00:00:00 --> 00:00:02 Stuart Gary: This is space Time Series 28, Episode
00:00:02 --> 00:00:05 65 for broadcast on 30 May
00:00:05 --> 00:00:08 2025. Coming up on SpaceTime,
00:00:08 --> 00:00:11 a new theory of gravity which brings the long sought
00:00:11 --> 00:00:13 after theory of everything closer to reality.
00:00:14 --> 00:00:17 Is there a hot side to the moon? And
00:00:17 --> 00:00:20 astronomers discover white dwarf pulsars for
00:00:20 --> 00:00:23 the first time. All that and more coming up
00:00:23 --> 00:00:24 on, Space Time.
00:00:25 --> 00:00:28 Voice Over Guy: Welcome to Space Time with Stuart
00:00:28 --> 00:00:28 Gary
00:00:45 --> 00:00:48 Stuart Gary: Scientists have developed a new theory of gravity which
00:00:48 --> 00:00:51 brings the long sought after theory of everything just
00:00:51 --> 00:00:54 a little bit closer to reality. A quantum
00:00:54 --> 00:00:57 theory of gravity would clear the path to answering some of
00:00:57 --> 00:01:00 the biggest questions in physics. The study
00:01:00 --> 00:01:03 detailed in the journal Reports on progress in Physics
00:01:03 --> 00:01:06 claims a unified theory combining gravity with the other
00:01:06 --> 00:01:09 fundamental forces of nature. That's electromagnetism and
00:01:09 --> 00:01:11 the strong and weak nuclear forces may well at long
00:01:11 --> 00:01:14 last be within reach. Bringing
00:01:14 --> 00:01:17 gravity into the fold has been the goal of generations
00:01:17 --> 00:01:20 of physicists who have struggled to reconcile the
00:01:20 --> 00:01:23 incompatibility of the two cornerstones of modern physics,
00:01:23 --> 00:01:25 namely quantum field theory and Albert
00:01:25 --> 00:01:28 Einstein's theory of general relativity. The
00:01:28 --> 00:01:31 key has been developing a new quantum theory of
00:01:31 --> 00:01:33 gravity, which describes gravity in ways
00:01:33 --> 00:01:36 compatible with the standard model of particle physics, the
00:01:36 --> 00:01:38 cornerstone of our understanding of the universe.
00:01:39 --> 00:01:41 And in the process, it's opening the door to an
00:01:41 --> 00:01:44 improved understanding of how the universe began.
00:01:45 --> 00:01:48 While the world of theoretical physics may seem remote from
00:01:48 --> 00:01:51 applicable technology, the findings are remarkable.
00:01:51 --> 00:01:54 See, modern technology is built on fundamental advances.
00:01:55 --> 00:01:58 For example, the GPS in your smartphone works
00:01:58 --> 00:02:01 thanks to Albert Einstein's theory of gravity. The
00:02:01 --> 00:02:04 study's authors, Miko Partanen and Giulka Tutti, both
00:02:04 --> 00:02:07 from Aalto University, say that within a few years their new
00:02:07 --> 00:02:09 hypothesis may well unlock, crucial
00:02:09 --> 00:02:12 understanding. If, it does turn out to lead to a
00:02:12 --> 00:02:15 complete quantum field theory of gravity, then eventually it
00:02:15 --> 00:02:17 will give answers to the very difficult problems of
00:02:17 --> 00:02:20 understanding singularities at the centre of black holes
00:02:21 --> 00:02:24 and even understanding the Big bang of creation itself.
00:02:24 --> 00:02:27 However, we're not there yet. Some fundamental
00:02:27 --> 00:02:30 questions of physics still remain under this so called theory
00:02:30 --> 00:02:33 of Everything. For example, current theories still can't
00:02:33 --> 00:02:35 explain why there's more matter than antimatter in the
00:02:35 --> 00:02:38 observable universe. And they still don't know what
00:02:38 --> 00:02:40 dark energy and what dark matter really are.
00:02:41 --> 00:02:44 The key to this new hypothesis was finding a way to
00:02:44 --> 00:02:46 describe gravity in a suitable gauge theory,
00:02:46 --> 00:02:49 A a kind of theory in which particles interact with each other through
00:02:49 --> 00:02:52 a field. The most familiar gauge field is
00:02:52 --> 00:02:55 the electromagnetic field. Talkey says that when
00:02:55 --> 00:02:58 electrically charged particles interact with each other, they interact
00:02:58 --> 00:03:01 through the electromagnetic Field, which is the pertinent
00:03:01 --> 00:03:04 gauge field. So when particles have energy, the
00:03:04 --> 00:03:07 interactions they have, just because they have energy would happen
00:03:07 --> 00:03:10 through the gravitational field. But a, challenge
00:03:10 --> 00:03:12 long facing physicists is finding a gauge theory
00:03:12 --> 00:03:15 for gravity, one that's compatible with the gauge theories
00:03:15 --> 00:03:18 of the other three fundamental forces, the electromagnetic force,
00:03:19 --> 00:03:22 weak nuclear force, and the strong nuclear force. The
00:03:22 --> 00:03:24 standard model of particle physics is itself a gauge
00:03:24 --> 00:03:27 theory which describes those three forces and has
00:03:27 --> 00:03:30 certain symmetries. The Tennant says the
00:03:30 --> 00:03:33 main idea is to have a gravity gauge theory with
00:03:33 --> 00:03:36 a symmetry that's similar to the standard model symmetries,
00:03:36 --> 00:03:39 instead of basing the theory on the very different kind
00:03:39 --> 00:03:41 of spacetime symmetry involved in Einstein's
00:03:41 --> 00:03:44 general relativity. Without such a hypothesis,
00:03:44 --> 00:03:47 physicists couldn't reconcile our two most powerful
00:03:47 --> 00:03:50 theories, quantum field theory and general relativity.
00:03:50 --> 00:03:53 Quantum field theory describes the world of the very
00:03:53 --> 00:03:56 small, tiny particles interacting in probabilistic
00:03:56 --> 00:03:59 ways. On the other hand, general relativity
00:03:59 --> 00:04:02 describes the grand physics of the cosmic world, the
00:04:02 --> 00:04:05 universe as a whole. So they're both descriptions of
00:04:05 --> 00:04:07 our, universe, but from very different perspectives.
00:04:08 --> 00:04:10 And both theories have been confirmed with extraordinary precision,
00:04:10 --> 00:04:13 yet they're still incompatible with each other. And because
00:04:13 --> 00:04:16 gravitational directions are weak, more precision is needed
00:04:16 --> 00:04:19 in order to study true quantum gravity effects beyond general
00:04:19 --> 00:04:22 relativity. Patanan says a quantum theory
00:04:22 --> 00:04:25 of gravity is needed in order to understand what kind of phenomena
00:04:25 --> 00:04:28 there are in cases where there's a gravitational field with
00:04:28 --> 00:04:31 high energies, the sort of conditions you'd find around black
00:04:31 --> 00:04:34 holes and very early in the universe's existence,
00:04:34 --> 00:04:37 just after the Big Bang. And they're the sort of
00:04:37 --> 00:04:39 places where existing theories of physics all stop
00:04:39 --> 00:04:42 working. Although the hypothesis is promising,
00:04:42 --> 00:04:45 the authors point out they've not yet completed its
00:04:45 --> 00:04:48 proof. It uses a technical procedure
00:04:48 --> 00:04:51 known as renormalization. That's a mathematical way of
00:04:51 --> 00:04:54 dealing with the infinities that show up in the calculations.
00:04:54 --> 00:04:57 So far, the authors have shown that while this works up to a
00:04:57 --> 00:05:00 certain point for so called first order terms, they're yet
00:05:00 --> 00:05:03 to make sure that these infinities can be eliminated throughout the
00:05:03 --> 00:05:06 entire calculation. You see, if renormalization
00:05:06 --> 00:05:09 doesn't work for higher order terms, you'll get infinite results.
00:05:09 --> 00:05:11 So it's vital to show that this renormalization
00:05:12 --> 00:05:14 continues to work, and therefore they still need to
00:05:14 --> 00:05:17 make a complete proof. Nevertheless, it's
00:05:17 --> 00:05:20 fascinating work. This is space time.
00:05:21 --> 00:05:24 Still to come, is there a hot side to the moon?
00:05:24 --> 00:05:27 And astronomers discover their first white dwarf
00:05:27 --> 00:05:30 pulsars? All that and more still to come on,
00:05:30 --> 00:05:31 spacetime.
00:05:39 --> 00:05:40 Jonathan Nally: Foreign.
00:05:47 --> 00:05:50 Stuart Gary: Claims. The Moon's near Earth facing side is actually
00:05:50 --> 00:05:53 hotter than its far side. The findings reported
00:05:53 --> 00:05:56 in the journal Nature, based on data from NASA's GRAIL
00:05:56 --> 00:05:59 spacecraft and the twin Ebb and Flow spacecraft, which have
00:05:59 --> 00:06:02 been studying the Moon from orbit. Our Moon is
00:06:02 --> 00:06:04 gravitationally tidally locked to the Earth. That
00:06:04 --> 00:06:07 means the same side always faces our planet.
00:06:07 --> 00:06:10 Even more fascinating is the dichotomy of the Moon,
00:06:10 --> 00:06:13 which has long intrigued scientists. You see, there
00:06:13 --> 00:06:15 are notable differences in geology,
00:06:16 --> 00:06:18 volcanism and crustal thickness between the
00:06:18 --> 00:06:21 lunar near and far sides. The Moon's near
00:06:21 --> 00:06:24 side appears darker and it's dominated by smooth
00:06:24 --> 00:06:27 ancient lava flows, indicating a high concentration
00:06:27 --> 00:06:30 of volcanism. On the other hand, the far side
00:06:30 --> 00:06:33 is far more rugged. The new study using data from
00:06:33 --> 00:06:35 Grail suggests that this dichotomy is caused by a 2
00:06:35 --> 00:06:38 to 3% difference in the lunar mantle's ability to
00:06:38 --> 00:06:41 deform on each side. The authors suggest
00:06:41 --> 00:06:44 that the reason is that the Moon's near side mantle
00:06:44 --> 00:06:47 is up to 170 degrees Celsius hotter than its
00:06:47 --> 00:06:50 far side. It's thought this thermal difference could be
00:06:50 --> 00:06:53 caused by the radioactive decay of thorium and titanium within
00:06:53 --> 00:06:55 the Moon's near side, which could be a remnant of the
00:06:55 --> 00:06:58 volcanic activity that formed the near side surface between
00:06:58 --> 00:07:01 3 and 4 billion years ago. The authors say
00:07:01 --> 00:07:04 the same methods which have now been used to study the Moon's
00:07:04 --> 00:07:07 interior from orbit could also be used to measure differences in
00:07:07 --> 00:07:10 the structure of other planetary bodies, such as the Red planet
00:07:10 --> 00:07:12 Mars, the Saturn moon Enceladus and the
00:07:12 --> 00:07:15 Jovian moon Ganymede. This is space
00:07:15 --> 00:07:18 time still to come. Astronomers discover
00:07:18 --> 00:07:21 a white dwarf star acting like a pulsar and the
00:07:21 --> 00:07:24 June solstice. The constellation Sagittarius
00:07:24 --> 00:07:27 and the Taurids meteor shower are among the
00:07:27 --> 00:07:29 highlights of the June night skies on Skywatch.
00:07:44 --> 00:07:47 A white dwarf and a red dwarf have been discovered closely
00:07:47 --> 00:07:50 orbiting each other and emitting radio pulses every two hours.
00:07:51 --> 00:07:54 The findings, reported in the journal Nature Astronomy, mean
00:07:54 --> 00:07:57 that neutron stars are no longer the only stellar
00:07:57 --> 00:07:59 bodies that emit such pulses. a key
00:07:59 --> 00:08:02 factor in this discovery could be the way the binary
00:08:02 --> 00:08:05 pair is spaced unusually far apart from each other.
00:08:06 --> 00:08:09 Thanks to follow up observations using optical and X ray telescopes,
00:08:09 --> 00:08:11 the study's authors were able to determine the origin of these
00:08:11 --> 00:08:14 pulsars coming from this binary system with
00:08:14 --> 00:08:16 certainty. The findings are important because they're
00:08:16 --> 00:08:19 helping to explain the sources of these strange radio emissions which
00:08:19 --> 00:08:22 are found right across the Milky Way Galaxy.
00:08:22 --> 00:08:24 This is space, time
00:08:40 --> 00:08:43 and time. Now to check out the night skies of Dune on
00:08:43 --> 00:08:46 Skywatch June is the fourth month of
00:08:46 --> 00:08:49 the old Roman calendar. It's named after Juno, who was
00:08:49 --> 00:08:51 the wife of Jupiter, is also the equivalent to the Greek goddess
00:08:51 --> 00:08:54 Hera. Another belief is that the month's name
00:08:54 --> 00:08:57 actually comes from the Latin word juniors, which means
00:08:57 --> 00:09:00 younger ones. It's a great time to look up
00:09:00 --> 00:09:03 the night skies and marvel at the majesty of the Milky
00:09:03 --> 00:09:06 Way as it puts on its spectacular overhead
00:09:06 --> 00:09:08 display. June also marks the winter
00:09:08 --> 00:09:11 solstice in the Southern Hemisphere, which this year happens at
00:09:11 --> 00:09:14 12:42 in the afternoon of Saturday, June
00:09:14 --> 00:09:16 21, Australian Eastern Standard Time.
00:09:17 --> 00:09:20 That's 10:42 in the evening of Friday, June 20,
00:09:20 --> 00:09:23 US Eastern Daylight Time, and 2:42 in the
00:09:23 --> 00:09:26 morning of Saturday, June 21, Greenwich Mean Time.
00:09:26 --> 00:09:29 and while it means the start of winter south of the equator, it means
00:09:29 --> 00:09:32 the arrival of summer for our lucky listeners in the northern
00:09:32 --> 00:09:35 part of the planet. The June solstice occurs when
00:09:35 --> 00:09:38 the sun reaches its most northerly point in the sky as
00:09:38 --> 00:09:41 seen from Earth zenith, appearing to be directly above
00:09:41 --> 00:09:44 the Tropic of Cancer. See, Earth's
00:09:44 --> 00:09:46 seasons are governed by the tilt of the planet's axis
00:09:46 --> 00:09:49 as it journeys around the Sun. Now, the Earth's
00:09:49 --> 00:09:51 axis is always pointing the same direction in space,
00:09:52 --> 00:09:55 regardless of the position of the planet Earth as it orbits around
00:09:55 --> 00:09:58 the Sun. So on the day of the June solstice,
00:09:58 --> 00:10:00 Earth's, south pole is tilted by 23.5 degrees away
00:10:00 --> 00:10:03 from the sun, while the North Pole is tilted by the same
00:10:03 --> 00:10:06 amount towards the Sun. The sun rising in the
00:10:06 --> 00:10:09 northeast and setting in the northwest. Of course,
00:10:09 --> 00:10:12 six months later, when the South Pole is tilted towards the sun,
00:10:12 --> 00:10:15 it's the Southern hemisphere summer. And in between,
00:10:15 --> 00:10:17 we have the autumn and spring equinoxes.
00:10:18 --> 00:10:21 Temperatures on Earth aren't determined by Earth's orbital
00:10:21 --> 00:10:24 distance from the sun, but rather the angle of the Sun's
00:10:24 --> 00:10:26 rays striking the Earth. So in summer,
00:10:26 --> 00:10:29 the Sun's high in the sky and the rays hit the planet at
00:10:29 --> 00:10:32 a steep angle. In winter, the Sun's lower in the
00:10:32 --> 00:10:35 sky and the rays strike the Earth at a far shallower
00:10:35 --> 00:10:38 angle. Now, in most parts of the world, the
00:10:38 --> 00:10:40 seasons begin on the day of the solstice, or
00:10:40 --> 00:10:43 equinox. However, Australia is weird.
00:10:43 --> 00:10:46 Here, seasons begin on the first day of a specific
00:10:46 --> 00:10:48 calendar month. That means the 1st of March for autumn, the
00:10:48 --> 00:10:51 1st of June for winter, the 1st of September for spring,
00:10:51 --> 00:10:54 and you guessed it, the 1st of December for summer.
00:10:55 --> 00:10:58 Okay, let's check out the stars. Well, almost
00:10:58 --> 00:11:01 overhead this time of the year, we find the constellation
00:11:01 --> 00:11:04 Virgo Virgo is named after the
00:11:04 --> 00:11:06 goddess of justice and the harvest in ancient Greek mythology,
00:11:06 --> 00:11:09 who used her scales to weigh good and evil.
00:11:09 --> 00:11:12 However, she became so disenchanted with the evil deeds of men,
00:11:12 --> 00:11:15 she wound up throwing away her scales and retreated to the
00:11:15 --> 00:11:18 heavens. interestingly, the ancient Egyptians
00:11:18 --> 00:11:21 also associate Virgo, with agriculture. There she was
00:11:21 --> 00:11:24 the goddess Isis who sprinkled the heads of wheat across
00:11:24 --> 00:11:26 the sky, forming the Milky Way. To
00:11:26 --> 00:11:29 science, Virgo is a tightly packed region
00:11:29 --> 00:11:31 containing some 2 galaxies, all
00:11:31 --> 00:11:34 gravitationally bound into a giant galaxy cluster
00:11:34 --> 00:11:37 some 60 million light years away. In
00:11:37 --> 00:11:40 fact, our own Local Group of galaxies, dominated by the
00:11:40 --> 00:11:43 Milky Way and Andromeda, are outlying members of this
00:11:43 --> 00:11:46 group. The Virgo Cluster is at the heart
00:11:46 --> 00:11:49 of what's known as the Virgo Supercluster, a massive
00:11:49 --> 00:11:52 galactic node in the large scale cosmic web. Like
00:11:52 --> 00:11:55 str of the universe, the mass of the Virgo
00:11:55 --> 00:11:58 Supercluster is so great that its gravity generates the
00:11:58 --> 00:12:00 Virgo centric flow, causing our Milky Way galaxy
00:12:00 --> 00:12:03 as well as Andromeda and all the other members of the local galactic
00:12:03 --> 00:12:06 group to move towards the supercluster at around 400
00:12:06 --> 00:12:09 kilometers per second. That's despite the accelerating
00:12:09 --> 00:12:12 expansion of the universe over cosmic timescales.
00:12:12 --> 00:12:15 The Virgo Supercluster is now thought to be a lobe on
00:12:15 --> 00:12:18 an even larger galactic supercluster called
00:12:18 --> 00:12:21 Laniakea, the center of which is known as the
00:12:21 --> 00:12:24 Great Attractor. despite the Virgo Cluster's size, it's
00:12:24 --> 00:12:27 so far away from us it's hard to see without a decently sized
00:12:27 --> 00:12:29 backyard telescope. You'll need something at least 100
00:12:29 --> 00:12:32 mm in diameter or larger in order to see it.
00:12:33 --> 00:12:36 Now, if you look directly straight up at zenith, you'll see
00:12:36 --> 00:12:39 the constellation Corvus the crow. Greek
00:12:39 --> 00:12:41 mythology tells us that Corvus could talk to humans,
00:12:41 --> 00:12:44 but he was a lazy bird. And so
00:12:44 --> 00:12:47 Apollo took away his ability to speak and banished
00:12:47 --> 00:12:49 into the heavens. One of the most
00:12:49 --> 00:12:52 spectacular highlights of the constellations Virgo and
00:12:52 --> 00:12:55 Corvus is the Spectacular Sombrero
00:12:55 --> 00:12:58 Galaxy M104. Visible with a good
00:12:58 --> 00:13:01 pair of binoculars or a small backout telescope, this
00:13:01 --> 00:13:04 stunning spiral galaxy is seen almost edge on, and
00:13:04 --> 00:13:07 it will provide you with a spectacular backlit view of its
00:13:07 --> 00:13:09 galactic bold stars and the molecular gas and dust
00:13:09 --> 00:13:12 leans in its arms. M
00:13:12 --> 00:13:15 M104 is located some 31 million light
00:13:15 --> 00:13:18 years away, and it's moving away from the Milky way at about
00:13:18 --> 00:13:21 1 kilometers per second. A light year
00:13:21 --> 00:13:23 is about 10 trillion kilometers, the distance a
00:13:23 --> 00:13:26 photon can travel in a year. At the speed of light, which is about
00:13:26 --> 00:13:29 300 kilometers per second in a vacuum and the
00:13:29 --> 00:13:32 ultimate speed limit of the universe. The
00:13:32 --> 00:13:35 Sombrero Galaxy has a diameter of around 50
00:13:35 --> 00:13:38 light years, making it about 30% the size of
00:13:38 --> 00:13:40 our Milky Way galaxy. It's surrounded by up to
00:13:40 --> 00:13:43 2 globular clusters. And it has an active
00:13:43 --> 00:13:46 central supermassive black hole at least a billion times
00:13:46 --> 00:13:49 the mass of our Sun. Now, by comparison,
00:13:49 --> 00:13:52 Sagittarius A, that's the supermassive black hole at the
00:13:52 --> 00:13:55 center of our own galaxy, has just 4.3 million times
00:13:55 --> 00:13:58 the Sun's mass. Globular clusters are
00:13:58 --> 00:14:00 either the central remnants of smaller galaxies
00:14:00 --> 00:14:03 cannibalized by larger ones, or, alternatively,
00:14:03 --> 00:14:06 they're tight balls comprising millions of
00:14:06 --> 00:14:08 stars, which all originally formed at the same time in
00:14:08 --> 00:14:11 the same collapsing molecular gas and dust cloud.
00:14:12 --> 00:14:15 By the way, the brightest star in Virgo is Spica, a
00:14:15 --> 00:14:18 spectroscopic binary located some 250 light years
00:14:18 --> 00:14:20 away. Spectroscopic binaries are
00:14:20 --> 00:14:23 stars that are orbiting so close together they can only be told
00:14:23 --> 00:14:26 apart by their individual spectrographic signatures.
00:14:27 --> 00:14:30 Now, looking about 20 degrees above the western horizon early
00:14:30 --> 00:14:33 in the evening this time of the year, you'll find the fourth brightest
00:14:33 --> 00:14:36 object in the sky, the dog star, Sirius.
00:14:36 --> 00:14:39 Only the sun, the Moon, and the planet Venus look
00:14:39 --> 00:14:42 brighter. Looking to the northwest or
00:14:42 --> 00:14:44 right of Sirius, you'll find another fairly bright
00:14:44 --> 00:14:47 star, Procyon, the brightest star in Canis
00:14:47 --> 00:14:50 Minor, the Lesser Dog. In Greek
00:14:50 --> 00:14:52 mythology, Canis Major and Canis Minor were
00:14:52 --> 00:14:55 Orion's hunting dogs. Procyon is a
00:14:55 --> 00:14:58 binary star system. It comprises a
00:14:58 --> 00:15:01 spectral type F main sequence white yellow star
00:15:01 --> 00:15:04 Procyon A and a faint white dwarf companion,
00:15:04 --> 00:15:07 Procyon B. Main sequence stars are
00:15:07 --> 00:15:09 those undergoing hydrogen fusion into helium in their
00:15:09 --> 00:15:12 cores. Astronomers describe stars in
00:15:12 --> 00:15:15 terms of spectral types, a classification system based
00:15:15 --> 00:15:18 on temperature and characteristics. The hottest,
00:15:18 --> 00:15:21 most massive, and most luminous stars are known as spectral
00:15:21 --> 00:15:24 type O blue stars. They're followed by
00:15:24 --> 00:15:27 spectral type B blue white stars. Then spectral
00:15:27 --> 00:15:29 type A white stars, spectral type F
00:15:29 --> 00:15:32 whiteish yellow stars, spectral type G yellow
00:15:32 --> 00:15:35 stars. That's where our sun fits in. Then there's spectral
00:15:35 --> 00:15:38 type K orange stars. And the coolest and least massive
00:15:38 --> 00:15:41 known stars are spectral type M red stars.
00:15:42 --> 00:15:45 Each spectral classification can also be subdivided using
00:15:45 --> 00:15:47 a numeric digit to represent temperature, with zero
00:15:47 --> 00:15:50 being the hottest and nine the coolest. And then
00:15:50 --> 00:15:53 you can add a Roman numeral to represent luminosity.
00:15:54 --> 00:15:56 Put all that together and our sun is officially
00:15:56 --> 00:15:59 classified as the G2V or G25
00:15:59 --> 00:16:02 yellow dwarf star. Also included
00:16:02 --> 00:16:05 in the stellar classification system are spectral types
00:16:05 --> 00:16:08 L, T and Y which are assigned to failed
00:16:08 --> 00:16:11 stars known as brown dwarves, some of which were born as
00:16:11 --> 00:16:14 spectral type M red stars but became brown dwarfs
00:16:14 --> 00:16:17 after losing some of their mass. Brown dwarves
00:16:17 --> 00:16:19 fit into a unique category between the largest planets which
00:16:19 --> 00:16:22 can be up to 13 times the Mass of say Jupiter, and the smallest
00:16:22 --> 00:16:25 spectro type M red dwarf stars which are around
00:16:25 --> 00:16:28 75 to 80 times the mass of Jupiter or around
00:16:28 --> 00:16:30 0.08 solar masses.
00:16:30 --> 00:16:33 Now the other type of star we just mentioned were white dwarves.
00:16:34 --> 00:16:37 There the stellar corpses of sun like stars.
00:16:37 --> 00:16:40 Having used up all its nuclear fuel supply fusing hydrogen
00:16:40 --> 00:16:43 into helium, these stars expand into red
00:16:43 --> 00:16:46 giants as they fuse helium into carbon and oxygen.
00:16:46 --> 00:16:49 The sun and stars like it aren't massive enough
00:16:49 --> 00:16:51 to fuse carbon and oxygen into heavier elements
00:16:52 --> 00:16:55 and so they turn off. Eventually the outer
00:16:55 --> 00:16:58 gaseous envelopes will float off into space as spectacular
00:16:58 --> 00:17:00 objects known as planetary nebula. What's
00:17:00 --> 00:17:03 left behind is a super dense white hot stellar
00:17:03 --> 00:17:06 core A about the size of the Earth. This is
00:17:06 --> 00:17:09 the white dwarf which will slowly cool over the
00:17:09 --> 00:17:12 eons. The white dwarf Procyon
00:17:12 --> 00:17:15 b is about 0.6 times the mass of the
00:17:15 --> 00:17:17 sun and has a diameter of around 8
00:17:17 --> 00:17:20 km. Located about
00:17:20 --> 00:17:22 11.6 light years away, Procyon A is about
00:17:22 --> 00:17:25 1.5 times the mass and twice the radius of our Sun.
00:17:26 --> 00:17:28 But it also has some seven times the Sun's
00:17:28 --> 00:17:31 luminosity. That makes it unusually bright for a star
00:17:31 --> 00:17:34 of this type of and that suggests that it's now starting
00:17:34 --> 00:17:37 to evolve off the main sequence, having fused
00:17:37 --> 00:17:39 nearly all of its core hydrogen into helium.
00:17:40 --> 00:17:43 So that means it's slowly expanding out to become a
00:17:43 --> 00:17:46 subgiant as it begins fusing its core helium
00:17:46 --> 00:17:48 into oxygen and carbon and burning hydrogen
00:17:48 --> 00:17:51 further out from the core. As it continues to
00:17:51 --> 00:17:54 expand, the star will eventually swirl to somewhere
00:17:54 --> 00:17:57 between 80 and 150 times its current diameter, in
00:17:57 --> 00:18:00 the process becoming a red or orange giant.
00:18:00 --> 00:18:03 This will probably happen within the next 10 to 100 million
00:18:03 --> 00:18:06 years. The two stars Procyon A and
00:18:06 --> 00:18:09 B orbit each other every 40.82 Earth years at
00:18:09 --> 00:18:12 an average distance of 15 astronomical units, about
00:18:12 --> 00:18:15 the distance Uranus is from the Sun. An
00:18:15 --> 00:18:18 astronomical unit is the average distance between the Earth and the
00:18:18 --> 00:18:20 sun which is around 150 million kilometers or
00:18:20 --> 00:18:23 8.3 light minutes. Now looking
00:18:23 --> 00:18:26 towards the north northwest right now and you'll see the
00:18:26 --> 00:18:29 constellation Leo the Lion, looking like a bunch of stars
00:18:29 --> 00:18:31 shaped like an upside down question mark.
00:18:32 --> 00:18:35 Located just 36.7 light years away.
00:18:35 --> 00:18:38 Arcturus is a bloated, aging red giant
00:18:38 --> 00:18:41 about 7.1 billion years old and nearing the
00:18:41 --> 00:18:44 end of its life. Having used up all its
00:18:44 --> 00:18:47 core hydrogen, it's now fusing helium into carbon
00:18:47 --> 00:18:50 and oxygen. This has caused the star, which
00:18:50 --> 00:18:53 is only slightly more massive than our sun, to expand out
00:18:53 --> 00:18:56 to around 25 times the sun's diameter, in the
00:18:56 --> 00:18:58 process becoming about 170 times as luminous.
00:18:59 --> 00:19:02 It will soon puff off its outer gaseous envelope as a
00:19:02 --> 00:19:05 planetary nebula, revealing its white hot stellar core.
00:19:06 --> 00:19:09 In Greek mythology, Arcturus was the guardian
00:19:09 --> 00:19:12 of the bear. This is a reference to it being next
00:19:12 --> 00:19:14 to the constellations Ursa Major and Ursa Minor, the
00:19:14 --> 00:19:17 greater and lesser bears. There's some
00:19:17 --> 00:19:20 indications that Arcturus could have a binary stellar
00:19:20 --> 00:19:22 companion, but the results remain inconclusive.
00:19:23 --> 00:19:26 There's also some speculation that it could have a large planet
00:19:26 --> 00:19:28 or substellar object around 12 Jupiter masses
00:19:28 --> 00:19:31 orbiting it. that's close to brown dwarf size. But
00:19:31 --> 00:19:34 again, the search remains inconclusive.
00:19:35 --> 00:19:37 To the east are the three brightest stars in the
00:19:37 --> 00:19:40 constellation Libra, the scales of Justice. They are
00:19:40 --> 00:19:43 visible about halfway about 40 degrees above the
00:19:43 --> 00:19:45 horizon. These represent the claws of
00:19:45 --> 00:19:48 Scorpius the Scorpion, which is chasing Orion across
00:19:48 --> 00:19:51 the sky. The brightest star in the constellation
00:19:51 --> 00:19:53 Scorpius is Alphascorpi or
00:19:53 --> 00:19:55 Antares, the Scorpion's Heart.
00:19:56 --> 00:19:59 Easily seen with the unaided eye, this red supergiant
00:19:59 --> 00:20:02 is some 550 light years away and it's one of the
00:20:02 --> 00:20:05 largest known stars in the universe. It has about
00:20:05 --> 00:20:08 18 times the mass and 883 times
00:20:08 --> 00:20:11 the diameter of our sun. And it has some 10
00:20:11 --> 00:20:13 times more luminosity than our Sun.
00:20:14 --> 00:20:17 Looking to the southeast now and you'll see the constellation
00:20:17 --> 00:20:20 Sagittarius the Archer. Sagittarius
00:20:20 --> 00:20:23 marks the direction of the center of our galaxy, the Milky way.
00:20:23 --> 00:20:26 It's located 26 light years away and is home to
00:20:26 --> 00:20:29 the galaxy's supermassive black hole, Sagittarius
00:20:29 --> 00:20:32 A. To the ancient Babylonians,
00:20:32 --> 00:20:35 Sagittarius was the God Nurgle the Centaur,
00:20:35 --> 00:20:37 a creature that was half man and half horse.
00:20:38 --> 00:20:41 By the time Greek mythology took over, Sagittarius was
00:20:41 --> 00:20:43 carrying his bow loaded with an arrow pointing towards
00:20:43 --> 00:20:46 Antares, the heart of Scorpius the Scorpion,
00:20:47 --> 00:20:50 the center of the Milky Way Galaxy and its supermassive
00:20:50 --> 00:20:52 black hole, Sagittarius a lie in the
00:20:52 --> 00:20:55 westernmost part of the constellation Sagittarius.
00:20:56 --> 00:20:58 One of the brightest stars in Sagittarius is Alpha
00:20:58 --> 00:21:01 Sagittari, or Rock Bat, meaning the Archer's Knee,
00:21:01 --> 00:21:03 a spectral type B blue star
00:21:03 --> 00:21:06 located 182 light years away. It is some
00:21:06 --> 00:21:09 2.5 times the diameter of the sun and it's about 40
00:21:09 --> 00:21:12 times as luminous. Astronomers think it's
00:21:12 --> 00:21:15 surrounded by a dense debris disk and a newborn companion
00:21:15 --> 00:21:17 star which is only just joining the main sequence.
00:21:18 --> 00:21:21 the overall brightest star in Sagittarius or Cas
00:21:21 --> 00:21:23 Australis, the southern part of the Bow,
00:21:23 --> 00:21:26 Epsilon Sagittaria is a binary star system
00:21:26 --> 00:21:29 located 143 light years away. The
00:21:29 --> 00:21:32 primary star is an evolved spectra type B blue giant.
00:21:32 --> 00:21:35 Now at the end of its life on the main sequence, it
00:21:35 --> 00:21:38 has about three and a half times the Sun's mass, almost
00:21:38 --> 00:21:40 seven times its radius, and it's radiating around
00:21:40 --> 00:21:43 363 times the Sun's
00:21:43 --> 00:21:45 luminosity. It's also a very strong X
00:21:45 --> 00:21:48 ray source, and it's spinning incredibly rapidly with an
00:21:48 --> 00:21:51 estimated radial velocity of some 236
00:21:51 --> 00:21:54 kilometers per second. The system also
00:21:54 --> 00:21:57 displays an excess of infrared radiation emissions,
00:21:57 --> 00:22:00 suggesting the presence of a circumstellar disk of dust.
00:22:00 --> 00:22:03 The second star in the system appears to be inside
00:22:03 --> 00:22:06 this debris disk. Astronomers are
00:22:06 --> 00:22:09 speculating that this may well develop into a spectral type
00:22:09 --> 00:22:12 G yellow dwarf star with about 95% of our
00:22:12 --> 00:22:14 Sun's mass. Sigma Sagittarius
00:22:15 --> 00:22:17 is the constellation's second brightest star. we know the name
00:22:17 --> 00:22:20 Nunci has Babylonian origins. However, its
00:22:20 --> 00:22:23 meaning remains a mystery. It is thought to represent
00:22:23 --> 00:22:26 the ancient Babylonian city of Urdu on the Euphrates
00:22:26 --> 00:22:29 River. If correct, that would make Nunqui the
00:22:29 --> 00:22:31 oldest known star name currently in use.
00:22:32 --> 00:22:35 It's a spectral type B blue star located
00:22:35 --> 00:22:37 about 260 light years away. It has about
00:22:37 --> 00:22:40 8 times the Sun's mass, about 4.5 times its
00:22:40 --> 00:22:43 radius, and some 3 times the
00:22:43 --> 00:22:46 luminosity of our Sun. Zeta Sagittaria, or
00:22:46 --> 00:22:49 a cell at the armpit, is a binary star system
00:22:49 --> 00:22:51 88 light years away from the Sun. It's
00:22:51 --> 00:22:54 currently speeding away from the solar system, but, may once have been
00:22:54 --> 00:22:57 as near as 1.5 light years from the sun about 1.4 million
00:22:57 --> 00:23:00 years ago. And that would make it a former close
00:23:00 --> 00:23:03 neighbor. One of the stars in the system is a
00:23:03 --> 00:23:06 spectrotype, a white giant, while the other is a spectre
00:23:06 --> 00:23:08 type a white supergiant, the pair orbiting each other
00:23:08 --> 00:23:11 every 21 Earth years. The system's
00:23:11 --> 00:23:14 combined mass is thought to be 5.26
00:23:14 --> 00:23:17 times the mass of our Sun. Delta Sagittarius
00:23:17 --> 00:23:19 appears to be a double star system located around
00:23:19 --> 00:23:22 348 light years away and listed is an
00:23:22 --> 00:23:25 orange giant. Then there's Eta
00:23:25 --> 00:23:27 Sagittaria, another double star system, this one located
00:23:27 --> 00:23:30 146 light years from Earth. the primary star
00:23:30 --> 00:23:33 in the system is an aging, bloated red giant
00:23:33 --> 00:23:36 on the asentopic giant branch. That means it's
00:23:36 --> 00:23:39 no longer fusing hydrogen or helium at its core and is
00:23:39 --> 00:23:42 instead fusing heavier elements, burning hydrogen
00:23:42 --> 00:23:45 and helium in the shell. It's already expanded out
00:23:45 --> 00:23:48 to some 57 times the radius of our sun and
00:23:48 --> 00:23:51 is now nearing the end of its life. The second
00:23:51 --> 00:23:54 star in the system is the spectral type F main sequence
00:23:54 --> 00:23:56 white yellow dwarf, which appears to be in a binary system with
00:23:56 --> 00:23:58 the primary star orbiting it every
00:23:58 --> 00:24:01 1270 Earth years. PI
00:24:01 --> 00:24:04 Sagittarius, or Ibalda, is a triple star system
00:24:04 --> 00:24:07 located 510 light years away. The
00:24:07 --> 00:24:10 primary star in the system appears to be a spectral type
00:24:10 --> 00:24:13 F white yellow giant, which has exhausted its core
00:24:13 --> 00:24:16 hydrogen and so is now off the main sequence and evolving
00:24:16 --> 00:24:18 into a red giant. We know PI
00:24:18 --> 00:24:21 Sagittarius has two nearby companions, but little
00:24:21 --> 00:24:24 is known about either of them. Beta Sagittaria, or,
00:24:24 --> 00:24:27 Arcap, the Achilles tendon is the designation shared by two
00:24:27 --> 00:24:29 separate star systems. One's about
00:24:29 --> 00:24:31 378 light years from Earth, the other
00:24:31 --> 00:24:34 139 light years away. Beta
00:24:34 --> 00:24:36 Sagittary A is a spectral type B blue dwarf star,
00:24:36 --> 00:24:39 while Beta Sagittarius B is a white yellow giant.
00:24:40 --> 00:24:42 Lying nearly at the very center of the constellation
00:24:42 --> 00:24:45 Sagittarius is Nova Sagittari, which was
00:24:45 --> 00:24:48 only discovered in 2015. And as its name
00:24:48 --> 00:24:51 suggests, Rest is a nova, a white dwarf in a binary
00:24:51 --> 00:24:54 system with another star, which is constantly drawing material
00:24:54 --> 00:24:57 off its companion. Now, once enough material
00:24:57 --> 00:24:59 reaches the surface of the white dwarf, this added mass
00:24:59 --> 00:25:02 triggers a thermonuclear explosion, causing the star
00:25:02 --> 00:25:05 to suddenly light up like a beacon and then slowly
00:25:05 --> 00:25:08 begin fading again over the following weeks and
00:25:08 --> 00:25:11 months. Now, this blast isn't strong enough to destroy
00:25:11 --> 00:25:14 the white dwarf, only the additional material that it's picked up.
00:25:14 --> 00:25:17 And with this additional material now burnt off, the same cycle
00:25:17 --> 00:25:20 can start over again, and the process can repeat itself
00:25:20 --> 00:25:23 on time scales ranging from every few years to tens of
00:25:23 --> 00:25:26 thousands of years apart. The
00:25:26 --> 00:25:29 Sagittarius constellation also hosts many star
00:25:29 --> 00:25:31 clusters and nebulae, including some of the best known
00:25:31 --> 00:25:34 astronomical objects in the sky. These
00:25:34 --> 00:25:37 include the lagoon Nebula, Messier 8, a
00:25:37 --> 00:25:40 spectacular Pinker Mission Nebula located 8 light
00:25:40 --> 00:25:43 years away, which measures 140 light years by
00:25:43 --> 00:25:46 60 light years across the central area of the
00:25:46 --> 00:25:49 Lagoon Nebula is also known as the Hourglass Nebula
00:25:49 --> 00:25:52 because of its distinctive shape. The shape is caused
00:25:52 --> 00:25:55 by matter propelled by a massive star forming in a region
00:25:55 --> 00:25:57 known as Herschel 36. One of the few star forming
00:25:57 --> 00:26:00 nebulae that's possible to see with the unaided eye,
00:26:00 --> 00:26:03 the Lagoon Nebula was instrumental in the discovery of what
00:26:03 --> 00:26:06 are known as Bok globules, more than 17
00:26:06 --> 00:26:08 of which have now been found in the nebula.
00:26:08 --> 00:26:11 Astronomers believe Bok Globules contain
00:26:11 --> 00:26:14 embryonic protostars destined to eventually become
00:26:14 --> 00:26:15 new stellar generations.
00:26:17 --> 00:26:19 Probably the best known nebula in Sagittarius is
00:26:19 --> 00:26:22 Messier 17, the Horsehead Nebula.
00:26:22 --> 00:26:25 It's located 4 light years
00:26:25 --> 00:26:28 away and is a dense region of ionized atomic
00:26:28 --> 00:26:31 hydrogen. Also known as the Omega, or
00:26:31 --> 00:26:33 Swan Nebula. It spans some 15 light years in
00:26:33 --> 00:26:36 diameter and has some 800 times the mass of our Sun.
00:26:37 --> 00:26:40 it's considered one of the brightest and most massive star forming
00:26:40 --> 00:26:43 regions in our galaxy with a geometry very similar to the
00:26:43 --> 00:26:46 Orion Nebula, except that it's viewed edge on rather
00:26:46 --> 00:26:48 than face on. The open star cluster
00:26:48 --> 00:26:51 NGC6618 is embedded within
00:26:51 --> 00:26:54 the nebulosity and it causes the gases of the nebula to
00:26:54 --> 00:26:57 shine due to intense radiation from these hot young
00:26:57 --> 00:27:00 stars. Open star clusters are loosely
00:27:00 --> 00:27:03 bound groups of a few thousand stars, which were originally
00:27:03 --> 00:27:06 all formed in the same molecular gas and dust cloud, but are
00:27:06 --> 00:27:09 not as tightly bonded together as the stars in globular
00:27:09 --> 00:27:11 clusters. It's thought open clusters generally
00:27:11 --> 00:27:14 survive for a few hundred million years, with the most massive
00:27:14 --> 00:27:17 ones surviving for maybe a few billion years.
00:27:17 --> 00:27:20 In contrast, the more massive globular clusters exert
00:27:20 --> 00:27:23 far stronger gravitational attraction to their members,
00:27:23 --> 00:27:26 and they therefore can survive much longer in cosmic
00:27:26 --> 00:27:28 time. The nebula is thought to contain over
00:27:28 --> 00:27:31 800 stars, including more than 100 of the
00:27:31 --> 00:27:34 largest, most massive spectral type OMB blue
00:27:34 --> 00:27:36 stars. More than a thousand
00:27:36 --> 00:27:39 additional stars are now being formed in the surrounding
00:27:39 --> 00:27:42 molecular gas and dust clouds. It's also one of the
00:27:42 --> 00:27:45 youngest known clusters in the galaxy, with an age of just a million
00:27:45 --> 00:27:48 years. The cloud of interstellar material
00:27:48 --> 00:27:51 forming the Nebula is roughly 40 light years in
00:27:51 --> 00:27:53 diameter, and it's thought to contain some 30 solar
00:27:53 --> 00:27:56 masses. Another famous
00:27:56 --> 00:27:59 nebulosity is the Trifid Nebula, Messier 20.
00:27:59 --> 00:28:02 It's another large star forming a mission Nebula
00:28:02 --> 00:28:04 containing many very young hot stars.
00:28:05 --> 00:28:08 Located somewhere between 2 and 9 light years from Earth,
00:28:08 --> 00:28:11 the Trifid Nebula has a diameter of around 50 light
00:28:11 --> 00:28:14 years. Now, the outside of the Trifid Nebula is
00:28:14 --> 00:28:16 a bluish reflection Nebula, while the inner region is
00:28:16 --> 00:28:19 glowing pink thanks to ionized hydrogen. There
00:28:19 --> 00:28:22 are two dark bands dividing the Trifid Nebula into
00:28:22 --> 00:28:25 three regions or lobes. Hydrogen in the
00:28:25 --> 00:28:28 nebula is being ionized by a central triple star system
00:28:28 --> 00:28:31 which formed in the intersection of the two bands
00:28:31 --> 00:28:33 creating the characteristic pink color.
00:28:34 --> 00:28:36 Other star forming regions such as
00:28:36 --> 00:28:39 NGC559, which is located
00:28:39 --> 00:28:41 5 light years from Earth contain both red emission
00:28:41 --> 00:28:43 and blue reflection regions.
00:28:44 --> 00:28:47 This grouping of the Lagoon Nebula, the Trifid
00:28:47 --> 00:28:49 Nebula and NGC 6559 is
00:28:49 --> 00:28:51 known as the Sagittarius triplet.
00:28:52 --> 00:28:55 Another spectacular sight in Sagittarius is the red
00:28:55 --> 00:28:57 Spider Nebula NGC
00:28:57 --> 00:29:00 6537. It's a planetary
00:29:00 --> 00:29:03 nebula some 8 light years from Earth. It
00:29:03 --> 00:29:06 is a prominent two lobe shape. this could be due to
00:29:06 --> 00:29:09 a binary companion or possibly magnetic fields and has
00:29:09 --> 00:29:12 an S shaped symmetry with the lobes opposite each other appearing
00:29:12 --> 00:29:14 similar. The central white dwarf
00:29:14 --> 00:29:17 remnant, the original star produces a powerful
00:29:17 --> 00:29:20 10 degree hot 3 kilometers per
00:29:20 --> 00:29:22 second stellar wind. And that wind is generating
00:29:22 --> 00:29:25 100 billion kilometer high waves of
00:29:25 --> 00:29:28 supersonic shocks which are formed as local gas is
00:29:28 --> 00:29:30 being compressed and heated in front of the rapidly expand
00:29:31 --> 00:29:34 lobes. Atoms caught in the shock front are
00:29:34 --> 00:29:37 radiating invisible light, giving the nebula its unique
00:29:37 --> 00:29:39 spider like shape and also contributing to its
00:29:39 --> 00:29:42 expansion. The star at the center of the Red Spider
00:29:42 --> 00:29:45 Nebula is shrouded by a dust shell, making its exact
00:29:45 --> 00:29:48 properties hard to determine. We think it has a
00:29:48 --> 00:29:50 surface temperature of around 25 degrees,
00:29:50 --> 00:29:53 although temperatures of up to half a million degrees can't be ruled
00:29:53 --> 00:29:56 out, which would make it one of the hottest white dwarf stars
00:29:56 --> 00:29:59 known as Now if you look directly south
00:29:59 --> 00:30:01 this time of year, you'll find the star Polaris
00:30:01 --> 00:30:04 Australis or more accurately Sigma Octanus,
00:30:04 --> 00:30:07 the nearest star to the southern celestial pole and
00:30:07 --> 00:30:10 consequently the counterpart to the north star Polaris.
00:30:11 --> 00:30:13 However, Sigma Octanus is much harder to see than
00:30:13 --> 00:30:16 Polaris because it's much fainter. Located
00:30:16 --> 00:30:19 some 270 light years away, it's now an orange
00:30:19 --> 00:30:21 giant nearing the end of its life.
00:30:22 --> 00:30:25 Turning to the southwest just above the horizon and we
00:30:25 --> 00:30:28 find Canopus, the second brightest star in the night sky
00:30:28 --> 00:30:30 after Sirius Aureus. It's located some
00:30:30 --> 00:30:33 310 light years away and is the brightest star in the
00:30:33 --> 00:30:36 constellation Carina, the Keel. Canopus
00:30:36 --> 00:30:39 is a supergiant some nine times the mass of the
00:30:39 --> 00:30:41 sun and some 71 times its diameter.
00:30:42 --> 00:30:45 The month of June also marks the first of two
00:30:45 --> 00:30:48 annual encounters with the Taureds meteor shower.
00:30:48 --> 00:30:51 The Taureds are generated as the Earth passes through a debris
00:30:51 --> 00:30:54 stream left by the Comet 2P anke, which
00:30:54 --> 00:30:56 itself could be pieces of a much larger comet that broke
00:30:56 --> 00:30:59 apart around 20 to 30 years ago, most
00:30:59 --> 00:31:02 likely following numerous interactions with the powerful gravitational
00:31:02 --> 00:31:05 field of the planet Jupiter. As their name
00:31:05 --> 00:31:08 suggests, the Taurids radiant or apparent point of
00:31:08 --> 00:31:11 origin is in the constellation Taurus the Bull.
00:31:11 --> 00:31:14 The Taurid's meteor shower is made up of larger, more
00:31:14 --> 00:31:16 massive material. Think of pebbles instead of dust
00:31:16 --> 00:31:19 grains. Earth, passes through this stream twice
00:31:19 --> 00:31:22 every year, once in June, then again in October when
00:31:22 --> 00:31:24 they're referred to as Halloween fireballs. The
00:31:24 --> 00:31:27 Taurids release material both by normal cometary
00:31:27 --> 00:31:30 activity and occasionally through close encounters with the
00:31:30 --> 00:31:33 gravitational tidal forces exerted by the Earth and other
00:31:33 --> 00:31:36 planets. And all this makes the Taured
00:31:36 --> 00:31:38 stream of material the largest in the inner solar system.
00:31:39 --> 00:31:42 Now, since this meteor stream is rather spread out in space,
00:31:42 --> 00:31:45 planet Earth takes several weeks to pass through it, causing an
00:31:45 --> 00:31:48 extended period of meteor activity compared with the much smaller
00:31:48 --> 00:31:50 periods of activity by other meteor showers.
00:31:51 --> 00:31:54 Now included in the Turret stream is a denser flow of
00:31:54 --> 00:31:57 gravelly meteors called the Turret Swarm. And they're
00:31:57 --> 00:31:59 thought to be a ribbon of rocks roughly 75 million
00:31:59 --> 00:32:02 km by 150 km across and held
00:32:02 --> 00:32:05 in orbit by Jupiter's gravity. Now,
00:32:05 --> 00:32:07 occasionally planet Earth passes through the larger
00:32:07 --> 00:32:10 meteors in this denser Taurid swarm.
00:32:10 --> 00:32:13 And one of the larger chunks in the Taurid swarm is now thought
00:32:13 --> 00:32:16 to have caused the infamous Tunguska event in the skies
00:32:16 --> 00:32:18 above Siberia on June 30,
00:32:18 --> 00:32:21 1908. The Tunguska event is now believed
00:32:21 --> 00:32:24 to have been the airburst of a 100 meter wide meteor
00:32:24 --> 00:32:27 in the skies above the Tunguska region of Russia, resulting
00:32:27 --> 00:32:30 in mass Devastation over a 2 square
00:32:30 --> 00:32:33 kilometer region of forest, turning trees into
00:32:33 --> 00:32:36 matchsticks. In fact, the blast was so
00:32:36 --> 00:32:39 bright it lit up the night sky in London a third of the
00:32:39 --> 00:32:41 way around the planet. The Tunguska event
00:32:41 --> 00:32:44 remains the largest known Earth impact event of a
00:32:44 --> 00:32:46 meteor in recorded modern times.
00:32:47 --> 00:32:50 It's always been considered to be a one in a thousand year event,
00:32:50 --> 00:32:52 assuming a random distribution of events over time.
00:32:53 --> 00:32:56 But there's a problem with that because of these new studies suggesting the
00:32:56 --> 00:32:59 event may have been caused by a Taurid swarm meteor. And
00:32:59 --> 00:33:02 with the Earth passing through the Taurid swarm periodically, it
00:33:02 --> 00:33:05 changes the odds considerably. If, this new study
00:33:05 --> 00:33:08 is correct, the swarm heightens the possibility of a cluster
00:33:08 --> 00:33:10 of large impacts on Earth over a short period of time.
00:33:11 --> 00:33:14 further complicating matters, the dune Taurids are actually
00:33:14 --> 00:33:17 two separate showers. The southern Taurids
00:33:17 --> 00:33:20 are associated with the comet 2P ANKI, while the northern
00:33:20 --> 00:33:22 taurids originate from the asteroid 2004
00:33:23 --> 00:33:25 TG10 at concentric kilometer wide
00:33:25 --> 00:33:28 asteroid classified as a near Earth object and a potentially
00:33:28 --> 00:33:31 hazardous asteroid of the Apollo group. Something to
00:33:31 --> 00:33:34 think about. Joining us now for the rest of
00:33:34 --> 00:33:37 our tour of the night skies of June is science editor
00:33:37 --> 00:33:38 Jonathan Nally.
00:33:38 --> 00:33:38 Jonathan Nally: G' day, Stuart Gary.
00:33:38 --> 00:33:41 Yeah, well, it's June, so June evenings start off with the
00:33:41 --> 00:33:44 constellation Orion low in the west. So
00:33:44 --> 00:33:47 Orion's one of our favorite constellations, isn't it? I love Orion. Everyone
00:33:47 --> 00:33:50 loves Orion. That's very easily recognizable. But it is low
00:33:50 --> 00:33:53 in the west, after sunset. And as the Earth
00:33:53 --> 00:33:56 turns during the evening, it dips below the horizon
00:33:56 --> 00:33:59 pretty quickly. And by the middle of the month, it's actually going to be gone after
00:33:59 --> 00:34:02 sunset. You won't be able to see it anymore. But it will reappear
00:34:02 --> 00:34:04 towards the end of the year in the eastern sky. And that, when Orion
00:34:04 --> 00:34:07 appears in the eastern star at the end of the year, that's when you know that for people
00:34:07 --> 00:34:10 in the Southern hemisphere, summer is arriving. Or for people in the
00:34:10 --> 00:34:13 Northern Hemisphere, they know that winter is arriving. So it's a good
00:34:13 --> 00:34:16 sign post the old Orion. But yeah, you get your last glimpse of it now
00:34:16 --> 00:34:18 basically in the evening, the first half of June.
00:34:18 --> 00:34:21 Also in the western part of the sky, there are two bright stars.
00:34:21 --> 00:34:24 One's called Sirius, the other one's called Procyon.
00:34:24 --> 00:34:27 Sirius is the brightest star in the night sky.
00:34:27 --> 00:34:30 Procyon is the eighth brightest, still very bright.
00:34:30 --> 00:34:32 And they have a few similarities, actually. They're both binary
00:34:32 --> 00:34:35 stars. And each of them is a, what they call a main
00:34:35 --> 00:34:38 sequence, a normal sort of star with a white dwarf going around it, a
00:34:38 --> 00:34:41 white dwarf star. And they're both within constellations that
00:34:41 --> 00:34:44 have the word dog in the name. Sirius is in the
00:34:44 --> 00:34:47 constellation Canis Major, or the Greater Dog. And
00:34:47 --> 00:34:50 Procyon is in the constellation Canis Minor, or
00:34:50 --> 00:34:50 the Lesser Dog.
00:34:51 --> 00:34:54 In the southwest, there's another bright star, Canopus. Canopus
00:34:54 --> 00:34:56 is my favorite star in the whole sky. I reckon it's the second brightest
00:34:56 --> 00:34:59 star in the night sky, about half as bright as Sirius. You
00:34:59 --> 00:35:02 only get a really good look of it. And look at it if you're in the southern hemisphere
00:35:02 --> 00:35:05 from people in the Northern hemisphere, sort of lower latitude, you
00:35:05 --> 00:35:08 can see it, certain times of the year. But, from down here, it's
00:35:08 --> 00:35:09 pretty much visible all the time.
00:35:09 --> 00:35:12 Stuart Gary: And it's actually the most luminous star in our neighborhood. It's
00:35:12 --> 00:35:13 huge.
00:35:13 --> 00:35:16 Jonathan Nally: Yeah, it is. It's about 10 times brighter than our sun,
00:35:16 --> 00:35:19 about 10 times its size. And fortunately it is
00:35:19 --> 00:35:21 about 310 light years away, which is very close in
00:35:21 --> 00:35:24 space terms. But if it was much closer than 310 light
00:35:24 --> 00:35:27 years away, it would be very, very bright
00:35:27 --> 00:35:30 indeed. I mean, if it was a fraction of that
00:35:30 --> 00:35:32 distance we really wouldn't have a night sky.
00:35:32 --> 00:35:35 Stuart Gary: Is it the case that Canopus was once closer to our
00:35:35 --> 00:35:38 star system than Sirius and then moved away and
00:35:38 --> 00:35:39 it's slowly coming back again?
00:35:39 --> 00:35:42 Jonathan Nally: I think it is the case, yeah. I think it is the case that, the
00:35:42 --> 00:35:45 distances have changed a little bit and Canopus at one point was
00:35:45 --> 00:35:48 brighter than CE Sirius I think. So, you know, we would.
00:35:48 --> 00:35:51 We're moving our solar systems moving through space and Sirius is
00:35:51 --> 00:35:53 moving through space and Canopus is moving through space. So the distances
00:35:53 --> 00:35:56 between each other are moving around a bit. But yeah,
00:35:56 --> 00:35:59 Canopus at the moment is not as bright as Sirius. Sirius is
00:35:59 --> 00:36:02 the brightest star. But you know, you go out to the naked
00:36:02 --> 00:36:05 eye telling one star apart of that
00:36:05 --> 00:36:08 brightness, turning one star apart from another is,
00:36:08 --> 00:36:11 it's not the easiest thing to do if you get a good look
00:36:11 --> 00:36:14 at both and you say, yeah, yeah, well, Sirius is brighter but you know, they
00:36:14 --> 00:36:17 both are very, very bright. But yeah, I don't know, Canopus is just of my
00:36:17 --> 00:36:20 favourites really. I guess because it was one of the first stars I identified when I was a kid
00:36:20 --> 00:36:23 and because it's a nice bright star far down in the Southern Star, we
00:36:23 --> 00:36:25 sort of got it all to ourselves sort of thing. So, it's, it's
00:36:26 --> 00:36:28 just got a sort of a sentimental value for me.
00:36:28 --> 00:36:30 Stuart Gary: We're very lucky in the southern hemisphere, aren't we?
00:36:30 --> 00:36:33 Jonathan Nally: Oh, ah, we're super lucky in the southern hemisphere. We've got lots of bright things. We've
00:36:33 --> 00:36:36 got the, center of the Milky Way galaxy overhead and we've got the
00:36:36 --> 00:36:38 Magellanic Cloud galaxies. There are plenty good things. Which is not to say
00:36:38 --> 00:36:41 that there aren't plenty of great things in the northern sky as well.
00:36:41 --> 00:36:44 But we, we do have a few extras it seems, down here that makes
00:36:44 --> 00:36:47 it a bit special. Now, high in the south, about two thirds of the
00:36:47 --> 00:36:50 up from the horizon, down in the south, you've got the Southern Cross this time of
00:36:50 --> 00:36:53 year and it's standing upright for a change because a lot
00:36:53 --> 00:36:56 of the year it's either upside down or on its left side or on its right side
00:36:56 --> 00:36:59 or whatever. But roundabout now, it's pretty Much standing
00:36:59 --> 00:37:02 upright. Nearby you've got the pair of stars
00:37:02 --> 00:37:05 known as the two Pointers, Alpha and Beta Centauri.
00:37:05 --> 00:37:08 We talk about those a lot on the show. The Milky Way runs
00:37:08 --> 00:37:11 right through this region of the Cross. It's sort of heading from east to west across
00:37:11 --> 00:37:14 the sky. And there are plenty of star clusters and nebulae for
00:37:14 --> 00:37:16 amateur astronomers to enjoy looking along its length even
00:37:16 --> 00:37:19 with a pair of binoculars. With a telescope it's great, particularly if you've got
00:37:19 --> 00:37:22 one that gives you a wide field of view. But just binoculars looks
00:37:22 --> 00:37:25 really superb along there. You do need dark skies though.
00:37:25 --> 00:37:28 City skies do make it very, very hard with all the
00:37:28 --> 00:37:31 light pollution. Now if you do have really dark skies and you've got a
00:37:31 --> 00:37:34 clear southern horizon, you might be able to see two smudges
00:37:34 --> 00:37:37 of light above the southern horizon. And those are these Magellanic Clouds I
00:37:37 --> 00:37:40 was talking about earlier. These are small, odd shaped
00:37:40 --> 00:37:42 galaxies that are very close to the Milky Way. They're the
00:37:42 --> 00:37:45 nearest sizeable galaxies to our own. And you can see them
00:37:45 --> 00:37:48 just with the naked. If you've got dark skies and you let your eyes
00:37:48 --> 00:37:51 get adapted into the dark, they just look like clouds. They look
00:37:51 --> 00:37:54 like tiny clouds. Hence their name, Magellanic Clouds.
00:37:54 --> 00:37:57 There's actually a bit of a push on to rename
00:37:57 --> 00:38:00 them. Do away with the name Magellan because, you
00:38:00 --> 00:38:02 know, in keeping with the way things are these days, you know, Mr.
00:38:02 --> 00:38:05 Magellan, or at least the voyage that he was on, was not too
00:38:05 --> 00:38:08 kind to some of the people and places that they
00:38:08 --> 00:38:11 visited on their around the world trip. So, in the spirit
00:38:11 --> 00:38:14 of that, some people are trying to have those clouds
00:38:14 --> 00:38:16 renamed Spawn, large milky clouds or something along that line sort of
00:38:16 --> 00:38:19 similar to the Milky Way. So we'll see how far that gets
00:38:19 --> 00:38:22 in the northern half of the sky as seen from the southern hemisphere at
00:38:22 --> 00:38:25 least. It does seem a bit bare this time of year. But there is the bright star
00:38:25 --> 00:38:28 Arcturus, which you can see about halfway up from the
00:38:28 --> 00:38:31 northern horizon. And got another bright star that's reasonably
00:38:31 --> 00:38:34 overhead from the latitude of St Sydney. That star is called
00:38:34 --> 00:38:36 Spica. And as the night goes on you'll see that things have
00:38:36 --> 00:38:39 changed because the Earth is rotating by midnight.
00:38:39 --> 00:38:42 Sirius has already set in the west, the brightest star has
00:38:42 --> 00:38:45 already set in the west. And a couple of other bright stars have appeared in the
00:38:45 --> 00:38:48 north. You've got Vega and Altair, which are very famous
00:38:48 --> 00:38:51 stars. They appear in lots of science fiction and TV
00:38:51 --> 00:38:54 series and those sort of things. And there's another star in the southeast
00:38:54 --> 00:38:57 actually another 1m very far in the southeast down the southern
00:38:57 --> 00:39:00 sky. It's one of these ones that you see really only from the southern hemisphere.
00:39:00 --> 00:39:02 It's called Achenar. And that's actually another one of my
00:39:02 --> 00:39:05 favorite stars. Again, probably just because it's sort of special because
00:39:05 --> 00:39:08 it's only visible from the south. And the Milky Way,
00:39:08 --> 00:39:11 which was stretching, as I said, was stretching east west sort of horizontally
00:39:11 --> 00:39:14 across the sky. It's now stretching from the northeast to the
00:39:14 --> 00:39:17 southwest sort of diagonally across the sky. That's just because the
00:39:17 --> 00:39:20 Earth is turning and we get a different perspective now, turning to
00:39:20 --> 00:39:23 the planets. What have we got? Well, we've got Jupiter at the
00:39:23 --> 00:39:26 moment is out of view. It's too close to the sun to be seen.
00:39:26 --> 00:39:29 That'll be that way for a little while. The same goes for Mercury, actually.
00:39:29 --> 00:39:32 Although if you are lucky, and by lucky I mean if you've got a good
00:39:32 --> 00:39:35 clear horizon and there's no buildings and trees and things in the
00:39:35 --> 00:39:38 way, you might just be able to spot Mercury very low above
00:39:38 --> 00:39:40 the western horizon after the sun have set in the last
00:39:40 --> 00:39:43 week or so of June. Other than that, it's,
00:39:43 --> 00:39:46 very, very close to the sun and very hard to see around mid
00:39:46 --> 00:39:49 evening time after it gets dark. Mars can be
00:39:49 --> 00:39:52 seen about halfway up from the horizon very easily. It's a sort
00:39:52 --> 00:39:55 of, it looks like a red star or an orangey
00:39:55 --> 00:39:57 reddish kind of star, as I said, about halfway up
00:39:57 --> 00:40:00 from the horizon to the north if you're viewing from the Southern
00:40:00 --> 00:40:03 Hemisphere or to the south if you're viewing from the Northern Hemisphere.
00:40:04 --> 00:40:06 So see if you can spot that one. You want to spot Saturn,
00:40:07 --> 00:40:10 you have to stay up a bit later. It rises above the Eastern Horizon
00:40:10 --> 00:40:12 about 1:30am at the beginning of the month and by about
00:40:12 --> 00:40:15 midnight at the end of June, which is a bit past
00:40:15 --> 00:40:18 my usual bedtime these days. But if you're out and about late, you should be
00:40:18 --> 00:40:21 able to spot it quite easily. It's fairly bright, has a slightly
00:40:21 --> 00:40:24 yellowish tinge. So it's coming up over the horizon
00:40:24 --> 00:40:26 about 1:30am at the beginning of the month.
00:40:26 --> 00:40:28 And finally we've got Venus, which will also be rising over the
00:40:28 --> 00:40:30 horizon. It follows Saturn, but at around about
00:40:30 --> 00:40:33 3:45am so you have to stay up very, very
00:40:33 --> 00:40:36 late for that one. night owls, will be able to get a view of that.
00:40:37 --> 00:40:39 You can't miss Venus, of course, as I always say is it's so big and
00:40:39 --> 00:40:42 bright, you just can't. It's the third brightest thing in the sky. After the
00:40:42 --> 00:40:45 sun and the moon. So nighttime of course, pretty easy to spot
00:40:45 --> 00:40:46 Venus.
00:40:46 --> 00:40:49 Stuart Gary: You were just coming home from the club at that time, weren't you?
00:40:49 --> 00:40:51 Jonathan Nally: Coming home from the club in my dreams I think. No, I think night
00:40:51 --> 00:40:54 owls, those night shifts and those people getting
00:40:54 --> 00:40:57 up early for morning shifts will be able to spot it. It's one of these things
00:40:57 --> 00:41:00 actually where there are a lot of UFO reports. When people say
00:41:00 --> 00:41:03 get up early in the morning. They're not accustomed to being up early in the morning and
00:41:03 --> 00:41:06 they look out and see this bright white light, doesn't seem to be moving and they
00:41:06 --> 00:41:09 think, oh, it's a ufo. It wasn't there yesterday.
00:41:09 --> 00:41:12 The reality is that it was there yesterday, just didn't notice it. And that's
00:41:12 --> 00:41:15 Venus. Sometimes Venus is visible in the morning sky and
00:41:15 --> 00:41:18 sometimes Venus is visible in the evening sky. And the same
00:41:18 --> 00:41:20 goes for Mercury. So it does tend to move around a little bit.
00:41:20 --> 00:41:23 But there's nothing like a view of Venus. And if you get out,
00:41:23 --> 00:41:26 as we say, if you go bush, you know, get away from the
00:41:26 --> 00:41:29 cities, get away from the city lights and everything. So you get really dark,
00:41:29 --> 00:41:32 dark skies. You know, when Venus is big and bright and
00:41:32 --> 00:41:35 up like that, you know, it throws shadows. It's bright enough to throw
00:41:35 --> 00:41:38 shadows. You can see where you're going just by the light of Venus alone.
00:41:38 --> 00:41:40 It's it's really quite remarkable if you think about Venus. Found
00:41:40 --> 00:41:43 this from a old Isaac Asimov book. Now I don't know whether he
00:41:43 --> 00:41:46 was the first one to come up with this idea or not, but I read it in
00:41:46 --> 00:41:49 ah, an old. Because he used to write science essays and
00:41:49 --> 00:41:52 science columns and science books and things as well as his science
00:41:52 --> 00:41:55 fiction. And he, he said that, you know, because we've got the moon
00:41:55 --> 00:41:58 going around the Earth, right. Which is a fairly big moon
00:41:58 --> 00:42:00 compared to the size of the Earth. Earth moons,
00:42:01 --> 00:42:02 it's a quarter of the.
00:42:02 --> 00:42:03 Stuart Gary: Size of the Earth. It's huge.
00:42:03 --> 00:42:06 Jonathan Nally: Yeah. Some people might call it a double planet system in a way. It's a very
00:42:06 --> 00:42:06 large moon.
00:42:06 --> 00:42:09 Stuart Gary: Just a little bit closer. The barycenter would
00:42:09 --> 00:42:12 be outside the Earth. And under
00:42:12 --> 00:42:15 those circumstances then we would be a binary system like
00:42:15 --> 00:42:15 Pluto and Charon.
00:42:15 --> 00:42:18 Jonathan Nally: That's exactly right. Now that, now what he proposed in this article
00:42:18 --> 00:42:21 was, and this could have changed the course of history actually if this
00:42:21 --> 00:42:24 had happened was that if the moon hadn't formed around
00:42:24 --> 00:42:27 Earth, if instead it had formed in orbit around
00:42:27 --> 00:42:30 Venus. And Venus is about the same size as the Earth.
00:42:30 --> 00:42:33 Then at the distance of Venus. When the moon
00:42:33 --> 00:42:36 was at its furthest from Venus, you would be able to see
00:42:36 --> 00:42:39 just with the unaided eye, you would be able to see Venus
00:42:39 --> 00:42:42 and its moon, theoretical moon, a hypothetical moon
00:42:42 --> 00:42:44 separated from the night sky. And you would see that moon's position
00:42:45 --> 00:42:48 changing from night to night. And you would be drawn to the inescapable
00:42:48 --> 00:42:50 conclusion that that small dot was circling
00:42:51 --> 00:42:54 the larger dot. Right. So something was going around
00:42:54 --> 00:42:56 something else. And of course, remember from our history about things,
00:42:56 --> 00:42:59 you know, working, things going around the Earth, or was the Earth going around the
00:42:59 --> 00:43:02 sun? So the sun going around the Earth. Earth going around the Sun. And for a
00:43:02 --> 00:43:04 long time, of course it was.
00:43:04 --> 00:43:06 Stuart Gary: People had the wrong idea, Galileo and Copernicus before
00:43:06 --> 00:43:07 him.
00:43:07 --> 00:43:10 Jonathan Nally: Yeah, well, see the. You know, it took until Galileo looking
00:43:10 --> 00:43:13 through his telescope to see that the moons were going around Jupiter.
00:43:13 --> 00:43:16 So something else, you know, and yet it moves and something's going
00:43:16 --> 00:43:18 around. Jup. Well, if the moon had formed in
00:43:18 --> 00:43:21 orbit around Venus, then we would have known since
00:43:21 --> 00:43:24 antiquity, you know, since prehistoric
00:43:24 --> 00:43:27 times, that something was going around something else out there in
00:43:27 --> 00:43:30 space. And therefore we would have known that not everything
00:43:30 --> 00:43:33 goes around the Earth, in other words. So this whole idea
00:43:33 --> 00:43:35 that the Earth being the center of everything, which sort of held us back
00:43:35 --> 00:43:38 for a very long time, might not have taken hold,
00:43:38 --> 00:43:41 or at least, not as widely taken hold or for as long
00:43:41 --> 00:43:44 as. So just one of those accidents of nature that the.
00:43:44 --> 00:43:47 The moon formed in orbit around the Earth rather than Venus.
00:43:47 --> 00:43:48 Interesting, isn't it?
00:43:48 --> 00:43:51 Stuart Gary: For a long time, people used to think that because
00:43:51 --> 00:43:54 Venus is covered in clouds and it's a bit closer to the sun
00:43:54 --> 00:43:57 than the Earth, then those clouds must mean lots of rain.
00:43:57 --> 00:44:00 Lots of rain means lots of water on the ground. Lots of water
00:44:00 --> 00:44:03 on the ground means lots of trees could have grown. Lots of
00:44:03 --> 00:44:05 forests. Probably tropical rainforest would have grown there.
00:44:05 --> 00:44:08 Jonathan Nally: Yeah, because Venus is closer to sun, therefore have been warmer. So,
00:44:08 --> 00:44:10 yeah, tropical rainforest and probably dinosaurs.
00:44:11 --> 00:44:13 Stuart Gary: Dinosaurs was the next thing that came up. You're right, yes.
00:44:13 --> 00:44:16 Some scientists even postulated that, well, if you've got tropical
00:44:16 --> 00:44:19 rainforests, you've probably got dinosaurs. How they reached that
00:44:19 --> 00:44:22 conclusion, I don't know, but that was. Yeah, that was very common back in the
00:44:22 --> 00:44:25 50s and 60s. A lot of scientists supported that idea.
00:44:25 --> 00:44:28 Jonathan Nally: It was. It was speculation and I mean, it was sort of a very
00:44:28 --> 00:44:30 uneducated guess, but, you know, we can sort of understand it.
00:44:30 --> 00:44:32 Stuart Gary: Canals on Mars, isn't it?
00:44:32 --> 00:44:34 Jonathan Nally: Yeah, the canals on our sea, the Hensman. It's
00:44:34 --> 00:44:37 hard for people these days, I suppose, to Think
00:44:37 --> 00:44:40 about this. But you go back to the turn of the 19th, 20th
00:44:40 --> 00:44:43 century, go back to the 1900 or whatever, it was
00:44:43 --> 00:44:46 widely assumed that there would be life on the other planets.
00:44:46 --> 00:44:49 Because if there's life on Earth, why wouldn't there be life on other planets?
00:44:49 --> 00:44:52 Because we didn't know what those other planets were like back then. We
00:44:52 --> 00:44:55 didn't have the technology to really establish what
00:44:55 --> 00:44:58 the atmospheres were made of, and you
00:44:58 --> 00:45:00 know, what the temperatures might be, all that sort of, at least without any great
00:45:00 --> 00:45:03 precision. And so even when the first NASA
00:45:03 --> 00:45:06 spacecraft were getting to Mars, it was
00:45:06 --> 00:45:09 still, people were thinking, well, that's going to show things on
00:45:09 --> 00:45:12 Mars, much of vegetation or whatever. But then the first picture
00:45:12 --> 00:45:15 started coming back which just showed a desert world with
00:45:15 --> 00:45:18 craters and things. So, for a long time
00:45:18 --> 00:45:20 people just assumed that there was going to be life
00:45:20 --> 00:45:23 on the other world. Then we started to learn that Mars
00:45:23 --> 00:45:26 actually really cold, it's got a thin atmosphere, and Venus,
00:45:26 --> 00:45:29 it's got a runaway greenhouse effect. So it's very, very hot and the air
00:45:29 --> 00:45:32 pressure would be very, very intense, you know, about 90 atmospheres or something
00:45:32 --> 00:45:35 and temperatures of over 400 degrees Celsius,
00:45:35 --> 00:45:38 450 something degrees Celsius, and possible sulfuric acid
00:45:38 --> 00:45:39 rain from the clouds.
00:45:40 --> 00:45:42 Stuart Gary: We've got snow on the cloud tops by the way.
00:45:42 --> 00:45:45 Jonathan Nally: We've got a far more sophisticated idea of what
00:45:45 --> 00:45:48 things are like out there now. But yeah, back in the, back in the early days when we didn't
00:45:48 --> 00:45:51 really know, people just assumed so. But you know, goodness
00:45:51 --> 00:45:54 knows how many things we take for granted as being true right
00:45:54 --> 00:45:57 now, this year, in 2025, which 100 years from
00:45:57 --> 00:46:00 now or 50 years, will be considered complete
00:46:00 --> 00:46:00 nonsense.
00:46:00 --> 00:46:03 So, I'm not critical of, people who thought various things in
00:46:03 --> 00:46:06 past times when they were, had some reason to think
00:46:06 --> 00:46:09 that might have been. It's when you get people who just totally
00:46:09 --> 00:46:12 ignore the evidence or you know, try and work their way around the
00:46:12 --> 00:46:15 evidence. So for instance, Lowell look at finding
00:46:15 --> 00:46:18 canals on Mars, but no one else could see them. But he just sort of stuck with
00:46:18 --> 00:46:20 it because he was, he was sure that there were canals on Mars and no one else could
00:46:20 --> 00:46:23 see them. So that's when you, have problems with.
00:46:23 --> 00:46:26 Stuart Gary: Well, the problem was he didn't translate Schiaparelli's original
00:46:26 --> 00:46:29 comments correctly. Schiaparelli was talking about canali, but
00:46:29 --> 00:46:31 he didn't mean canals, he meant channels, something.
00:46:31 --> 00:46:34 Jonathan Nally: Like water channels or riverbeds, that kind of thing. Yeah, they got translated
00:46:34 --> 00:46:36 into canals, which in English means an
00:46:36 --> 00:46:38 artificial water channel.
00:46:38 --> 00:46:41 Stuart Gary: Well, they were building a huge canal network in England at the time,
00:46:41 --> 00:46:41 weren't they?
00:46:41 --> 00:46:44 Jonathan Nally: Yeah. Yeah. And, And he was, he was essentially seeing what
00:46:44 --> 00:46:47 he wanted to see. He got it into his mind and that was the end of it.
00:46:47 --> 00:46:50 And, Yeah, well, that mean that's just a human failure,
00:46:50 --> 00:46:53 isn't it, really? And on that philosophical note, Stuart Gary, we just solved all
00:46:53 --> 00:46:56 the world's problems once again, aren't we Good. And I'll see you next
00:46:56 --> 00:46:56 month.
00:46:56 --> 00:46:59 Stuart Gary: That's science editor Jonathan Nelly. And this is Space
00:46:59 --> 00:46:59 Time.
00:47:15 --> 00:47:17 And that's the show for now. Space Time
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