Lightning Strikes Mars: The First Detection of Electrical Discharges and NASA's New Look at Comet 3I Atlas

This is Spacetime Series twenty eight, episode one hundred and forty three for broadcasts on the fifth of December twenty twenty five. Coming up on Space Time, lightning detected on Mars for the first time, NASA's new images of interstellar Comet three I Atlas, and scientists discover that moss can survive in the vacuum of space. All that and more coming up on space Time. Welcome to space Time With Stuart. Gary, NASA's Mars Perseverance rover has captured evidence of electrical discharges, that is, lightning in the red planet's atmosphere. The findings, reported in the journal Nature, were recorded in two dust devil whirlwinds. Inside Jests wrote Crater on Mars, winds occasionally stir up fine dust, and it was at the center of two of these dust devils that the six world car sized Rovers supercam microphone recorded some especially strong signals. Analysis showed there were electromagnetic and acoustic signatures of electric disccharges comparable to the small static electricity shocks that can be experienced on Earth when touching a door handle in dry weather. Although long theorized, this is the first confirmation of the existence of electrical discharges in the Martian atmosphere. The phenomena can be explained by friction between tiny dust particles. They become charged with electrons, then release their charges in the form of electric arcs a few centimeters long, accompanied by a loud, audible shock wave. On Earth, that's well known that dust particles can become electrically charged, especially in desert regions, although this rarely results in actual discharges. But on Mars, the thin atmosphere, mostly made up of carbon dioxide makes this phenomenon much more likely to occur. See the amount of charge needed to form sparks is much lower than on Earth. The discovery of these electrical discharges profoundly changes sciences understanding of Martian atmospheric chemistry. These phenomenas show that the Martian atmosphere can reach significant levels of charge, speed up the formation of highly oxidizing compounds, and these substances can destroy organic molecules on the surface as well as numerous atmospheric compounds, thereby profoundly upsetting the photochemical balance of the atmosphere. The discovery could or explain the surprisingly rapid disappearance of methane on Mars, which has now been a subject of scientific debate for several years. The electrical charges required for these discharges are likely to affect the transportation of dust on Mars, thus playing a central role in Martian climate, the dynamics of which are still largely unknown. Of course, they also pose a risk to electronic equipment on current missions to the Red planet's surface, and they could also constitute a danger for future man missions to Mars. The microphone on the supercame instrument aboard Perseverance was first activated on Mars in twenty twenty one, the day after the rover landed on the Red planet. Switched on every day. It's now collected over thirty hours of sounds from the Red planet, the wind blowing the nose of the blades of the Ingenuity helicopter, and now some fifty electrical discharges. This is space time still to come. NASA's new images of interstellar Comet three I atlas, and a new study has shown that mass can survive the deadly vacuum of space for up to fifteen years. All that and more still to come on space time Hot on the hills of the European Space Agency's observations of the interstellar Comet three I outlas. NASAREUS published its own observations pieces. Observations using its Exo Mars Trace Gas orbiter improved the comet's predicted location by a factor of ten, capturing the alien visitor as the comet passed relatively close to Mars, approaching to about twenty nine million kilometers of the red planet on October. The third EXO Mars got about ten times close to three Our outlas than telescopes on Earth and observe the comet from a new viewing angle. The triangulation of this stata, combined with data from Earth, helped make the comet's predicted path much more accurate. It also helped put an end to all those wild claims that three are outlas maybe an alien spacecraft. NASA is Mayven. The Mars Atmospheric and Volatile Evolution Orbiter also monitor the comet for ten days as it slipped behind the Sun and out of view of the Earth. Mayven observed three Our outlas in ultraviolet light, exposing the glow of hydrogen silently pouring off the comet's icy surface. These data helping astronomers uncover new clues about the comets hidden chemistry, Hence about ancient water and other star systems, and even the ratio of hydrogen to deteryrium could reveal where this vagabond traveler was born, long before it was spotted in our solar system. Last July, as well as Maven, NASA also turned the Mars Reconnaissance orbited towards three I Atlas, capturing one of the closest images of the comet. Yet Meanwhile, down on the Martian surface, Perseverance rover also grabbed a faint glimpse of the comet from its position on the rim of Jezro Crater, and it doesn't end there. NASAs Stereo spacecraft captured images of the comet between September the eleventh and October the two and the joint NASA ISA Sooher spacecraft observed the comet from October fifteenth to the twenty sixth. Images from NASA's Punch mission, which launched earlier this year, revealed the comet's tail during its observations between September the twentieth and October the third. NASA's Psyche and Lucy missions currently on their respective outbound journeys to study various asteroid targets further out in the Solar system were also able to observe three I atlas. On September the eighth and ninth, PSAKI acquired four observations of the comet over eight hours from the distance of fifty three million kilometers away, and these images will further help scientists refine the comet's dejectory. Then, on September sixteenth, Lucy took a series of images from three hundred and eighty six million kilometers distant. Stacking all these images together provides details on the comet's coma and tail back. In August, both the web and spheric telescopes also captured imagery. Comet three I outlets will fly closest to the Earth around decemn the nineteenth. That's when it will pass at a distance of two hundred and seventy four million kilometers, which is still almost twice the distance between the Earth and the Sun. Needless to say, astronomers will continue to observe the comet as it continues its journey through our solar system, passing the orbit of Jupiter in early twenty twenty six, traveling at some two hundred and fifty thousand kilometers an hour before finally vanishing back into interstellar space, never to return. This is space time still to come. A new study has shown that mosc can survive the deadly vacu of space for up to fifteen years, and the December solstice, the ticking time bumb of Edacarina and the rock comet Phaeton are among the harlots of the December night skies on SkyWatch. A new study has shown that moss could survive in the deadly vacuum of space for up to fifteen years. The findings, reported in the journal Ice Science, are based on moss sports samples sent to the International Space Station, where they survived exposure to the vacuum of space for up to nine months before returning to Earth. The studies lead author, Tomomichi Fujita from Hakkaida University, says most living organisms, including humans, can't survive even briefly in the vacuum of space. However, the mos sports retain their vitality after nine months of direct exposure. He says the findings provide striking evidence that the life that's evolved here on Earth possesses, at least at a cellular level, intrinsic mechanisms to endure the conditions of space. Tom A. Michi and colleague subjected a well studied moss commonly known as spreading earth moss to both real and simulated space environment conditions, including high levels of ultraviolet radiation, extreme high and low temperatures, and vacuum conditions. They tested three different structures from the moss protain mata or juvenile moss, brood cells or specialized stem cells that emerge under stress conditions, and sporophytes or encapsulated spores, in order to find out which are the best chance of surviving in space. The authors found that ultraviolet radiation was the toughest environment to survive, and the spora sites were by far the most resilient of the three moss parts. None of the juvenile mass survived high radiation levels or extreme temperatures. The brood cells had a high red of survival, but the incse spores exhibited a thousand times more tolerance to ultraviolet radiation, and the spores were also able to survive and germinate despite being exposed to one hundred and ninety six degrees celsius for over a week, as well as after living in fifty five degrees celsius heat for a month. The samples had an eighty percent survival rate and were able to successfully germinate when they returned to Earth. The authors then analyzed how well the moss survived in a computer model, which predicted that the spores could have survived for up to five thousand, six hundred days it's around fifteen years. The authors say the results demonstrate the remarkable resilience of mass spores and revealed the potential of terrestrial plants to endure extreme environments. This space time time out to turn our eyes to this skies with December SkyWatch. December is the twelfth and final month of the year in both the Jillian Anchorgorian calendars. December got its name from the Latin word decem, meaning ten. That's because it was originally the tenth month of the year in the Old Roman calendar, which began in March. Of course, the astronomical highlight of the month is the December solstice, which this year occurs at two or two in the morning of Monday December the twenty second Australian Eastern daylight time, that's ten o two in the morning of Sunday, December, the twenty first US Eastern Standard time, and fifteen oh two in the afternoon Greenwich meantime. This is when the sun appears to read zenith directly over the Tropic of Capricorn in the United States. In the northern hemisphere, it marks the winter solstice, signifying the first day of winter. But the good news is that from now on the days start to get longer again. On the other hand, south of the equator, summer has well and truly arrived and the days are usually at their warmest. Seasons occur because of the tilt of the planet spin axes, which is inclined at twenty three point four degrees in relation to the Sun. Now generally speaking, Earth's axis always points to the same position in space regardless of the position of the Earth as it orbits around the Sun. So on the day of the December solstice, the earth South pole is tilted towards the Sun, so its southern hemisphere gets more daylight and more direct sunlight, so it's hotter and its southern hemisphere is in summer. Six months later, during the June solstice, the north pole is tilted towards the Sun, and so it's the northern hemisphere which experiences summer, or the southern hemisphere gets less daylight longer nights, and the sunlight strikes the surface of the planet at a shallower angle, meaning less heat, and so the southern hemispheres in winter. In between these two we have the March and September equinox. That's when the northern and southern hemispheres get roughly equal amounts of daylight and heat, giving us the seasons of spring and autumn. Now earlier, we said that generally speaking, Earth's axis always points to the same position in space, regardless of Earth's orbital position around the Sun. And while that's true in our day to day lives, over geologic time approximately twenty five thousand, seven hundred and seventy two years, a gravity induced effect known as axial procession causes a slow and continuous change in the orientation of Earth's rotational axis. It can see the same effect in the procession of a spinning top as its axis traces out a pair of cones joined by the aspises. Earth's precession was historically called the procession of the equinoxes, because the equinoxes moved westwards along the ecliptic relative to the fixed background stars. This slow procession of the Earth axis means that over twenty five thou seven hundred and seventy two years, the positions of the south and north celestial poles appears to move in circles against the space fixed background stars. So while today the star Polaris lies approximately at the north celestial pole, this will change over time and gam Cepi will ultimately become the north star in about three thousand, two hundred year from now. It also means the seasons would slowly move through different calendar months, but we make adjustments to the calendar compensate for that. In most parts of the world, the seasons begin on the day of the solstice or equinox. These are known as astronomical seasons and are based on Earth's orbital position and tilt as it travels around the Sun. However, in Australia, seasons begin on the first day of a specific calendar month, that is March for autumn, June for winter, September for spring, and December for summer. These are known as meteorological seasons and are based on the annual temperature cycle and divided into four consistent three month periods in order to simplify weather tracking and climate trends. They align more closely with the seasons as they are typically experienced in terms of weather. Because of the relatively small amount of elongation in Earth's orbit around the Sun, earth seasons are determined by its axial tilt rather than orbital distance. Currently, Earth's closest orbital position to the Sun, known as perihelian, occurs about two weeks after the December solstice, and it's furthest from the Sun, known as aphelion, about two weeks after the June solstice. That means the next perihelion will occur at four fifteen in the morning of Sunday, January fourth, twenty twenty six Australian Eastern daylight time. That's when the Earth will be just one hundred and forty seven million, ninety nine thousand and eight hundred and ninety four kilometers from the Sun. That's twelve fifteen in the afternoon of Saturday, January the third, US Eastern Standard time, at a quarter past five in the afternoon Greenwich meantime. Like axial procession, Earth's orbit also changes gradually over geologic time, getting more or less elongated and changing perihelian and ophelion. Even the degree of the child of Earth's axis changes over thousands of years. Now. Collectively, all these changes are known as Malenkovitch cycles, after the Serbianjeev physicist and astronomer Miluta Milankovitch, who in the nineteen twenties hypothesized that variations in extent tricity axial tild In procession resulted in cyclic variations in solar radiation reaching the Earth, and that this orbital forcing strongly influenced Earth's climatic patterns. Okay, let's start our tour of the December night skies in the west, where midway up from the horizon is Former Halt, the brightest star, and the constellation Pisces of Strenus the southern fish. Former Halt is a very young, white, spiritual type, a main sequence star about one point eight times the diameter of the Sun and located reasonably nearby, just twenty five light years away. A light year is about ten trillion kilometers the distance of Ferton can travel in an Earth year at three hundred thousand kilometres per second, speed of light in a vacuum and the ultimate speed limit of the universe. Main Sequence stars are those undergoing hydrogen fusion into healium in their cause. Astronomers describe stars in terms of spectual types. The classification system based on temperature and characteristics. The hottest, most massive, immerse lumine the stars are spectro type of blue stars. They're followed by spectual type B blue white stars, then spectual type A white stars, specual type F whitish yellow stars, spectual type G yellow stars. That's where our Sun fits in, by the way. Then comes spetual type K orange stars, and the coolest and least massive known stars are spectual type M red stars. Now, each spectral classification can also be subdivided using a numeric digit which represents temperature, with zero being the hottest and nine the courlest, and a Roman numeral to represent luminosity. So our Sun is a G two V or G two five yellow dwarf star. Also included in the stellar classification system are spectral types LT and Y, which are assigned to failed stars known as brown dwarves, some of which were actually born as spectual type M red dwarf stars, but they became brown dwarves after losing some of their mass. Brown dwarves fit into a unique category between the largest planets, which are about thirteen times the mass of Jupiter, and the smallest spectrotype m red dwarf stars, which are about seventy five to eighty times the mass of Jupiter or roughly zero point zero eight solar masses. In two thousand and eight, astronomers detected planets orbiting around formal Halt. At this stage, it's not known if anyone was looking back. Five thousand years ago, the ancient Mesopotamians used former Halt to mark the northern hemispheres winter solstice. Now turning to the left of former Halt is Akina or Alpha Aridney, the brightest star in the constellation Aridnis the River. Located one hundred and thirty nine light years away. Akina has seven times the diameter of the Sun and rotate some fifteen times faster, giving it a very obvious oblate shape. The effect of this rapid rotation is that the star flattens at its poles that bulges in the middle. In fact, its equatorial diameter is about fifty percent greater than its polar diameter. It turns out Akinar is actually part of a multiple star system, Alpha Aridney A and Alpha Ridney B. The primary star Alpha Ridney A is a hot blue spectral type B main sequence star. Its smaller companion, Alpha Ridney B is a spectral type A white star. They pair all but each other around a common center of gravity at a distance of about twelve astronomical units. 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. Moving further left from Akinar and just above the horizon is Canopus, the brightest star in the southern constellation of Koreina the Kiel, and it's also the second brightest star in the night sky after Sirius Cainopus is a white giant star nearing the end of its life. It's located about three hundred and ten light years away. It has about eight and a half times the mass of the Sun, but it's expanded out to about seventy one times the Sun's diameter. Kinopus has some thirteen hundred times the brightness of the Sun, and in fact it's the brightest star within seven hundred light years of Earth. Its name originates in mythology from the time of the Trojan wars and the navigator for Menelaus. The King of Sparta, located between Canopus and the Southern Cross in Karna and the Trumpet sixteen open star cluster is the ticking time bomb that is at a Carena, a pair of huge blue stars undergoing the final violent phase of their existence for exploding its massive core collapse supernovae. The binary system is located some seven thousand, five hundred light years away and is buried in the great Nebula of Krena, a massive cloud of gas and dust stretching some six point five to ten thousand light years wide. The stars in et Acarina are classified as highly I loomined the spectrotype O blue hypergiants. The primary star is estimated to be around one hundred and fifty to two hundred times the mass of our Sun, with some five million times the Sun's luminosity, eight hundred times its radius, and a surface temperature of up to thirty two thousand, five hundred kelvin. The primary star in the binary pair is also the only known star to produce ultraviolet laser missions. The companion star, although smaller than the primary just eighty solar masses and twenty times the Sun's radius, is even hotter, with surface temperatures of around thirty seven thy two hundred kelvin. The two stars all but each other every five point five four earth years, ticuned in the gigantic, twin lobed cloud of gas and dust known as the homunculous Nebula, A bipolar emission and reflection Nebula, the primary star in this binary pair, has lost about thirty solar masses in recent times. Both at a Karina and its surrounding shroud of dust generate huge amounts of infrared radiation, making it the brightest infrared source in the sky. Ed Akarina experiences tremendous outbursts. During one event, it became almost as bright as the star serious known as the Greater eruption, it began in eighteen thirty seven and reached its peak in eighteen forty three, when it was one of the brightest objects in the night sky, for gradually fading away again by eighteen fifty six. At Acrena underweight another slightly smaller eruption in eighteen ninety two, and has again been steadily brightening since about nineteen forty. Both these stars are now nearing the end of their lives, and the main sequence and they're expected to go Supernerva in an astronomically short space of time. When they do go supernerva, Edicrina will be visible in the daylight skies even here on Earth. In fact, they could become brighter than the full moon for months on end. No one knows exactly when Edacrina will go super and Ova. A single star, a star originally around one hundred and fifty times as massive as the Sun, would typically reach core collapse as a will free it within about three million years. At low metallicity. Many massive stars will collapse directly to form stellar mass black holes with no visible explosion, or possibly a subluminous super and ova, and a small fraction will produce a parent stability super and ova, but its solar metallicity and above is expected to be sufficient mass loss before collapse to allow a visible Supernerva or peer Now. If there's still large amount of expelled material close to the star, the shock wave formed by the supernerva explosion impacting on the circumstellar material could effectively convert the kinetic energy into radiation, resulting in a superluminous supernova or hypererva several times more luminous than a typical core collapse supernerva, and much longer lasting highly massive progenitors may also eject sufficient nickel to cause a superluminous supernerva simply from the radioactive decay now the resulting rim that would then form a black hole. Since it's highly unlikely that such a massive star could ever lose enough mass from its core not to exceed the limit for a neutron star about two point three or two point four solar masses, but the existence of a massive companion star brings many of the possibilities into play. If etacrine array was rapidly stripped of its outer layers, it might become a less massive WC or WO type star. When core collapse is finally reached, this would result in a type one B or type one C supernova due to the lack of hydrogen sibly helium, and these supernovae are thought to be possible progenitors for some types of gamma ray bursts. Now, a typical core collapse Supernerva at the distance of Etycarina would look as bright as the planet Venus, the third brightest object in the sky after the Sun and Moon. On the other hand, a super iluminous supernova could be five magnitudes brighter, possibly the brightest super and ov and recorded history, but I'm pleased to say that based on our current data, Eticrena is not expected to produce a gamma ray burst, and its axis isn't currently aimed anywhere ney of the Earth, and at seven five hundred light years away, the star is unlikely to directly affect terrest your life forms on Earth thanks to our planet's atmosphere and magnetosphere, but the ozone layer of the planet could be damaged, as would orbiting spacecraft and any astronauts in space at the time. At least one papers projected that a complete loss of the ozone layer is a plausible consequence, and that would result in a significant increase in ultraviolet radiation reaching the planet's surface from the Sun. That would require a typical supernerva to be closer than fifty light years from Earth, and even a potential hypernerva, which still need to be closer than where Etekarina is now. Another analysis of the possible impact of supernova and Etykarina discusses more subtle effects from the unusual illumination, such as possible militaronin suppression resulting in insomnia and increased risk of cancer and depression. Okay, on that note, let's turn to the east and looking just above the horizon, is the star that outshines Canopus to take the title of the brightest star in the night sky, namely Serious the Dog Star. And next to it in the east northeastern skies, just above the horizon, it's the constellation of Orion the Hunter. There you'll see a very bright red star. It's a red super giant called bettle Girls. Better known to most people these days, it's beetlejuice. Don't say it three times in ancient times, before centuries of mispronunciation, its name actually started at It's ibdal Jauza. Bettlegirls is one of the largest and most luminous stars visible with the unaided eye. Located some four hundred and thirty light years away, this splurted old red giant is reaching the end of its life. It's truly massive, some eleven hundred times the diameter and one hundred thousand times the brightness of our sun. Like at a Carina, Bettlegirs is destined to explode as a core collapse super and ova sometime in the near future. Bettlegirls marks the right shoulder of Orion the Hunter. Although it's all upside down from our perspective here in the Southern hemisphere. That's because Orion was a hunter in Greek mythology, so the constellation was viewed from the northern hemisphere. The earliest known depiction of the Orian constellation was on a prehistoric mammoth ivory carving found in a cave in the Arch Valley in West Germany. That was in nineteen seventy nine. Archaeologists estimate that it had been fashioned between thirty two thousand and thirty eight thousand years ago. The distinctive pattern of Orion has been recognized in numerous cultures around the world, including the ancient Babylonian star catalogs dating back to the Late Bronze Age. In Greek mythology, Orion was a gigantic, supernaturally strong hundred of ancient times. He was the son of a Gorgon and Poseidon, also known as Neptune, the god of the Sea in the Greco Roman tradition. But the goddess guy became angry at ouran after he boasted that he would kill every animal on earth, so she sent a Scorpion to sting Orion to death. However, O Fayshus, the Serpent Bearer, revived Oryan with an antidote, and this is given to me the reason why the constellation Scorpius chases a Rhyin across the sky, with a constellation Opytius standing midway between them. The other major stars in Orian include Rigel Orion's left foot, a blue super giant. Having exhausted its core hydrogen, Rigel has swollen out between seventy nine and one hundred and fifteen times the Sun's radius. It's currently fusing heavier and heavy elements at its core, meaning it too will soon likely go super and over and collapse to form a neutron star. Rigel's estimated to be somewhere between one hundred and twenty two hundred and seventy nine thousand times the luminosity of the Sun. It's a binary system located eight hundred and sixty light years away, and it has a companion start raichi'll B, some five hundred times fainter than the super giant rageal A and visible only through a telescope. Rochill B itself is a spectroscopic binary system comprising two main sequence blue white stars. Spectroscopic binaries are double star systems orbiting each other in such a way they can only be visually separated from our vantage point here on Earth by their different spectroscopic signatures. The two stars making up right Will B are estimated to have three point nine and two point nine times the mass of the Sun, respectively, and one of these stars, Rajil b B, may itself also be a binary system. Rachel B also appears to have a very close visual companion of Radial C, almost identical in appearance. The third brightest star in Oriyan is Bellatrix, Orion's left shoulder. It's a spectrotype B main sequence blue star with about eight point six times the mass and six times the radiest of the Sun. Bellatrix is about two hundred and fifty light years away. It has an estimated age of about twenty five million years. That's old enough for a star of this mass to start consuming hydrogen in its core and begin to evolve away from the main sequence and turn into a blue giant. Now, if you look at the three stars which make up Orian's built, you'll see another three stars which make up Orion's sword, hanging from the belt, and again that's hanging upwards for those of the southern hemisphere. And if you look carefully at the middle star, you'll notice it's a bit fuzzy looking. That's because it's not a star, but the great nebula of Orian Messia forty two okay to just one three hundred and forty four light years away. Messia forty two is the nearest massive star forming region to Earth. Its nebula is estimated to be some twenty four light years across, and it has the mass of more than two thousand suns. The Orion nebula is one of the most scrutiniz photographed objects in the night sky, and it's among the most intensely studied celestial features. The nebula has revealed much about the process of house stars and planetary systems are formed from collapsing molecular gas and dust clouds. By studying M forty two, astronomers have directly observed protoplanetary discs, round dwarfs, intense and turbulent motions of gas, and the photoionizing effects of massive nearby stars in the nebula. The Orian nebula contains a very young open cluster known as the Trapezium due to the asterism of its four primary stars. Now the Trapezium itself is a component of the much larger Orian nebula cluster and association of about two thy eight hundred stars, all within a diameter of just twenty light years. One of the most stunning nebula in the constellation Orian is the spectacular Horsehead nebula Barnard thirty three. The horse Seat is a dark nebula located just to the south of the star Almattack, which is the furthest east on Orion's built, and it is part of the much low Arin molecular cloud complex located around fifteen hundred light years away. The horse said nebula was first recorded in eighteen eighty eight. It's one of the most identifiable nebulas in astronomy. That's because of the shape of its swirling clouds of dark dust and gases, which bear an amazing resemblance to a horse's head when viewed from Earth. One of the astronomical highlights of the December night skies is the annual Geminids meteor shower, which usually peaks around December thirteenth and fourteenth, radiating out from the direction of the constellation Gemini. The Geminids are unusual in that they're not generated by a comet, as most other meteor showers are, but are produced by the debris trail left behind by the asteroid thirty two hundred Phaeton. That makes the Geminids, together with the Quadrantids, the only major meteor showers not originating from a comet. Thirty two hundred Phaeton is highly unusual. Its high orbital eccentricity more closely resembles that of a comet than an asteroid, and in fact, it's speculated that it may be an asteroid that's simply run out of all the volatile gases that normally characterize a comet. Paton's orbit crosses all the inner terrestrial planets Mercury, Venus, Earth, and Mars, and because it does come relatively close to the Earth, this five kilometer white space rock is classified as potentially hazardous. Theton will make its closest approach to Earth on December fourteenth, twenty ninety three, but at that time it will still pass a relatively comfortable too million, nine hun and sixty thousand kilometers away from our planet. Interestingly, Paton's named after the son of the Greek sun gog Helius. Legend has it a Phaton almost destroyed the Earth by stealing Helios's chariot, scorching the Earth with the Sun, almost causing the apocalypse. Paton approaches the Sun closer than any other named asteroid, with a perihelium of less than twenty one million kilometers that's less than half of Mercury's perihelium distance. Coming so close to the Sun causes the asteroid's surface to reach over seven and fifty degrees celsius. Observations by asy stereo spacecraft or dust trails radiating off its surface, and in twenty ten, Phaton was detected actually ejecting dust into space. Astronomers think the intense heat generated by its close approaches to the Sun causes fractures in the gravel and rocks on the asteroid's surface, similar to mudcracks in the dry lake bed, and Paton's composition also fits the notion of a cometary origin. It's classified as a type B asteroid because it's composed of primarily dark material. Type B asteroids are thought to be primitive, volatile rich elements of the early Solar System. Its composition, orbit and dust trail have led astronomers to refer to Phaton as a rock comet. The geminids meteors have a yellowish hue, and they tend to be a bit larger and more solid than typical meteors from comets. Think of grains and rocks rather than dust particles. They also move more slowly, traveling at about thirty five kilometres per second, compared to some cometary meteor showers, which travel it speeds up to seventy two kilometas a second. And interestingly, the Geminids are also thought to be intensifying every year, with recent showers seeing up one hundred and sixty meteors per hour under optimal conditions. In the northern hemisphere, expect to see up to one hundred and twenty meteors per hour between midnight and four am, but only from a dark sky well north of the equator. The radiant rises about sunset, reaching a usable elevation from local evening hours onwards. In the southern hemisphere, the Geminids aren't nearly as spectacular. You won't see as many, perhaps just ten to twenty an hour. That's because the radiant doesn't rise above the horizon at all. Now for listeners in the northern hemisphere, there's a second meteor shower in December, the ersiods, which radiate out from the direction of URSA minor the Little Dipper. The erciods are generated by debris left behind by the comet eight peet tuttle. They are compact stream peaking during the night of December the twenty second, in the early morning hours of December the twenty third, if you look towards the ball of the Little Dipper you might see about ten meteors an hour. And now with the rest of the day Summer night skies were joined by Senior Science Right Jonathan Nalley. Stuart Well, this time I thought we'd start off with the moon actually and the effect that it has on stargaging, because to people who aren't astronomers, either amateur or professional, the moon is lovely. You know, it's up there, it looks very pretty, It looks lovely, and it helps us see in the dark at night time. The Moon's great, isn't it. Well not if you're an astronomer, or most astronomers, at least some amateur astronomers. They love the moon. They they look through the jallow strepe of the moon that the pictures of the moon. They study the moon. Some professional astronomers do the same, but I think it's fair to say that the majority of astronomers don't. And the majority of astronomers really don't like the moon. And I'll explain why, because the moon is just amusance to most astronomers, because the moonlight gets scattered in our atmosphere and it makes the night sky appear to be a dark gray instead of black. You probably noticed yourself. You go out in the night where there's a full moon, you don't see as many stars. But when there's no moon up, the sky's much darker and you can take quite a few more starts. That's because of this moonlight has been scout. You know, it was scattered in their atmosphere, and that makes the sky glow a little bit in the sense, and so that means it becomes impossible to see the faintest stars, and it makes it very hard to see what problem is called beach sky objects such as galaxy and things which you need. It's all stir to see. But with the sky sort of faintly glowing a little bit, that ruins the contrast Normally you'd have stars and galaxies and means on a pitch background. But when your sky is glowing on a little bit, it's not pitch black anymore. And if looking at something that is really faint and gray to start with, which is a galaxy, then that really makes it a lot harder. So that's why the best stargazing is done when the moon is below the horizon. So very often anamateur astronomer will delay their viewing for a few hours at night time till the moon's bye down, because you get a much much nicer view. And you will get a good idea of this if you look at a star map, any star map, and you think, oh, look at what the stars I can see out there in the night sky. Then you go outside and it's a full moon and you you can't see hardly any cult. And if you have to live in a big city as well, and you've got the additional problem of white pollution nearby, then you might not even be able to see some of the brightest stars. You know, you might only be able to pick out six or seven bright stars. So anyway, the moon's not a favorite of many astronomers. And the reason I mentioned it is that this month we start off with the moon. It's a little bit more than half full, and it's nice and high in the sky. It's just when it begins, so you don't see quite as many stars and things as you as you do at other times of the night on other days. And just because the moon's around the beginning of December, give it a few days and it will have disappeared because the moon moves each night, moves because it goes around the Earth out once every four weeks roughly, So what is it fifteen degrees or suddenly it moves each night, So give it a few nights and it will have moved out of the way and see the low horizon. So yeah, so a beginning of this month you've got the moon up a little bit, so it's see a few things are drowned out and it's glare. That's the price we have paid for having a nice, big, close natural satellite. Anyway, what can we see well for a start this time of the year, we can see the too brighter stars, It definitely can see those. That's serious and Cannopous serious is quite low down in the east as darkness falls, and chinopis also is low down, but it's more to the southeast. Much higher in the southeast, we've got a bright star called Akana. Now, this is the star that marks the southernmost point of a constellation most people have never heard of. It's called Erdanus, which means the river. It's a big, long, winding, thin constellation starts up near the celesti of equator and the wander's way down towards the sort of far southern sky. Acina has an interesting star. It's sort of bluish color, and scientists have found that it is spinning so fast that it's actually flattened itself into an elliptical shape. It's much wider at its equator than it is measured from pole to pole, and it is in fact the least rounded star, least spherical star that we know of so far in the entire multiagality, because it's spinning because stars you think of a star as being. It's made of plasma y gas, which can think of things a spinning ball of liquid, and it just sort of spins out at the equator and flattens down at the poles. Yes, Acina is really interesting. It's the least rounded star we know of now above the eastern horizon looks more to the north, we find serious and go a little bit to the Norse. They go to the left. There's the constellation of Orion, which has risen up over the horizon, bringing with it it's two brighter stars. It's got ry Gel and Beetle Juice, two very famous stars. And you can always easily picked up the constellation far and even when it's down low and there's other things in the way, because it has three stars in a straight line right through the middle logs. They are the stars in the belt of the clothes that Orion the Hunter is wearing, the Iron constellation of the Hunter, and right through the middle is belt. Now, if you're looking for the Southern Cross at the moment, it's upside down, and it's way down on the southern horizon. In fact, depending on the latitude of where you're viewing from, it might even be below the horizon. It will be quite a few people in fact, so you might not be able to see it at all. And if that's the case for you, you're going to have to wait until the early morning hours. After midnight. Then as the Earth is rotated a bit, the Southern Cross will have risen higher in the sky. If you're not keen on on the waves up after midnight, you're gonna have to wait a few months. In fact, time to see the Southern Cross is middle of the year, March through August, when it's up nights at high during the evening out of Sunder's Seat now low down on the northeastern part of the sky are two star clusters that we speak about quite often on the show, and these ones are really worth seeking out. One is quite large and one is quite small. The large one is called the Hyats and it's part of the Constellation of Chorus. The Hyades looks like a sort of a wedge or triangle shaped group of stars, quite spread out, but in the definite triangle sort of shape, and there's an unrelated but much brighter red star called Alzebraon in one corner of this triangle. Aldeboron is the brighter star in the Constellation of Chorus. The other cluster is a bit more to the north and it's smaller, and it's called the Clear Things or the Seven Sisters. We've spoken about this from many times on the show, and despite the name Seven Sisters, most people can actually only make out about six. And again it depends on light pollution and when the moon's up and all that sort of thing, and how good your eyes are and over the real glasses like I do. That's sort of it. And yeah, even though you can see about six of the stars, the crust actually has about a thousand members in it. It's quite a big star cluster, but most of them are very faint. You know, with a pair of an oculars you'll see more. The telescope you see more. Again, but even so, you know, like long exposure photographs will reveal up there about a thousand stars. But don't worry about they Just get a pair of an ocular or a small telescope under this custer and your thank yourself for doing so, because it is really, really pretty. It's just the most glorious little cluster of bright, sparkly stars. And if there's a bit of upper atmospheric wind, which is what makes the stars twinkle, be got just a little bit of twinkle with the clear these it just looks like a little bunch of jewels hanging in the sky. It's really lovely. They've just done some new studies of the play it is and they've discovered that it's actually part of a much larger open star cluster about three times is big. There are two other sections to it, and they now call it the play is complex because it's so huge. Still haven't worked out exactly how far away it is from us. There's always been some discrepancy there that's still there. But they now know by looking at other stars in the area, and they're all part of the same open star cluster. They didn't know until just this month go. So they're learning new things all the time. And this is why you need, you know, you cat to fly on the naked eye, And that's why astronomers have big geloscopes. And what to say about, you know, not knowing the distance of things. That really is remarkable how even in the SPA and age there are other stars and clusters and galaxies whatever, we don't really know the distance, you know. It's funny that we can know pretty accurately, at least in terms of red shift how far away millions and millions of galaxies are, but even things just fairly nearby within our own galaxy, it can be quite hard to pin down the distance. There are various different techniques that astronomers can use to measure distances, and some are really good at getting accurate distances if something's quite close, and there are pretty good techniques like red shift for measuring how far away something is if it's a long long way away, but sometimes in the middle area it's a bit harder to pin down exactly half far things are. So in terms of the planet and can we see, well, the only planet that's up at the moment in the early evening is Saturn, but that's okay. Saturn is really good to look at, you know what, it's rings and everything. It's fairly bright sat and at the moment, and it has a yellowish tinge which does make it stand out. Next planet up is Jupiter. It's not above the horizon as evening falls. You've got to wait until about eleven PM at the beginning of December for it to rise over the northeast horizon. But each night it'll be rising a little bit earlier, so by the end of the month it will be only nine pm when it's coming up over the horizon. So that makes it a bit easier for people to get out and have a look. Now, and how to find it? What if you look for that constellation a ry and I mentioned earlier, and you've got the when if it sparks called beetle Juice. If you just look between Beetle Juice and the horizon just sort of straight down, Jupiter is right there between veal Juice and their horizons, which can't be Jupiter. It's really big and bright. Mercury, little planet Mercury in the most planet. It's visible only in the half hour or so before sunrise this month, but it will be extremely hard to spot because it's going to be right in the middle of the sort of door glow before the sun has risen, but its sky is getting light. So Mercury is a tiny little dot of light to begin with, so with the bright sky behind it, bright orange sky with the sunrise, probably won't be able to spot it. And unfortunately, the other two main tennants that we normally look at, Venus and Mars, they're also lots in the glare of the morning and the evening twilight, respectively, all months. So we're going to have to waste a good two or three months before they come back on the scene again. And that's Stewart is the sky for them. That's Senior science writer Jonathan Nally and this is Spacetime and that's the show for now. 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