What if Planet 9 was a primordial black hole? Could we detect it? | Night Sky News October 2019

[Music] hello everybody and welcome back to this month's night sky news where we go through everything that's gonna be visible in the night sky this coming month and everything that's happened in space news in the past month every single paper a journal article that I mentioned will be linked in the description down below for you and I've also put timestamps for those of you that just really want to skip ahead and hear about Planet 9 being a primordial black hole possibly maybe anyway before we get to that let's start by looking up the first thing I want to talk about this month is that mercury is going into retrograde on the 31st of October what that means is that it's going to appear night by night as if mercury is going backwards in the sky compared to all of the background stars that rise in the east and set in the West mercury will appear to get more eastward as the nights go on now that's all to do with our perspective from it it's the fact that mercury orbits our Sun about 4 times faster than the earth does and so it overtaking us as it goes round in its circular orbit so if you imagine that you're driving a pretty slow car around a racecar track and a really fast car comes zooming past you goes round to the other side from your perspective in a slow car it looks as if the fast car on the other side of the track is going in the opposite direction to you when in reality it's just going around the track in a circle and it's the same sort of thing that we see on earth when we observe mercury in the sky problem is thousands of years ago in the pre light pollution era and pre Netflix days people look to the sky of entertainment and things to do in the evening and so they would notice this much more than say you what I would notice this looking towards the east before sunrise to happen to notice every morning that mercury had changed position slightly not how we'd expect and so people attributed a lot of superstition to these times when mercury would go into retrograde and so modern day astrologers also continue this superstition linking mercury in retrograde with human events that are taking place on earth which we know is absolute because is mercury is an inanimate planet and it has been over seeing the Sun for four-and-a-half billion years and it doesn't care at all about human endeavors on earth but it's linked with like people losing their keys and we shouldn't make big decisions and the thing that I still can't quite believe is the a major publication in the UK actually ran a story on Mercury going into retrograde on the 31st of October which happens to be brexit deadline day and so they made this link between mercury going into retrograde and Briggs at deadline day saying it's going to be chaos because of mercury going into retrograde I mean Briggs it's probably going to be chaos anyway and it'll have nothing to do with Mercury inanimate planets do not care about our politics then into November an opportunity to do one of my favorite things in the sky which is use the moon to find cooler more difficult to find objects and so on the first the second of November the moon is gonna be right in between Jupiter and Saturn on the skies I mean one of these waxing crescent I eat it's a crescent moon that's getting bigger it's going towards a full moon and so on the first November it's gonna be closer to Jupiter and by the second November it will be closer to Saturn so if you have binoculars somewhere in the house break them out I know I say this every month I'm like a broken record but seriously if you haven't done it yet you must because there's so much that you can actually see by looking at Jupiter and Saturn we've also got a transit of the Sun by mercury coming up on the 11th of November as well that's gonna be something that you'll be able to observe anywhere in the world except sort of eastern Asia and Oceania you guys gonna miss out on that unfortunate it'll be night time for you when it occurs the rest of us though we should be able to see this if we have access to a solar telescope with a filter on it so it makes it safe to actually look at the Sun and observe mercury passing in front of it and if you thinking well that's no use cause clearly I don't own anything like that look up if your local astronomy Society does have something like that and perhaps even if they're putting on an event to observe the transit of mercury as well because I know a lot of them will be doing and they do amazing work in communities to make sure that people do have access to telescopes to see these kind events so a shout out 12 the local astronomy groups doing amazing work if you don't have access to a local astronomy society there will be some live streams of the event through NASA and ISA as well and then also all of the astrophotography images that will come online in the days following which I'm really looking forward to seeing ok on to my favorite part now the part where we discuss what's happened in space news in the past month first up the Nobel Prize for Physics in 2019 is it been announced and it went to astronomers it was jointly awarded with half going to Divya quello and Mikkel Mayo for their discovery of the very first exoplanet in 1995 and I made a video on that last week that went through the history of that entire field one of my decade by decade videos looking at how all the results sort of piled together to add to our understanding and the other half went to Jim Peebles for his contribution to the field of theoretical cosmology this was really sort of a lifetime achievement Nobel Prize award rather than the award that went to Cuellar a male which was more of a discovery prize Jim Peebles really made the field of cosmology doable essentially he came up with a lot of the theory that described the universe in its very early stages so first of all he explained what the signal was that Penzias and Wilson who won the Nobel Prize previously detected in the Cosmic Microwave Background he said that it had to be this afterglow of the Big Bang he came up with all of the theory describing what the universe would have been like in the very early stages after the Big Bang and then also said this is how we would observe this and how we would test if that was indeed true which a lot of people then went off to do and won Nobel prizes for it where where as Jim was the one that actually came up with the idea of how to do it in the first place and that's happened a number of times in his career so I'm really glad to see that the Nobel Prize Committee has actually awarded Jim the prize this year because I've heard he's also one of the nicest men in the world as well so I think the Astronomy community was very happy to hear this month that he had been acknowledged now one of my favorite news stories this month was about satin and you all know Saturn is my favorite planet hands down so it was very pleased to hear this result that they'd found 20 more moons around Saturn making its total number of moons that are known up to 82 pipping Jupiter to the post which has 79 moons these were all discovered using the Subaru telescope in Hawaii which had previously discovered 17 new moons of Jupiter last year and how they did that was take images of the surrounding regions of Jupiter and Saturn and just noticed night by night if anything had mu of course they also have to make sure that their survey is complete they make sure that every single night they're detecting down to a certain faintness which would give you a certain size object at that distance so for Jupiter it meant that they could actually detect everything down to about a mile across whereas for Saturn they could only detect things that were about three miles across so this is why it's actually likely that Saturn does indeed have more moons of Jupiter because we count in 79 around Jupiter that are at least a mile across whereas we counted at 82 and we've only got the things that are three miles across and up we haven't even got down to the mile across the level around Saturn just because it's much further away of these 20 new moons they found around Saturn though 17 are all grouped together they orbit around Saturn in a retrograde motion ie they orbit in the opposite direction to which Saturn rotates and they all have very very similar orbital parameters and so the authors of the paper that announced this discovery said it was probably that they were in the past one single moon and some sort of impact has actually broken that moon up into these 17 different fragments which might explain why Saturn ends up having more moons than Jupiter just like when they discovered the moons of Jupiter though they're asking people to suggest names for these new moons that have been found around Saturn I think you can name five of them and they're asking people to tweet their suggestions to at Saturn's lunacy and it will put that Tagg down in the description below so that I actually kept the spelling right and you could actually then be sent to the right place but obviously they're looking for you know serious and realistic suggestions for names that probably have some link to Saturn in Roman mythology and in Greek mythology as well so as much as I'd want to call a moon you know like moon emic Saturn face unless I can find some reference to that in Greek mythology we're probably not going to get that one past them the other big news this month was a really cool detection that has been made possible thanks to the music spectrograph on the VLT if you haven't heard of muse it's an amazing instrument and it's one that literally astronomers are currently clamoring over to use because it doesn't just take a single image or a single spectra of an object which is where we take the light from an object split it through a prism and and get it sort of fingerprint of all the different wavelengths it has in that object it can take many all at once over a huge area of sky also with a very very high resolution as well and so you can really probe a lot of detail in whatever object you're looking at and that was key for what's been done this month which is detect the filaments the gas in filaments that connects galaxies in the universe so when we put all the laws of physics into a computer and we start with you know just this like soup of hydrogen gas that would have been the early universe and we just sort of let it run over time with all the laws of physics just in there everything starts to clump together under gravity because all of a sudden you have like two particles that are clumped together and they become like the densest thing in the universe even there was just two clump together and then it sort of snowballs from there and the structure we end up getting out of these simulations is this weird web-like structure where you have these big nodes where there's a lot of stuff that are all connected by these long thin filaments and we think that the nodes that's where all the galaxies form and then these filaments are just the leftover hydrogen gas that can actually then feed into galaxies to give them more fuel to make stars now we've obviously observed galaxies before because well they're really really right because they're made of like hundreds of billions of stars they'd be pretty difficult to spot but the gas sort of bridges or filaments connecting them we've not really been able to observe to confirm that that is the actual structure of the universe because well you can't see a lot of gases can you like gas here right now can't see it so to actually detect this gas they had to go to one of the densest parts of the universe it was what's called a proto closer of galaxies so something that will eventually grow to be one of these huge clusters of galaxies we see today in the current universe but they observed it in the very early universe it's 12 billion light years away so the light that's being emitted from it that we're detecting now is coming from a universe that was under 2 billion years old and the thing is about this cluster is that the galaxies within it are forming a lot of stars because the universe was much denser back then so the star formation rate was much higher and also the rate at which supermassive black holes was being fed was much higher as well and that means the limit at which you can feed a black hole was reached very quickly and so a lot of that material never actually made it into the black hole and instead was shot out in these huge radiation jets so all of the radiation from the extra star formation and all of the radiation from the over feeding of black holes basically was shot out into this sort of intra cluster medium and hit into all of the gas there it excited a lot of the electrons in the gas to higher energy levels which when they dropped down would emit a very specific wavelength of light we call it the lyman-alpha line is very common wavelength of emission that we see from hydrogen all across the universe then using these filaments the gas isn't very dense and so the glow that we get from it is very very faint I worked out that it was something like a billion billion times fainter than Jupiter in the night sky that gets ridiculous but with muse by observing it for a very very long time in great great detail they were able to detect this lyman-alpha emission from hydrogen gas in the filaments acting the galaxies in this cluster and revealing the rogue of something like three billion light-years long and so really did permeate the structure of the universe at least in the early universe the assumption is obviously then there that because we see that structure in the early universe and simulations and it continues until our present-day universe that we must also have that structure now as well we've at least been able to prove that it is there in the early universe though and that is definitely a milestone in proving that it is here in our current universe still as well and now the result I think maybe what we're waiting for right this paper that came out this month by Jacob Schultz and James Irwin that was just titled is planet 9 a primordial black hole which probably wins in my book anyway like the award for the best title of any academic paper in 2019 just because it's like almost entitled like a YouTube video right that's trying to make you click on it and it was such an intriguing paper to read the idea that they've come up with here is very compelling it sounds like it's pulled out of science fiction but actually when you read through their arguments it does make sense so let's start at the beginning planet 9 you probably thinking wasn't Pluto Planet 9 and yeah we'd downgraded it unfortunately to a dwarf planet I talked about that in a previous video I'll link it up in a card when I figure out which one it was and for those who don't know the history the reason that people went searching for Pluto in the first place was because Neptune's orbit is a bit strange it's a lot more elliptical than the rest of the planets in the solar system and people didn't really understand why it would be so strange and the idea was raised that perhaps there was another planet beyond Neptune that it was interacting with that would be disturbing its orbit when they found Pluto they thought that that would be that planet of course there's more research was done on Pluto people realized that it was actually a lot smaller than they originally thought and so it wasn't actually large enough to perturb the orbit of Neptune as much as it was then of course the Kuiper belt and all of these what we call trans Newtonian objects T and O's were all discovered sort of a secondary asteroid belt right out on the far edge of the solar system and then people thought what perhaps the entire collective of all of those things is what's perturbing Neptune's orbit then they realize that also the orbits of the tno s these transmute o nyan objects were also very strange a lot of them clumped together as if they were being shepherded by some other much larger planet that was out there and so for a long time now this idea of a planet 9 has been discussed amongst solar system astrophysicists there's been a lot of in-depth searches done for it including one of the Zooniverse citizen science projects as well but got people to rule out a big swath of space that planet 9 current couldn't me be obviously what makes the search difficult is that this planet is probably going to be at something like 500 times the earth-sun distance it would have an incredibly long orbital period and so it's not expected to move that much in the sky so it makes it very difficult to spot it but what the shots and Unwin paper from this month did which I thought was very interesting was linked that problem that people are working on with another unexplained problem which is that a survey that's looking for gravitational lens objects it's called the ogle survey OGL II has found some unexplained gravitational lenses that they can't account for their brief brightening in sort of the direction of the Galactic bulge in the southern hemisphere that when they calculate well how big is the mass of the object that we think is causing this lensing it's about 0.5 times the mass of the earth - about 20 times the mass of the earth that's the range that they're sort of working with and it's very similar to the range that people have estimated that planet Nine's mass would be to have this effect on these trans-neptunian objects I think that range is something like 5 to 15 times the mass of Earth and so they've said perhaps both of these problems can be explained if planet 9 isn't actually a planet a rocky planet that's you know five times the mass of Earth but instead is a black hole that's causing these brief micro lensing events the algo survey is also picking up and when they say primordial black hole what they mean there is a black hole that wasn't formed you know from a star living its life dying going supernova and producing a black hole they mean a black hole that was produced in the very early days of the solar system okay I clearly meant to say universe they're a not solar system a primordial black hole is one that is formed in the early universe and it would be incredibly small in comparison to what we think of a black hole if it was five times the mass of the earth it would be something like five centimeters across which is about the diameter of this plant pop like this would be the size of the black hole that could be in the solar system five hundred times the distance from the earth to the Sun right now now it might sound a little bit far-fetched but when people consider well how did this sort of Planet 9 you know form and get out there in the first place there's three different options the first is that it formed in situ formed out 500 times the distance of the Earth and the Sun in the outer solar system from whatever you know rubble and remnants from the formation of the Sun were there the second is that it formed may be round near Uranus and Neptune and actually migrated outwards to where it is now and the third is that it is a captured free-floating planet which sounds far-fetched but actually is people start stimulate more planetary formation models they find that actually a lot of planetesimals as we call them the things before they actually reach sort of planet status do get flung out in that process so it wouldn't be unlikely that a planet that had been flung out from around another star could actually be captured by the gravity of the Sun and end up orbiting very very far out and that's actually the most favored of all of those three options at the minute because there's problems with the first two the first one where you fall out in sissu is that it's not very dense out there and so they're physically isn't enough time for that very undead's matter to clump together to form something that's 5 to 15 times the mass of the earth in the four and a half billion years that the Sun and the solar system has been around for the second option where you form something in the denser regions towards Uranus and Neptune then it migrates out is also problematic because you need an event that first of all kicks the planet to go further out but then also stops it in its current orbit as well so you'd probably need for the Sun to have had some sort of close flyby with another star at some point in its history and there's no other evidence for that having happened in the other objects in the solar system as well so the most favored formation mechanism for planet 9 is a captured free-floating planet and the authors pointed out that actually the probability of that happening is no different from the probability of capturing a primordial black hole either obviously the problem with planet 9 turning out to be a primordial black hole would be that all of these specific searches for Planet 9 in the optical and infrared pointless because you'd never be able to see a black hole with that kind of radiation what the authors suggest though is a way that we could confirm if it was a black hole that was out there so the black hole orbiting the solar system would have actually collected a halo of matter around it and then also a halo of dark matter as well we think there's sort of two protons worth of dark matter in every teaspoon of space in the solar system and it would have accreted a lot of that matter towards it it wouldn't have actually necessarily accreted it to make itself grow in mass but it would have this big large halo of mass sort of that it's shepherding around along its orbit and if the dark matter in that halo was to what we say annihilate with some anti dark matter so we have matter and we have antimatter which we have a lot more matter in the universe than we do have antimatter but it's there in traces and when the two come together they do annihilate they essentially turn pure mass into energy by Einsteins E cause MC squared and so if that were to happen we should be able to detect that radiation with the gamma and x-ray telescopes that we currently have in orbit around Earth combining those detection x' with the ogle microlensing and the known orbits will the trans-neptunian objects what allow us to build a model of whether it really was a primordial black hole what we were seeing and how massive that primordial black hole would have to be so it's a really interesting idea one that at first glance I thought would be completely theoretical but after reading the paper and seeing that actually they gave a way that we could actually observational II constrain this as well I am so invested in this idea now because you know that black holes are my favorite and if it turns out the solar system has its own like kept black hole oh that would just make my entire year alright I think that was a very exciting note sky news for this month there was everything in there my favorite planet my favorite object in black holes so I hope that you also enjoyed it as well I wish you all happy stargazing and some clear skies you can't see this right now but behind the camera is all of our clothes in just just piles and piles of suitcases and they've been like that for about a month since we moved in because we haven't had any wardrobes and today is finally the day that we're gonna get wardrobes I am waiting on an immanent IKEA delivery and I have never been more excited to build flat-pack furniture in my life I don't know one tell me I had lipstick on my teeth these were all discovered using the Subaru telescope coupe oh I just had the best thought muse should cover their song supermassive black hole but for primordial black hole for Planet nine like if they ever actually detect it that would be incredible oh my universe if anybody knows any of the members of muse send them this clip and tell them dr. Becky has asked has begged for them to cover that song because that would just make why wouldn't you make my year would make my entire life let's put it that way you

Channel: Dr. Becky

Views: 78,082

Rating: 4.9245477 out of 5

Keywords: space, astronomy, dr becky, astrophysics, mercury transit, mercury retrograde, moon, jupiter, saturn, nobel prize, exoplanets, cosmology, saturn moons, lyman alpha, cosmic web, planet nine, planet 9, pluto, neptune, trans neptunian object, TNO, solar system, orbits, gravity, primordial black hole, black hole, dark matter, astronomer, astrophysicist

Id: AplFPtHY09E

Length: 24min 27sec (1467 seconds)

Published: Wed Oct 23 2019