WEBVTT 1 00:00:00.240 --> 00:00:05.040 This is Spacetime Series twenty six, Episode fifty four, for broadcast on the 2 00:00:05.080 --> 00:00:10.880 fifth of May twenty twenty three. Coming up on Spacetime, changing our view 3 00:00:10.880 --> 00:00:16.640 of the nature of dark matter, Europe's Integral Spacecraft, Safer Last and Rocket 4 00:00:16.679 --> 00:00:22.600 Labs, New Electrons Sounding Rocket, All that and more coming up on Spacetime. 5 00:00:24.079 --> 00:00:45.679 Welcome to Spacetime with Stewart Garry. A new study claims that ultra lightweight 6 00:00:45.799 --> 00:00:51.560 particles based on the hypothetical Axeon acting in waves could provide the answer to the 7 00:00:51.640 --> 00:00:57.159 long standing mystery of dark matter. It's a disturbing fact that most of the 8 00:00:57.200 --> 00:01:00.880 matter in the universe, amounting to his staggering eighty five percent by mass, 9 00:01:02.159 --> 00:01:07.519 cannot be observed and consists of particles not accounted for by the standard model of 10 00:01:07.519 --> 00:01:11.480 particle physics, the foundation stone upon which science is understanding of the universe is 11 00:01:11.519 --> 00:01:17.599 based. What that means is that everything we see in the universe, from 12 00:01:17.640 --> 00:01:22.959 the largest galaxies and stars, through the planet's asteroids, moons, right down 13 00:01:23.000 --> 00:01:26.719 to the Earth. People, houses, cars, trees, dogs and cats 14 00:01:26.120 --> 00:01:30.959 make up only fifteen percent of the total mass of the universe. And for 15 00:01:32.040 --> 00:01:38.480 a scientist that's really disturbing. As For the other eighty five percent, scientists 16 00:01:38.560 --> 00:01:42.920 refer to it as dark matter they not exist because they can see it's gravitational 17 00:01:44.000 --> 00:01:48.640 influence on the things we can see. Without dark matter, galaxies would fling 18 00:01:48.680 --> 00:01:53.239 apart as they rotate. But as to what dark matter is or that's the 19 00:01:53.319 --> 00:01:59.640 mystery for us, it's invisible mysteries as something scientists like to solve. So 20 00:02:00.040 --> 00:02:04.519 finding the particle that makes up dark matter is an urgent problem in modern physics. 21 00:02:05.159 --> 00:02:07.960 Not only would it solve many problems in our current understanding of the universe, 22 00:02:08.080 --> 00:02:13.159 but it would also provide a glimpse into a realm of new physics beyond 23 00:02:13.199 --> 00:02:17.719 the standard model, and that is intriguing. While some theoretical models proposed the 24 00:02:17.759 --> 00:02:23.400 existence of ultra massive subatomic particles as a possible candidate for dark matter, others 25 00:02:23.439 --> 00:02:30.439 suggest ultra lightweight particles. Now, a report in the journal Nature Astronomy has 26 00:02:30.479 --> 00:02:36.120 provided the most direct evidence yet that dark matter does not constitute ultra massive particles, 27 00:02:36.159 --> 00:02:40.560 but instead comprises particles so light that they travel through space in waves. 28 00:02:42.479 --> 00:02:46.439 If correct, this work could resolve an outstanding problem in astrophysics first race two 29 00:02:46.439 --> 00:02:53.800 decades ago. Problem was why do models that adopt ultra massive dark matter particles 30 00:02:53.840 --> 00:02:59.360 failed to correctly predict the observational position and brightnesses of multiple images of the same 31 00:02:59.439 --> 00:03:05.199 galaxy created through gravitational lensing. We know dark matter does not emit, absorb, 32 00:03:05.319 --> 00:03:08.879 or reflect light, which makes it difficult to observe using traditional astronomical techniques. 33 00:03:09.520 --> 00:03:14.599 Today, the most powerful tool sitists have for stating dark matter is through 34 00:03:14.680 --> 00:03:20.080 gravitational lensing. The phenomenon first predicted by Albert Einstein in this theory of general 35 00:03:20.120 --> 00:03:24.000 relativity. Now, in this theory, mass causes space time to curve, 36 00:03:24.280 --> 00:03:29.960 and that creates the appearance that light bends around massive objects such as stars, 37 00:03:30.000 --> 00:03:34.759 galaxies, or groups of galaxies. Now that bending light acts like a lens, 38 00:03:35.000 --> 00:03:39.439 allowing you to see clearly more distant objects. It's an important astronomical tool, 39 00:03:40.199 --> 00:03:45.680 and conversely, by observing this bending of light, astronomers can infer the 40 00:03:45.719 --> 00:03:51.159 presence and distribution of dark matter. Now in gravitational lensing, when the foreground 41 00:03:51.280 --> 00:03:57.120 lensing object and the background lensed object, both constituting individual galaxies, are closely 42 00:03:57.159 --> 00:04:00.520 aligned, modible images of the same background an object can be seen in the 43 00:04:00.560 --> 00:04:06.000 sky, but the positions and brightnesses of the multiply lensed images all depends on 44 00:04:06.080 --> 00:04:11.599 the distribution of dark matter in the four ground lensing object, thus providing a 45 00:04:11.680 --> 00:04:16.439 especially powerful probe of dark matter. Back in the nineteen seventies, hypothetical particles 46 00:04:16.480 --> 00:04:21.639 referred to as weakly interacting massive particles or whimps were proposed as the most likely 47 00:04:21.720 --> 00:04:27.120 candidates for dark matter. Now, the whimps were thought to be ultra massive 48 00:04:27.399 --> 00:04:30.720 that is, more than at least ten times as massive as a proton, 49 00:04:30.399 --> 00:04:35.639 that they interact only with matter through the week nuclear force. The particles emerged 50 00:04:35.680 --> 00:04:41.199 from supersymmetry theories, which would developed to fill deficiencies in the standard model. 51 00:04:41.639 --> 00:04:45.920 However, over the past two decades, adapting ultra massive particles for dark matter 52 00:04:46.079 --> 00:04:51.959 have left astrophysicists struggling to correctly reproduce the positions and brightnesses of multi lensed images. 53 00:04:53.720 --> 00:04:58.160 In these studies, the density of dark matter is assumed to decrease smoothly 54 00:04:58.199 --> 00:05:02.920 outwards from the centers of galaxi, in accordance with theoretical simulations employing ultra massive 55 00:05:03.000 --> 00:05:09.600 particles beginning also in the nineteen seventies, but in dramatic contrast to whimps, 56 00:05:09.759 --> 00:05:14.639 versions of theories that seek to rectified efficiencies in the Standard model, or those 57 00:05:14.839 --> 00:05:18.199 such a string theory, which seek to unify the four fundamental forces of nature, 58 00:05:18.399 --> 00:05:23.480 meaning the three in the Standard model. These strong and weak nuclear forces 59 00:05:23.600 --> 00:05:28.839 and the electromagnetic force, along with gravity, have been advocating the existence of 60 00:05:29.040 --> 00:05:34.199 ultra light particles referred to as axions. These hypothetical particles are predicted to be 61 00:05:34.319 --> 00:05:39.680 far less massive than even the lightest particles in the Standard Model, and therefore 62 00:05:39.800 --> 00:05:44.680 constitute an alternative candidate to dark matter. Now, according to the theory of 63 00:05:44.720 --> 00:05:48.800 quantum mechanics, ultra light particles travel through space in waves, interfering with each 64 00:05:48.800 --> 00:05:56.040 other in such large numbers as to create random fluctuations in density. These random 65 00:05:56.079 --> 00:06:00.560 density fluctuations in dark matter give rise to well, I guess you call them 66 00:06:00.560 --> 00:06:04.759 crinkles in space time for the dark matter surrounding galaxies. Now, you'd expect 67 00:06:04.759 --> 00:06:11.759 that different patterns of spacetime around galaxies depending on whether dark matter constitute ultra massive 68 00:06:11.839 --> 00:06:15.639 or ultra light particles, in other words, smooth or wrinkly, or to 69 00:06:15.759 --> 00:06:20.319 give rise to different positions and brightnesses for moudibly lensed objects of background galaxies. 70 00:06:21.079 --> 00:06:26.000 The new work led by Alfred Amrit from the University of Hong Kong. It's 71 00:06:26.040 --> 00:06:32.120 calculated how gravitationally lensed images generated by galaxies incorporating ultra light dark matter particles would 72 00:06:32.160 --> 00:06:38.800 differ from those incorporating ultra massive dark matter particles. Their research has shown that 73 00:06:38.879 --> 00:06:44.040 the journal level of disagreement found between the observed and predicted positions, as well 74 00:06:44.040 --> 00:06:48.560 as the brightnesses of mudibly lensed images generated by models incorporating ultra massive dark matter, 75 00:06:48.879 --> 00:06:55.160 can be resolved if you simply adapt models incorporating ultra light dark matter particles. 76 00:06:55.399 --> 00:07:00.600 And they also show that models incorporating ultra light dark matter particles can reproduce 77 00:07:00.680 --> 00:07:05.360 the observed positions and brightnesses of multiply lensed galaxy images. Now, this is 78 00:07:05.399 --> 00:07:12.120 an important achievement, revealing the crinkly rather than smooth nature of space time around 79 00:07:12.160 --> 00:07:17.519 galaxies. The possibility that dark matter does not comprise ultra massive particles also alleviates 80 00:07:17.519 --> 00:07:24.800 other problems in both laboratory experiments and astronomical observations. You see, laboratory experience 81 00:07:24.839 --> 00:07:30.399 have been unsuccessful in finding whimsy, long favored candidate for dark matter. These 82 00:07:30.480 --> 00:07:34.720 experiments are now in their final stretch. They'll culminate with the plan down experiment, 83 00:07:35.240 --> 00:07:39.839 and that will leave whimps with no place to hide if they're not found. 84 00:07:41.000 --> 00:07:45.639 Also, if dark matter comprises ultra massive particles, then according to cosmological 85 00:07:45.680 --> 00:07:49.319 simulations, there should be hundreds of satellite galaxies surrounding our Milky Way galaxy. 86 00:07:49.560 --> 00:07:55.639 However, despite intensive searches, only fifty or so satellite galaxies have ever been 87 00:07:55.639 --> 00:07:59.920 discovered around the Milky Way. On the other hand, if dark matter comprised 88 00:08:00.279 --> 00:08:05.120 ultra light particles instead, then the theory of quantum mechanics predicts that galaxies below 89 00:08:05.160 --> 00:08:09.959 a certain mass simply can't form owing to the wave interference of these particles, 90 00:08:09.240 --> 00:08:13.199 which would explain why there is a few said light galaxies around the Milky Way. 91 00:08:13.759 --> 00:08:20.120 The studies authors say that incorporating ultra light rather than ultra massive particles for 92 00:08:20.240 --> 00:08:26.680 dark matter resolves several long outstanding problems simultaneously, both in particle physics and in 93 00:08:26.759 --> 00:08:35.440 astrophysics. It's an interesting and fascinating prospect this spacetime still to come. The 94 00:08:35.519 --> 00:08:41.919 European Space Agency's Intrial Spacecraft now Safe and Rocket Labs developed a new version of 95 00:08:41.960 --> 00:08:46.559 the Electron rocket, especially for use in hypersonic experiments or that and more is 96 00:08:46.600 --> 00:09:09.159 still to come on spacetime. The European Space ages is Integral spacecraft is safe 97 00:09:09.200 --> 00:09:13.080 at last, following an extended series of fixes developed by mission managers. The 98 00:09:13.159 --> 00:09:18.200 Integral Space Observatory was designed to study some of the universe's most energetic events, 99 00:09:18.360 --> 00:09:24.200 things like gamma ray bursts, black holes, and supernovae, but in twenty 100 00:09:24.279 --> 00:09:28.440 twenty, the probe's thrusters suddenly failed that to keep the mission alive, these 101 00:09:28.480 --> 00:09:33.759 has developed a new series of specialized maneuvers to continue flying the spacecraft using only 102 00:09:33.759 --> 00:09:39.360 its reaction wheels. These are rotating gyrodigms inside the satellite that allow it to 103 00:09:39.480 --> 00:09:46.200 store and use angular momentum to change its orientation. However, the spacecraft's original 104 00:09:46.320 --> 00:09:50.519 safe mode system, which activates the switch off scientific instruments and rotate the spacecraft 105 00:09:50.559 --> 00:09:54.519 so that its solar arrays always faced the Sun, relied on the thrusters to 106 00:09:54.639 --> 00:10:00.080 spin the spacecraft safely in the event of an emergency. The safe mode it 107 00:10:00.120 --> 00:10:03.120 was triggered a year later when the charge particles struck a sensitive part of intricles 108 00:10:03.159 --> 00:10:09.399 electronics, disabling one of its reaction wheels and causing the spacecraft to spin away 109 00:10:09.440 --> 00:10:13.120 from the Sun. Mission managers were able to override the issue and rescue the 110 00:10:13.159 --> 00:10:18.679 spacecraft, but it's left the probe without a safe mode. So now Integal's 111 00:10:18.720 --> 00:10:22.720 team have developed a new workaround in which newly uploaded algorithms determine the best way 112 00:10:22.799 --> 00:10:28.399 for the reaction wheels to operate in order to maneuver the spacecraft during safe mode. 113 00:10:28.080 --> 00:10:35.360 This is spacetime still to come rocket Lab's new Electron signing rocket variation, 114 00:10:35.840 --> 00:10:41.200 and we explore the Constellation Scorpio, the spectacular M six and M seven open 115 00:10:41.279 --> 00:10:46.200 star clusters, and the Etta Akwood's meteor shower produced by Halley's Comet. In 116 00:10:46.279 --> 00:11:07.360 the May edition of SkyWatch, Rocket Labs developed a modified version of its highly 117 00:11:07.399 --> 00:11:13.639 successful Electron orbital launch vehicle specifically designed for suborbital hypersonic test flights. Companies been 118 00:11:13.679 --> 00:11:20.360 selected to provide hypersonic launch services under a Multi Service Advanced Capability Test Bed or 119 00:11:20.480 --> 00:11:24.519 MACTB project, which was awarded by the United States Naval Surface Warfare Center on 120 00:11:24.559 --> 00:11:30.679 behalf of the US Department of Defense and the Defense Innovation Units Hypersonic and High 121 00:11:30.759 --> 00:11:35.480 Cadence Testing Capabilities or HIGHCAT program. The you modified version of the Electron to 122 00:11:35.559 --> 00:11:41.000 be called the HASTE, or Hypersonic Accelerated Suborbital Test Electron, were launched from 123 00:11:41.000 --> 00:11:46.200 the company's new Wallops Island Flight Facility complex on the Virginian mid Atlantic Coast. 124 00:11:46.960 --> 00:11:52.080 HASTE uses the same carbon composite structure and three D printed Rutherford engines as the 125 00:11:52.120 --> 00:11:58.360 electron, but with a modified kickstage for hypersonic payload deployment, a larger seven 126 00:11:58.440 --> 00:12:05.320 hundred kilogram payload capacity, and custom payload fairings to accommodate larger platforms. This 127 00:12:05.799 --> 00:12:24.320 space, time and time matter. Turn our eyes to the skies and check 128 00:12:24.360 --> 00:12:28.840 out the celestious sphere for the month of May on SkyWatch. May is the 129 00:12:28.919 --> 00:12:33.519 fifth month of the year in both the Julian and Grigorian calendars. The month 130 00:12:33.720 --> 00:12:37.759 was named for the Greek goddess Mayer, who was identified with the Roman era 131 00:12:37.840 --> 00:12:43.399 goddess of fertility Bernadia, whose festival was held in May. But I guess 132 00:12:43.399 --> 00:12:46.440 more importantly for many of our listeners, May typically marks the start of summer 133 00:12:46.519 --> 00:12:52.159 vacation season in the United States and Canada. Let's start out tour of the 134 00:12:52.240 --> 00:12:56.759 night skies by looking east, where you'll see the constellations Scorpius, the scorpion 135 00:12:56.399 --> 00:13:01.440 in Greek mythology, the constellation was named the Scorpius, who was sent to 136 00:13:01.480 --> 00:13:05.120 Earth by the goddess Skaia in order to slay Arian the Hunter after he bursted 137 00:13:05.120 --> 00:13:09.440 that he could kill all the animals on Earth. Scorpius stung Orion in the 138 00:13:09.519 --> 00:13:15.759 shoulder, but Orion's life was spared by Ophiucius the Healer, and it was 139 00:13:15.840 --> 00:13:20.360 placed in the heavens along with Scorpius, who continues to pursue him for eternity. 140 00:13:20.000 --> 00:13:24.039 I Ran the Hunter has become the hunted forever, with Scorpius rising in 141 00:13:24.080 --> 00:13:28.279 the east this time of year to triumphantly chase and defeat a Ryan who sits 142 00:13:28.279 --> 00:13:33.279 in the west. Meanwhile, oh Fucius the Healer rises in the east, 143 00:13:33.360 --> 00:13:37.120 following behind Scorpius to chase and crush him into the earth as the Scorpion sets 144 00:13:37.120 --> 00:13:41.639 in the west. And so this ancient story continues to play out in the 145 00:13:41.639 --> 00:13:48.000 heavens year after year. Interestingly, parts of the story predate the Greeks, 146 00:13:48.320 --> 00:13:52.200 with Orion known in ancient Egypt as a Cyrus, the god of the underworld 147 00:13:52.240 --> 00:13:58.360 and of regeneration. The brightest starr in Scorpius is Alpha Scorpie or Antarius, 148 00:13:58.480 --> 00:14:03.720 a scorpion's heart in ancient Greece, and Tari's name means the equal of Mars, 149 00:14:03.960 --> 00:14:09.039 the god of war. That's because it scored in orange, appearance is 150 00:14:09.159 --> 00:14:13.360 very similar to that of the red planet, and also because it passes very 151 00:14:13.360 --> 00:14:18.679 close to Mars every seven hundred and eighty earth days, easily seen with the 152 00:14:18.759 --> 00:14:22.639 unaided eye. And Tarres is some five hundred and fifty light years away, 153 00:14:22.960 --> 00:14:26.039 but it looks so bright because it's around fifty seven thousand, five hundred times 154 00:14:26.080 --> 00:14:30.559 as luminous as the Sun and is one of the largest known stars in the 155 00:14:30.679 --> 00:14:35.799 universe. And Tarres is a red supergiant about eighteen times the mass and eight 156 00:14:35.879 --> 00:14:41.240 hundred eighty three times the diameter of the Sun. Were it placed where the 157 00:14:41.279 --> 00:14:45.759 Sun is in our solar system, yielding golf, all the terrestrial planets Mercury, 158 00:14:45.879 --> 00:14:48.759 Venus, Earth, and Mars, and its visible surface would extend almost 159 00:14:48.759 --> 00:14:54.440 as far at as Jupiter. A light year is about ten trillion kilometers, 160 00:14:54.720 --> 00:14:58.600 the distance of photon can travel in a year at three hundred thousand kilometers per 161 00:14:58.639 --> 00:15:01.200 second, the speed of light in a vacuum, and the ultimate speed limit 162 00:15:01.240 --> 00:15:07.639 of the universe. Astronomers believe and Harris began life around twelve million years ago 163 00:15:07.799 --> 00:15:13.080 as a spectrotype ORB blue star. Astronomers describe stars in terms of spectral types, 164 00:15:13.279 --> 00:15:18.320 a classification system based on temperature and characteristics. The hottest, most massive, 165 00:15:18.360 --> 00:15:24.480 and most luminous stars are known as spectrotype blue stars. They're followed by 166 00:15:24.559 --> 00:15:30.559 spectrotype B blue white stars, then spectralotype A white stars, spectrotype F whitish 167 00:15:30.600 --> 00:15:33.919 yellow stars, spectral type G yellow stars. That's where our Sun fits in. 168 00:15:35.120 --> 00:15:39.759 Then there's spectrotype K iron stars, and the coolest and least massive stars 169 00:15:39.879 --> 00:15:45.320 and learn as spectrotype M red stars. Each spectral classification system can also be 170 00:15:45.360 --> 00:15:50.360 subdivided using a numeric digit to represent temperature, with zero being the hottest and 171 00:15:50.559 --> 00:15:54.080 nine the coolest, and then you add a Roman numeral to represent luminosity. 172 00:15:54.679 --> 00:15:58.440 So put it all together and you can describe our Sun as being a G 173 00:15:58.679 --> 00:16:04.080 two V or G two five yellow dwarf star, one of millions spread across 174 00:16:04.159 --> 00:16:11.120 our galaxy. Also included in the stellar classification system a special types LT and 175 00:16:11.440 --> 00:16:15.120 Y, which are assigned to fauled stars known as brown dwarves, some of 176 00:16:15.159 --> 00:16:18.879 which were actually born at spectral type M red stars but became brown dwarves after 177 00:16:18.960 --> 00:16:23.519 losing some of their mass. Brown dwarves fit into a unique category between the 178 00:16:23.600 --> 00:16:27.440 largest planets, which are about thirteen times the massive Jupiter, and the smallest 179 00:16:27.440 --> 00:16:32.600 spectral type M red dwarf stars, which are about seventy five to eighty times 180 00:16:32.600 --> 00:16:37.519 the massive Jupiter or zero point zero eight solar masses like the similar sized red 181 00:16:37.519 --> 00:16:42.600 giant battle Girls in the constellation of Ryan and Tari's Laumost certainly end its life 182 00:16:42.639 --> 00:16:48.039 as a spectacular type two or cork collapse supernerva, probably sometime within the next 183 00:16:48.159 --> 00:16:52.240 hundred thousand years or so. When it does explode at Lapierre as bright as 184 00:16:52.240 --> 00:16:56.440 the full moon for several months on end, and will be clearly visible during 185 00:16:56.519 --> 00:17:02.399 daylight hours here on Earth. And Taris has a companion star, Antari's B, 186 00:17:02.919 --> 00:17:06.960 located between two hundred and twenty four and five hundred and twenty nine astronomical 187 00:17:07.039 --> 00:17:11.720 units away from the primary. An astronomical unit is the average distance between the 188 00:17:11.759 --> 00:17:15.480 Earth and the Sun, which is about one hundred and fifty million kilometers or 189 00:17:15.519 --> 00:17:21.200 eight point three line minutes. Special analysis of Antarrees B indicates it's pulling a 190 00:17:21.200 --> 00:17:26.680 lot of material off its bloated red super giant companion. Located near Antaries is 191 00:17:26.720 --> 00:17:33.680 the M four globular cluster. Globular clusters are tight balls densely packed with thousands 192 00:17:33.680 --> 00:17:37.200 to millions of stars which were either all originally formed at the same time from 193 00:17:37.279 --> 00:17:41.079 the collapse of the same molecular gas and dust cloud, or alternatively, their 194 00:17:41.119 --> 00:17:45.720 galactic centers the remains of ancient galaxies that have been merged into the Milky Way 195 00:17:45.759 --> 00:17:51.480 Galaxy over billions of years. M four is composed of a million or so 196 00:17:51.720 --> 00:17:56.160 stars originally born some twelve billion years ago. The M four globular cluster is 197 00:17:56.200 --> 00:18:00.839 located some seven thousand, two hundred lie years away, making it one of 198 00:18:00.839 --> 00:18:04.960 the nearest globular clusters to Earth. Easily seen through a pair of small binoculars, 199 00:18:06.119 --> 00:18:08.400 it covers an area of the sky is seen from Earth as big as 200 00:18:08.400 --> 00:18:12.680 the full moon. Astronomers estimate there are some one hundred and fifty or so 201 00:18:12.759 --> 00:18:18.480 globular clusters orbiting in the halo of the Milky Way. Located near the tail 202 00:18:18.559 --> 00:18:22.680 of the scorpion are two open star clusters, known as M six and M 203 00:18:22.799 --> 00:18:27.880 seven. Open star clusters are loosely bound groups of a few thousand stars which 204 00:18:27.880 --> 00:18:32.480 are all originally formed from the same molecular gas and dust cloud at the same 205 00:18:32.559 --> 00:18:37.599 time, but are not as densely bound as globular clusters. Open clusters generally 206 00:18:37.599 --> 00:18:41.279 survive for a few hundred million years, with the most massive one surviving for 207 00:18:41.359 --> 00:18:45.720 maybe a few billion years now. In contrast, the far more massive globular 208 00:18:45.720 --> 00:18:49.440 clusters exert fast, stronger gravitational attraction on their members, which is why they 209 00:18:49.440 --> 00:18:53.200 can survive so much longer. M six, which is also known as the 210 00:18:53.200 --> 00:18:59.200 butterfly cluster, is some twelve light years across and located about sixteen hundred light 211 00:18:59.240 --> 00:19:02.839 years away. It contains around eighty stars, which were all less than a 212 00:19:02.920 --> 00:19:07.640 hundred million years old, which is quite young in cosmic terms. The M 213 00:19:07.759 --> 00:19:11.759 seven or Ptolemy cluster is named after the famous Greek astronomer a mathematician, Claudius 214 00:19:11.759 --> 00:19:17.160 Ptolemy. It's about nine hundred eighty light years away, and he's far more 215 00:19:17.200 --> 00:19:21.359 dispersed than him. Six, covering an area around twenty five light years across 216 00:19:21.960 --> 00:19:26.039 and at around two hundred million years, it's about twice as old. Born 217 00:19:26.079 --> 00:19:30.680 in the year one hundred, Ptolemay lived in Egypt while I was under Roman 218 00:19:30.839 --> 00:19:34.160 rule. He wrote over a dozen scientific treaties, the first of which was 219 00:19:34.200 --> 00:19:38.720 an astronomical work now known as the Almagest. While some of his works were 220 00:19:38.880 --> 00:19:44.440 very insightful, much of it was error prone, and measurements were simply modified 221 00:19:44.440 --> 00:19:48.400 and changed to fit his theories. He's best known for refining a geometric theory 222 00:19:48.440 --> 00:19:53.480 for the universe, one which uses cycles and epicycles to place the Earth at 223 00:19:53.480 --> 00:19:57.319 the center of the cosmos, with all the other bodies orbiting around it. 224 00:19:59.119 --> 00:20:03.960 Unlike most ancient Greek mathematicians, Ptolema's writings never ceased to be copied and commented 225 00:20:04.039 --> 00:20:10.119 upon, both in late Antiquity and in the Middle Ages. However, it's 226 00:20:10.200 --> 00:20:15.599 likely that only a few truly mastered the mathematics necessary to understand his works. 227 00:20:15.319 --> 00:20:22.480 That's evidenced by the many abridged and watered down introductions Totolem's astronomy that were popular 228 00:20:22.519 --> 00:20:29.559 amongst the Arabs and Byzantines alike. Galileo Galilee and Isaac Newton eventually overthrew his 229 00:20:29.680 --> 00:20:36.440 geocentric theory more than a thousand years later. By the way, the m 230 00:20:36.559 --> 00:20:40.960 in terms like M four, M six, and M seven are abbreviations for 231 00:20:41.160 --> 00:20:45.880 Messier in honor of the eighteenth century French astronomer Charles Messier, who developed an 232 00:20:45.880 --> 00:20:51.559 astronomical catalog of fuzzy nebulous objects in the skies. See. Messier was a 233 00:20:51.559 --> 00:20:55.720 comet hunter, and he compiled the list of one hundred and three fuzzy objects 234 00:20:55.759 --> 00:21:00.480 which one commets and served from his perspective, could be ignored. Later, 235 00:21:00.519 --> 00:21:04.200 other astronomers added additional celestial objects to the list, bringing the present catalog up 236 00:21:04.200 --> 00:21:08.440 to one hundred and ten. Our solar system. In fact, most of 237 00:21:08.440 --> 00:21:11.920 the stars we see when we look up in the night sky are located in 238 00:21:11.960 --> 00:21:17.680 the Milky Way galaxies Orion Arm. The Orion Arm, also known as the 239 00:21:17.720 --> 00:21:21.599 Orion Spur or the Orion Signus Arm, depending on which name you prefer, 240 00:21:21.920 --> 00:21:26.160 is some three thousand, five hundred light years wide and around ten thousand light 241 00:21:26.240 --> 00:21:30.200 years long. The Irian Arm is named after the Orion constellation, which is 242 00:21:30.200 --> 00:21:34.960 one of the most prominent constellations in the Southern Hemisphere summer and Northern Hemisphere winter. 243 00:21:36.759 --> 00:21:41.440 Some of the brightest and most famous celestial objects in the constellation include battel 244 00:21:41.480 --> 00:21:45.000 Gers, Rigel, the stars of the Orion Belt, and the Orion Nebula, 245 00:21:45.240 --> 00:21:49.519 all located within the Orion Arm. The Orion Arm is located between the 246 00:21:49.599 --> 00:21:53.880 queen As Sagittarius Arm, which is more towards the galactic center from our position, 247 00:21:55.160 --> 00:21:57.160 and the Percy's Arm, which is more towards the outer edge of the 248 00:21:57.160 --> 00:22:00.640 galaxy from our point of view. The Perseus Arm is one of the two 249 00:22:00.759 --> 00:22:06.480 major arms of the Milky Way, yeah, there being the Scutum Centaurus Arm 250 00:22:06.720 --> 00:22:10.920 long thought of as a minus structure spur if you will, between the two 251 00:22:11.000 --> 00:22:15.759 longer adjacent arms Perseus and Karna Sagittarius. Evidence was presented in mid twenty thirteen 252 00:22:15.960 --> 00:22:19.400 that the Orion Arm might actually be a branch of the Perseus Arm, or 253 00:22:19.440 --> 00:22:26.599 possibly a completely independent arms segment itself within the Orion arm our. Solar System, 254 00:22:26.920 --> 00:22:29.799 Sun, the Earth, and all the other planets we know are located 255 00:22:29.839 --> 00:22:33.240 close to the Inner Rim in what's known as the Local Bubble, about halfway 256 00:22:33.279 --> 00:22:37.680 along the Orion Arms length, approximately twenty six thousand light years from the galactic 257 00:22:37.799 --> 00:22:42.359 center. The Local Bubble is a cavity in the interstellar medium in the Irione 258 00:22:42.480 --> 00:22:47.359 Arm, containing, among other things, the local interstellar cloud, which contains 259 00:22:47.400 --> 00:22:52.519 our Solar System and the g Cloud. It's at least three hundred lights across, 260 00:22:52.000 --> 00:22:56.079 and it has a neutral hydrogen density of just zero point zero five atoms 261 00:22:56.119 --> 00:23:00.279 per cubic centimeter. There's just one tenth of the average for the interstellar medium 262 00:23:00.359 --> 00:23:04.519 across the Milky Way, at about a six that of the local interstellar cloud. 263 00:23:06.160 --> 00:23:08.799 The hot diffuse gas in the local bubble amidst X rays and is the 264 00:23:08.839 --> 00:23:14.559 result of a supernova that exploded sometime during the past ten to twenty million years. 265 00:23:15.160 --> 00:23:18.279 It was once thought that the most likely candidate for the remains of the 266 00:23:18.359 --> 00:23:23.039 supernova was Jiminga, a pulsar and the constellation Gemini. However, later it 267 00:23:23.119 --> 00:23:29.279 was suggested that multible supernova in a subgroup be one of the plats moving group 268 00:23:29.480 --> 00:23:34.119 was more likely responsible becoming a rimnant supershell. Our solar system has been traveling 269 00:23:34.160 --> 00:23:38.119 through this region of space occupied by the local bubble for the last five to 270 00:23:38.200 --> 00:23:44.400 ten million years. Its current location is in what's known as the local interstellar 271 00:23:44.480 --> 00:23:48.640 cloud, a minor region of slightly denser material within the bubble. The cloud 272 00:23:48.680 --> 00:23:53.839 formed when the local bubble and another bubble called the Loop one bubble met gas 273 00:23:53.880 --> 00:23:57.920 within the local interstellar cloud. As a density of about zero point three Adams 274 00:23:57.920 --> 00:24:03.200 per cubic centimeter. From what we can tell, the local bubble isn't spherical. 275 00:24:03.440 --> 00:24:07.599 It seems to be narrower, and the galactic plane becoming somewhat egg shaped 276 00:24:07.680 --> 00:24:11.319 or elliptical, and may even become wider above and below the galactic plane becoming 277 00:24:11.400 --> 00:24:15.519 shaped more like an hour glass. And it's not alone. It's abutting other 278 00:24:15.599 --> 00:24:21.680 bubbles of lesser dense interstellar medium, including the Loop one Bubble. The Loop 279 00:24:21.720 --> 00:24:26.880 one bubble was created by super nervy instellar winds in the Scorpius Centauris association, 280 00:24:26.079 --> 00:24:30.519 some five hundred layers from the Sun. The Loop one bubble also contains the 281 00:24:30.559 --> 00:24:36.680 star and taris that we spoke about earlier. Astronomers have identified several well, 282 00:24:36.720 --> 00:24:40.519 I guess you'd call them tunnels, which connect the cavities of the local bubble 283 00:24:40.559 --> 00:24:44.240 with that of the Loop one bubble. Collectively, they've been referred towards the 284 00:24:44.240 --> 00:24:48.359 Loopers tunnel, other bubbles which are adjacent to our local bubble, and then 285 00:24:48.400 --> 00:24:52.839 as the Loop two bubble and the Loop three bubble. Looks like astronomers still 286 00:24:52.880 --> 00:24:56.440 have a problem when it comes to thicking up cool names. Also visible this 287 00:24:56.480 --> 00:25:00.960 month is the Edder Akwards meteor shower, which is generated as the Earth passes 288 00:25:02.000 --> 00:25:06.559 through the dust and debris trail left behind by Halley's comet. Comet P one 289 00:25:06.599 --> 00:25:11.319 Halley's a well known short period comet which visits the Inner Solar System every seventy 290 00:25:11.319 --> 00:25:15.000 five to seventy six years. The fifteen kilometer wide mountain of rock and ice 291 00:25:15.160 --> 00:25:19.720 will make its next close up appearance in twenty sixty one. It's named in 292 00:25:19.799 --> 00:25:25.039 honor of the British astronomer Edmund Halley, who in seventeen oh five, after 293 00:25:25.079 --> 00:25:30.119 examining ancient Chinese, Babylonian and medieval European records, successfully predicted its return in 294 00:25:30.240 --> 00:25:36.519 seventeen fifty eight. However, he died in seventeen forty two before his prediction 295 00:25:36.599 --> 00:25:41.839 could be confirmed. The comet's highly elliptical and elongated orbit takes it from between 296 00:25:41.839 --> 00:25:45.720 the orbits of Mercury and Venus out almost as far as the orbit of Pluto. 297 00:25:45.359 --> 00:25:49.400 Howe's orbit is in retrograde, meaning it orbits the Sun in the opposite 298 00:25:49.400 --> 00:25:53.319 direction to the planets, that is, clockwise, from above the Sun's northern 299 00:25:53.359 --> 00:25:59.160 pole. This retrograde orbit results in at having one of the highest velossities relative 300 00:25:59.200 --> 00:26:03.279 to the Earth of any object in the Solar System traveling at some seventy point 301 00:26:03.359 --> 00:26:07.400 five six kilometus per second, or if you prefer, two hundred and fifty 302 00:26:07.400 --> 00:26:11.400 four thousand and sixteen kilometers per hour. As well as the eto Achard's meteor 303 00:26:11.400 --> 00:26:17.880 shower every May, Halley's comet also produces the Orionids meteor shower in Lead October. 304 00:26:18.440 --> 00:26:22.160 Astronomers think Commet Halley was originally a long period comet which took thousands of 305 00:26:22.240 --> 00:26:26.880 years to travel to the Inner Solar System from the Aorc Cloud, but was 306 00:26:26.960 --> 00:26:32.079 gravitationally perturbed into its current orbit by close encounters with the giant outer planets. 307 00:26:32.680 --> 00:26:37.039 The Orc Cloud is a hypothetical sphere of comets and asteroids beyond the heliosphere, 308 00:26:37.200 --> 00:26:41.880 a mixture of vagabonds from the Solar System and objects from deep space which have 309 00:26:42.000 --> 00:26:47.680 been collected by the Sun's gravitational pool. Occasionally, as the Sun passes by 310 00:26:47.720 --> 00:26:51.759 another star, an Orc Cloud object will get perturbed and be flunked towards the 311 00:26:51.799 --> 00:26:56.839 Inner Solar System. The Outer Akwards meteor shower runs from the nineteenth of April 312 00:26:56.000 --> 00:27:00.599 through to the twenty eighth of May, peaking around me The fifth, with 313 00:27:00.720 --> 00:27:04.079 around fifty five meteors an hour, making it one of the Southern Hemisphere's best 314 00:27:04.079 --> 00:27:10.519 celestial showers. However, back in nineteen seventy five they were running ninety five 315 00:27:10.640 --> 00:27:14.440 meteors an hour, and in nineteen eighty it was up to one hundred and 316 00:27:14.480 --> 00:27:18.039 ten. Even better, the bright yellow meteors often appear as streaks known as 317 00:27:18.079 --> 00:27:22.799 trains. As their name suggests, they radiate out from the direction of the 318 00:27:22.799 --> 00:27:29.200 constellation Aquarius and the start at Aquary. Just look towards the east after midnight 319 00:27:29.200 --> 00:27:33.759 and before dawn for the best view. Jonathan Nelly's the editor of Australian Sky 320 00:27:33.799 --> 00:27:37.480 and Telescope magazine. He joins us now for the rest of our tour of 321 00:27:37.519 --> 00:27:42.000 the May night skies on SkyWatch Stewart. Yeah, well, it's main hour. 322 00:27:42.039 --> 00:27:45.200 So if you're lucky enough to have some nice dark skies where you live, 323 00:27:45.319 --> 00:27:48.880 if you go out in the early evening, you'll see the Mookie Way 324 00:27:48.960 --> 00:27:52.400 stretching all the way across the sky from the southeast to the northwest. It's 325 00:27:52.440 --> 00:27:55.440 really quite a specky side if you can see it under dark skies with dark 326 00:27:55.440 --> 00:27:57.880 adapted eyes. That's our galaxy, seem from the inside. It's just absolutely 327 00:27:57.920 --> 00:28:03.359 glorious. The brightest star in the night sky, Serious can be seen during 328 00:28:03.400 --> 00:28:06.400 May about halfway up from the western horizon. If you look out to the 329 00:28:06.400 --> 00:28:10.519 western you go halfway up the sky from the horizon to overhead because it is 330 00:28:10.599 --> 00:28:12.039 big bright star, and that's sirious, the brightest star in the night sky. 331 00:28:12.119 --> 00:28:15.559 A little bit further, sort of down to the south, there's another 332 00:28:15.559 --> 00:28:18.079 bright star. It's the second brightest star in the night sky. That's called 333 00:28:18.119 --> 00:28:22.279 Canopus. And low down on the western horizon you can still make out the 334 00:28:22.279 --> 00:28:26.759 shape of the constellation a Ryan above the trees or houses, whatever, or 335 00:28:26.759 --> 00:28:29.599 on the horizon where you live. It's still there for only a few more 336 00:28:29.599 --> 00:28:32.880 weeks. Really, it's getting very very low now. It's making its last 337 00:28:32.920 --> 00:28:36.839 appearance before disappearing from view for the next six months or so. Way down 338 00:28:36.839 --> 00:28:38.279 in the deep south of the sky, we've got the famous Southern Cross, 339 00:28:38.319 --> 00:28:41.880 of course, which at this time of the year is nice and high, 340 00:28:41.960 --> 00:28:44.960 and it's standing upright, so it looks like a sort of a kite shape, 341 00:28:45.039 --> 00:28:48.680 very small kite shape. To its left, you see two bright stars 342 00:28:48.720 --> 00:28:52.640 in the constellation Centaurus. Astronomers call them the two Pointers because if you draw 343 00:28:52.640 --> 00:28:55.440 a line through them, it sort of points towards the Southern Cross. The 344 00:28:55.480 --> 00:28:59.839 two pointers are known as Alpha and Betasentauri, and if you look at Alpha 345 00:29:00.119 --> 00:29:03.039 a telescope, you'll actually see that it's two stars, and there's a third 346 00:29:03.079 --> 00:29:06.799 star as well. It's some distance away and too faint to be seen through 347 00:29:06.920 --> 00:29:11.880 sort of normal backyard telescopes. It's called Proximus Centauri, and Proximus Centauri is 348 00:29:11.880 --> 00:29:15.359 actually the closest start of our solar system. It's a small star. It's 349 00:29:15.440 --> 00:29:17.839 very dim, so you really need to know where to look for it, 350 00:29:17.880 --> 00:29:18.880 and you need to have a big enough telescope. But if you just look 351 00:29:18.920 --> 00:29:22.680 towards Alpha Centauri, it's roughly there. So you're looking towards the postest star 352 00:29:22.759 --> 00:29:26.680 system to our star system. To the right of the Southern Cross, we've 353 00:29:26.680 --> 00:29:30.559 got the constellations Karna, Vela and Puppas, which is some of my favorite 354 00:29:30.559 --> 00:29:33.480 area of the sky. It's just it's just wonderful. You look. You 355 00:29:33.559 --> 00:29:36.720 just get a pair of anoculars on the this and just sweep through this area. 356 00:29:36.759 --> 00:29:40.000 There are star clusters and niggling things. It's just glorious because it's in 357 00:29:40.039 --> 00:29:45.000 the milky way, and so there's lots of stuff to see. And yeah, 358 00:29:45.119 --> 00:29:48.160 yeah, it was a big constellation called Argo Navas the ship of the 359 00:29:48.240 --> 00:29:52.279 Argonauts, and got split up, and the three main constellations you've got split 360 00:29:52.359 --> 00:29:56.440 into Karna, Vela and Puppas. Pappas is the poop deck, Carina is 361 00:29:56.480 --> 00:29:59.920 the keel, and Vila is the sales. And there was a fourth constellation 362 00:30:00.000 --> 00:30:03.160 as well. It's just nearby called Pixus, that's the compass. Would have 363 00:30:03.200 --> 00:30:06.640 been a big constellation. I mean, these things look nothing like, nothing 364 00:30:06.680 --> 00:30:08.920 like a ship, nothing like a sail or a poop deck or or whatever. 365 00:30:10.000 --> 00:30:14.559 It's just that people decided to put their favorite ideas or mythologies or garators 366 00:30:14.559 --> 00:30:17.240 that they're into the sky. So they made up their own join the dots 367 00:30:17.279 --> 00:30:18.200 fares. You would not to go out and look in the sky and think, 368 00:30:18.240 --> 00:30:21.279 oh, look there's a big ship. You know, the sales and 369 00:30:21.319 --> 00:30:23.720 everything. So don't don't don't get full. Don't go out thinking you're going 370 00:30:23.720 --> 00:30:26.200 to see something like that. Now, down in this area of the sky, 371 00:30:26.440 --> 00:30:30.400 if you have dark enough skies and you've got to your eyes dark adapted, 372 00:30:30.400 --> 00:30:33.079 you should be able to spot something called the Omega Centauri star cluster which 373 00:30:33.119 --> 00:30:37.279 has about ten million stars in it, and it's about seventeen thousand light years 374 00:30:37.319 --> 00:30:40.079 away. And there's also a galaxy down this part of the world too, 375 00:30:40.839 --> 00:30:44.480 that part of the sky I should say called NGC five one two eight. 376 00:30:44.519 --> 00:30:48.039 You often hear it called Centaurus A. It's about ten to fifteen million light 377 00:30:48.119 --> 00:30:49.799 years away, and there's a huge galaxy. But both of these things don't 378 00:30:49.799 --> 00:30:52.960 look like that to the naked eye, but you can just make them out 379 00:30:53.039 --> 00:30:56.920 as a little fuzzy dots. It looks like a star that's a bit fuzzy, 380 00:30:56.000 --> 00:30:59.680 and if you get some binoculars onto them that it really looks like a 381 00:30:59.720 --> 00:31:03.640 fuzzy staff each of these things. And if you get telescope onto Raga Centauri 382 00:31:03.079 --> 00:31:07.640 or Centaursa, they really look quite tremendous. They're really really impressive things. 383 00:31:07.759 --> 00:31:11.240 So you can actually see these things with the naked eye just there's little, 384 00:31:11.240 --> 00:31:14.599 tiny fuzzy blobs. They may not look impressive, but when you look at 385 00:31:14.640 --> 00:31:18.079 a picture of what they really are and think, wow, my eyes are 386 00:31:18.079 --> 00:31:23.759 actually seeing these things from ten million light years away. That's a huge black 387 00:31:23.799 --> 00:31:27.319 hole in Centaura, say too, because it's one of the biggest radio sources 388 00:31:27.359 --> 00:31:30.440 in the sky. Yeah. Look, that's why I called it NNGC five 389 00:31:30.480 --> 00:31:34.240 one two eighth when I interially spoke about it, because that's its catalog name. 390 00:31:34.519 --> 00:31:38.079 Pretty much everyone calls it Centaurus A these days, that Centaurus they really 391 00:31:38.119 --> 00:31:44.000 refers to the radio source that is inside and just say the black hole. 392 00:31:44.039 --> 00:31:47.160 Because in the very early days of radio astronomy, when astronomers are pointing these 393 00:31:47.240 --> 00:31:49.640 radio tooles goes around the sky, they would find these big sources of radio 394 00:31:49.960 --> 00:31:53.359 ways and they didn't really know what they were. They could pinpoint them. 395 00:31:53.359 --> 00:31:56.960 It was pretty obvious that it was coming from this galaxy in this instance, 396 00:31:56.279 --> 00:32:00.079 but they didn't really know what was producing these radio waves. There's Sagittarius AY, 397 00:32:00.240 --> 00:32:04.480 and there's there's Cassier PA, and there's centauraus A. There's quite a 398 00:32:04.480 --> 00:32:07.200 few of them like that, and as they found other ones in those constellations 399 00:32:07.359 --> 00:32:10.079 called them BC whatever. So, yeah, it's an impressive galaxy. Add 400 00:32:10.079 --> 00:32:14.279 and when you look at a picture taken with a big telescope or even vamited 401 00:32:14.319 --> 00:32:16.880 telescopes these days, it's it's a weird looking galaxy, strange looking thing that 402 00:32:16.960 --> 00:32:20.720 it's big dust laying going through the middle of it, or rather around the 403 00:32:20.759 --> 00:32:22.640 outskirts of it. So this is why I say, when you go outside 404 00:32:22.640 --> 00:32:24.480 and if you can spot, if you can spot, if you get a 405 00:32:24.480 --> 00:32:28.119 star map and you can actually spot this thing with the naked eye. It's 406 00:32:28.160 --> 00:32:31.000 just a little fuzzy blob, no brighter than a star. It doesn't look 407 00:32:31.000 --> 00:32:35.519 impressive that way, but when you think that you are actually seeing this galaxy 408 00:32:35.599 --> 00:32:38.880 from ten or more million light years away with your eyes, and that the 409 00:32:38.960 --> 00:32:44.079 light that is coming into your eyes right now left there ten million years ago, 410 00:32:44.359 --> 00:32:50.880 it's really quite incredible to its put space into perspective in it. We've 411 00:32:50.880 --> 00:32:54.960 talked about Proximus Centaura, that the closest start to Earth a few moments ago, 412 00:32:55.000 --> 00:32:59.640 that's only just over four light years away. Centaurus A is over ten 413 00:32:59.680 --> 00:33:01.960 million light years away, So that's the sort of difference you can see just 414 00:33:02.000 --> 00:33:05.599 with the naked eye. It's incredible. Anyhow, moving on, we've got 415 00:33:05.640 --> 00:33:07.799 the northern half of the sky moving up to the north. Now, the 416 00:33:07.799 --> 00:33:09.279 northern half of the sky from our part of the world doesn't really seem to 417 00:33:09.279 --> 00:33:13.039 have many bright star fields at this time of year, at least during the 418 00:33:13.119 --> 00:33:15.200 evening. There are some famous constellations there that you can see, such as 419 00:33:15.359 --> 00:33:19.640 Leo, Cancer and Virgo. Leo looks quite good. Virgos just this big, 420 00:33:19.680 --> 00:33:22.920 sort of seemingly empty space. But astronomers, amateur astronomers love Virgo because 421 00:33:23.039 --> 00:33:27.000 when you get a telescope out and have a look into that part of space, 422 00:33:27.039 --> 00:33:29.559 there are actually lots and lots of galaxies. They're too faint to be 423 00:33:29.559 --> 00:33:31.039 seen with the naked eye, but a telescope can pick them up, and 424 00:33:31.079 --> 00:33:35.960 they're just you're a huge galaxy cluster in the constellation Virgo. But you do 425 00:33:36.000 --> 00:33:37.319 need a telescope to see them. But if you wait till after midnight, 426 00:33:37.400 --> 00:33:40.440 you're going to get some spectacular constellations coming up at this time of the year, 427 00:33:40.559 --> 00:33:45.279 rising over the eastern horizon. And I'm talking Sagittarius. I'm talking Scorpius, 428 00:33:45.319 --> 00:33:49.359 which most people know of Scorpio and most people have heard of those two 429 00:33:49.400 --> 00:33:52.839 constellations. And there's another couple called Scutum and Opayucas, which most people haven't 430 00:33:52.880 --> 00:33:57.279 heard of. But that part of the Milky Way region that these constellations are 431 00:33:57.279 --> 00:34:00.799 in is amazing. It's a bit like I was talking earlier about Pappas and 432 00:34:00.880 --> 00:34:05.039 Villa and Karina, lots of things to see well, Sagittarius and Scorpius, 433 00:34:05.079 --> 00:34:07.800 so many things to see, our star clusters of various kinds, and Nebulian 434 00:34:07.960 --> 00:34:13.360 dark Nebulian star fields and things. It's just really tremendous. Even just binoculars 435 00:34:13.360 --> 00:34:16.639 are good enough if you've got dark skies to have to spend hours just looking 436 00:34:16.679 --> 00:34:20.519 around that part of the sky really is incredible. And you know, that's 437 00:34:20.519 --> 00:34:22.719 one of the reasons why astronomy is so big in the Southern hemisphere, and 438 00:34:22.880 --> 00:34:27.920 why radio astronomy in particular has been big here is because we get a good 439 00:34:28.000 --> 00:34:31.000 view down here of the Sagittarius region, which is towards the center of our 440 00:34:31.039 --> 00:34:34.840 galaxy. When you look towards Sagittarius, you're looking towards the center of our 441 00:34:34.840 --> 00:34:37.880 galaxy. So you're looking right right into the middle of the city of stars 442 00:34:37.880 --> 00:34:40.800 that we live in our galaxy. Right, So there's lots of things happening 443 00:34:40.800 --> 00:34:44.679 there and lots of things for astronomous and study. Now, let's see what's 444 00:34:44.679 --> 00:34:47.079 happening with the planets at the moment for this month. Venus is the main 445 00:34:47.119 --> 00:34:52.239 attraction at the moment. It's nice and bright in the northwestern sky after sunset, 446 00:34:52.360 --> 00:34:54.480 you really can't miss. It's because it's just big and bright. Mars 447 00:34:54.840 --> 00:34:59.159 is a little bit higher than Venus and a little bit further around to the 448 00:34:59.239 --> 00:35:02.320 north. It's not as bright as Venus. It's just a sort of a 449 00:35:02.360 --> 00:35:07.960 medium brightness orange red sort of star. But if you take a look each 450 00:35:07.079 --> 00:35:12.519 night after sunset during this month, you'll see that those two planets are seeming 451 00:35:12.559 --> 00:35:15.119 to move towards each other, that the gap between them is narrowing down. 452 00:35:15.239 --> 00:35:17.920 They're not actually doing that in space, of course, it's just the line 453 00:35:17.920 --> 00:35:22.159 of sight effect from our vantage point here on Earth. But by the end 454 00:35:22.239 --> 00:35:24.280 of June they're going to be right up closer to each other they are, 455 00:35:24.360 --> 00:35:28.840 so as the next four or five, six, seven weeks go, they're 456 00:35:28.840 --> 00:35:31.800 going to sort of slowly come to together in the western sky, and at 457 00:35:31.840 --> 00:35:35.920 the end of June they'll be right close to each other, which max mcare 458 00:35:35.920 --> 00:35:37.480 a really really good view in this month. If you go out on the 459 00:35:37.519 --> 00:35:42.280 twenty fifth twenty fifth of May, you'll see that Venus and the Moon and 460 00:35:42.440 --> 00:35:45.320 Mars will all be roughly roughly in a straight line at the moon in between. 461 00:35:45.360 --> 00:35:47.599 So they've got Venus, the Moon, and Mars. That'll be an 462 00:35:47.599 --> 00:35:52.159 easy way to identify those two planets if you're having any trouble, because you 463 00:35:52.199 --> 00:35:53.519 go out and see the Moon and you think and you say, right, 464 00:35:53.519 --> 00:35:55.920 oh, well, that bright star just below it, or that star and 465 00:35:55.960 --> 00:36:00.599 inverted commas, the bright star below it is the planet Venus, and that 466 00:36:00.679 --> 00:36:04.559 orangey red star just above them to the right, that's actually the planet Mars. 467 00:36:04.639 --> 00:36:07.559 So go out on the twenty fifty fign if you've got good weather and 468 00:36:07.599 --> 00:36:09.199 have a look, and you'll be able to stop them quite easily. The 469 00:36:09.280 --> 00:36:13.920 other two main planets that are easy to see, Jupiter and Saturn, well 470 00:36:13.960 --> 00:36:15.599 they can be found in the early morning sky, so you're gonna have to 471 00:36:15.639 --> 00:36:20.840 get up early. At the start of May, Saturn is rising over the 472 00:36:20.880 --> 00:36:25.079 eastern horizon just after midnight and then it's visible for the rest of the night 473 00:36:25.239 --> 00:36:30.199 throught sunrise. Jupiter is coming up at about four am at the moment, 474 00:36:30.599 --> 00:36:34.960 so you've got to be really a night owl or an early birds at least 475 00:36:34.960 --> 00:36:37.000 to see it coming up over the horizon. If you're getting up at six 476 00:36:37.000 --> 00:36:39.880 o'clock in the morning, is something that Jupiter will be some distance above the 477 00:36:39.920 --> 00:36:44.599 horizon and you can't miss Jupid or either because it's it's nice and big and 478 00:36:44.679 --> 00:36:47.519 bright. And if you're awake in the early hours of the morning on the 479 00:36:47.639 --> 00:36:52.239 fourteenth of May, take a look outside and you'll see the Moon and Saturn 480 00:36:52.519 --> 00:36:55.440 very close to each other. So if you're having trouble figuring out which one 481 00:36:55.480 --> 00:37:00.079 of those things is Saturn, get outside early hours of May fourteenth and you'll 482 00:37:00.119 --> 00:37:05.199 see that bright looking thing just next to the moon is Saturn. And similarly, 483 00:37:05.320 --> 00:37:07.559 on the eighteenth, the Moon will have moved a little bit further along 484 00:37:07.559 --> 00:37:10.719 in its orbit and then you'll have the Moon next to Jubiter. So if 485 00:37:10.719 --> 00:37:14.000 you don't know which one Jupiter is, have we looked in the early morning 486 00:37:14.039 --> 00:37:16.639 hours of the eighteenth and look for the moon and the bright thing right next 487 00:37:16.679 --> 00:37:20.639 to it will be Jupiter. And that stupart is the sky for this month. 488 00:37:20.760 --> 00:37:23.920 That's Jonathan Ally, the editor of Astray in Sky and Telescope Magazine, 489 00:37:24.559 --> 00:37:45.559 and this Spacetime, and that's the show for now. 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