This is Spacetime Series twenty nine, Episode forty three, broadcast on the tenth of April twenty twenty six. Coming up on Spacetime, climate change now slowing Earth's spin at an unprecedented rate, magnetic waves discovered deep inside the Sun, and that mystery medical evacuation from the International Space Station earlier this year finally explained all that and more. Coming up on space Time. Welcome to space Time with Stuart Gary. A new study has found that climate change is slowing Earth's rotation at an unprecedented rate compared to the past three point six million years. A report in the Journal of Geophysical Research has found that climate change is lengthening Earth's stay because rising sea levels slow Earth's rotation, increasing the average length of the day by one point three to three milliseconds per century. The author's reconstructed ancient day length fluctuations using fossil remains of single submarine organisms known as benthic for aminifera. An exact twenty four hour day is not a given. The length of day changes due to gravitational effects of the Moon, as well as numerous geophysical processes on Earth acting within its interior, its surface, and in the atmosphere, but today's climate change also affected the length of the day. Previous studies by the same researchers had already shown that between the years twenty twenty twenty, an average Earth day had lengthened by a rate equivalent to one point three to three milliseconds per century due to climate change related factors, especially the redistribution of continental ocean mass due to the melting of polar ice sheets and mountain glaciers. The new study builds on that, showing that this now is happening faster than at any previous time over the past three point six million years. One of the. Studies authors was the Vaciani Chavati from the University of Vienna. Says the planet's spinning causes centrifugal force to move more water towards the equator, and that slows down the planet's rotational rate. It's exactly the same as figure skaters, who spin more slowly once they stretch their arms out and move more rapidly once they bring their hands closer to their bodies. But what remained unclear until now was whether there were earlier periods when climate increased the length of the day at a similarly rapid pace. To answer that question, sherivandian colleagues use the fossilized remains of benthic for a minute fera. The chemical composition of these fossils allow scientists to inferse sea level fluctuations and then mathematically derived the corresponding changes in day length. But to draw more robust conclusions, the authors also used a probabilistic deep learning algorithm, a physics informed the fusion model, which captures the physics of sea level change or remaining robust to the large uncertainties inherent in paleoclimate data. The growth and melting of large continental ice sheets repeatedly cause significant day length variations through sea level changes. Chevandi says that compared to values from the twenty first century, however, it's clear that today's increase in day length stands out in the climate history of the past three point six million years. Only once, around two million years ago, did the rate of change in the length of the day even come close to the current rate. The authors say that by the end of the twenty first century, climate change is expected to affect the length of the day even more strongly than the moon now, although these changes are only in milliseconds. They can cause problems in many areas, including time keeping and navigation, which requires very accurate information on Earth's rotation. This space time still to come. Magnetic waves discovered deep inside the Sun, and that mystery medical evacuation from the International Space Station back in January has finally been explained. All that and more still to come on space time. Scientists have detected large scale magnetic waves moving deep inside the Sun. The discovery, reported in the General Nature Astronomy, could help scientists predict solar activity. The waves, which are driven by powerful magnetic fields far below the solar surface, provide a new window into parts of the Sun that are otherwise inaccessible, thereby giving astronomers a new tool to study how our local star's magnetic field is formed and how it evolves over time. The Sun's interior is the dynamic ocean of hot, electorally charred gas known as plasma, which is shaped by rotation and magnetic forces. These magnetic fields drive the Sun's eleven year solar cycle, sunspots and powerful eruptions such as solar flares, a coronal mass ejections which can disrupt satellites, communication and navigation systems, and affect power grids on the Earth. Until now, the magnetic behavior deep inside the Sun was largely hidden from observation. But in this new study, scientists from New York University analyzed more than a decade of the Sun's natural vibrations, a process known as helio was still a seismology. Their work revealed evidence of previously undetected global scale magnetic waves influenced by the Sun's internal magnetism. By measuring how these waves move, the authors can infer the strength and structure of magnetic fields deep below the Sun's surface. So the findings are providing a new approach for studying the Sun's interior and its magnetic evolution over time, with implications for improving space weather forecasting, as well as understanding magnetic activity in other stars throughout the universe. This is space time still to come. That mystery medical evacuation from the International Space Station earlier this year has finally been explained, and the splendors of the Southern Cross and it's two pointer stars out from Bittersentry, the super giant Canopus, and the Lyrid's meteor shower are among the highlights of the April night skies on SkyWatch. Well it seems that medical evacuation from the International Space Station earlier this year has finally been explained at the Center. It was four time nasarats Michael Fink. Apparently he suddenly fell ill while eating dinner after preparing for a spacewalk. He couldn't talk and remembers no pain, but after seeing him in distress, his crewmate's requested help from flight surgeons on the ground. Fink says it came completely out of the blue and was amazingly quick. The fifty nine year old retired Air Force colonel says the episode lasted about twenty minutes and he felt fine afterwards, and it still does today, and he's never experienced anything like that, either before or since. Doctors have ruled out a heart attack. Think and his fellow SpaceX crew eleven Expedition seventy four astronauts were some five and a half months into their stay aboard the International Space Station when the episode occurred. The space station's ultrasound machine was initially used in orbit, and then follow up tests were conducted when he returned to Worth. NASA are now pouring through other astronauts and medical records to see if any similar events may have affected other crew members. Although it's not uncommon for astronauts to get sick in space, this was the first time ever that a medical emergency evacuation had to be carried out from the International Space Station this space Time SkyWatch is next, and time Matter check out the night skies of April on SkyWatch. April is the fourth month of the year in the Gregorian calendar and the fifth in the Early Julian calendar. The Romans gave this month the Latin name of Prilus. Although the name's origins aren't certain, traditional entomology suggest as from the verb aparia to open, as in it being the season when the trees and flowers begin to open as the northern hemisphere moves into spring. April is also Prevention of Cruelty to Animals month, and so it's a good time to consider adopting a shelter pit or donating to an animal welfare charity. High in the southern sky during April, you'll find the Southern Cross and its two pointer stars, Alpha and Beta Centauri. The more distant of the two pointer stars from the Southern Cross is Alpha Centauri, which also happens to be the nearest star system to our own located some four point three light years away. Alpha Centauri actually consists of three stars. There's Alpha's scentaury A in B, which orbit each other, and proximate centaury which orbits the pair, and at four point twenty five light is distant. Is currently the nearest start of the Earth other than the Sun. A light year is about ten trillion kilometers, the distance of photon can travel in a year at three hundred thousand kilometers per second, the speed of light in a vacuum, and the ultimate speed limit of the universe. Like the Sun, Alpha centaury A is a specual type G yellow dwarf star. It's slightly bigger, having about a tenth more mass than the Sun and is about fifty percent more luminosity. Astronomers describe stars in terms of spetual types, a classification system based on temperature and characteristics. The hottest, most massive, and most luminous stars are known are spectual type of blue stars. They are followed by spectual type B blue white stars, then spetual type A white stars, specual type F whitish yellow stars, spetual type G yellow stars. That's where our Sun fits in spectrotype K orange stars, and the coolest and least massive stars of all are spectual type M red dwarf stars. Each spetual classification is further subdivided using a numeric digit to represent temperature, with zero being the hottest and nine the coolest, and then a Roman numeral to represent luminosity. So our Sun is a spectrotype G two V or G two five yellow dwarf star. Also included in the stellar classification system are special types LT and Y, which are assigned to failed stars called brown dwarves. These is sometimes born a spectual type M red dwarf stars, but become brown dwarves after losing some of their mass. Brown dwarves fit into a category between the largest planets, which are about thirteen times the mass of Jupiter, and the smallest spectrotype M red dwarf stars, which are around seventy five to eighty times the mass of Jupiter or about zero zero point zero eight Solar masses orbiting in a binary system with alpha centaury a is alpha centaury b, a spectrotype K orange dwarf star, a little smaller and cooler than the Sun, with about zero point nine times the Sun's mass. And about half its luminosity. Alpha centaury A and b aorbit each other around a common center of gravity every seventy nine point nine to one earth years. The distance between the two stars varies between roughly that of Pluto and the Sun and that of Satin in the Sun. The third star in the system, Proxima centaury, sometimes called Alpha centaury C, is a spectuotype m red dwarf star with roughly a seventh diameter and about an eighth the mass of the Sun. It takes around five hundred and fifty thousand earth years to orbit Alpha centaury A and B. The nearer of the two pointer stars to the southern cross is Beta centaury also a triple star system, but this one located a far more distant three hundred and ninety. Light years away. All three are massive, young blue stars, far larger and more luminous than the Sun. Two of the stars, name Beta centaury Aa and Beta century AB, orbit each other, while the third star, Betasentory B, orbits the primary pair every fifteen hundred earth years. Bettersentory AA and AB are known as a spectroscopic binary, orbiting each other every three hundred and fifty seven Earth days. Spectroscopic binaries are double star systems orbiting each other so closely and at such an angle that they can only be visually separated from our point of view here on Earth, at least by their spectroscopic signatures. Both these stars are now reaching the end of their time on the main sequence and will soon run out of the core hydrogen they use for fusion, the process which makes stars like the sunshine. The two point of stars Alpha and Bettersentaury and named after Cirron the Centaur, a mythological Greek being half man half horse. Sirron taught many the gods and heroes, but was placed among the stars after accidentally being shot with a poison arrow by Hercules. Next to the pointer stars is the spectacular Southern Cross or Crux, the smallest but one of the best known of the eighty eight constellations in the sky. The Southern Cross is considered an important constellation for navigation, and is featured on the flags of several nations, including Australia, Brazil, New Zealand, Papua New Guinea, and Samoa. In April, the Southern Cross relies on its side in the early evening but becomes more and more upright as the night progresses. The bottom and brightest star in the Southern Cross is Alpha Crusis or a Crux, which is actually a multiple star system located three hundred and twenty one light years away. It consists of three stars, A one Crusus, which is a spectroscopic binary, and A two Cruises. A two Crusus in the primary star in A one Crusus are both spectral type B blue stars with the surface temperatures of twenty six thousand and twenty eight thousand kelvin respectively. The two components orbit each other every fifteen hundred earth years at an average distance of around four hundred and thirty astronomical units. An astronomical unit is the average distance between the Earth and the Sun roughly one hundred and fifty million kilometers or eight point three light minutes. The spectroscopic binary A wine Cruises is thought to comprise two stars with about ten and fourteen times the mass of the Sun, respectively. The pair orbit each other every seventy six earth days at a distance of around one hundred and fifty million kilometers. In other words, one astronomical unit the masses of a two cruises and the larger component of A Wine Cruises are expected to eventually explode as core collapse supernovae, ending up as neutron stars, while the smaller component of A one cruises could survive as a white dwarf. The left hand and second brightest star in the Southern Cross is called Beta cruss There's also a spectroscopic binary consisting of two stars orbiting each other every five earth years at an average distance which varies between five point four and twelve astronomical units. Beta Crusus is located some two hundred and eighty light years away. The primary star, Beta Crusus A, is a special type B beta cefi variable blue star which changes in brightness over a period of around four to four and a half hours. It has about sixteen times the Sun's mass, about eight times its diameter, and a surface temperature of some twenty seven thousand kelvin. By comparison, our Sun is a surface temperature of just six thousand. The second star in the system, BITA Crucis B, has about ten solar masses. A third companion has also been detected in the system. However, it appears to be a low mass pre main sequence star. Which hasn't yet commenced nuclear fusion. Need Beta Crusus is This spectacularly young open star cluster, known as the Kappacrusus cluster or in GC forty seven fifty five, are more commonly referred to as the jewel Box, the name given to it by a famous eighteenth century astronomer, John Herschel. Open star clusters are groups of stars which were originally all born at the same time out of the same collapsing molecular gas and dust cloud. Although somewhat still gravitationally bound to each other, stars in open clusters eventually separate, moving to other parts of the galaxy. As the name suggests, the jewel Box is a stunning collection of more than one hundred bright, colorful stars located some six four hundred and forty light years away, although its exact distance is somewhat difficult to determine because of the nearby Coalsack nebula, which obscures some of the light. The Coalsack is a dark nebula containing lots of gas and dust blocking out background stars. In Australian Aboriginal dream time legend, the Coalsack forms the head of the Emu constellation with the dark dust la into the Milky Way, forming the emu's body and legs. The central parts of the jewel box are framed by bright stars, making up an a shaped asterism. These are among the brightest known blue, white, and red supergiants in the Milky Way. Gamma Cruisius, which is located at the top of the Southern Cross, is the third brightest star in the constellation. It's also one of the nearest red giants to our solar system, located just eighty eight point six light years away. Although only thirty percent more massive than the Sun, it's expanded outer envelope has bloated out to some eighty four times the Sun's radius and is radiating some fifteen hundred times more luminosity than the Sun. As a red giant no longer on the main sequence, Gamma Crusis is nearing the end of its life. Its surface temperature is some three thousand, six hundred and twenty six kelvin, and it has a prominent reddish orange appearance. The star on the right hand side of the Southern Cross is Delta crusis, a massive, hot, and rapidly rotating star that's in the process of evolving into a red giant and will eventually end up as a white dwarf. The stellar corpse of sun like stars, Dilda Crusus, is located some three hundred and forty five light years away. It is about nine times the Sun's mass and eight times it's radius. It's presently radiating at around ten thousand times the luminosity of the Sun at an effective temperature of twenty two thousand, five hundred and seventy kelvin, causing it to glow with a blue white hue. The smallest star in the Southern Cross is Epsilon Cruisis, which is located in the space between Delta and Alpha Crusus. It's a red giant some two hundred and twenty eight light years away. It is about one. Point four to two times the mass of the Sun and about thirty two times it's radius. Its surface temperature of four one hundred and forty eight kelvin means it's sometimes referred to as an orange giant. The Southern Cross is at its highest point in the southern sky this time of year, and he's pointing directly at the southern celestual pole. It's within the constellation Centaurus. The Centaur, the half man half horse of Greek mythology we mentioned earlier. The creature is holding a bow loaded with an arrow. The centaur's front leg is marked by the two pointer stars Alpha and Beta Centaurus. His back arches over the southern cross, and just above this is Amiga Centauri, a spectacular globular cluster visible with the unaided eye from dark locations. Unlike open star clusters, globular clusters are tightly packspiest containing thousands to millions of stars which were originally all thought to have been born at the same time from the same molecular gas and dust cloud. Amiga Centauri is about sixteen thousand light years away. It's one of the largest and brightest of the hundreds of globular clusters known to orbit around the Milky Way Galaxy. Centaurus was included among the forty eight constellations listed by the second century astronomy a Ptolemy, and it remains one of the eighty eight modern day constellations. The constellation Orion the Hunter is still clearly visible in the northwestern sky this time of year, with its rectangle of four stars surrounded by a central trio of stars which form Orion spilt To the right or east of Orion is the constellation Gemini and its two brightest stars, paul Axe and Casta. This time of year, the Gemini twins are almost directly due north for Southern Hemisphere sky watchers. The higher of the two stars, paul Axe, is a red giant some eleven times that I Am of the Sun and located just thirty four light years away. The other star, Castor, is much further away, some fifty one light years. Look to the east and you'll see the star Regulus, the brightest star in the constellation of Leo. The lion Regulus, which means little King, is located seventy seven light years away, and it's about three and a half times as massive as the Sun. At about one hundred and forty times is luminous. Regulus is a binary companion star which takes one hundred and thirty thousand years to orbit. The primary to the right of Regulus and virtually due east in the sky right now is the star Spiker, located directly below the four stars in the constellation Corps. The crow Spiker is the brightest star in the constellation Virgo, also known as Alpha Virginis. It's the sixteenth brightest star in the night sky, and is another spectroscopic binary comprising two stars closely orbiting each other every four earth days. In fact, the two stars in Spiker are orbiting so close together that the gravitational interaction between them has caused them to become rotating epsiloidal variables, distorting them into the shape of a rugby league or gridiron football. Light from this binary changes in brightness as the two stars orbit each other, exposing their elongated hemispheres to us. Spiker is located some two hundred and sixty light years away. It is some two thousand times as luminous as the Sun. Spiker means ear of wheat, which Virgo is holding in a hand. It's so named because it marks the start of the harvest season in the northern hemisphere. The primary is a blue giant variable better Cepheid, which undergoes small rapid variations in brightness because of pulsations in the star's surface thought to be caused by the unusual properties of iron at temperatures of two hundred thousand degrees in the stellar interior. It is about ten times the Sun's mass and about seven and a half times its diameter. Once a spectral type B blue white main sequence star, it's now pulsating rapidly, rotating at more than one hundred and ninety nine kilometres per second over a zero point one seven three eight earth day period. It's one of the nearest stars to the Earth, which is expected to end its life as a type two core collapse supernova. The second star in the system is also thought to be a spectual type B blue white giant about seven solar masses and three point six times the sun star diameter. Okay, going back to the southern cross and looking to the right or west, you'll see the star Canopus. It's the second brightest star in the night sky after Sirius. Even though Canopus is three hundred and twelve light years away, it looks incredibly bright because it's huge one hundred times the diameter of the Sun and ten thousand times is luminous. This year's second major meteor shower, the Lyriids, will peak on April the twenty second and twenty third. The Lyroids appear to radiate out from the constellation Lyra close to the star Vega, one of the brightest stars in the sky this time of year. The source of the meteor shower are particles of dust and debris shed by the long period Comet c. Eighteen sixty one g one thatcher sky watches in the northern Hemisphere get the best view of the Lyriids. However, listeners at mid southern Hemisphere latitudes can also see the shower between midnight and dawn. Patient observers will be rewarded with around eighteen meteors per hour before dawn from dark sky locations and joining us now for the rist of our tour of the April night skies. Senior science writer and Sky and tell Us About magazine contributor Jonathan Nally. Got a shirt all its April. So after nightfall and April, we've got the milky Way, which to be seen spanning the sky from horizon to horizon, or at least stop holding it, can they Stuart? Well, Yes, after nightfall on April evenings, we've got the milky Way which can be seen spanning the sky from horizon to horizon, or at least it does. You can see it if you're lucky, because it depends on what your local light pollution situations like. So far, I live in the suburbs of the big city. I can't actually see the Milky Way. I cannot see the glow of our galaxy scene from the inside, which is what the Milky Way is, our view of our galaxy from the inside. I used to work in Darwin in the Northern Territory at the local radio station there, and I used to live in Sydney, so go down for holidays to Sydney and drive between the two, which is about I think three and a half four thousand kilometers, which is a long drive, and so I didn't get to see the Milky Way until I was in the Australian outback where there's no lights other than what the sky provides. Then it is spectacular. Yeah, if you're away from sources of light pollution, you can see the Mooky Way and it's amazing. But for so many people that live in the city, myself included, it just just cannot see the thing because of the light pollution. It's really really bad. But you know, if you're lucky and you do live in a darker location, or you're on going on holidays or driving through the outback or whatever, you should be able to see it at this time of year. Stretching across the sky from the southeast to the northwest. But even if you can't see the glow of the Monky Way, you can still trace its part by virtue of some of the bright stellar signposts along its length. These are the bright stars that can be seen even under the worst light pollution scenarios. You can't see the faint glow of the Milky Way, which is the accumulation of millions and millions of stars that you can't make out with the naked eye, but there are certain bright stars and the constellations along the length of the Mooky Way. You can always see them. So starting way down in the south, as we can see it from down the southern part of the planet from below the equator, they've got Alpha and Beta Centauri, a pair of stars known as the Pointers. That's because if you draw a line between the two of them and extend it onwards, it points that line points roughly to the next collection of brightish stars, which is the constellation of the Southern Cross. The Alpha and Beta two Pointer stars. They are the third and the eleventh froight of stars in the night sky. Alp and Vita, third and eleventh brightest stars, and the two brighter stars in the southern Cross are the thirteenth and the twentieth brightest. Now moving further along the Lookie Way, and a little off its right hand edge is a star called Canopus, as is the brightest star in the constellation called Corina, and it's actually the second brightest star in the whole night sky. And if we go still a little bit further along, we come to the brighter star in the night star that's serious, which is the so called Dog star because it's the brightest star in the constellation of Canus Major, which is the larger or greater Dog. So yeah, Venus, you you got the second brightest star in this A little further along, you've got the brighter star in the night sky. And not far away from that is another star called pro Psion. A little bit further along the Lookie way, this is the brightest star in Canous Minor, the lesser or smaller God constellation, and it's the eighth brighter star that we can see from Earth. Then we're going to look further along the Milky Way again, and we've got the two bright stars in the constellation Arah and you've got beetle juice Skars tenth brightest star, and rye Gel the seventh brightest star. I think it's really interesting to note that all but one of those stars that I've just mentioned that they seem to be single stars. You look up in the Knights Kind they just looked like a star, almost all of them, in fact, all but one in fact multiple star systems. So you've got Alpha Centauri and Beta Centauri, and they are both triple star systems. The Alpha star in the Southern Cross is a seven star systems got seven stars, while it's sibling, the next brightest star in the Southern Cross, Beta is a triple star. You've got Sirius and Precion are both binary stars. Beetle Juice is a binary and rye Gel has at least four stars in its system. So out of all the stars we've just gone through along the length of the Milky Way that you can see in the night Star during the April oft least in the evening, of all those ones I mentioned, only Canopus is a single star. And this actually pretty typical of the situation out there in space. Multiple star systems are the norm. So stars like Canopus, stars like our Sun solo stars, you know, they're not rare. I'm not trying to say they're rare, but they guess you might call on the exception a lot of stars out there are multiple stars. They don't seem like that to the naked eye, but some of them you can get even a small telescope on them, like Alphas Ontauri. You can get a small telescope under that and you can see that. You can see it's two main stars. There is a third tiny one called Proximus and Taure that is very faint and you have to know exactly where to look for a bigger telescope. But some of these stars you can see their double or triple nature if you get a telescape on anyhow, that's the little two of the Milky Way. It's go closer to home now, and that what the planets are doing this month. As darkness begins to fall, there are two planets visible in the evening. Star hovering above the western horizon is Venus. It's bright, certainly, but it's a bit lost within the twilight glow, the sunset glow. At least before the first part of April. For the second half of the month, it's pretty much in the same spot in the sky because the sun is setting a little bit earlier each night. The sky is a bit darker, so Venus and slightly darker sky background, so it makes it a bit easier to see. The other bright star lighting up the eaven sky is Jupiter. It forms a nice triangle with two of those stars I mentioned earlier, Prosion and Beetle Juice. But the big thing, the main planetary action happening this month, is in the pre dawn sky, So you're going to be up early if you're up around about about five o'clock in the morning Australian Eastern time, whatever that works out to be in your time zone. If you're up there and have a look above the eastern horizon, not too far up, just just above the eastern horizon, you should see what looks like three stars in a row going vertically up the sky. There are actually three planets. Starting from the lowest timbing going upwards. We've got Saturn, Mars, and Mercury. So that's pretty cool to see three planets all in a row close to the horizon. But if you keep watching as each day goes by, you'll see them splot In fact, I was going to say slowly but quite rapidly slide towards each other, so much so that from the nineteenth to the twenty second they'll be really quite super close. A little tight training will only about three or four moon stands apart. It's going to look wordy spectacular, probably people ringing up radio stating saying, what's that little collection of life? So I can see out in the sky there. If you've got a pair of monoculars a small telescope, it'll be a really really great view. But if you don't have that, just own eyes is fine. Go out about five o'clock in the morning between the nineteenth and twenty second, look to the east, straight to the east where the sun's going to come up, and you see this tight little triangle of three dots of light, and that I actually the planets seven miles in Mercury. I have to say, Stuart, I'm not really a good one for getting up early in the morning, but I'm going to make an exception in this case. I will be getting up to have a look at this inglish cross with the weather. Get up early in the morning. I think the morning doesn't really exist to you, doesn't That's when they come home. What you're out just going all night, but they still have this goes are we showing our aids? That's called clubbing, clubbing. See again, shame mate and that's Stewart is the Night's Night April. That's senior Science writer and Skye Telescope Magazine contributed Jonathan Nelly and this. Space Time and that's the show for now. Spacetime is available every Monday, Wednesday and Friday through at bytes dot com, SoundCloud, YouTube, your favorite podcast download provider, and from space Time with Stuart Gary dot com. Space Time's also broadcast through the National Science Foundation, on Science Own Radio and on both iHeartRadio and tune In Radio. And you can help to support our show by visiting the Spacetime Store for a range of promotional merchandising goodies, or by becoming a Spacetime Patron, which gives you access to triple episode commercial free versions of the show, as well as lots of bonnus audio content which doesn't go to weir, access to our exclusive Facebook group, and other rewards. Just go to space Time with Stuart Gary dot com for full details. You've been listening to space Time with Stuart Garry. This has been another quality podcast production from Bytes dot com
