S26E66: Ancient galaxy dies suddenly // Inmarsat denies cyber-attack // Meteorite rocks Queensland // June Skywatch

AI Transcript

STUART GARY: This is SpaceTime series 26 episode 66 for broadcast on the second of June 2023. Coming up on space time, an ancient galaxy suddenly dies. Inmarsat says Australian satellite outages were not caused by cyber attacks and northern Queensland residents rocked by a meteor all that and more coming up on space time.

Welcome to space time with Stuart Garry.

STUART GARY: Astronomers say they're stunned after the James Webb space Telescope discovered an ancient galaxy called GS 9209 which suddenly and mysteriously died, halting all star formation. The observations reported in the journal nature suggest that the galaxy formed most of its stars during a hyperactive starburst period between 600 million and 800 million years after the Big Bang 13.82 billion years ago.

STUART GARY: But then just over 12.5 billion years ago, it suddenly stopped making new stars. In fact, when the team observed it at 1.25 billion years after the Big Bang, no star formation had taken place in the galaxy for around half a billion years.

STUART GARY: The findings are surprising because here in our local Universe, most massive Galaxies take billions of years to shut down star formation despite being around 10 times smaller than the milky way galaxy GS 92 9 has a similar number of stars. These have a combined mass of around 40 billion times that of our sun and were all formed rapidly before star formation in the galaxy suddenly stopped.

STUART GARY: Analysis also shows that like most if not all Galaxies GS 9200 and nine contains a super massive black hole at the center. But interestingly, it's around five times larger than what astronomers might anticipate for a galaxy of that size.

STUART GARY: And that could be the key astronomers think that the supermassive black hole could be responsible for the sudden shutdown of star formation if correct. The discovery provides new insight in the processes involved in the early Universe's star formation and the role which supermassive black holes have in halting that formation.

STUART GARY: You see the growth of supermassive black holes release huge amounts of high energy radiation and that can heat up gas, preventing it from collapsing and also push gas out of Galaxies altogether. Either way you end up not having the feed material needed for stellar formation. And so this could have cause star formation in G S 92 oh nine to stop.

STUART GARY: Webb's already shown that Galaxies were growing larger and earlier than science had ever suspected. But this new work is giving scientists a really detailed first look at the properties of these early Galaxies charting in detail, the history of Galaxies like G S 92 oh nine which managed to form as many stars as our own milky way just 800 million years after the Big Bang.

STUART GARY: This is space time still to come. Imar Sat says a satellite outage which affected much of Australia wasn't caused by cyber attacks and the residents of North Queensland treated to a spectacular meteor shower all that and more still to come on space time.

STUART GARY: Inmarsat has denied suggestions that two recent outages of its I four F One satellite could have been due to denial of service cyber attacks by an unfriendly foreign power. The British commercial satellite operator says two recent failures of its satellite which provides LBA services for Eastern Asia and the Pacific region were due to a partial loss of power.

STUART GARY: I four F One provides the South Pan satellite based augmentation system which increases the accuracy of global satellite navigation systems from a meter down to just centimeters. The system supports services ranging from maritime safety operations and aircraft navigation to farmers giving them improved precision for crop sowing, fertilizing and spraying, thereby reducing their costs and improving efficiency.

STUART GARY: Imar says the sudden loss of power invoked automatic procedures on the satellite that led to the suspension of services while engineers are still investigating the cause of the power loss. The London based company has ruled out space debris or anything malicious such as a cyber attack. The I four F One satellite was built by Eads Astrium which is now part of Airbus defense and space using a Eurostar 300 GM bus.

STUART GARY: The 5990 kg spacecraft was launched back in 2005 aboard an Atlas five rocket space launch complex 41 at the Cape Canaveral Space Force Base in Florida with an initial 13 year design life. It's now been operating for 18 years. Imas says the Airbus built I Six F One satellite launched in December 2021 is slated to replace many of the I four F ONE S L BAND services in coming weeks.

STUART GARY: This is space time. Still to come. North Queensland residents are treaded to a spectacular night show as a meteor lights up their skies and pros the brightest star in Canis major, the bloated aging red giant Atari, the super red giant Antares and the June Solstice are among the highlights of the night skies on June sky watch.

STUART GARY: Queenslanders are on the hunt searching for meteorite fragments from a meteor which lit up the night skies of northern Queensland last week. A meter white space rock flashed across the sky with a glowing green light seen from as far south as Mackay north to Cairns and as far West as the Gulf Of Carpenter sightings were reported across the state with hundreds of people taking to social media to share videos.

STUART GARY: Astronomer Brad Tucker from the Australian National University says the meteor was estimated to have been between half a meter and a meter in size and it would have been traveling at 100,000 to 150,000 kilometers an hour.

STUART GARY: Citizen scientists are now searching the outback for its landing site with the tiny golf town of Croydon ground zero. That's because a sonic boom was felt by local residents at that location suggesting the meteor could have landed near the town.

STUART GARY: The sight boom itself would have actually been generated by shock waves as the meteor hit thicker layers of atmosphere and began fragmenting while most of it would have burnt up. Some larger fragments may have made it all the way down to the ground.

STUART GARY: Tucker says he's fairly certain the fireball was caused by a meteor rather than space junk because Meteors have a characteristic look, they're a bright solid light and they often have a blue or green color. Tucker says a significant fraction of this meteor would have had bits of iron and nickel in it and it's that which would have caused it to glow blue green.

STUART GARY: This is space time and time now to check out the night skies of June on skywatch. June is the fourth month of the old Roman calendar and he's named after Juno who was the wife of Jupiter and also the equivalent to the Greek goddess Hera.

STUART GARY: Another belief is that the month's name actually comes from the Latin word EOR, which means younger ones. June is a great time to look up at the night skies and marvel at the Majesty Of The Milky Way, which puts on a spectacular overhead display.

STUART GARY: This time of year. June also marks the winter solstice in the southern hemisphere and summer solstice north of the equator, which this year happens at 12 57 in the morning of Thursday, June the 22nd Australian Eastern Standard Time.

STUART GARY: It's 10 57 in the morning of Wednesday, June, the 21st us eastern daylight time and 2 57 in the afternoon, Greenwich. Meantime, here in the southern hemisphere, it's the time of the winter solstice and of course, it means the arrival of summer for our lucky listeners north of the equator.

STUART GARY: The June Solstice occurs when the sun reaches its most northerly point in the sky as seen from Earth. Zenith appearing to be directly over the tropic of cancer. Contrary to popular belief that the seasons on Earth occur when the Earth's orbit around the sun is at its nearest or furthest points, they're actually governed by the tit of Earth's axis as it journeys around the sun in a year.

STUART GARY: So on the day of the June Solstice, the Earth's south pole is tilted by 23 a half degrees away from the sun, the sun rises north of east and sets north of West six months later, when the south pole is tilted towards the sun, it's the southern hemisphere summer and in between, we have the autumn and spring equinoxes almost overhead.

STUART GARY: This time of year, we have the constellation Virgo, the constellations named after Virgo, the goddess of justice and the harvest. In ancient Greek mythology who used her scales to weigh good and evil.

STUART GARY: However, she became so disenchanted with the evil deeds of men, she threw away her scales and retreated to the heavens. Interestingly, the ancient Egyptians also associated Virgo with agriculture there.

STUART GARY: She was the goddess Isis who sprinkled the heads of wheat across the sky forming the milky way to science. Virgo is a tightly packed region of space containing some 2000 Galaxies all gravitationally bound into a gigantic galaxy cluster located some 60 million light years away of which our local group of Galaxies is simply an outlying member.

STUART GARY: A light year is 10 trillion kilometers. The distance a photon can travel in a year at the speed of light which is about 300,000 kilometers per second in a vacuum.

STUART GARY: And the ultimate speed limit of the Universe, the mass of the Virgo supercluster is so enormous that its gravity generates the so called Virgo centric flow causing our milky way galaxy as well as Andromeda and all the other members of our local group to move towards the supercluster at around 400 kilometers per second.

STUART GARY: That's despite the accelerated expansion of the Universe over cosmic timescales, the Virgo supercluster is now thought to be nothing more than a lobe of an even bigger galaxy supercluster known as Laak Kia. The center of which is known as the Great Attractor, Lani AA and the Great Attractor are among the largest known structures in the Universe.

STUART GARY: Despite the Virgo cluster size, it's so far away. It's difficult to see without a decent size backyard Telescope. You'll want something at least 100 millimeters in diameter or larger located right next to Virgo and directly overhead.

STUART GARY: This time of year is the constellation Corvis. The Crow Greek mythology tells us Corvis could talk to humans but he was a lazy bird. And so Apollo took away his ability to speak and banished him to the heavens.

STUART GARY: One of the highlights in the constellations Virgo and Corvis is the spectacular sombrero galaxy M 104 visible with a good pair of binoculars or a small Telescope.

STUART GARY: This stunning spiral galaxy is seen almost edge on providing a spectacular backlit view of its galactic, bold stars and the molecular gas and dust lanes in its arms M 104 is located some 31 million light years away and he's moving away from the milky way at about 1000 kilometers per second. The sombrero galaxy has a diameter of about 50,000 light years.

STUART GARY: That's about 30% the size of our own galaxy. The milky way it's surrounded by up to 2000 globular clusters and an active central supermassive black hole at least a billion times the mass of our sun.

STUART GARY: Now, by comparison, Sagittarius, a star that's the supermassive black hole at the center of the milky way has just 4.3 million times the mass of the sun globular clusters are tight balls containing millions of stars which were all either originally formed at the same time from the same collapsing molecular gas and dust cloud or they're the surviving cores of small Galaxies that have been cannibalized by larger ones.

STUART GARY: By the way, the brightest star in Virgo is Spiker a spectroscopic binary located some 250 light years away. Spectroscopic binaries are double star systems orbiting so close to each other or at such an angle that they can't be visually separated, at least not from our viewpoint on Earth.

STUART GARY: Under these conditions. Their spectrum will actually be a combination of the spectra of both of the stars in the system.

STUART GARY: But as these stars orbit each other, one of the stars will be moving sort of towards us, the other will be moving sort of away from us. So the star moving towards us will have a spectra that will be slightly blue shifted into high frequencies, shorter wavelengths, will the star moving away from us will have its spectra slightly red shifted to lower frequencies longer wavelengths.

STUART GARY: And so the two stars in the system can be separated by their Doppler shift looking about 20 degrees above the western horizon in the early evening is the fourth brightest celestial object in the sky.

STUART GARY: The dog star Sirius, only the sun, the moon and the planet Venus look brighter to the north West or right of Sirius is another fairly bright star called pros, the brightest star at the constellation Canis Minor, the lesser dog in Greek mythology, Canni Minor and Canis major were Orion's hunting dogs.

STUART GARY: Peron is a binary star system comprising a spectral type F main sequence white star proc A and a faint white dwarf companion Peron B. Main sequence stars are those undergoing hydrogen fusion into helium in their cause.

STUART GARY: Astronomers describe stars in terms of special types, a classification system based on temperature and characteristics. The hottest most massive and most luminous stars are known as spectra type O blue stars. They're followed by spectral type B blue white stars, then spectral type A white stars, spectral type F whitish yellow stars, spectral type G yellow stars.

STUART GARY: That's where our sun fits in spectra type K, orange stars. And then the coolest and least massive of all stars are spectra type M red stars commonly referred to as red dwarfs.

STUART GARY: Each spectral classification is also subdivided using a numeric digit to represent temperature with zero being the hottest and nine, the coolest and a Roman numeral to represent luminosity. Now put all that together and our sun is officially classified as A G two V or G 25 yellow dwarf star.

STUART GARY: Also included in the classification system are spectral types L T and Y, which are assigned to failed stars known as brown dwarves, some of which were actually born as spectral type M red dwarf stars but became brown dwarves after losing enough of their mass, brown dwarfs fit into a category between the largest planets which are about 13 times the mass of Jupiter and the smallest spectral type M red dwarf stars which are around 75 to 80 times the mass of Jupiter or 0.8 solar masses.

STUART GARY: The white dwarf Proce Bee has about 0.6 times the mass of the sun and a diameter of about 8600 kilometers.

STUART GARY: A white dwarf is the stellar corpse of a sun like star having used up its nuclear fuel supply fusing hydrogen into helium in the main sequence. It then expands into a red giant and begins fusing helium into carbon and oxygen stars like our sun aren't massive enough to fuse carbon and oxygen into heavier elements.

STUART GARY: And so they turn off their attic gaseous envelopes flown off into space as spectacular objects called artery nebula. What's left behind is a super dense white hot stellar core about the size of the Earth called a white dwarf which will slowly cool over the eons of time located about 11.6 light years away.

STUART GARY: Pro on a has about 1.5 times the mass of the sun and about twice its radius. It also has about seven times the sun's luminosity making it unusually bright for a star of this time. And that suggests that it started to evolve off the main sequence.

STUART GARY: After having fused nearly all of its core hydrogen into helium, it means the star is about to expand into a sub giant as it begins fusing core helium into carbon and oxygen and burning a hydrogen in its outer shell as it continues to expand, the star will eventually swell to somewhere between 80 and 100 and 50 times its current diameter.

STUART GARY: It'll then become a red giant. This will probably happen within the next 10 to 100 million years. The blink of an eye in astronomical terms, the two stars prose on A and B orbit each other every 40.82 Earth years at an average distance of 15 astronomical units about the distance of uranus orbit around the sun.

STUART GARY: An astronomical unit is the average distance between the Earth and the sun, which is about 150 million kilometers or 8.3 light minutes looking to the north, north West now, and you'll see the constellation Leo The Lion looking like a bunch of stars shaped like an upside down question Mark located just 36.7 light years away.

STUART GARY: And the constellation booties, the herdsman is ocurre a bloated aging red giant about 7.1 billion years old and nearing the end of its life, having used up all its core hydrogen.

STUART GARY: It's now fusing helium into carbon and oxygen that's caused the star, which is only slightly more massive than the sun to expand outwards to around 25 times the sun's diameter and become about 170 times as luminous, it'll soon puff off its outer gasses envelope as a planetary nebula in the process revealing its white hot stellar core.

STUART GARY: In Greek mythology. Aus was the guardian of the bear. Now, this is a reference to being next to the constellations, Ursa major and Ursa minor. The greater and lesser bears. There's some indications that auras could have a binary stellar companion, but the results remain inconclusive, at least for.

STUART GARY: Now, there's also speculation that it could have a large platter or subs stellar object orbiting it something about 12 Jupiter masses in size. But again, the research remains inconclusive looking to the east and you'll see the three brightest stars in the constellation of Libra.

STUART GARY: The scales of justice are visible about halfway about 40 degrees above the horizon. These also represent the claws of Scorpius, the Scorpion which is chasing a rhine across the sky. The brightest star in the constellation Scorpius is Alpha Scorpion or Antares.

STUART GARY: The Scorpion's heart easily seen with the unaided eye. This red super giant is some 550 light years away and it's one of the largest known stars in the Universe. Antares has about 18 times the mass and an incredible 883 times the diameter of the sun and it's about 10,000 times more luminous than our sun too.

STUART GARY: Ok. Turning to the southeast now and there you'll see the constellation Sagittarius, the archer. It's important because it marks the direction of the center of our galaxy, the milky way and of course, located some 27,000 light years away in that direction is the galaxy's central supermassive black hole Sagittarius, a star to the ancient Babylonians.

STUART GARY: Sagittarius was the God Norgle, the Centaur, a creature half man and half horse. By the time Greek mythology took over Sagittarius was carrying a bow loaded with an arrow and pointing directly towards Antares, the heart of Scorpius, the Scorpion, the center of the milky way and its supermassive black hole Sagittarius, a star lie in the westernmost part of Sagittarius.

STUART GARY: The brightest star in Sagittarius is epsilon Sergei or Co Australis, the southern part of the bow epsilon. Sergi is a binary system located 100 and 43 light years away.

STUART GARY: The primary star is an evolved spectra type e blue giant at the end of its life on the main sequence, it is about 3.5 times the sun's mass and about seven times its radius and is radiating around 363 times the sun's luminosity.

STUART GARY: It's also a very strong x-ray source and is spinning very rapidly with an estimated radial velocity of some 236 kilometers per second the system also displays an axis of infrared radiation emissions suggesting the presence of a circumstellar disc of dust. Now, the second star in the system appears to be inside this debris disk, astronomers think it's a spectra type g yellow dwarf star with about 95% the mass of the sun.

STUART GARY: The second brightest star in Sagittarius is Sigma sari or the name no is Babylonian. However, its meanings are known, it's thought to represent the ancient Babylonian sacred city of Urdu on the Euphrates River.

STUART GARY: Now, if correct, they would make non, the oldest known star name in current use non is a spectra type B blue star located about 260 light years away. It has about eight times the sun's mass 4.5 times its radius and about 3300 times the sun's luminosity alphas, Agita or Ruck Bat, meaning the Arch's knee is a spectral type B blue star located some 182 light years away.

STUART GARY: It has some 2.5 times the diameter of the sun and about 40 times the sun's luminosity. Astronomers think it's surrounded by a dense debris disc and a newborn companion star which is only now about to join the main sequence.

STUART GARY: The Sagittarius constellation also hosts many star clusters nebulae including some of the best known astronomical objects in the sky.

STUART GARY: These include the Lagoon Nebula messier eight, a spectacular pink emission nebula located 5000 light years away and measuring some 140 light years by 60 light years across the central region of the Lagoon Nebula is also known as the hourglass nebula because of its distinctive shape caused by a matt propelled by a massive star forming region called Herschel 36 1 of the few star forming nebulae that it's possible to see with the unaided eye.

STUART GARY: The Lagoon Nebula was instrumental in the discovery of Boch globules, more than 17,000 of which have been found in the nebula. Astronomers think bulk globules contain embryonic proto stars destined to eventually become new stellar generations.

STUART GARY: Also located in this region of space is the stunning messy S 17 better known to pretty well everyone as the horsehead nebula, it's located some 4890 light years away and is a dense region of ionized atomic hydrogen, also known as the Omega or Swan nebula. It banned some 15 light years across and has about 800 times the mass of the sun.

STUART GARY: It's considered one of the brightest and most massive star forming regions in our galaxy. With the geometry similar to the Orion nebula, except that it's being viewed edge on rather than face on the open star cluster NGC 66 A lies embedded in the nebulas and its gasses cause the nebula to shine due to the intense radiation from its hot young stars.

STUART GARY: Open star clusters are loosely bowing groups of stars usually containing a few 100 to thousands. They're thought to have originally all been formed in the same molecular gas and dust cloud. But they're not as densely bound together as globular clusters, open star clusters generally survive for a few 100 million years where the most massive ones may be surviving for a few billion.

STUART GARY: Now, by contrast, the more massive globular clusters exert such a strong gravitational attraction on their members. They can survive for tens of billions of years or longer. The nebula is thought to contain up to 800 stars.

STUART GARY: More than 1000 additional stars are also being formed in the surrounding molecular gas and dust clouds. It's also one of the youngest known clusters with an age of just a million years. The cloud of interstellar material which formed the nebula is roughly 40 light years in diameter and it contains at least 30,000 solar masses.

STUART GARY: The trifid nebula messier 20 is another large star forming emission nebula containing many young hot stars located between 11,000 light years away. The trifid nebula is a diameter of around 50 light years. The outside of the trio is a bluish reflection nebula.

STUART GARY: While the inner region glows pink thanks to ionized hydrogen, there are also two dark bands dividing the T Trafford nebula into three regions or lobes hydrogen. In the nebula is being ionized by a central triple star system which formed at the intersection of the two dark bands creating its characteristic pink color.

STUART GARY: Another star forming region in this part of the sky is N G C 6559 located some 5000 light years away and containing both red emission and blue reflection regions. Now, the grouping of these three nebulae, the Lagoon Nebula, the trier nebula and G C six double 59 is known as the Sagittarius triplet.

STUART GARY: Another object worth looking out for is the red spider nebula N G C 6537. It's a planetary nebula about 8000 light years away. It has a prominent two lobe shape that could be due to a binary companion or simply magnetic fields and it has a fascinating s shaped symmetry with the lobes opposite each other appearing similar.

STUART GARY: Again, this is believed to be due to the presence of a companion star to the central white dwarf. As for the central white dwarf, the remnant of the original star, it produces a powerful 10,000 degree hot 3000 kilometer per second stellar wind which is generating 100 billion kilometer high waves from supersonic sharks formed as the local gas is being compressed and heated in front of the rapidly expanding lobes.

STUART GARY: Atoms caught up in these shocks are red, adding in visible light giving the nebula its unique spider like shape and also contributing to the nebula's expansion.

STUART GARY: The star at the center of the red spider nebula is surrounded by a dust shell making its exact properties hard to determine its surface temperature is probably somewhere around 250,000 degrees. Although a temperature of up to half a million degrees can't be ruled out, which would make it among the hottest white dwarf stars known.

STUART GARY: Now, looking directly south right now, you'll see the star polaris australis or more accurately, Sigma Octus.

STUART GARY: It's the nearest start of the southern celestial pole and consequently the counterpart to the northern star polaris. However, Sigma Oc Tanti is far harder to see than polaris as it's much fainter located some 270 light years away. It's an orange giant reaching the end of its life.

STUART GARY: Now turning to the southwest and just above the horizon, you'll see the star Canopus. It's the second brightest star in the night sky after Sirius Canopus is located some 310 light years away and is the brightest star at the constellation Karina. The keel Canopus is a super giant some nine times the mass of the sun and 71 times its diameter.

STUART GARY: The month of June also marks the first of two annual encounters with the Torres meteor shower. The Torres are generated as the Earth passes through the debris stream created by the comet two P Anke, which itself could be part of a larger comet which broke apart about 20,000 to 30,000 years ago.

STUART GARY: Most likely following numerous interactions with the powerful gravitational field of the planet Jupiter as their name suggests the torre's radiant or apparent point of origin is in the constellation Tous, the ball, the torrent's meteor shower is made up of large or massive material, think of pebbles instead of dust grains, Earth passes through the stream twice every year.

STUART GARY: Once in June, then again in October where it's called the Halloween fireballs. The tours releases material birth by normal cometary activity and also occasionally by close encounters with the tidal gravitational force of the Earth and other planets.

STUART GARY: Now, all this combines to make the torrid stream of material the largest in the inner solar system. And since the meteor stream is rather spread out in space, the Earth will take several weeks to pass through it causing an extended period of meteor activity compared with the much smaller periods of activity for other meteor showers.

STUART GARY: Now included in the turret stream is a denser flow of gravelly meteoroids called the Torit swarm. It's thought to be a ribbon of rocks, roughly 75 million kilometers wide by 100 and 50 kilometers across and held in orbit by Jupiter's gravity. Now, occasionally the Earth will pass through some of the larger meteoroids in the denser Torit swarm. And that can make things rather interesting on Earth.

STUART GARY: In fact, one of the larger chunks of the turrets swarm is now thought to have been the cause of the infamous Tanggu meteor event in the skies over Siberia on June, the 30th 19 oh eight The Tagus Event is now believed to have been the air burst of a 100 m wide meteor over the Tagus region of Russia causing mass devastation and flattening more than 2000 square kilometers of forest into matchsticks.

STUART GARY: In fact, the blast was so bright. It lit up the skies in London, a third of the way around the planet Togusa remains the largest known Earth impact event in recorded history. It was considered a one in 1000 year event assuming a random distribution of events over time.

STUART GARY: But new studies suggest the event may have been caused by a torrid swarm meteor and with Earth passing through the swarm periodically, it changes the odds significantly. Now, if this study is correct, the swarm heightens the possibility of a cluster of large impacts on Earth over a relatively short period of time for the complicating matters. The gene Toros are actually seen as two separate showers.

STUART GARY: The southern Toros are the ones associated with the comet two P Anke. While the northern Toros originate from the asteroid 2004 T G 10, an eccentric kilometer wide asteroid classified as a near Earth object and a potentially hazardous asteroid of the Apollo group. Jonathan Nally is the editor of Australian Sky and Telescope Magazine. He joins us now for the rest of our tour of the June night skies.

JONATHAN NALLY: Good day Stewart. Well, yeah, it's June. So for us in the southern hemisphere down here where I observe from, we've got the galaxy, our milky way stretching across the sky from the east to the West at this time of year in the sort of early evening when it's nice and dark down here because it's winter time.

JONATHAN NALLY: So, yeah, milky way, stretching all the way across the sky from the east to the West. We've got the southern cross down here in the south. It's about two thirds of the way up from the horizon, from the southern horizon and pretty much upright. It looks a bit like a kite and it's pretty easy to see because most of its stars are nice and bright over in the West just above the horizon.

JONATHAN NALLY: You've got the brightest star in the night sky Sirius, but it's about to disappear. It'll give it another few weeks and it'll be below the western horizon after sunset. So it'll be gone for this season around to the left of Sirius in the sort of south western part of the sky. We've got the second brightest star in the night sky that's called Canopus.

JONATHAN NALLY: And it's in the constellation Karina. If you in a dark location with clear skies and you can get a good view of the southern horizon, have a look to the south and see if you can spot the two Magellanic cloud Galaxies. Now, these Galaxies are quite large but they're very faint. They look like dull smudges or clouds.

JONATHAN NALLY: That's why they call the Magellanic cloud because Magellan spotted them and thought, oh, what are those clouds up there in the sky? And they didn't move. So obviously, they're not clouds. They're actually Galaxies, tens of thousands of light years away from it. So they are the nearest sizable Galaxies to our own.

JONATHAN NALLY: So if you've got some good dark skies, as they say, you can look down to the south and see if you can spot these two Galaxies, One's bigger and one's more, you've got the large Malan cloud and the small Malan cloud up in the northern half of the sky, the sky seems a little bit bare this time of the year, but there's a couple of bright stars, there's a bright star called Arch Tous, which can be seen about half way up from the northern horizon, much higher, almost overhead.

JONATHAN NALLY: In fact, there's another bright star called Spiker. Now, Arc Tous is a red giant star that's a couple of billion years older than our sun. It's the same mass as the sun. It has ballooned up to be about 25 times bigger because it's older when, when these sort of stars get old, they enlarge.

JONATHAN NALLY: So this one's 25 times bigger than ours. And at the moment, Spiker, the other star I mentioned it's a binary star system and a pair of stars in this system orbit each other so closely that it only takes four days to go around each other and their mutual gravitational pull has stretched each of these stars from a round shape into an egg shape with a pointy bit pointing towards each each other.

JONATHAN NALLY: So that's pretty amazing. I mean, two massive stars. Can you imagine that orbiting around each other? Only taking four days?

JONATHAN NALLY: Honestly, some of the things that are out there in space are pretty mind blowing. And we live in a fortunately very sedate, quiet soul of this where these sort of things don't happen. Otherwise, we might be in trouble. Now, as the night goes on, you'll see that things have changed as the Earth is turning by midnight.

JONATHAN NALLY: As I say, Sirius has gone in the West in the north, we've got the bright stars, Vega and alta have appeared and in the South East, we've got site called Ana, which is started to the end of a really long constellation with no other bright stars around it.

JONATHAN NALLY: So it sort of sticks out like a sore thumb. So it's pretty easy to spot. And the milky way which was stretching from east to West across the sky is now stretching basically from north to south. That's because the Earth has turn on.

JONATHAN NALLY: So things that were below the horizon a few hours ago have now come up into view over the eastern horizon and things that were visible in the western sky disappearing from view as they go down below the western horizon. Now, let's look at the planets, the innermost planet Mercury is pretty much out of view at the moment.

JONATHAN NALLY: You really won't have any chance of spotting it because Mercury orbits so close to the sun, it doesn't appear very far from the sun in the sky. When we have a look at it, start that again because Mercury orbits so close to the sun, it doesn't appear very far from the sun when we look for it in the sky.

JONATHAN NALLY: So at the moment, its orbit is taking it around to the other side of the sun from us. And so it's lost in the solar glare. It'll be back next month though. Venus is very easy to see at the moment. If you go out and look to the West after sunset, you just won't miss it unless you've got cloudy skies.

JONATHAN NALLY: But if you've got nice clear skies, you'll just see this big bright, bold star looking thing, but that's the planet Venus and you won't mistake it for any other stars around because it is much brighter, the biggest brightest things out there other than the moon.

STUART GARY: The thing about planets, they don't twinkle like stars do in the night sky do.

JONATHAN NALLY: They, they don't twinkle like stars when they're a reasonable elevation above the horizon. The common explanation for that is that stars are so far away that they are effectively a point, they're effectively a tiny point of light and that light that's coming through, our atmosphere gets disrupted and disturbed and broken up by the air currents in our atmosphere.

JONATHAN NALLY: Whereas the planets, even though they appear to be tiny dots of light as well, they do actually have a discernible size and that helps compensates for the twinkling effect.

JONATHAN NALLY: But if the planet is way down low just above the horizon, then they do seem to twinkle, they can see the twinkle. There have been plenty of incidents. I mean, I had a friend ring me up once.

JONATHAN NALLY: I said there's this red light, I've been going out every night and there's this red light out over the ocean from where I live and it's winking and blinking and I don't know what the air force is doing out there or UFO or whatever it is.

JONATHAN NALLY: So I quickly check my software that's MARS and because it's so low down on the horizon, it's having to shine through more atmosphere sort of coming sideways towards us than it would if it was directly overhead where you're going through less atmosphere.

JONATHAN NALLY: So, yes, the planets can twinkle if they're low down and it relates to all sorts of UFO reports and other things and also not so much a twinkling effect, but people have been startled for instance by Venus just talking about Venus.

JONATHAN NALLY: You know, when you're driving along a road and you go an avenue of trees on one side or either side that are carefully spaced apart, you can get a sort of a strobe effect. If there's anything on the other side of it. Yeah. Well, that, that can really fool the eye and the mind.

JONATHAN NALLY: And I recall one report of a woman driving along and there was this big bright light out to the side and she was driving through an avenue of trees and just the optical effects made it trick her into thinking this light was following her.

JONATHAN NALLY: Whereas it wasn't, it was just this sort of optical illusion you get when you drive through an avenue of trees with a light out, it's very easy to be fooled by things you're not expecting to see. And if you don't quite know what they are, that's why we do have a lot of so called UFO reports.

JONATHAN NALLY: Now, Venus, ok. We're talking about Venus, but up higher than Venus, if you go out and look for Venus, you can't miss it. Big, bright white thing. If you look up above Venus, you'll see what looks like a medium brightness, reddish star. This is what we were just talking about.

JONATHAN NALLY: It's not actually a star, it's the planet Mars. Ok. So you won't see a twinkling most likely, but it's not very big and it's not super bright, sort of medium brightness.

JONATHAN NALLY: Now, keep an eye on both Venus and Mars over the next few weeks and you'll see them get closer and closer and closer together. And by the end of the month they'll be really close together as we see them from Earth. They're not close together actually in space. Of course, it's just a line of side effect.

JONATHAN NALLY: But if you do have good weather over the next few weeks, go out just five minutes each evening if you can and just look at Venus and look at Mars and just compare their positions night after night, after night and you'll see that they're slowly drawing together and that's just these planets going around in their orbits and us going around in our orbit and getting a changing perspective line of sight perspective from where we are.

JONATHAN NALLY: So you can actually really not seeing it in real time as such. But if you call it night after night, real time, I guess you can say that night after night we're seeing in real time the dance of the planets around the sun.

JONATHAN NALLY: So that's really fun to do, you know, particularly you take one of your kids outside and say, look, that's Venus, it's Mars and let's go out like a couple of nights from now or next week and see how they've changed. It really is quite nice to see that the things up in the sky are not static or some things are not static. At least the planets do move a nice walk.

JONATHAN NALLY: Yeah, you're out walking the dog or whatever, just look up. Most people don't look up too much, you know, so just look up and have a look at the sky and you see there's lots of good things to see, one of which will be Saturn.

JONATHAN NALLY: Now, Saturn can be seen rising over the eastern horizon about an hour before midnight, start of June and take a look on the 10th 10th of June. If you're having trouble spotting which one is Saturn and you'll see that the moon is very close to it. So if you go out and see the moon can't miss the moon, the bright star in inverted commas near it is actually the planet Saturn.

JONATHAN NALLY: It has a slightly yellowish sort of tinge and the last one, Jupiter, if you want to see Jupiter, or you're going to have to be a bit of a real night owl or a very early riser because coming up over the eastern horizon about an hour or so an hour and a half before dawn. Ok.

JONATHAN NALLY: So if you're up early or you pulling an all nighter, you might be able to go outside before you go to bed. Have a look for Jupiter. You can't miss just like Venus. It too is big and bright. I think it's a bit brighter than Saturn at the moment.

JONATHAN NALLY: Saturn two is quite bright, but Jupiter and Venus typically are very, very bright so you won't be able to miss it. My eyes see Jupiter is pretty much white ish, but Saturn has a definite yellow tinge. Mars is definitely a ruddy reddish orange, Venus is generally bright white and so is Mercury, but it does depend on your eyes.

JONATHAN NALLY: It depends on whether you're looking through air pollution. It depends on the planet's down low or up high because, you know, certain wavelengths draw by the atmosphere, particularly when they're down low. So that's actually a good test to go outside with someone, you know, and say, ok, what color do you see?

JONATHAN NALLY: And in fact, because our eyes, if it's night time and there are no lights around, everything's dark, our eyes are using the part of the retina that is good for picking up low light levels, but it is not really good at color. That's why things mostly seem black and white at night because light is everything's pretty dim at night.

JONATHAN NALLY: Whereas during the daytime, when everything is nice and bright, we don't have any trouble seeing color. And that reminds me actually of the famous scientist George Gamma. His famous thing about, he proved scientifically that the moon is better than the sun.

JONATHAN NALLY: Did you know this? He actually, he actually proved that the moon is better than the sun because he said the moon shines at night time and it gives us illumination when everything is dark, which is really handy you see, but the sun, well, it only shines during the daytime when it's light.

STUART GARY: Anyway, that's Jonathan Ally, the editor of Australian Sky and Telescope Magazine. This is space time and that's the show for now. SpaceTime is available every Monday, Wednesday and Friday through Apple podcasts. Itunes, Stitcher Google Podcast, pocket casts, Spotify a Cast Amazon music bites dot com, Soundcloud, YouTube, your favorite podcast download provider.

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