00:00:32.469 --> 00:00:36.390 astronomy the study of exoplanets and Some of 00:00:36.390 --> 00:00:38.990 the weird worlds that have been discovered in 00:00:38.990 --> 00:00:42.689 recent years So grab a comfortable spot under 00:00:42.689 --> 00:00:47.909 the night sky and let's get started We kick things 00:00:47.909 --> 00:00:50.789 off with the first quarter moon which arrives 00:00:50.789 --> 00:00:54.460 tonight That means each night this week the moon 00:00:54.460 --> 00:00:57.259 will be waxing, getting brighter and rising a 00:00:57.259 --> 00:01:00.340 bit later each evening. It's a great time for 00:01:00.340 --> 00:01:03.759 lunar observing. The shadows cast across the 00:01:03.759 --> 00:01:06.680 surface give craters and mountain ranges some 00:01:06.680 --> 00:01:10.140 awesome 3D definition through binoculars or a 00:01:10.140 --> 00:01:13.579 telescope. By the end of the week, the moon will 00:01:13.579 --> 00:01:16.760 be edging towards this month's full moon, known 00:01:16.760 --> 00:01:20.299 as the Flower Moon, which also happens to be 00:01:20.299 --> 00:01:24.099 another micro moon. That simply means that it's 00:01:24.099 --> 00:01:26.560 farther from Earth in its slightly elliptical 00:01:26.560 --> 00:01:30.599 orbit, and about 14 % smaller than a super moon. 00:01:31.700 --> 00:01:35.140 Now onto the planets. Let's start with the evening 00:01:35.140 --> 00:01:38.469 show. Right after sunset, look to the west and 00:01:38.469 --> 00:01:41.329 you'll spot Jupiter, still holding on in the 00:01:41.329 --> 00:01:44.969 twilight. It's bright and steady, easy to spot 00:01:44.969 --> 00:01:47.890 with the naked eye. It'll set before midnight, 00:01:48.129 --> 00:01:51.590 so catch it early. A little higher up, you'll 00:01:51.590 --> 00:01:54.790 find Mars, the red planet. It's fainter than 00:01:54.790 --> 00:01:58.109 Jupiter, but that warm, ruddy glow gives it away. 00:01:58.400 --> 00:02:02.079 This week the moon passes near Mars in the evening 00:02:02.079 --> 00:02:05.299 sky, resulting in a lovely pairing to check out 00:02:05.299 --> 00:02:09.819 tonight, just after sunset. Let's shift our gaze 00:02:09.819 --> 00:02:13.319 to the early morning. Venus, the morning star, 00:02:13.599 --> 00:02:16.500 is rising in the east about 30 to 40 minutes 00:02:16.500 --> 00:02:20.599 before sunrise. It's brilliant, by far the brightest 00:02:20.599 --> 00:02:23.840 planet in the sky, and if you have a clear eastern 00:02:23.840 --> 00:02:27.740 horizon, it's hard to miss. Just above Venus 00:02:27.740 --> 00:02:31.259 sits Saturn, fainter and more subdued in golden 00:02:31.259 --> 00:02:34.180 light, but still visible with binoculars and 00:02:34.180 --> 00:02:36.639 definitely worth a look through a telescope if 00:02:36.639 --> 00:02:40.090 you're up before dawn. Mercury is also hanging 00:02:40.090 --> 00:02:42.930 out low in the eastern sky, but this one's a 00:02:42.930 --> 00:02:46.509 bit trickier. It's hugging the horizon and may 00:02:46.509 --> 00:02:49.169 get lost in the morning light. If you want to 00:02:49.169 --> 00:02:52.530 try for it, aim for about 20 minutes before sunrise 00:02:52.530 --> 00:02:55.610 and make sure you have a completely unobstructed 00:02:55.610 --> 00:03:05.949 view of the east. This week we have a special 00:03:05.949 --> 00:03:09.830 opportunity to see an asteroid. From now until 00:03:09.830 --> 00:03:12.930 the end of the week is an excellent viewing window 00:03:12.930 --> 00:03:16.469 to spot Vesta, the brightest asteroid visible 00:03:16.469 --> 00:03:20.689 from Earth. Vesta is one of the largest bodies 00:03:20.689 --> 00:03:23.770 in the asteroid belt, hanging out between Mars 00:03:23.770 --> 00:03:28.780 and Jupiter. It spans about 326 miles across, 00:03:29.159 --> 00:03:32.300 that's roughly the size of Arizona, and it's 00:03:32.300 --> 00:03:36.539 the second largest asteroid after Ceres. What 00:03:36.539 --> 00:03:39.659 makes Vesta especially cool is that it's big 00:03:39.659 --> 00:03:42.300 and reflective enough that you might actually 00:03:42.300 --> 00:03:46.020 see it with binoculars. Under really dark skies, 00:03:46.280 --> 00:03:49.400 you might even catch it with the naked eye. Right 00:03:49.400 --> 00:03:52.840 now, Vesta is near opposition. That just means 00:03:52.840 --> 00:03:56.780 it's directly opposite the Sun in our sky, and 00:03:56.780 --> 00:04:00.000 also the closest it will get to Earth this year. 00:04:00.699 --> 00:04:04.620 It rises around sunset, stays up all night, and 00:04:04.620 --> 00:04:08.180 sets at sunrise. Those are prime viewing conditions. 00:04:09.180 --> 00:04:12.120 To find it, look toward the constellation Libra, 00:04:12.340 --> 00:04:14.979 which is climbing in the southeastern sky after 00:04:14.979 --> 00:04:19.040 dark. It's nestled just to the east of Virgo, 00:04:19.120 --> 00:04:22.209 so if you can find the bright star Spica, You're 00:04:22.209 --> 00:04:25.490 on the right track. You'll need a good star chart 00:04:25.490 --> 00:04:29.329 or a stargazing app to pinpoint Vesta's exact 00:04:29.329 --> 00:04:32.709 location, since it looks just like a faint star. 00:04:33.370 --> 00:04:36.790 Here's one handy trick. If you make note of Vesta's 00:04:36.790 --> 00:04:39.389 position one night and come back a day or two 00:04:39.389 --> 00:04:43.209 later, you'll notice that it's moved. That slow 00:04:43.209 --> 00:04:46.089 shift is how you know you're looking at an asteroid. 00:04:46.899 --> 00:04:50.199 Right now Vesta is shining at about magnitude 00:04:50.199 --> 00:04:54.100 5 .6, which puts it right on the edge of naked 00:04:54.100 --> 00:04:57.259 eye visibility, but binoculars will give you 00:04:57.259 --> 00:05:01.620 a much better chance. A basic pair of 7x50s or 00:05:01.620 --> 00:05:05.339 higher will do just fine. So if you're outside 00:05:05.339 --> 00:05:07.920 this week enjoying the night sky, take a few 00:05:07.920 --> 00:05:11.160 minutes to track down Vesta. And if you'd like 00:05:11.160 --> 00:05:14.009 to know more about the asteroid belt, Go back 00:05:14.009 --> 00:05:17.730 and listen to episode 46, where we also take 00:05:17.730 --> 00:05:20.769 a moment to highlight Ceres, the largest object 00:05:20.769 --> 00:05:30.310 in the belt. We've gazed at the moon and planets 00:05:30.310 --> 00:05:33.709 of our solar system. We've chased meteor showers. 00:05:33.970 --> 00:05:36.990 We've traced the constellations, but tonight 00:05:36.990 --> 00:05:40.870 we're heading out even farther. to planets orbiting 00:05:40.870 --> 00:05:45.990 stars that aren't our sun. These are the exoplanets, 00:05:46.230 --> 00:05:48.850 and once you start exploring them, it's hard 00:05:48.850 --> 00:05:52.269 not to feel a sense of wonder that borders on 00:05:52.269 --> 00:05:55.529 science fiction, except that it's all very real. 00:05:56.610 --> 00:06:00.089 For most of human history, we had no solid evidence 00:06:00.089 --> 00:06:05.170 that exoplanets existed at all. We guessed. Philosophers, 00:06:05.389 --> 00:06:08.769 like Epicurus in ancient Greece, thought other 00:06:08.769 --> 00:06:12.649 worlds must exist. After all, why would the universe 00:06:12.649 --> 00:06:16.790 be built just for us? But until the late 20th 00:06:16.790 --> 00:06:19.850 century, the existence of other planetary systems 00:06:19.850 --> 00:06:23.870 was a complete unknown. Throughout my childhood, 00:06:24.110 --> 00:06:26.509 I always wondered if there were other planets 00:06:26.509 --> 00:06:30.050 out there. The science to find them simply didn't 00:06:30.050 --> 00:06:34.610 exist. That started to change in 1992, with a 00:06:34.610 --> 00:06:37.310 discovery that was both groundbreaking and kind 00:06:37.310 --> 00:06:41.569 of weird. Astronomers Alexander Walceson and 00:06:41.569 --> 00:06:45.810 Dale Frail found two planets orbiting a pulsar. 00:06:46.290 --> 00:06:49.769 That's a dead, collapsed star spinning like a 00:06:49.769 --> 00:06:52.550 cosmic lighthouse and blasting out radiation. 00:06:53.290 --> 00:06:56.649 Not exactly a peaceful place. But there they 00:06:56.649 --> 00:07:00.750 were, two exoplanets, small and rocky, caught 00:07:00.750 --> 00:07:04.350 in the gravitational grip of a dead sun. The 00:07:04.350 --> 00:07:07.389 way they discovered the exoplanets was unique. 00:07:08.089 --> 00:07:11.629 Pulsars are like cosmic clocks, and pulse in 00:07:11.629 --> 00:07:15.529 very regular intervals. In this case, the pulsar 00:07:15.529 --> 00:07:19.310 being studied is about 2300 light years away. 00:07:20.110 --> 00:07:23.149 Every now and then, scientists noticed the pulses 00:07:23.149 --> 00:07:26.990 were a little off. although the off -beats still 00:07:26.990 --> 00:07:31.230 came at predictable intervals. After some theorizing, 00:07:31.610 --> 00:07:34.310 Waltzesen and Frail determined there had to be 00:07:34.310 --> 00:07:37.689 two planets up to four times the mass of Earth 00:07:37.689 --> 00:07:42.149 orbiting the pulsar approximately every 67 and 00:07:42.149 --> 00:07:46.850 98 days. Just three years later came the breakthrough 00:07:46.850 --> 00:07:51.230 that truly kickstarted the exoplanet era, 51 00:07:51.230 --> 00:07:55.199 Pegasi b. This was the first planet discovered 00:07:55.199 --> 00:07:59.240 orbiting a sun -like star. It's a gas giant, 00:07:59.399 --> 00:08:02.779 but it orbits extremely close to its star, completing 00:08:02.779 --> 00:08:06.540 a full orbit in just over four days. Imagine 00:08:06.540 --> 00:08:09.819 if your year lasted less than a school week. 00:08:10.540 --> 00:08:13.500 This type of world came to be known as a hot 00:08:13.500 --> 00:08:17.660 Jupiter. Massive like our own Jupiter, but much 00:08:17.660 --> 00:08:21.990 closer to its star. The reason we found hot Jupiters 00:08:21.990 --> 00:08:24.949 first is simply because they're big, they orbit 00:08:24.949 --> 00:08:27.910 fast, and they interact with their stars in a 00:08:27.910 --> 00:08:31.250 way that we can actually detect. You'd think 00:08:31.250 --> 00:08:34.490 we'd just point our telescopes at stars and spot 00:08:34.490 --> 00:08:38.049 their planets, but it's not that easy. Imagine 00:08:38.049 --> 00:08:41.269 trying to see a tiny, unlit mosquito buzzing 00:08:41.269 --> 00:08:44.330 around a floodlight from hundreds of miles away. 00:08:44.750 --> 00:08:48.049 The star completely overwhelms the faint light 00:08:48.049 --> 00:08:51.169 from the planet, especially since exoplanets 00:08:51.169 --> 00:08:54.029 don't give off their own light, they just reflect 00:08:54.029 --> 00:08:58.149 it. So, astronomers had to get clever. The first 00:08:58.149 --> 00:09:01.210 method that really worked was the radial velocity 00:09:01.210 --> 00:09:05.350 method, also called the wobble method. As a planet 00:09:05.350 --> 00:09:08.690 orbits a star, its gravity tugs on the star just 00:09:08.690 --> 00:09:11.669 a little bit, enough to make the star wobble 00:09:11.669 --> 00:09:15.240 very slightly. We can measure that wobble by 00:09:15.240 --> 00:09:19.100 looking at the star's spectral lines. Those are 00:09:19.100 --> 00:09:21.919 the fingerprints of elements in the starlight. 00:09:22.620 --> 00:09:25.720 If the lines shift back and forth like a Doppler 00:09:25.720 --> 00:09:29.000 effect, we know the star is being tugged and 00:09:29.000 --> 00:09:32.840 a planet is the likely culprit. Then came the 00:09:32.840 --> 00:09:35.580 transit method, which completely changed the 00:09:35.580 --> 00:09:38.899 game. If a planet happens to pass in front of 00:09:38.899 --> 00:09:42.480 its star from our line of sight, the light from 00:09:42.480 --> 00:09:46.039 the star dips just a tiny bit. If it does this 00:09:46.039 --> 00:09:49.360 on a regular schedule, we probably have a planet. 00:09:50.000 --> 00:09:53.320 This method is what made the Kepler Space Telescope 00:09:53.320 --> 00:09:57.990 a superstar. Launched in 2009, Kepler stared 00:09:57.990 --> 00:10:02.110 at more than 150 ,000 stars and ended up discovering 00:10:02.110 --> 00:10:06.649 more than 2 ,600 confirmed exoplanets, with thousands 00:10:06.649 --> 00:10:10.009 more candidates. It was like turning on a light 00:10:10.009 --> 00:10:13.370 in a dark room. Suddenly, we weren't just hoping 00:10:13.370 --> 00:10:16.950 there were other worlds, we knew. But even with 00:10:16.950 --> 00:10:21.029 Kepler and now TESS, the Transiting Exoplanet 00:10:21.029 --> 00:10:24.710 Survey Satellite, it's still a challenge. Planets 00:10:24.710 --> 00:10:27.509 have to line up just right for the transit method 00:10:27.509 --> 00:10:30.669 to work. If their orbit tilts even slightly, 00:10:30.809 --> 00:10:34.149 we might miss them entirely, and some signals 00:10:34.149 --> 00:10:36.870 are so faint they can get lost in the stellar 00:10:36.870 --> 00:10:39.769 noise, like trying to hear a whisper during a 00:10:39.769 --> 00:10:44.070 rock concert. However, the tools keep getting 00:10:44.070 --> 00:10:47.970 better. Enter the James Webb Space Telescope. 00:10:48.629 --> 00:10:52.450 Not only can Webb detect exoplanets, it can analyze 00:10:52.450 --> 00:10:55.320 their atmospheres. That's done through something 00:10:55.320 --> 00:10:59.299 called transmission spectroscopy. When a planet 00:10:59.299 --> 00:11:03.000 passes in front of its star, a tiny bit of starlight 00:11:03.000 --> 00:11:06.539 filters through the planet's atmosphere. By studying 00:11:06.539 --> 00:11:09.240 that light, we can tell what the atmosphere is 00:11:09.240 --> 00:11:13.159 made of. Water vapor, methane, carbon dioxide, 00:11:13.539 --> 00:11:16.659 and more. It's like doing a chemical test on 00:11:16.659 --> 00:11:20.500 something a hundred light years away. Let's talk 00:11:20.500 --> 00:11:24.000 about some notable exoplanets, and some of these 00:11:24.000 --> 00:11:31.919 are quite weird. HD 189733b is a cobalt blue 00:11:31.919 --> 00:11:36.659 gas giant with winds up to 5400 miles per hour, 00:11:37.320 --> 00:11:40.860 and it's thought to have glass rain that whips 00:11:40.860 --> 00:11:46.269 sideways. Kepler -16b orbiting two suns is a 00:11:46.269 --> 00:11:50.110 real -life Star Wars scenario, like the planet 00:11:50.110 --> 00:11:55.269 Tatooine, where Luke Skywalker grew up. Wasp 00:11:55.269 --> 00:11:58.730 -12b, which is so close to its star that it's 00:11:58.730 --> 00:12:02.230 slowly being consumed, is actually falling apart. 00:12:04.539 --> 00:12:08.860 GJ 1214b is a mini -Neptune, covered in thick 00:12:08.860 --> 00:12:12.460 clouds of water vapor, and maybe even has a planet 00:12:12.460 --> 00:12:15.919 -wide ocean. And you may have heard of this one, 00:12:16.299 --> 00:12:20.759 Trappist 1, a red dwarf star with seven rocky 00:12:20.759 --> 00:12:24.200 planets. At least three are in the habitable 00:12:24.200 --> 00:12:27.700 zone, a place where liquid water might exist. 00:12:28.169 --> 00:12:31.029 We're still trying to answer the big questions. 00:12:31.210 --> 00:12:34.870 How common are Earth -like planets? Are we likely 00:12:34.870 --> 00:12:38.169 to find one nearby? And the biggest of them all, 00:12:38.190 --> 00:12:41.269 could any of them harbor life? We're getting 00:12:41.269 --> 00:12:44.850 closer to finding the ingredients for life, and 00:12:44.850 --> 00:12:48.009 future missions like the Nancy Grace Roman Space 00:12:48.009 --> 00:12:51.610 Telescope and the European Space Agency's PLATO 00:12:51.610 --> 00:12:55.960 mission will keep scanning the skies. Some upcoming 00:12:55.960 --> 00:12:59.679 concepts even include star shades, screens that 00:12:59.679 --> 00:13:02.559 block out a star's light so we can see the faint 00:13:02.559 --> 00:13:06.220 planets next to it. So next time you're looking 00:13:06.220 --> 00:13:10.639 at the sky, pick a star. Odds are it has planets. 00:13:11.000 --> 00:13:15.139 Maybe rocky, maybe gaseous, maybe icy, maybe 00:13:15.139 --> 00:13:18.779 just like Earth. We've gone from guessing they 00:13:18.779 --> 00:13:22.480 existed to discovering more than 5 ,000 of them, 00:13:22.700 --> 00:13:31.019 and We're just getting started. If you found 00:13:31.019 --> 00:13:33.659 this episode helpful, let me know and feel free 00:13:33.659 --> 00:13:36.840 to send in your questions and observations. The 00:13:36.840 --> 00:13:39.940 easiest way to do that is by visiting our website, 00:13:40.240 --> 00:13:44.139 StarTrails .Show. This is also a great way to 00:13:44.139 --> 00:13:47.080 share the show with friends. Until next time, 00:13:47.220 --> 00:13:49.799 keep looking up and exploring the night sky. 00:13:50.379 --> 00:13:51.440 Clear skies everyone!