Earth in a Cosmic Void? Black Holes Before Galaxies and SpaceX's Latest Triumph

This is Spacetime Series twenty nine, episode sixty seven, for broadcast on the fifth of June twenty twenty six. Coming up on Spacetime is Planet Earth in a cosmic void? After all? A new study confirms a black hole that formed before its galaxy and another wind for SpaceX over Boeing. All that and more coming up on space Time. Welcome to space Time with Stuart Gary. It's an hypothesis which has been around for decades and refuses to go away. Are we in a cosmic void? Astronomers now know that the ultimate large scale structure of the universe is built like a giant web, composed of strands of galaxies, galaxy clusters, and supers surrounding vast empty voids of almost nothing. The Earth, our Solar System, and the entire local galactic group, including the Milky Way and its neighboring satellite galaxies, were always thought to be on the edge of one of these cosmic strands, but ongoing readings have kept challenging that IDEA recent research reported in the Journal of the Monthly Notices of the Royal Astronomical Society has suggested that Earth main in fact be at the center of a two billion light ye white cosmic void. If so, it could explain why our local universe appears to be expanding faster than expected. Earth in the Milky Way might be drifting through a coloss or cosmic void spanning two billion light years. This massive region contains significantly less matter than the rest of the universe, thereby directly challenging the long helded cosmological principle that matter is distributed evenly throughout space. The finding suggest that our galactic home sits within a rare, low density pocket of the cosmos, making our life local neighborhood one of the largest and most unusual structures ever identified. And this unique positioning would provide a potential solution to the hubble tension that's the persistent disagreement between direct measurements of the universe's expansion rate. It could explain why our local universe appears to be expanding faster than expected. See if we were located in an underdense region, the local expansion would naturally appear faster to observers on Earth, potentially resolving this cosmic mystery without the need for any new physics or exotic energy theories like dark energy. In fact, the authors of the study now believe it's a hundred times more likely that we do reside in such a cosmic void compared to being in a region of average density, and that's a discovery that could fundamentally shift our perspective on the Big Banks after Marth Hubble constant was first proposed by Edwin Hubble in nineteen twenty nine to express the rate of the universe's expansion. It can be measured by observing the distance of celestial objects and how fast they're moving away from us. The stumbling block, however, is that extrapulating measurements of the distant early universe toy today using the standard cosmological model, predicts a slower rate of expansion than measurements of the nearby, more recent universe show. This is the Hubble tension. One of the studies authors in genal Banique from the University of Portsmouth says a potential solution of this inconsistency is that our galaxy is close to the center of a large cosmic void. It would cause matter to be pulled by gravity towards the high density exterior of the void, where the filaments are located. That would also lead to the void becoming even emptier with time. Now, as the void's emptying out, the velocity of objects away from us would be larger than if the void weren't there, and this would give the appearance of a faster local expansion rate. So a local solution like a local void would be a promising way to go about solving the problem. For the idea to stand up, Earth in our Solar system would need to be near the center of a void about a billion layers in with a density about twenty percent below the average density of the universe, and directly counting galaxies does support this theory. That's because the number density in our local universe is lower than in neighboring regions. However, the existence of such a large, deep void is controversial. That's because it doesn't measure specially well with the standard model of cosmology that suggests matter today should be far more uniformly spread out on such large scales. Despite this, the new data shows that baryon acoustic oscillations pressure waves generated by the Big Bang support the idea of a local void. These sound waves traveled for only a short time before becoming frozen in place. Once the universe cooled enough for neutral atoms to form, and they act as a sort of standard ruler whose angular size can be used to chart cosmic expansion history. A local void slightly distorts the relation between the bary on acoustic ostellations angular scale and the red shift because the velocity is induced by local void at its gravitational effect slightly increase the red shift. On top of that due to cosmic expansion. Redshift is the rate at which an object moves away from you because of the expansion of the universe. By considering all available barrier on acoustic oscillation measurements over the last twenty years, the authors showed that avoid model is about one hundred million times more likely than avoid free model with parameters designed to fit the cosmic microwave background radiation observations taken by the Plank satellite, so called homogeneous Plank cosmology. The cosmic microwave background radiation is the leftover energy from the Big Bang, generated when the universe cooled enough for the first atoms to form some trendred and eighty thousand years after singularity. The next step for researchers is to compare their local void model with other methods in order to estimate the history of the universe's expansion. This involves looking at galaxies that are no longer forming stars. By observing their spectra, it's possible to find what kinds of stars they have and in white proportion. Since more massive stars have shorter lives, they're absent from the older galaxies, thereby providing a way to establish a galaxy's age. Astronomers can then combine this age with the galaxy's redshift, how much the wavelength of light has been stretched, to tell us how much the universe has expanded while light from the galaxy was traveling towards us, and this will shed new light on the universe's expansion history. This is space time still to come. A new study confirms a black hole that formed before its galaxy, and another wind for SpaceX overbowing all that and more still to come on space time. Astronomers using the Web Space telescope have identified a super massive black hole in the early universe that must have formed before its host galaxy. For years, scientists have been debating the question of which comes first, the galaxy or its central black hole, and the truth is we don't really know for sure, but scientists have long thought it could be much easier for the galaxy to form first, with large stars within the galaxy consuming their fuel and collapsing, the form black holes, which can then gobble up surrounding material and merge with other black holes over time to form more. And more massive entities. But it's been hard to figure out how black holes millions to billions of times the mass of our Sun, thousands of which have now been detected in the early universe, could have grown so quickly from such small seeds. Now are reporting the journal Nature and in the Monthly Notices of the Royal Astronomical Society claims the new web observations have detected clear evidence that at least some super massive black holes were enormous from their very beginning, forming without a stellar collapse phase and without a significantly more massive host galaxy to feed them. One of the studies the authors, ROBERTA. Meelino from Cambridge University, says it's a paradigm shift, a turtle revisit of the classical scenarios of how black holes form and grow. The author's conclusions are based on detailed observations of Able twenty seven forty four QSO one, a pretatypical little red dot that existed just seven hundred million years after the Big Bang. Although ABLE twenty seven forty four QSO one is only thirteen hundred light years wide and its lightest been traveling for some thirteen point one billion years, it's easier to study the most other little red dots because it's been gravitationally lensed by galxy cluster. Able twenty seven forty four also earnest Pandora's cluster, so it's both magnified and triply imaged, appearing in three different locations across the sky. Initial studies revealed compilling evidence that it may be little more than a cloud of glowing hydrogen and helium gas circling a super massive black hole estimated at some forty million times the mass of our Sun. But as with other early black holes, the scis covered by web there was uncertainty about whether it really was that massive. See before now, all the mass measurements of black holes in the early universe have been indirect based on assumptions of what we know about super massive black holes in the local universe, and we didn't really know if these assumptions also applied to the distant universe. So the authors recognize that if this black hole is as massive as it looks, they should be able to use the integral field unit on webs needing for its spectrograph to trace the effects of its gravity on the gas swelling around it, while also mapping the distribution of various elements in the gas. So the authors use these observations to map motions of hydrogen gas around the black hole. When they plotted the rotation velocity as a function of distance from the center, they found that the gas has capellarian motion, in other words, at orbits a central point, in the same way as the planet's or but our sun in our Solar system. That's important because it tells the authors that most of the mass in the super massive black hole is concentrated at the center. If the mass were more distributed, as it would be if there were lots of nearby stars, the gas would not have this perfect Keplarian rotation. Since keplari immersion is governed by the simple laws of gravity, the authors were able to use this gas velocity measurement to calculate the black hole's mass directly, a feat that had not previously been possible. They found that not only was the super massive black hole immense roughly fifty million solar masses in size, It makes up, at a minimum at astonishing two thirds of the system's total mass, and this proportion is thousands of times greater than in nearby galaxies, where super massive black holes make up only a tiny fraction of a host galaxy's total mass. The where observation supported these results, showing that the gas throughout ABLE twenty seven forty four qso one is almost entirely hydrogen and helium, with very little of the heavier elements like oxygen that would be expected in a galaxy rich in stars and stellar debris with a metallicity less than zero point five percent that of the Sun. Able twenty seven forty four qso one is also one of the most pristine galactic environments ever measured. It's the first direct measurement of a black hole mass within the first billion years after the Big Bang, and it's consistent with previous measurements. The outsized mass of ABLE twenty seven forty four qso one relative to its host galaxy suggests that it could not have formed gradually from much smaller stellar mass black holes merging together, So it seems the authors have found a black hole that does not have a substantial host galaxy and that has pre dated stellar processes. This is evidence of primordial black holes or direct collapse black holes, which have been theorized but until now not confirmed whether able twenty seven forty four qso once black hole evolved from a heavy sea that formed within the first seconds of the Big Bang, or somewhat later from the collapse of a giant cloud of gas. It was almost certainly born big and may still be in the early stages of building up a galaxy around it. This is space time still to come. Another win for SpaceX over Boeing and the June solstice. The constellation Sagittarius and the towards Medial shower are among the highlights of the June night skies on SkyWatch. NASA's just awarded SpaceX six more crew transfer missions to the International Space Station because Boeing still can't certify it Styleliner spacecraft as safe for human operation. Ongoing problems with Starliner has seen Boeing spend a decade and billions of dollars on the spacecraft, which couldn't even safely return its own astronauts back to Worth on its first man mission. When Boeing did finally fly its first and so far only man flight aboard the CST one hundred Styliner to the space station, problems with a vehicles proportion system and persistent healing leaks forced NASA to abandon plans to use the same vehicle to return the crew back to Earth. Instead, they will have stranded on the space station for nine months until rival company SpaceX were able to set a Dragon spacecraft there on a rescue mission. Unlike Boeing, SpaceX has been reliably transporting people to and from the orbiting up post since twenty twenty. It's now successfully launched nineteen man missions using Dragon, including thirteen for NASA and six for private companies. Even more embarrassing for Boeing, NASA gave them four point two billion dollars to develop Stylner, they only gave SpaceX around half that amount two point six billion, to develop its crew Dragon. Of course, Dragon first began flying for NASA on cargo emissions to the space station years earlier, but SpaceX always intended Dragon to eventually carry people. Now, making the scene even more interesting is a third player, Sera space which has been quietly developing its dream Chaser lifting buddy spaceplane design. Although originally developed as a manned space transport vehicle for journeys to and from the space station, dream Chaser is now being evolved into a third cargo and resupply ship as part of NASA's commercial resupply Services to program for space station operations that zero space insists. Future man missions for dream Chaser are further down the line. As it is, dream Chaser will join SpaceX's Cargo Dragon and Orbital Sciences Signus cargo ships in the space station supply role. The first of the dream Chaser space plane's Tenacity, has already completed a series of milestones, including electromagnetic interference testing, high speed ground tow tests, recovery rehearsals, following landing, communications testing with mission control using NASA tracking and data relay systems, and acoustic testing at the Kennedy Space Center. Tenacity is now back at Sierra Space's Louisville, Colorado factory for flight software qualification and final thermal protection system closeouts. It will then move into final mission specific paylert integration target completion by December. Its maiden test flight won't be to the space station, just to Loweth orbit, it'll undertake its orbital test four NASA aboard a United Launch Alliance Vulcan Centaur rocket from the Cape Canaveral Space Force Space in Florida. Once in orbit, it'll be taken through a series of control and inflight maneuvers it tests its orbital reaction systems and atmosphere re entry capabilities, ultimately gliding to a controlled landing on the former Space Shuttle runway at the Kennedy Space Center. This is space. Time, Okay, time that out to turn our eves to the skies as we check out the celestious sphere for the month of June on SkyWatch. June is the fourth month of the year in the Old Roman calendar. It's named after Juno, who was the wife of Jupiter and is also the equivalent of the Greek goddess Hera. Another belief is that the. Month's name comes from the Latin word Junorees, which means the younger ones. June also marks the windness solstice in the Southern Hemisphere, and of course it means the arrival of summer for our lucky listeners north of the equator. It will happen at six twenty four in the evening of Sunday June the twenty first Australian Eastern Standard time. That's four twenty four in the morning Sunday June twenty first, US Eastern daylight time and eight twenty four in the morning Greenwich meantime. The June solstice occurs when the Sun reaches its most northerly point in the sky is seen from Earth Zenith, appearing to be directly over the Tropic of Cancer. It all happens because the seasons are governed by the tilt of Earth's axis as it journeys around the Sun. Every year, on the day of the June solstice, the earth south pole is tilted by twenty three and a half degrees away from the Sun, so the Sun rises north of east and sets north of west. When the south pole is tilted towards the Sun, it's the southern hemispheres summer. Between these two we have the autumn and spring Equinox. Variations in temperatures on Earth aren't determined by the Earth's orbital distance from the Sun, but rather the angle of the Sun's ray striking the Earth. In the summer, the suns high in the sky and the rays hit the Earth at a steep angle, but in winter, the sun's lower down in the sky and the rays strike the Earth at a more shallow angle. In most parts of the world, seasons begin on the day of the equinox and solstice. However, in Australia, seasons begin on the first day of a specific calendar month March for autumn, June for winter, September for spring, and December for summer. Okay, let's turn to the constellations, and almost directly overhead this time of the year, we have the spectacular constellation Virgo. The constellation Virgo is named after Virgo, the goddess of justice and the harvest in ancient Greek mythology, who used his scales to weigh good and evil. However, she became so disenchanted with the dear of evil men she threw away his scales and retreated to the heavens. They're Interestingly, the ancient Egyptians also associate Virgo with agriculture. There she was the goddess Isis, who sprinkled heads of wheat across the sky. Forming the Milky Way. To science, Virgos a tightly packed region at space containing some two thousand galaxies, all gravitationally bound into a giant galaxy cluster located some sixty million light years away. Now our own. Local group of galaxies, which is primarily bound by the Milky Way, and Andromeda are an outlying member of this cluster. Now, the Virgo cluster is the heart of the Virgo Supercluster, one of the largest known structures in the universe, a massive galactic node in the large scale, cosmic web like structure. Of the universe. The mass of the Virgo supercluster is so great that its gravity generates the Virgo centric flow, causing our Milky Way galaxies, all as Andromeda, and all the other members of the local group to move towards the supercluster at about four hundred kilometres per second. That's despite the accelerated expansion of the universe over cosmic timescales. The Virgo Supercluster is now thought, in turn, to be simply a lobe of an even bigger galaxy supercluster called Laniakia, the center of which is known as the Great Attractor. Despite the Virgo cluster size, it's so far away it's hard to see without a decently sized backyard telescope. You'll need something at least one hundred millimeters in diameter or larger. Directly overhead right now is the constellation Corvus. The crow. Greek mythology tells us that Corvus could talk to humans, that he was a lazy bird, and so Apollo took away his ability to speak and banished into the heavens. One of the highlights and the constellations Virgo and Corvus is the spectacular Sombrero galaxy M one o four. Visible with a good pair of binoculars or a small telescope, there stunning spiral galaxy you've seen almost their john, providing audiences with a spectacular back lit view of its galactic bold stars and the molecular gas and dust lanes in its arms. M one zero four is located some thirty one million light years away, and it's moving away from our Milky Way galaxy at about one thousand kilometas per second. A light year is ten trillion kilometers the distance of photon can travel in a year at the speed of light, which is about three hundred thousand kilometas per second in a vacuum and the ultimate speed limit of the universe. The Sombrero galaxy has a diameter of about fifty thousand light years, about thirty percent the size of our Milky Way. It's surrounded by around two thousand globular clusters and has an active central super massive black hole at least a billion times the mass of the Sun. Now. By comparison, the Sagittarius, a star that's the super massive black hole at the center of our Milky Way galaxy, is just four point. Three million times the mass of the Sun. The globular clusters are tight stellar balls comprising millions to billions of stars which were either the central remnants of a smaller galaxy cannibalized by a larger one, or they were originally all part of the same stellar nursery, formed at the same time in the same collapsing molecular gas in dust cloud. The brightest star in the constellation Virgo is Spiker, a spectroscopic binary located some two hundred and fifty light years away. Spectroscopic binaries are pairs of stars so close to each other that they could only be separated using a spectrograph to determine the individual chemical makeup of each component. Looking about twenty degrees above the western horizon in the early evening this time of the year, you'll find the brightest star in the night sky, the Dog Star. Serious only the Sun, the moon, and the planet Venus looked brighter. To the northwest or right of Sirius from the southern hemisphere is another fairly bright star called Procion, the brightest star in Canis minor, the lesser dog. In Greek mythology, Canis Major and Canis Minor were Orion's two hunting dogs. Prosion is another binary star system, this one comprising a spectral type F main sequence white yellow star Proceeon A, and a faint white dwarf companion Proteon B. Main Sequence stars are those undergoing core hydrogen fusion to helium. Astronomers describe stars in terms of spectual types, a classification system based on temperature and characteristics. The hottest, the most massive, most luminous stars in the sky are known as special type O blue stars. They're followed by spectro type B blue white stars, then spectual type A white stars, spectral type F white yellowish stars, followed by spectrotype G yellow stars that's where our sun fits in, then spectrotype K irene stars, and the coolest and least massive stars known are spectual type M red dwarf stars. Each specual classification can further be subdivided using a numerical digit to represent temperature, with zero being the hottest denying the coolest, and then you can out a Roman numeral to represent luminosity. Now put that all together, and our own local star as Sun, becomes a G two V or G two five yellow dwarf star. Also included in the stellar classification system are spectrotypes LT and Y, which are assigned to failed stars known as brown dwarves, some of which were born as spectual type M red dwarf stars but became brown dwarfs after burning off some of their mass. Brown dwarves fit into a category between the largest planets, which are around thirteen times the mass of Jupiter, and the smaller spectual type M red dwarf stars, which are between seventy five and eighty times the mass of Jupiter or zero point zero eight solar masses. White dwarves are the stellar corpses of Sun like stars, having used up their nuclear fuel supply fusing hydrogen into helium in their core. These stars expand into red giants as they begin fusing helium into carbon and oxygen. However, some like stars aren't massive enough to fuse carbon and oxygen into heavier elements, and so they turn off. They're outer gaseous envelopes then float off into space as spectacular objects known as planetary nebulae. What's left behind is a super dense, white outstellar core about the size of the Earth, a white dwarf, which will slowly cool over the eons. The white dwarf, Procion B is about zero point six times the mass of the Sun and has a diameter of around eighty six hundred kilometers. Located some eleven point six light years away. Prosion A has about one and a half times the mass and twice the radius of our Sun. Interestingly, Prosion A has about seven times the Sun's luminosity. It makes it unusually bright for this type of star, and that suggests that it's starting to evolve off the main sequence. After having fused nearly all of its care hydrogen into helium. It's expanding out to become a subgiant as it begins fusing core helium into oxygen and carbon, and burning hydrogen into helium in the sh shell around the core. As it continues to expand. The star will eventually swell somewhere between eighty and one hundred and fifty times its current diameter, becoming a bloated red or orange giant. That'll probably happen within the next ten to one hundred million years. The two stars press on A and B all but each other every forty point eight to earth years, at an average distance of fifteen astronomical units. That's about the distance of Mercury's orbit around the Sun. An astronomical unit is the average distance between the Earth and the Sun, about one hundred and fifty million kilometers or eight point three light minutes. Looking to the north northwest from the southern hemisphere this time of year, and you'll see the constellation Leo the Lion, looking more like a bunch of stars shaped like an upside down question mark, located thirty six point seven light years away. A Tourists is a bloated, aging red giant about seven point one billion years old and nearing the end of its life. Having used up all its core hydrogen, it's now using helium into carbon and oxygen. This has caused the start, which is only slightly more massive than our Sun, to expand out to around twenty five times the Sun's diameter, becoming about one hundred and seventy times as luminous. It'll soon puff. Off its outer gaseous envelope as a planetary nebulae, exposing its white hot stellar core and becoming a white dwarf. In Greek mythology, Acturus was the guardian of the bear. This is a reference to it being next to the constellations Ursa Major and Ursa Minor, the greater and lesser bears. There's some indications that Arcturus could have a binary stellar companion, but the results are inconclusive at the stage. There's also speculation that it could have a large planet or substellar object about twelve Jupiter masses orbiting it. Now that's close to brown dwarf size, but again the research remains inconclusive. To the east, when viewing from the southern hemisphere this time of year, are the three bright stars and the constellation Libra, the scales of Justice. They're visible about halfway They are about forty degrees above the horizon. Now, these also represent the claws of Scorpius, the scorpion which is chasing a rin across the sky. The brightest star in the constellation Scorpius is Alpha Scorpii, or Antaries, the scorpion's heart easily seen with the unaided eye. The red super giant Antares is located some five hundred and fifty light years away, and it's one of the largest known stars in the universe. It has about eighteen times the mass, about eight hundred and eighty three times the diameter of our sun, and Tara's is also around ten thousand times more luminous than our Sun. Now looking to the southeast from the southern hemisphere and you'll see the constellation Sagittarius. The archer. Sagittarius is important because it marks the direction towards the center of our Milky Way galaxy. In fact, located just twenty seven thousand light years away in the direction of Sagittarius, is the home of the galaxy's central super massive black hole. Sagittarius a star to the engine Babylonians, Sagetarius was the god Nrgle the Centaur, a creature half man and half horse. By the time Greek mythology took over, Sagittarius was also carrying a bow loaded with an arrow, pouring directly towards Antares. At 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. Sagittarius has many spectacular highlights. Alpha Sagittaria or rook Bat meaning the Archer's Knee, is a special type beat blue star located some one hundred and eighty two light years away. It is two and a half times that I am of the Sun and is about forty times as luminous. Astronomers think. It's surrounded by a dense debris disk and as a newborn companion star which is only just starting to join the main sequence. The brightest star in Sagittarius is Epsilon Sagittary or Calcistrallas, the southern part of the bow. Epsilon Sagittari is a binary system located some one undred and forty three light years from Earth. The primary star is an evolved spectual type B blue giant nearing the end of its life on the main sequence. It has about three and a half times the mass of the Sun, almost seven times the Sun's radius, and he's radiating around three hundred and sixty three times the Sun's luminosity. It's also a strong X ray source, and he's spinning very rapidly, with an estimated radio velocity of some two hundred and thirty six kilmetus per second. The system also displays an excess of infrared radiation emissions, suggesting the presence of a circumstellar disc of dust. The second star in the system appears to be inside this debris disc. Astronomers think it's going to be a spectrotype G yellow dwarf star with about ninety five percent the mass of the Sun. Sigma Sagittari or Nunkey, is the constellation's second brighter star. The name Nunkey's Babylonian. However, its meaning has been lost through the sunds of time. It's thought to represent the ancient Babylonian sacred city of Urd two on the Euphrates River. Now if correct, they would make Donkey the oldest stellar name currently in use. It's another spectrotype B blue star located's some two hundred and sixty light years away. It has about eight times the Sun's mass, about four and a half times it's radius, and some three thousand, three hundred times the Sun's luminosity. Zetas Sagittaria, or a cellar the Armpit is a binary star system located some eighty eight light years away, and it's currently speeding away from our Solar system. Astronomers think that it may have been as near as one and a half light years from the Sun around one point four million years ago. That would have made it an extremely close former neighbor. One of the stars in the system is a spectrotype a white giant, while the other is a spectrotype a white supergiant. The pair orbiting each other every twenty one earth years. The system's combined mass is about five point two six times the mass of the Sun. Delta Sagittaria or cals Meridianalys appears to be a double star system located three hundred and forty eight light years away and listed as an orange giant. Then there's Ether Sagittary, another double star system. It's one located one hundred and forty six light years from Earth. The primary star is an aging, bloated red giant on the asyntopic giant branch. That means it's no longer fusing hydrogen or helium in its core and as instead fusing heavier elements in the core and burning hydrogen and helium in its shell. It's already expanded out to some fifty seven times the radius of the Sun and is now nearing the end of its life. The second star in the system is a spectrotype F main sequence white yellow dwarf, which appears to be in a binary system with a primary star orbiting it every one two hundred and seventy earth years. PI Sagittary or Albalder is a triple star system located around five hundred and ten light years away. The primary star appears to be another spectrotype F white yellow giant, and it looks like it's just about exhausted its core hydrogen and he's now moved off the main sequence and evolving into a red giant. PI Sagittary has two nearby companions, but we know little about them. Beta Sagittary, or our Cab the Achilles tendon, is a designation shared by two separate star systems, one around three hundred and seventy eight light years from Earth, the other on three hundred and seventy nine light years away. Beta Sagittary A is a spectrotype B blue dwarf star or Beta Sagittary B, is a white yellow giant lying in the very center of the constellation is Nervous Sagittary, which was only discovered in twenty fifteen, and as the name suggests, is a nerva, a white dwarf in a binary system which is constantly drawing material off a close orbiting companion star. Once enough mass reaches the surface of the white dwarf, the added mass will undergo a thermo nuclear explosion, causing the star to briefly light up like a beacon and then slowly fade again over the following few weeks or months. The blast isn't enough. To destroy the white dwarf, only the additional material it's picked up. Now. Once the star's gone other and the additional mass has been burnt off, the same cycle starts over again, and the process repeats itself and time scars ranging from every few years to tens of thousands of years. The Sagittarius constellation also hosts many star clusters and nebulae, including some of the best known astronomical objects in the sky. These include the spectacular lagoon Nebula Messier eight, a stunning pink emission Nebula that's located five thousand light years away and measures one hundred and forty light years by sixty light years across. The central area of the Lagoon nebula is also known as the hourglass nebula. That's because of its distinctive shape because of matter propelled by a massive star forming region called Herschel thirty six. It's one of the few star forming nebulae possible to see with the unaided eye. The Lagoon nebula was instrumental in the discovery of Boch globules, more than seventeen thousand of which have now been found in the nebula. Astronomers believe these globules contain embryonic press phido stars destined to eventually become new stellar generations. Probably the most famous nebula in Sagittarius is messi As seventeen, better known as the Horsehaed nebula. It's located some eight hundred ninety light years away in a dense region of ironized atomic hydrogen, also known as the Amiga or Swan nebula. It spans some fifteen light years in diameter and as some eight hundred times the mass of our Sun. It's considered one of the brightest and most massive star forming regions in our galaxy, with a geometry similar to the Iryon nebula, except that we're seeing it edge on rather than face on. The open star cluster NGC sixty six eighteen lies embedded in the nebulosity and causes gases from the nebula to shine due to intense radiation from all the hot yang stars. Open star clusters are loosely bound groups of a few thousand stars which were originally all formed in the same molecular gas and dust cloud, but they're not as densely bound gravitationally. As globular cloud lusters. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for maybe a few billion. In contrast, the more massive globular clusters exert so much stronger gravitational attraction on their members that they can survive for much longer billions and billions of years. The nebula's thought to contain around eight hundred stars, including over one hundred of the largest most massive spectrotype O and B blue stars. More than one thousand additional stars are also being formed in the surrounding molecular gas and dust clouds, and with an age of just a million years, it's also one of the youngest clusters known in the galaxy. The cloud of interstellar material which formed the nebula is roughly forty light years across and contains some thirty thousand solar masses. Another spectacular site worth searching for in Sagittarius is the Trifford nebula Messi twenty. It's another large star forming a mission nebula containing many very young hot stars. Located between two thousand and nine thousand light years away. The Triffid nebula has a diameter of approximately fifty light years. The outside of the Triffid is a bluish reflection nebula, while the inner region is glowing pink thanks to ionized hydrogen. There are two dark bands dividing the Triffid nebula into three regions or lobes. Hydrogen in the nebula's ionized by a central triple star, which formed in the intersection between the two dark bands, creating its characteristic pink color. Another star forming region NGC six double five nine, located some five thousand light years away, contains both red emission and blue reflection regions. The grouping of the Lago nebula, the Triffid nebula, and NGC six double five nine are known as the Sagittarius triple and are a spectacular site to go searching for it in the night skies, but it doesn't end there. Another stunning object easily worth a look is the Red Spider nebula n GC sixty five three seven. It's a planetary nebul about eight thousand light years from Earth. It has a prominent two lobe shape, possibly due to a binary companion of magnetic fields and as an S shaped symmetry, with the lobes opposite each other appearing similar. This is believed due to the central companion to the central white dwarf. The central white dwarf, the remnant of the original star, produces a powerful and ten thousand degree hot three thousand killing meter a second stellar wind, which is generating one hundred billion killed me at a high waves of supersonic sharks formed as the local gas is being compressed and heated in front of the rapidly expanding lobes. Atoms caught in the shock waves are radiating invisible light, giving the nebula its unique spida like shape and also contributing to the expansion of the nebula. A star at the center of the red Spider nebula surrounded by a dust shell, making its exact prop but he's hard to determine. We think its surface temperatures probably somewhere around two hundred and fifty thousand degrees, although a temperature of up to five hundred thousand degrees can't be ruled out, and that would make it among the hottest one. Dwarf stars known. Looking directly south is the star Polaris Astrallus, or more accurately Sigma Octantius, the nearest star we have in the southern hemisphere to the south celestial pole, and consequently the closest counterpart we have to the north star Polaris. However, Sigma Octantus is far harder to see than Polaris because it's much fainter. Located some two hundred and seventy light years away, it's an orange giant reaching the end of its life. Turning to the southwest and just above the horizon this time of the year, we find Canopus, the second brighter star in the night sky after Sirius. It's located three hundred and ten light years away and is the brightest star in the constellation Carena. The kiel Canopus is a super giant some nine times the mass of the Sun and seventy one times its diameter. The month of. June also marks the first of two annual encounters with the Torred's meteor shower. The taureads are generated as the Earth passes through the debris stream created by the comet two Panche, which itself is thought to be a piece of a larger comet that broke apart somewhere between twenty thousand and thirty thousand years ago, most likely following numerous interactions with a powerful gravitational field of the king of planet Jupiter. As their name suggests, the Tourred's radiant, or apparent point of origin is in the direction of tourists. The ball the Turret's media shows unique in that it's made up of larger, more massive material pebbles instead of dust grains. Earth passes through the stream twice every year, once now in June, then again in October, called Halloween fireballs. The turreds release material birth by normal cometary activity and also occasionally by close encounters with the gravitational tidal force of the Earth and other planets, and this makes the Tourred stream of material the largest in the Inner Solar System. Now, since this stream of materials rather spread out in space, Earth will take several weeks to pass through it, causing an extended period of meta activity compared to the much smaller periods of activity associated with other meteor showers. Included in the stream is a denser flow of gravelly meteoroids called the Taurred Swarm, thought to be a ribbon of rocks roughly seventy five million by one hundred and fifty million kilometers across. Occasionally one hundred Earth passes through the larger meteoroids in the denser Taurred Swarm. In fact, one of the larger chunks of the Turret Swarm is now thought to have caused the infamous Tunguska event in the skies over Siberia back on June thirtieth, nineteen o eight. Astronomers believe the Tannguska event was the air burst of one hundred meters wide meteor over the Tannguska River region of Russia, causing mass devastation and flighttening over two thousand square kilometers of forest in the mattsticks. The blast was so bright it was enough to light up the night sky in London, a third of the way around the planet. Tuanguska remains the largest known Earth impact event in recorded history. It was considered a one in one thousand year event assuming a random distribution of events over time, but the new studies suggesting the event may have been caused by a turret swarm meteor and with the Earth passing through that swarm periodically, this tends to change those odds quite significantly. If the study is correct, this swarm heightens the possibility of a cluster of large impacts on the Earth over a very short period of time. For the complicating matters, the June Tourreds are actually two separate showers. The Southern Tourreds associated with the comet two p Nke or the Northern Tourrets originate from the asteroid two thousand and forty G ten and eccentric kilomet a wide asteroid plassified as an Earth object and potentially hazardous asteroid of the Apollo Group and joining us now for the rest of our tour of the June night skies. Seeing your science writer and Sky and Telescope magazine contributor Jonathan Nale, a student. Yet, well, we're almost midway through the year, and the sky has changed quite a lotically of the last few months, because you know, the constations of summer and lea, the southern summer had disappeared and northern winter had disappeared. And as the sun is shitting one of those constellations since Oryon is very low on the western horizon now and it's vanished and from view as each night passes nearby. A little bit higher in the sky, you've got the constellation Canus Major, but it's bright Stars series, the brightest star of the sky. That's still reasonably higher in the western sky, but it's sinking lower and lower night After that, that's it until the seasons are changing to its north. North from Canus Major, you've got a smaller cousin Canus Minor. There's the smaller dog it's still visible, and further north still from that, you've got the constellation Gemini, which is really easy to spot because it's got these two bright stars fairly close to each other, twin stars Castor and Pollus. That's where the Yea constellation gets the name for it that'll soon be gone as the weeks go by as well. On the pluff side though, with those constellations disappearing, but other ones are coming up in the eastern sky night after night as we roll further towards the middle of the year, and so we've got some of these really impressive constellations coming up, such as Scorpious and Sangittarius. Scorpius is a huge constellation that looks like its name, like a scorpion. Sagittarius is the constellation that's around the region of the center of our galaxies. So there are plenty of things to see there because we're looking into the thickest part of the Milky Way. And in the middle of the sky again towards the south, we've got other mighty constellations such as Centaurus. We've got Cruts or Cooks, the Southern Cross. You've got Veela, Karina, Lupas, and others. Now, a lot of people have never heard of those constellations, but regular stargaze is recognize them because all of those, in fact, all of the constellations I've mentioned, they live along the extent of the Milky Way, all very close to it. The Milky way, being that sort of fuzzy band of light you can see stretching across the night sky if you have dark enough sky conditions. So looking to the south, for us in the southern hemisphere, at least we've got the Southern Cross. Everyone wants to see the Southern Cross. It's about two thirds of the way up from the southern horizon at the moment. For once, it's standing upright, and it looks a bit like a Kite's got the shape of the kite, and it's quite small. The stars that comprise the Southern Cross, they're actually quite bright, So bear that in mind. I trying to have a look for it. It's small and it looks like a kite. And I wouldn't wait too long either, because as light delusion gets worse, we're seeing less and less of those five stars. The kite shape was made up of four bright stars, and there the fifth star that's in there as well, And for a lot of people in a lot of places now you can't see the fifth star anymore because it's the fainter of those five, and it's gone gone from view from the naked eye, which is really quite telling about the state of light pollution. Where most people live, particularly in a country like Australia where the vast majority of people living in what half a dozen big cities. So the light pollution is now so bad that we can't see one of the stars at Southern Cross, which is pretty disappointing if you asked me, and you're quite right that as it gets worse, even the brighter stars may one day gear. In fact, I saw a comment from someone recently on social media, someone visiting from Australia from China, i think, and they were saying, oh, ten things I've noticed about living in Australia, and one of them was I can see stars. I can actually see stars. That takes me right back to when the TV program Cosmos, presented by Carl Sagan back at right at the beginning of the nineteen eighty I remember reading that when that was shown around the world that producers of that program received lots of fanily. There's including fan letters from people in huge cities like Tokyo or pressures like that, and these people are saying, they're literally saying they didn't know the stars are real. They thought they had made up for science fiction because they had never seen stars. Well, there's that famous anecdote of people in New York during a major blackout ringing up emergency services and complaining because they can see all these stars in the sky and they didn't know what they were. This is the thing, This is the thing. People who live in the most massive cities are so much light pollution. Look, even where I live, there are knights. When I go out and I look up and I can see you have like a dozen stars, which is ridiculous when there are over the entire globe of the sky North More Southern Ministry at the whole life, only half of which you can see at any one time. Of course, over the entire globe, there's I think about five seven hundred stars that are bright enough to be made out individually binding by average eye sight, not counting all the medi billions of stars that make up the nookie way, which is that fuzzy glow that you can't you can't make out individual stars in there with just your own eyes, which and which you can do if you get out into a dead that were somewhere where there's no light around it. Oh yes, it's the most amazing. Yeah, that's that's what we're missing. That is what I used to work at a radio station in Darwin and would regularly commute between Darwen and Sydney, about a three thousand kilometer run. But do it over a couple of days and. The night skies as you drive up the Stuart Highway or absolutely brilliant. The sky is just a carpet of color. You know, this is this is one of the real tragedies of modern life that there's all sorts of fantastic things done in the environmental sector to preserve the lands and the waters and the forests and the trees and all that sort of stuff, which is fantastic, but not enough is yet being done to preserve our view of the night's dye, which sadly we're losing. There are a lot of good people doing a lot of good work on this, and there are dark sky regions and sights and things that have been set up all around the place, But for where the majority of people live, there's really not much hope at the moment, and I really can't see much changing. You go out into a desert and it's night time and you can see all the stars, and a cloud drifts by. You'll see a big black patch. The cloud will be a big black patch sliding above your head right and to block out the stars above. But in the city you see a cloud go past at nighttime and it's lit up like daylight. You can see the cloud, you know, like with a light gray color because it's picking up all this light that's coming up from all these lights on the ground below. And it's not just the cities. The Sighting Spring Observatory, for example, which is what seven hundred kilometers away nick knebarabran need Dubbo in the far west of New South Wales. The astronomers there can't turn the telescope east without seeing the lights of Sydney reflect off the clouds and off the air yep. And for quite a few decades now it's been the case. Anyway, back to those little points of light in the sky where was I was mentioned serious earlier, the brightest star in the sky, and the brightest star in the constellation came as major. The next brightest star in the United Sky is Canopus. That's the brightest star in Consternation Carina. And you can find this very low down in the south where if you're down here in the Southern hemisphere now compared to our sun Canopus is a superstar. It's about ten times as massive. Massive in the sense of its mass, not size in terms of size. It's about seventy times wider than our Sun, and it's about ten thousand times brighter than our Sun. Serious on the other hand, which is the brightest star we can see the night sky. It's only twenty five times as bright as the Sun, not ten thousand times, But it is much brighter in our sky than Canopus because it's a lot closer. It's only about eight and a half light years away, whereas Canopus is about three hundred and ten light years away. So a lot of these stars up there, you can't really tell from their brightness how far away they are, for some of them might be dim and close, and those might be bright but far away. In the northern part of the sky the moment of scenes from the Southern Hemist release, there are a couple of interesting bright stars. We've got Arkturists, which is about halfway up from our northern horizon and higher still in the night sky is one called Spiker. Ark Tourists is a red giant star. There's a couple of billion years older than our Sun. It's about the same mass as our Sun, but it's ballooned up to be about twenty five times bigger as well. If it's a big big star. Spiker is a binary star system who's just gone through to the interesting Spikeer's a binary star system who's pair of stars. They all each other so close to they're so close together, and they go around each other every four days. Mind you, they're so close together that their gravity, they're neutral gravity has pulled each of them out of shape, and so each of them is sort of like an egg shape rather than being traditional round star. Isn't it amazing? You can think that an entire star has been pulled out of shape by the gravity of another star right in next door, and they've spin around each other every four days. It's just mind bulb. Anyhow, as the night goes on, you'll see that things have changed. By midnight, Serious that's gone. That's set in the west, but not a couple of bright stars. They've got Viga and old Aar have appeared in the north way way way down in the southeast. We've got another star called Akana, another bright star that's turned up, that's come up over the east of horizon. All these changes of course occurred because the Earth is turning on a taxis and things that were below the horizon in the east have now come up into view, and the ones over in the west they're gone down out of you. Now, let's look at what the planets are doing this month. It's really quite interesting. At sunset at the beginning of the month, we've got Venus and Jupiter really prominent in the northwest, about a third of the way up on the horizon. Venus is the one that took down a bit lower and is brighter. Now, keep an eye on them, because night by night you'll see them appearing to move closer and closer to each other, and by the tenth of June they'll be side by side when you look on a star map. At least when you look on the real sky, there'll be several degrees apart. And then we can tell how much a degree is because the width of the moon is half a degree, so one degree is two moon wis apart, and you sat with several degrees apart. But also low down in the northwest there's another planet, Mercury, which starts the month quite low, but it's rising a little higher and higher ed to night and so by the time we get to the seventeenth, we'll have Mercury, Venus and Jupiter pretty much all together in the same part of the sky, and the Moon will have come along as well, so you'll have Mercury, Venus, the Moon, and Jupiter all arranged in the sort of the diamond shape. And on the following night, the Moon will have moved a bit in its orbit again, so the diamond samp will now have changed to a straight line. About all the four is things in a straight line, so that should be really impressive to see if you've got nice clear skies on the seventeenth and the eighteenth of the month. Now to see the other two bright planets, you're going to have to be up early because Shatun rises over the eastern horizon about two point thirty in the morning, followed by Mars a couple of hours later, So if you're an early riser to go to work for something, can get up a sixth prove or whatever before dawn when it's still dark, you should be able to see them quite easily. And finally Stewart on the twenty first bit, but the mid year salstice, it's the winter solstice for us in the southern Hemisphere and the summer solstice for our friends up in the North. So on this day the sun is at its most northerly point in the sky and the hours of darkness will be roughly longest on that day for us. You're in the shout and short stuff there in the North. And that's do. It's the night's stay forardon. That's senior science writer and skytte tell us Acout Magazine, contributed Jonathan Nelly, And this is space Time, and that's the show for now. 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