WEBVTT 00:00:07.509 --> 00:00:10.150 Howdy Star Gazers and welcome to this episode 00:00:10.150 --> 00:00:13.710 of Star Trails. Drew here, and I'll be your guide 00:00:13.710 --> 00:00:17.269 to the night sky for the week starting May 25th 00:00:17.269 --> 00:00:21.510 through the 31st. This week a new moon promises 00:00:21.510 --> 00:00:24.789 darker skies, and have you ever wondered why 00:00:24.789 --> 00:00:29.109 we have red, blue, and yellow stars, but no green 00:00:29.109 --> 00:00:33.390 ones? More on that in a moment. Also, this is 00:00:33.390 --> 00:00:35.929 going to be a shorter episode this week because 00:00:35.929 --> 00:00:39.869 I'm losing my voice. I apologize for the raspy 00:00:39.869 --> 00:00:43.250 narration. Whether you're tuning in from the 00:00:43.250 --> 00:00:46.250 backyard, the balcony, or just your imagination, 00:00:46.530 --> 00:00:49.950 I'm glad you're here. So find a cozy spot, let 00:00:49.950 --> 00:00:52.750 your eyes adjust, and let's see what the sky 00:00:52.750 --> 00:00:57.200 holds for us this week. We kick things off this 00:00:57.200 --> 00:01:00.240 week with the moon in a waning crescent phase. 00:01:00.979 --> 00:01:04.000 It's just a sliver in the pre -dawn sky, only 00:01:04.000 --> 00:01:08.159 about 4 % illuminated. It's a great time for 00:01:08.159 --> 00:01:11.900 stargazers to enjoy truly dark skies before moonlight 00:01:11.900 --> 00:01:16.319 returns. Then on the night of May 26, we hit 00:01:16.319 --> 00:01:20.069 the new moon. That means this is your prime window 00:01:20.069 --> 00:01:23.790 for deep sky observing. No moonlight at all to 00:01:23.790 --> 00:01:28.430 wash out faint galaxies or nebula. By May 31st, 00:01:28.469 --> 00:01:31.590 the moon is back as a waning crescent, now about 00:01:31.590 --> 00:01:35.450 24 % illuminated, and beginning to reappear in 00:01:35.450 --> 00:01:39.129 the western sky after sunset. It's just enough 00:01:39.129 --> 00:01:43.250 to show off that beautiful Earthshine glow that's 00:01:43.250 --> 00:01:46.769 light reflected off Earth that dimly illuminates 00:01:46.769 --> 00:01:50.849 the shadowed portion of the moon. Now onto the 00:01:50.849 --> 00:01:53.370 planets, and if you've been listening in recent 00:01:53.370 --> 00:01:56.609 weeks, this is going to all sound familiar, because 00:01:56.609 --> 00:02:00.109 not much has changed. In the evening sky, you 00:02:00.109 --> 00:02:03.150 can still catch Jupiter just after sunset in 00:02:03.150 --> 00:02:06.750 the northwest. It's bright but slipping closer 00:02:06.750 --> 00:02:09.629 to the horizon each night as it moves toward 00:02:09.629 --> 00:02:12.830 conjunction with the sun. If you want to look, 00:02:12.870 --> 00:02:16.169 get out early, around twilight, before it sets. 00:02:17.090 --> 00:02:20.810 Mars is much easier to spot. You'll find it high 00:02:20.810 --> 00:02:24.270 overhead after dark, shining with its trademark 00:02:24.270 --> 00:02:28.009 reddish hue. It's not as bright as it was earlier 00:02:28.009 --> 00:02:30.969 in the year, but still a rewarding target for 00:02:30.969 --> 00:02:34.629 binoculars or a telescope. Meanwhile, in the 00:02:34.629 --> 00:02:38.009 morning sky, Venus continues to dominate the 00:02:38.009 --> 00:02:41.449 east just before dawn. It's the brightest object 00:02:41.449 --> 00:02:44.610 in the sky aside from the moon, and it rises 00:02:44.610 --> 00:02:48.030 well before the sun, perfect for early risers. 00:02:48.990 --> 00:02:52.629 Just above Venus, you'll find Saturn in the southeastern 00:02:52.629 --> 00:02:56.110 sky. It's much fainter than Venus, but still 00:02:56.110 --> 00:02:59.590 visible to the naked eye under clear skies, and 00:02:59.590 --> 00:03:10.689 a telescope will reveal those iconic rings. With 00:03:10.689 --> 00:03:14.090 the new moon arriving on May 26, we have a perfect 00:03:14.090 --> 00:03:17.250 window for deep sky viewing. So if you have a 00:03:17.250 --> 00:03:20.289 telescope or even just a decent pair of binoculars, 00:03:20.810 --> 00:03:23.830 here are five cosmic showpieces worth tracking 00:03:23.830 --> 00:03:28.870 down. First up is Messier 13, the Great Hercules 00:03:28.870 --> 00:03:32.889 Cluster. This dense ball of stars lies about 00:03:32.889 --> 00:03:36.930 22 ,000 light -years away and is easy to find 00:03:36.930 --> 00:03:41.050 in the constellation Hercules. Through a telescope, 00:03:41.229 --> 00:03:44.800 it sparkles with thousands of tiny stars. like 00:03:44.800 --> 00:03:49.139 someone spilled stardust across the void. Next 00:03:49.139 --> 00:03:53.919 is Messier 5 in the constellation Serpens. It's 00:03:53.919 --> 00:03:56.860 one of the oldest globular clusters we know, 00:03:57.319 --> 00:04:01.439 about 13 billion years old. That means it's been 00:04:01.439 --> 00:04:05.000 around since nearly the dawn of the galaxy. Look 00:04:05.000 --> 00:04:08.159 for a tightly packed core surrounded by a soft 00:04:08.159 --> 00:04:13.069 halo of light. Over in Virgo, check out the Sombrero 00:04:13.069 --> 00:04:18.470 Galaxy or Messier 104. It's a spiral galaxy seen 00:04:18.470 --> 00:04:22.209 almost edge -on with a bright central bulge and 00:04:22.209 --> 00:04:25.490 a dark dust lane that gives it that classic hat 00:04:25.490 --> 00:04:30.750 shape. It stands out even in modest scopes. Then 00:04:30.750 --> 00:04:34.949 we have Messier 3, a globular cluster in Canes 00:04:34.949 --> 00:04:38.769 Venetici. It's packed with variable stars, more 00:04:38.769 --> 00:04:42.610 than 270 of them, which makes it a real laboratory 00:04:42.610 --> 00:04:46.730 for studying how stars evolve. It's bright, round, 00:04:47.029 --> 00:04:50.750 and rewarding through almost any telescope. And 00:04:50.750 --> 00:04:53.629 finally, for a true showstopper, aim for the 00:04:53.629 --> 00:04:58.910 Whirlpool Galaxy or Messier 51. It's a face -on 00:04:58.910 --> 00:05:02.470 spiral interacting with a smaller companion galaxy, 00:05:02.810 --> 00:05:05.870 and under dark skies, you might even glimpse 00:05:05.870 --> 00:05:09.509 the spiral arms twisting outward. It's a favorite 00:05:09.509 --> 00:05:19.129 for a reason. I'm sure you've noticed that some 00:05:19.129 --> 00:05:23.649 stars are different colors. A star's color depends 00:05:23.649 --> 00:05:27.279 on its temperature. But here's the twist. For 00:05:27.279 --> 00:05:30.920 all the colors we can see in stars, there's one 00:05:30.920 --> 00:05:35.439 that's curiously missing – green. You have red 00:05:35.439 --> 00:05:39.740 stars, orange stars, white, blue, but green is 00:05:39.740 --> 00:05:42.959 nowhere to be found, and that's strange because 00:05:42.959 --> 00:05:45.920 the universe is packed with glowing, energetic 00:05:45.920 --> 00:05:49.639 objects, and plenty of them emit green light. 00:05:50.240 --> 00:05:53.560 So why doesn't the sky have any green stars? 00:05:54.400 --> 00:05:57.600 Stars shine because of their surface temperature. 00:05:58.100 --> 00:06:01.040 The hotter the star, the bluer its light appears. 00:06:01.600 --> 00:06:05.439 The cooler it is, the redder. Our own sun, for 00:06:05.439 --> 00:06:08.759 example, is classified as a G -type star with 00:06:08.759 --> 00:06:12.019 a surface temperature of about 5 ,800 Kelvin. 00:06:13.279 --> 00:06:16.399 It actually emits most of its light in the green 00:06:16.399 --> 00:06:19.800 part of the spectrum, but we don't see it as 00:06:19.800 --> 00:06:25.220 green. Stars don't shine in just one color. They 00:06:25.220 --> 00:06:28.319 emit light across a wide range of wavelengths, 00:06:28.839 --> 00:06:31.879 and our eyes, clever as they are, don't pick 00:06:31.879 --> 00:06:35.879 out individual bands. When a star's spectrum 00:06:35.879 --> 00:06:39.379 peeks in the green zone, our brain blends all 00:06:39.379 --> 00:06:42.360 the surrounding colors together and interprets 00:06:42.360 --> 00:06:46.819 the result as white. It's exactly the same principle 00:06:46.819 --> 00:06:49.959 used in old -school televisions and computer 00:06:49.959 --> 00:06:53.939 monitors. Those screens create white by blending 00:06:53.939 --> 00:06:57.480 three colors, red, green, and blue, at the right 00:06:57.480 --> 00:07:00.980 intensity. When all three are mixed evenly, your 00:07:00.980 --> 00:07:04.980 eye sees white. So when a star peaks in green, 00:07:05.120 --> 00:07:07.540 but also gives off a balanced amount of every 00:07:07.540 --> 00:07:11.339 other color, your brain says, that's white, even 00:07:11.339 --> 00:07:13.980 if green is doing most of the heavy lifting. 00:07:14.680 --> 00:07:19.000 If a star somehow emitted only green light, just 00:07:19.000 --> 00:07:22.620 that wavelength, no extras. We would see it as 00:07:22.620 --> 00:07:26.800 green, but that's not how stars work. Their energy 00:07:26.800 --> 00:07:30.660 is spread out in a smooth curve, not a laser 00:07:30.660 --> 00:07:35.319 -sharp spike. Red and blue stars have lopsided 00:07:35.319 --> 00:07:39.160 spectrums. They emit strongly in just one part 00:07:39.160 --> 00:07:43.379 of the spectrum, so that color stands out. While 00:07:43.379 --> 00:07:46.199 there may be no green stars, the universe is 00:07:46.199 --> 00:07:49.980 still full of color. Take Beetlejuice, the reddish 00:07:49.980 --> 00:07:53.439 shoulder of Orion. That color comes from its 00:07:53.439 --> 00:07:57.560 relatively cool temperature, about 3 ,500 Kelvin. 00:07:58.279 --> 00:08:02.420 Then there's Rigel at Orion's knee, blazing blue 00:08:02.420 --> 00:08:05.800 -white with a temperature more than 11 ,000 Kelvin. 00:08:06.939 --> 00:08:09.720 Sometimes atmospheric conditions even create 00:08:09.720 --> 00:08:13.730 fake color effects. Stars near the horizon, for 00:08:13.730 --> 00:08:16.689 example, can appear to shimmer red, blue, or 00:08:16.689 --> 00:08:19.490 even green as their light passes through layers 00:08:19.490 --> 00:08:22.850 of Earth's atmosphere. It's like the twinkling 00:08:22.850 --> 00:08:26.649 version of a prism. And then there are optical 00:08:26.649 --> 00:08:31.149 illusions. Take Alberio, a famous double star 00:08:31.149 --> 00:08:35.450 in Cygnus. One component appears gold, the other 00:08:35.450 --> 00:08:39.450 blue. That contrast can be so striking that some 00:08:39.450 --> 00:08:42.470 observers describe the blue star as looking slightly 00:08:42.470 --> 00:08:45.850 green. It's not actually green, but your eyes 00:08:45.850 --> 00:08:48.690 get a little tricked by the color pairing. And 00:08:48.690 --> 00:08:52.450 let's not forget, stars emit light beyond what 00:08:52.450 --> 00:08:57.110 our eyes can see. Some glow fiercely in ultraviolet 00:08:57.110 --> 00:09:00.610 or infrared wavelengths. That's where telescopes 00:09:00.610 --> 00:09:03.990 like the James Webb and Hubble come in. They 00:09:03.990 --> 00:09:06.950 can detect these invisible colors and convert 00:09:06.950 --> 00:09:10.409 them into images we can see, giving us a richer, 00:09:10.669 --> 00:09:19.009 more complete view of the universe. If the stars 00:09:19.009 --> 00:09:21.629 spoke to you this week or if a question's been 00:09:21.629 --> 00:09:24.389 on your mind, I'd love to hear it. Visit our 00:09:24.389 --> 00:09:28.610 website StarTrails .Show where you can contact 00:09:28.610 --> 00:09:32.730 me and explore past episodes. Be sure to follow 00:09:32.730 --> 00:09:37.070 us on Mastodon, Blue Sky, and YouTube. Links 00:09:37.070 --> 00:09:40.169 are in the show notes. Until we meet again beneath 00:09:40.169 --> 00:09:42.509 the stars, clear skies everyone.