Let's Find Out - The Basics of Astronomy | ASMR

Episode Date: July 17, 2019

•How did we know the distance to the Moon before we could bounce lasers off it? •What breakthrough gave scientists access to which elements stars are made of just from their light? •What clues did Edwin Hubble use to discover our universe isn't thousands, but millions, of light-years across and we are in fact drifting in an island of billions of stars which itself is only one among billions of other galaxies? Astronomy has unlocked much of the cosmos. Let's find out the basic discoveries, epiphanies, and deductions that will help us average folk understand the Universe more deeply. Thanks for watching. #Astronomy #ASMR #space ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬ ►socials... The podcast (audio versions) of my content: ▸🎧 Spotify: https://spoti.fi/2u11T58 ▸🎧 iTunes: https://itunes.apple.com/us/podcast/letsfindoutasmrs-podcast/id1448116527?mt=2 ▸📧 Email................... [e-mail] ▸📧 Instagram........... @lets_find_out_asmr ▸📧 Twitter................. @Glycoversi ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬ ►Support for the channel... ▸Shop on Amazon here: https://amzn.to/2LnNXd6 ▸PayPal ......... https://www.paypal.me/LetsFindOutASMR ......... [e-mail] ▸Patreon ........ https://www.patreon.com/LetsFindOutASMR Want to just give a gift? ▸📩 Wishlist (for the channel): http://a.co/9vUJ8eF ▸📪 If you'd like to mail me something: Let's Find Out ASMR (Rich) P.O. Box 1582 Palm City, FL 34991 Or do you transact in nerd? ▸₿ Bitcoin: (A scannable QR code) ........ http://i.imgur.com/wKIsPIB.png (wallet address) ........ 1XPhPoyeqc3Xf1uktCPXCzfdEdi9PA7Xh

guys, bringing it to you old school, holding the microphone, because it feels good. But what's really going on is that it's July of the year 2019. And although there's no hoverboards yet, we can at least reminisce and saturate ourselves in nostalgia for the moon landings, which happened exactly this month, 50 years ago. And no, I'm not a moon landing denier. I believe in science. And that's why I trust that this book is an authority and therefore I can be the deliverer, the messenger if you will, call me Mercury of the frontier, our final frontier, at least one of them because the mind I think is arguably a more important frontier, more significant for us and least frontier to delve into. That's why I like psychology and history

and philosophy. But aside from that, I really, really have a passion for some of the more interesting, awe-inspiring information that we know currently. And it taps into our deepest desires to just explore and dive into the great unknown. So let's honor the great explorers of the... intellect. One second. That guy, he deserves every bit of the recognition that he gets and that his name, the fact that his name has been synonymous with genius. I genuinely do appreciate that guy. I revere him and his intellect and the thousands of other men and women like him who have added to

our total, some total of human knowledge about the world in the past and, um, putting us to drive relentlessly into the future to hopefully amount to something better than the current state of humanity that we have. So what I are so is I think for anybody to be truly raptured by the enormity of things that we do know, the universe is ridiculously complex as is you know our minds but it's amazing it's truly inspiring to know how much we've been able to get clued in to the inner workings of the universe so for me to understand for me to appreciate exactly what geniuses like this guy really went through it's useful to get a general knowledge of of what what it takes and what's behind and the methods and the seriousness with which we try to sincerely probe the natural laws of

the universe it's not just you know it's uh i guess in a way i just want to show appreciation for the actual the rigor that it takes to be a scientist and the patients and the observations and the scrutiny that, you know, men today are still getting men and women, as well as men like Galileo, you know, and people who are generally on. Now further ado, let's get into a little part of a series, increasingly astronomy-based, that I'm going to be doing in the next couple months. I'm going to be talking about the Apollo program.

the M87 black hole, and yeah just more astronomy in general. So I hope you guys like it. Let's dive into the heavens. Essentially what we know, what we can predict, and the right is speculations about alien life, phenomena that we expect maybe, such as, you know, wormholes in hyperspace. Everyday objects like that.

Stepping stones, and I like this opening statement, this opening statement, it really puts into perspective, sets us up to learn the background of what astronomers currently are extremely, extremely confident in how they've figured out. They're their current toolkit for exploring the universe. It says, the travelers in the Star Trek universe boldly go where no one has gone before to explore the final frontier space. No human has yet visited any object outside our solar system, but that's not stopped us from exploring new worlds,

at long range using telescopes on the surface of the Earth and from satellites orbiting in our atmosphere. The data from these observations are then compared with what we can infer about stars and galaxies and other phenomena. in the cosmos from laws of physics in astronomy theory and observation always go hand in hand a theory about stars is useless without observations to test the predictions of the theory okay and observations of a new of a startling new phenomenon remain they're going to remain a mystery until they can be understood from

within the whole framework in physics and mathematics already. Together the theory and the observation can take us on a journey to the furthest reaches of the universe and back in time to when the universe was formed. It makes a point saying that standard of success in experiment and science in general is a coalescence of observation and theory. The observation doesn't fit the theory. We have to readjust the theory. The theory doesn't define the observation.

Again, it's wrong. It needs to be readjusted because, or the observation just needs to be reinterpreted, maybe. Making maps of space. Astronomers, they're interested in the evolution of stars and galaxies and how they're born and how they change over time and eventually die. some of them to anthropomorphize it and in the tracing and tracing the origin and ultimately the fate of the entire universe putting this type of knowledge together knowledge of the distances between cosmic objects it enables astronomers to achieve an understanding of their domain and in more accurately map out within what territory they're actually working By studying the light emitted by stars and galaxies, astronomers are able to find what kinds of different objects exist in parts of the universe. But they also need to measure the distances to the cosmic objects, so they know where they are in relation to one another.

How can the distances to the stars and galaxies even that we have no hope of ever visiting, even with an on-man space space? be measured. It sounds like an impossible task. But astronomers, being the optimists that they are, having faith in persistent adherence to what is true from observed fact and what is logical from mathematical equations, they found that stepping stones they've taken have effectively helped them to understand and continually understand the ever unfolding this part of here. It's all done with triangles. It goes back in the history and lets us know that that ninth grade geometry course you took is actually the fundamental or one of the huge cornerstones of our understanding of the universe,

let alone electronics and all technologies that we have. It's why the bridges you go over rarely, if ever, collapse. It's why the buildings are meant to sway, to absorb impacts, to withstand some earthquakes, perhaps. As the Chinese proverb says, the longest journey begins with a single step. Geographical exploration of the universe, of course, starts with a simple piece of geometry involving triangles. the first step into the universe uses exactly the same kind of surveying techniques used here on earth to measure the distances to distant objects such as mountains without actually having to go up there that's how we were able to actually measure the elevation of say Mount Everest because

it's not like we can drill go up to the summit and drill a hole vertically down just drop a measuring tape to see how high it is, we actually measure it by triangulating it. And we'll explore what that is right now. So the idea itself isn't new, it's, but with the aid of new instruments here on Earth and in satellites orbiting the Earth, it reaches further than ever before. It all depends on the geometry of triangles. If you know, as we are studying Pythagorean theorem, the right triangles, the length of one side of a triangle, the base, say, if you know that length, and you can measure the angle of each of the other two sides, it's a simple matter to calculate how far it is from the base of the triangle, the opposite tip process is called triangulation.

The troubled triangulation is that you need a longer baseline to measure the distances to more distant objects. So here with a mountain, I can observe a peak of the distance from here to this guy over here. And I'm sorry for those of you just listening, but just picture two humans on a flat ground at the base of a mountain, different, you know, maybe a mile or two apart, both looking at the same peak. These humans, as long as one defines his perspective, as I will say the adjacent side. And then this guy, mile away, defines his perspective as the hypotenuse. At least these guys are going to be able to know that. See, they're going to be able to know the two angles and the distance here.

And that's going to give them the distance from this guy to the mountain and this guy to the mountain summit as well. How are they going to measure the angles, though? As far as doing that, I believe it's, you can visually, you can visually determine those angles. So once you do, it's just a simple matter of applying the known distance and the known angles right here. And of course, the third angle is out too. It's the whole experiment is set up so that the third angle here is a right triangle at 90 degrees. You just use your trig functions.

trade functions and you can figure out the distance. Third point, observers are... Triangulation is not restricted to measuring distances on Earth. It works very well for measuring the distance to our nearest neighbor in space. One observer has his friend go all the way over maybe 20 miles away. A significant distance where the moon is no longer directly overhead of the second guy. What's going to happen is that the guy standing directly under the moon when the moon is at the zenith in the sky. His angle with relationship to the second guy is going to form a right triangle.

Then that means the other guy is going to be over here at more of an acute angle. So then it's easy work to figure out the distance of the moon, about 384,000 kilometers. The geometry of triangles. Actually, the phenomena that in a different part of the sky to the two observers measuring it is called what we call parallax. It's the same thing as if you camera there for you guys watching. You can see the book, the text on the book, move as I move the camera back and forth, even though I'm keeping my finger, holding my finger out.

For those of you just listening. listening. It's the same thing you guys do. You can undo if we, you see the moon out and you can actually hide it behind the tip of your thumb. Do it right there. And if you close one eye and switch back and forth between the eyes, parallax is what we call that phenomenon, where the background object, the moon or the text of this book, appears to shift. But that's really just because you're shifting your perspective with each eye and that's actually a huge a really significant tool that astronomers use especially you know before advanced technologies were invented to measure distances to the planets and the Sun and

other cosmic interact with the things that we we use as a fixed just for the purposes of measuring the moon, we use the stars as a fixed background so that we can see if we travel 100 miles on Earth and then look at the moon in both situations. What actually happens is that this guy, he's going to see these stars back here, and this guy is going to see these stars, a different set of stars behind the moon. and we all, and the stars are a fairly constant phenomenon, so we know we can use those as a standard against which to measure the distance.

Bring the using parallax to measure things beyond the moon, which is most things in the universe for us. It works, at least for objects in our solar system, but we have to go to opposite ends. of the earth. So not just, you know, 10 or 50 miles away, but thousands of miles away to form a long enough base triangle, make the measurement possible. Just to give you guys an idea on the earth, further away from us than the moon is. Our triangle, if it's the same baseline, it's going to be really, really, really thin. So what we have to do is try our best to create a

as big a baseline as possible. Make this one the right triangle. So we know that angle and we know the distance between here to here because we know the diameter of the earth. We know this angle. Well yeah, we know both angles, really.

So then we can figure out the distance X and Y. So it's just pretty amazing how powerful and of course how powerful they are. And of course, once we had the technology to send satellites in orbit, then we have the ability to increase, you know, if we have two satellites or even one satellite orbiting the Earth. We have the ability to increase that baseline and start measuring things much further away. And actually, you know, something interesting

that astronomers figured out pretty early on is that we can measure stars. by waiting until the orbit of the actual Earth around the Sun is on the opposite side is halfway complete So measurements taken 180 days apart actually makes a huge makes a baseline of you know 180 million miles which is a lot bigger than whatever the diameter of the earth is 1,000 miles or something so you can imagine the object could be much, much, much further away using that method. Parallax of Mars was determined accurately in 1671, almost 350 years ago. That's amazing.

100 years before, French astronomer Jean Rischet expedition to French Guyana, South America, to measure the position of Mars against the background of stars. At a certain time on the appointed night, where several months, nights to account for the weather. On the same nights and at the same times back in Paris, the Italian-born astronomer in Giovanni Cassini, which are many of you history astronomy buffs rather, are familiar with the name Cassini. Also, we have observations of the position of Mars against the background of the stars. So when Ryshe's expedition returned, they collaborated and were able to calculate the distance. These measurements were

were particularly important because they made it possible to work out the geography of the entire solar system. The cause of which described the motion of the planets around the sun were described early in the 17th century by Johannes Kepler and explained by Isaac Newton with his theory of gravity. They state that if planet A is twice as far from the sun as planet B, then the orbital period of planet A, the time it takes to orbit, one orbit, is a certain multiple of the orbital period of planetary relativity, it doesn't deviate. So astronomers thus had to measure at least one planetary distance directly in order to put real numbers into the equations, even though they already knew the orbital periods of, for the planets. by measuring the distance or first sizes of galaxies that could even use triangulation to estimate the distances between them from how small the galaxies looked on the sky.

Bring the distance to just... They were able to calculate the distance from the sun to each of these. They knew these distances, they were able to use Kepler's laws to calculate the distance from the sun to all the other planets. so including the earth in addition they could use newton's laws to calculate what the mass of the sun must be to hold the planet observed orbits by the end of the 17th century astronomers were able to calculate the distance from the earth

to the sun fairly accurately the observations have been improved since then though we can even measure the distance to Venus directly by bouncing radar signals off it. In the distance from the Earth to the Sun is now known to be 149 million kilometers, about 4,000 times the distance around the equator of the Earth. But even 200 years ago, the calculated distance was more, was 140 million kilometers, in error of less than 7%.

is ridiculously, uh, it's amazing. That's, especially back then when jaded by the, we take things for granted, you know, we get upset when the internet connection takes a second longer, even a half second longer than it should, or we think it should. These guys back then, they had no electricity, no steam engines even. I mean, this is three, four hundred years ago. It's no wonder that they took their, entire adult lives to meticulously and diligently observe the stars and the motions of the planets. Once they were able to, you know, make predictions about where they're going to be in the night sky, and those predictions come true with a very minimal error. That's astonishing, really. It's

really awesome. It's really something. So, the stepping stones, it takes the earth 12 months. the radius of the Earth's orbit, the distance from the Earth to the Sun, is roughly 150 million kilometers, 90 million miles. Distance is called one astronomical unit or AU, so whenever you see, you know, so this and this, this common is 20 AU from the Sun or something like that, yeah, the unit. It's vitally important in astronomy because it provides a new baseline with which to measure the parallaxes for more distant. Like I said, at intervals of six months, the Earth is at opposite sides of the sun, of course, grabs up the night. Few of the stars even seem to have shifted as in the parallax effect. But the shift is very, very, very slight because the stars are so far away. some idea of how small the effect is.

In the 1830s, the first star studied in this way, known as 61 signet, found to have a parallax shift of just 0.3.1 seconds of arc. Let me get my little pad. 0.31 seconds of arc. What that translates to is that the night sky we have, you know, if we look on the horizon, we have a half circle, and this circle is divided into 180 to. degrees because the whole circle would be 360 degrees right so an easy way to formulate that in your head is you can break these up in the halves so if we broke

180 and a half that would be 90 degrees call that zero call that 180 and this in half would be 45 you can break that in the thirds nicely so that's 15 degrees and so from here to just here you don't looking into the sky, it's pretty much almost the horizon. You break that in the 15 units. Each of those little units right there is one degree. One degree. Now, if we take that one degree and zoom in,

this is a really bad drawing, one degree is broken up into 60 arc. So there's 30 and there's 60, right? And so if you can imagine again, and remember this whole thing right here is just one degree right here and there's 180 of those from horizon to horizon in the night sky when you look, look at it. And so this one degree, so you can imagine where I'm going with this. This one degree broken up in the 60 arc minutes and I put degrees there.

actually little apostrophies and that's broken into so one arc a minute then broken further into 60 arcs and break it in half it's 30 seconds 60 and break it up in when you get any higher resolution what they do is use the conventions for the metric system for breaking units into fractions of fractions of hundreds, thousands, millions, billions. So they would use the Latin prefixes, micro for millions, nano for billions. So if it's taking measurements of galaxies, you know, billions of years away,

and there's slight measurements, they want to maybe the width of a galaxy 10 billion years away, they might be measuring this. that in not degrees, not minutes, not even seconds, but microseconds, arc seconds, really. That's what they call it. So it's degrees that it certainly wasn't a 160th. Oh, sorry. So one third of an arc second would be one third of 160th of 160th of 1, 180.

Breaking the sky in 2 million pieces, if you can imagine that. two million pieces of pie to measure the slight slight slight shift that we were able to measure through the parallax effect of one of the closer stars against the much more distant background stars and using that we were able to figure out that see if they say the figure out roughly the distance to 61 signine And I like how they elaborate on it. That comparison, the full moon covers 30 seconds. 30 seconds.

Yeah, 30 seconds. I would think it's, I guess, I guess, a degree is a little bit bigger than it looks on paper. The apparent shift in 61 signai as the Earth goes around the sun was equivalent to about one six thousandth of the diameter of the moon. diameter of the moon, the apparent, because it's apparent to us from our perspective. That's what the moon, how much space the moon takes up in the night sky. The distance to the stars are so great that the astronomers had to invent new units with which to describe them.

They are so far away from the earth that the distance between the earth and the sun Again, the radius. I hovered just one second of arc on the sky, then you would be one parsec away from the earth. The distance between the... ...that they took, you know, the sun... ...instances like... ...hon Solo's Kessel Run.

It does have a very futuristic sounding ring to it, doesn't it? Parsack. So it's a unit of distance. That's 30 million million kilometers. It's really, yeah. hard to visualize that's an understatement 3.26 light years to give our units so you know more familiar understanding so actually yeah I think when I first learned this um not too long ago is 3.26 light years very roughly you can equate it and make the analogy between a foot

foot or a foot in a meter. The light year would be the foot, the parsec would be roughly three times what the light year is, being the yard. So converting the parallax measurement into distance, we find that 61 signi is 3.4, or roughly 10 light years, 3.4 parsecs away. Just over 11 light years. And amazingly this makes it one of the closest stars to the sun. When you look up at the night sky on a dark and cloud-free night,

it seems to contain countless stars and poets of wax lyrical about the view, but the human eye is not very sensitive to faint light, even under the perfect, most perfect conditions or cloud and far from city lights, the most you can see at any one time is about only 3,000 stars. But nonetheless, I mean, that's still not. I live unfortunately a little too close to West Palm Beach, Port St. Lucie. I've been out in the mountains, I think two years ago. I went out into the mountains with my girlfriend. And I actually, to do a double take when I stepped out of the car and looked up one night.

On a clear night, I guess it had been a little cloudy a couple nights. and it opened up one night and I looked up and I thought there was maybe a meteor shower or an aurora or something because I could see the Milky Way as an actual stream of a concentrated stream of stars crossing the entire night sky

and to me that was it was the winter times it was cold and a jacket on and fresh mountain. It was just one of the most divine experiences I've had. It was beautiful. Needless to say, I stood out there for a good long while, looking at the star, just basking in that hall,

than just what a few eyes can see. The true number of the sky only began to be appreciated at the beginning of the 17th century. It was in the 1600s when Galileo Galilei turned his telescope on the night sky. He found that what seemed to be a faintly glowing cloud of light was actually a myriad of individual stars, each too faint to be seen by the unaided human eye. He announced his discoveries in the book, The Starry Messenger, which was published in 1610.

At that time, there was no accurate way to ask you. estimate the distances to the vast majority of these stars until very recently only a few stellar distances actually had been measured directly by parallax by the end of the 19th century just 60 stellar distances had been measured in this way at the end of the 20th century though the situation had improved dramatically when the hipparchus satellite from a famous creek orbiting near clear of the obscuring influence of the Earth's atmosphere, measured the distances of large number of stars with unprecedented accuracy, pinned down the parallaxes of more than 100,000 stars, accuracy of, say, 2,000ths of an arc second. But even this impressive achievement gives the distances to less than 1 millionth of the total numbers of the stars in the Milky Way,

taking the range of directly measured stellar distances out to a few hundred parsecs. So even with the aid of satellites like Hipparchus, astronomers still need other techniques to measure distances to stars outside our local region of space. The most important of these techniques is called a twin cluster method. It gives the distance to a large group of stars. a large group of stars called the Aedes cluster. Hiades? Maybe the Hyades. These stars are about 40 parsecs or 130 light years away from us

and all move as a group through space, meaning they're gravitationally bound to each other. Aparchus has just proven, I guess recently, confirmed the distance from us to that cluster. Because this cluster contains hundreds of stars with different colors and brightness is, the fact that they are all the same distance away helps astronomers to understand how brightness is related to the color of the light emitted in subtle ways. The color of a star has no relation to its distance.

Its brightness tells us how far away it is. So the color of a star has no relation to the distance. It's the brightness that tells us how far away they are. It says, then they see a star with the same color as the one of the types of highity stars. They can estimate its distance by comparing its brightness or faintness with the hiatus star. Crucially, the subtle differences in color of the stars involved are in. fueled by a technique called spectroscopy. Probably the single most important tool astronomers use.

And it's really cool here. This little excerpt they decided to put is an overview of what spectroscopy is. It's essentially how white light... Let me show you guys real quick. To make it real practical. I'm going to show you that. that on my bookshelf, when I turn them white, colors that it makes are only made up of red, white, or red, red, blue, and green LEDs, buried, uh, whose brightness is buried.

And that makes all the visible colors to us. Here's white light and when I get close, I'll show you guys exactly how, exactly how you can get, You can analyze different shades of white light and it can be broken up into various colors. Various colors of along the spectrum. Fraction happening in the camera lens there that was able to, hopefully all remember to leave that part in. Really shed light. It's super cool in person, obviously. You can put your eye right up next to the LED.

Make sure it's kind of dim, by the way, if you try this. if you want to try this at home. Um, and you can see it looks white from a distance. Just like a, you know, a TV looks white from a distance and you put your eye right up next to it. And all it is is three different colors, red, blue and green at equal in an equal intensity. If I made the red go way up and kept the blue and green the same, it would turn into a more pink hue or red. I think when you, you know, red and blue raised when green is kept low, that makes more purple. Blue and green, I think, make yellow, even though I know blue and yellow make green. It's,

to me it's awesome. So all the amazing properties of light is what allows astronomers to know so much when they say, oh, yeah, that star has this amount of composition of iron in it, this percentage of carbon and hydrogen, they're able to actually figure that out using spec. It depends on the fact that any particular chemical, the element, any chemical, they radiate energy if they're hot. At the very, very precise wavelengths of the rainbow spectrum, the electromagnetic spectrum,

that correspond to the orbital distances of their electrons. Alright, so I know there's going to be at least a couple of you physicists, more intelligent and knowledgeable people out there than myself. So feel free to correct me in the comments, but from what I understand, if we have an atom, and we have some protons and neutrons in the center there in the nucleus, nucleus the atoms kind of made of these different shells just to keep it two-dimensional and it's surrounded by electrons on these shells now if one of these

these few shoot a light which has wave-like properties but nonetheless can be emitted in particle form at least just for the purpose of My understanding of it. When it gets blasted, when this atom, say a metal bar is being blasted by light, so we have a piece of metal being bombarded by sunlight, let's say. And light is hitting it in the form of waves, but it's also energy. It's giving energy to this electron. And what that's going to do, it's like giving an energy bar to a guy

so that you can hike up the mountain. So now this electron sits up here, here in this whole atom as a whole absorbs light from a particular wavelength that corresponds to the distance or at least the energy that it took to jump that to that higher energy state of the orbital and now later on as atoms and electrons have a tendency to release or at least move down to a lower energy state. This electron, say it's over here now, it's going to jump back down to a lower energy state,

just like a guy who could jump off a cliff safely into the water for our family-friendly purposes here. When it does that, it's going down to a lower energy state, which means it's getting rid of energy. much energy anymore. A photon velocity, that's the speed of light in a vacuum. But it doesn't have a measurable mass. So it's massless.

It's a massless particle. That's how it works. Spectroscopy measures light. Prism breaks it into red, all the way to blue. Pure white light that's made up of the visible spectrum. SARS, its certain wavelengths are actually missing. completely black because that star is full of elements that don't um oh that absorb yeah that's what it is they absorb light from these specific wavelengths so the star itself

as a whole won't be emitting light from those wavelengths because there's atoms over here absorbing them just like a the reason the trees you know leaves are green is because of the sun that it's getting except doesn't accept the wavelength green for some reason so it bounces that back and takes all the other colors to chlorophyll and that's what it is synthesis so for some reason green just doesn't jive with it so the fling test here And this over here gives you kind of an idea. Oroscopic barcode corresponds to a particular element because the light emitted by elements has been studied using simple flame tests. So a sample of a known element, perhaps a piece of copper wire, is heated often using a simple Bunsen burner. And the light in it, the light it radiates when it's heated is passed through a triangular prism. This spreads the light out and produces a pattern of lines that is unique to that element.

And then they can build up a database of what unique spectroscope each element produces as they test different elements. The 1800s. Then the first person noticed that light from the sun when passed through a prison to make a spectrum contain many distinct lines. British physicist William Wallaston 1802. He had no idea what they were, but he discovered that. And the German Joseph Fraunhofer counted 574 lines.

But the person who explained it, famous, Guy every electrical engineer knows, Kirkoff. These were lines caused by the presence of different elements in the atmospheres of stars. He pioneered the basic principle. in scientific spectroscopy in collaboration with Robert Bunsen, appropriately enough. So the spectroscopic studies of light from the sun's atmosphere clips in 1868 showed a distinctive pattern of lines which did not correspond to any no. It concluded that there must be an element in the sun that had not been discovered.

gave the element the name helium from Helios, the Greek. Helium was actually identified on Earth in 1895. In Lockyer received a knighthood, partly as a result of his famous prediction in 1897. Spectroscopy had actually found an element in our nearest star before it had been found. Which is one of the many, many you have to respect.

science for. And science isn't some entity, it's not some god, it's a method, it's a methodology of coming up with interesting ideas and testing them, seeing if they work. And I love that most science isn't completed by, you know, even Einstein who made the most famous breakthrough ever. He acknowledged that he was standing on the shoulders of giants and that's the only reason in his own words he could see so far. It's, uh, it being a very democratic, very communal, cooperative enterprise, even though sometimes it's definitely not when it comes to egos and who made what, who's going to keep the Nobel Prize money.

It's also a testament to the humility of an individual to recognize he would make where he was if it wasn't for, you know, this guy making an observation that the sun produced definite lines like this. And then some other guy coming along and counting the lines. There is the important use of spectroscopy and astronomy. Although the lines corresponding to a particular, always produced in the same distinctive wavelengths, if the object is making the lines, as it's moving when it comes to astronomy and especially galaxies you have objects moving

so fast that they're actually approaching speeds that you have to name in terms of light speed relative to light speed so uh in percentages of light speed and that's when the the idea behind red and blue shifting stars and galaxies comes into play If the object is moving towards us, the lines are actually shifted to shorter or bluer wavelengths. I think of blue is being more high energy and it really is when you go to nightclubs, they want to stimulate you, they'll put blue lights, and if they want to mellow you out, they'll put red lights in, because red lights are less energetic wavelengths. So of course the cosmological objects are moving further away, and their wavelengths are being stretched, and therefore those objects are being red shifted. And this is known as the Doppler effect, and it enables astronomers to measure how fast stars are moving through space.

How fast galaxies are rotating and have how fast even binary systems such as stars. are orbiting each other. Spectroscopy tells us what stars are made of, how fast they're moving, what mass they have. So without spectroscopy, there would be little more to astronomy than making pretty patterns called constellations in the night sky. Cortague group of galaxies in NGC-7320. Color coding shows the different redshift values of the quartet members. Wow, look at that. So you can see the red specs right there.

Those and of course all the blue that dominates. It's an exaggeration of the red and blue Doppler effects. The shifts they undergo. So the result of applying such methods is that we're now, we now have a clear idea of of the distances between the stars and also of their sizes. The distance from one star to even its nearest neighbor is usually tens of millions of times its own diameter, except for binary systems, of course.

For example, the sun has a diameter of 1.39 million kilometers, and it's pretty typical for a main period star, like our sun, our star. If the sun were the size of an aspirin on this scale to the nearest star would be another aspirin, 140 kilometers away. I really, really, really love examples like that because it really proves just how far away the stars are. If I made the mark of a period, you know, I'd have to still go like a mile away to get to the nearest star. The other star was also the mark of a period. So by using every possible

technique for measuring distances to stars, astronomers have been able to map the collective, the collection of stars in which we live. This is the Milky Way. It's a island in space. Galaxies. This is rather like trying to map a forest from the inside by working out the distances in relative positions of the trees in all different directions surrounding you. I like that analogy, that's pretty good. The process is aided by the fact that in parts of the galaxy there are great clouds of gas in dust between the stars. These clouds, they contain large amounts of which can be detected by radio telescopes, measuring in just a the radio wavelength.

The overall shape of our galaxy is a flattened disk containing hundreds of billions of stars. We of course don't know what it looks like from the outside, but we assume based on looking at other galaxies, it looks something like this. Platten disk of stars embedded in a halo of globular clusters. Hundreds of billions of stars in our galaxy, all of which mostly pretty similar to our star. The disc is only 300 parsecs thick at its outer regions, roughly 1% as thick as its width, but it has a bulge in the center measuring 7,000 parsecs across. And in 1,000 parsecs thick galaxy from the outside, it would look kind of like a huge fried egg, I guess. Surrounding the whole disc is a halo of about 150 known bright star systems called globular clusters.

So they're basically really, really, really dense miniature galaxies, little baby galaxies. And all the stars in them are really old from what I understand. They contain tens of thousands all the way up to millions of stars in really, really tight spaces. From the way those, you know, our stars and the globular clusters surrounding our galaxy move, astronomers have had, you know, they've been forced to kind of say they don't really understand. There's a huge, like a really huge part of the equation that they're not being able to account for. And so they're just calling it dark matter and dark energy, I guess. Or no, maybe dark energy has to do with the expansion of the universe.

But dark matter at least surrounding the whole galaxy and holding it, they think is holding it in a gravitational grip. And really my little pet theory is that we tend to look at black holes as just something else to observe or look for in space. Something confined to a, you know, something we're... We don't understand and, you know, it's down to a singularity, but at least that singularity is confined to that one point in space that it happens to be and somehow crams all that matter into. But it might be a wrong perspective. I'm really intrigued by the idea that maybe a black hole is some type of donut shape, you know, or, you know, some other shape we can't even. imagine and perhaps in the black hole all that matter is uh all this matter this black hole that is

apparently has the the gravity of millions of our sons and so that means it must have that much matter contained inside a point you know the size of an atom there's something like a magnetic field in the earth where creates uh why physics is isn't run off of feelings and emotions and hunches. Or at least, most galaxy has a distinctive structure. With bright trails of stars called the central bulge. And this is a very common feature of disk galaxies like the Milky Way. It's why they're called spiral galaxies.

The most important distinction between the central bulge and the disk proper, however, is that the stars in the bulge, in the globular clusters, stars and the halo surrounding the galaxy are all really old stars. It's 12 billion years old. I mean that's almost as old as the, uh, what we think the universe is currently. For historical reasons, they're known as population two stars. There's also very little gas or dust in the bulge, which makes sense, because if that was old, that would mean all the gas has plenty of time to do.

plenty of time to ultimately coalesce and condense into either sucked into other stars existing or formed into their own planet solar stellar systems. The disc, now the disk where the spiral arms twine outwards contains gas and dust and some old stars but also middle-aged stars and all the young ones. as population one stars. Sun being a, we actually are a population one star system. New stars are still being formed in the disk all the time. All the stars in the disk together

with the gas and dust orbit around the center of the galaxy. Each star moves independently just as each planet in our system moves independently, but they do form patterns. Stars closer to the center, just as Mercury and Venus in us, they move faster than those around the edge, traveling at a speed of about 250,000 years per second in its own orbit, carrying us along with it, of course. But the galaxy is so large that even this speed makes it take 225 million years

to orbit the galaxy once. It's only made it around about 20 times. since our star system. Sun and his family of planets orbits the galaxy at a distance of about 9 kilo parsecs from the center or two-thirds of the way out to the edge of the disk. So we're actually right on the inside edge of what we call the Orion arm based on the Orion's belt. We're not in the center and there's nothing in particular there's nothing particularly special about our place in the Milky Way. And the size and shape of the Milky Way galaxy were only really described properly in the 1920s.

Before then, most people, the stars they could see in the sky made up the entire universe, everything there was. But Hubble, of course, was a huge influence on disproving that theory. We were able to clarify these little fuzzy blobs we called nebulae, meaning clouds, are in distinct shapes shown by, you know, every other telescope out there. Best by Hubble, though. And we were able to finally reveal that, let's see if this is going to talk about that. We were able to look at features in those distinct clouds and discover that they themselves actually were made up of billions of stars.

So we knew that they couldn't be inside our galaxy. Even though we didn't have a notion of what a galaxy properly was, we thought that we were just kind of in a sea of stars, and outside of that sea was just empty space, I guess. Same time that astronomers started to appreciate and understand the geography of the Milky Way, some of them began to wonder whether these nebula might be other islands in space. They were just so distant that maybe their accumulation of light from all their stars just ended up looking like a faint patch in our night sky.

This suggestion caused a fierce debate. Most important thing on most astronomers' minds in the early 1900s, especially in light on the tail end of Einstein's. discovery of relativity because that would um mainly because rush in a new world view it would require a paradigm shift because that would mean that distances of these galaxies were greater than anything we had ever even considered before that so it opened up the view of the universe to be millions of times larger than we once thought And we once thought small distances before that were low.

You can imagine the backlash when astronomers had only really just recently right before that discovered that the Milky Way itself was several tens of kilometers or no sorry kilo parsecs across So you know maybe a hundred thousand light years was of course, you know it's still unimaginably long and large distance, but now we discovered that the universe, or at least some galaxies that we could observe, were not tens of thousands of light years across or distant. There were millions, millions of light years distant, and that opened up a whole new revelatory perception of our universe and our place in the universe. Naturally with how we're at the time, They didn't want to give up their paradigm. So status quo maintained that it was just clouds of gas

that we were mistaking for really distant galaxies. The only way to find out whether that was true or not was to try to identify individual stars in the galaxies. And that's exactly what Hubble did. They noticed... supernova they used stellar exploding stars called Nova and really big ones are called Supernova and noticed that all of them have about the same amount of brightness as well and so they were able to use that Nova that they observed in the Milky Way get

their distance and once they got their distance they were able to discover that if they were to observe another one in the future, they could compare the brightness or luminosity of that supernova, that nova, with the new one that they're observing now and be able to tell just how far away the new nova must be. A kind of star called a sepheid. This is a sepheid variable. They have a brightness that can be inferred from their other properties. If you know the true brightness of a star, it's easy to work out how far away it is.

By measuring how bright it appears, just like if you know a car light shines at an exact luminosity, when you're right up next to it, you can measure that. A year from now, you see that same car and you know that it's that same model headlight. You see it five miles away. You can go back and get the data and record what it is. record what it is and be able to be able to deduce how far away that headlight you're looking at is based on the known properties you've previously measured. If the astronomers could identify over sepheids in the nebulae that was being contested,

they would be able to work out roughly how far away they were. Briefly, this is the telescope, one of the ones used in working out the size of our galaxy. Just to give you an idea on the scale right there, that's a bench. That's a bench for a good comparison relative to human size, how big these things were. So those things probably 50, 60 feet long. This is, this is stuff that they built in the early 1900s, late 1800s even. I always love how an effort in technology and in a invention, innovation went into the tools that early astronomers used. For me it's a testament to the optimism and hope.

Right here is supernovae 1987A, Stiller explosion, photographed in March of 1987 and they were to have found other ones they alphabet, as you you can imagine. Just tacking letters onto the end of the year. Central bulge of stars surrounded by a thinner disc. I'm pretty sure this is Andromeda right here. It turned out to be just possible to make these crucial measurements for stars in some of the nebula in the 1920s, using what was then the best telescope. It's actually still in use today. He actually just saw it says it's as a 100 inch diameter mirror called the Hooker Telescope, after the guy who paid for it, the benefactor. It's located on top of Mount Wilson near Pasadena in California.

Crucial measurements was Edwin Hubb. He identified both Cepheid and Nove. Nova, Nova, Novee, and Nebulae. that are now known to be the closest galaxies to the Milky Way. It turned out that not all of the nebula were other galaxies. Some of them were actually clouds of dust, and these objects play an important part in the life cycles of stars, in the origin of planetary systems like our own. To avoid confusion,

for to avoid confusion, astronomers kept the name nebulae for the clouds. within the Milky Way. And we used, yeah, and of course just used the, I guess, current term for the universe, the galaxy, for greater star systems beyond the Milky Way. Even with the 100-inch telescope, it was very difficult to make observations needed to calculate the distances to the galaxies, though. The moon being both the same size, same observation. same apparent size in our sky, perfectly cover each other up and so when we do experience a full solar eclipse, we're able to see the solar flares and other stellar

prominences like the corona, beautiful halo, first began to make measurements of the distances and though the galaxies did indeed lie beyond the Milky Way, they did not seem to be as big as ours, but it's all a matter of perspective. One of the few things we can actually measure is the area the galaxy covers on the sky. All galaxy close up will, of course, cover the same area as a big galaxy far away. In the same way the moon completely covers the sun during a total solar eclipse, because although the sun is almost 400 times bigger than the moon, it's also almost 400 times further away.

Really, uh, that's a really interesting coincidence. would be other than Venus even has a moon. Mercury doesn't. Or be able to cover up the sun to that accurate of a precision, a closeness to the same size as the sun. But anyways, as telescopes got better, astronomers were able to measure the distances to the other galaxies more and more accurately.

So they used many different stepping stones, not only sepheids in Novei, but also comparisons of the brightness of things such as globular clusters in one galaxy with those and another. After more than half a century of effort, they found that the galaxies were about ten times further away than Hubble had once thought. And the Hubble actually, because it doesn't look like they're really getting around to this, Cepheid variables are, they obviously, by their name, they vary in brightness in a very predictable way. And Hubble was able to use that to determine that. They were coming from not just tens of thousands of light years away, but millions of light years away. The reason Hubble was able to analyze Cepheid variables and determine the distance is because they all,

they exhibit a luminosity or brightness that's in very close correlation with the period or the frequency at which they vary the luminosity varies so they have variable brightness that goes up and down as the star turns around and Hubble was able to look at some variables

some varying stars all the way in the Andromeda nebula and Triangulum 2 the third largest galaxy. Cepheid variables do in our own galaxy, but they're way, way dimmer based on looking at at least tens, if not hundreds, of different Cepheid variables relatively close by in our Milky Way.

He was able to tell that, no, no, no, there's things way too dim to be inside our own galaxy. Once he presented this, he was only 35, that's another amazing feat about this thing. Once he presented that in public, all the other scientists had no choice but to, you know, accept this, well-received, very diligently cultivated observational evidence. And if it wasn't for Einstein, he might have been one of the more famous, famous scientists. of the 20th century, even though he still kind of is.

Pretty interesting. Not only sephiates in nowhere, comparisons of brightest things, such as globular clusters, being just millions of densely packed stars in a very small space. Cross galaxies are measured, we already said that. After more than half a century of effort, they found that the galaxies were about ten times further away than he thought, as much than they did in the sky.

So, sepheets in Novi are still very much used in the 1990s using sepheed distances of Hubble Space Telescope. Sefayette variables at the University of Sussex finally showed that the Milky Way is an average galaxy of its type. Car position in it, as it says, as it wants to emphasize. There's nothing particularly important. It Way galaxy. Clear understanding of the sizes of galaxies and the distances between them. As well as disk spiral galaxies, like the Milky Way, there are much larger elliptical galaxies, which don't have a disk or spiral shape, but they're like ellipsoid, almost like rugby balls, or really fat frisbees.

been built up by cosmic cannibalism, which that's just a vivid way of saying that there are mergers between different types of sharply defined shapes of galaxies. Smaller elliptical galaxies, elliptical galaxies in small irregular galaxies which have no distinct shape. The largest elliptical galaxies contain several thousand, so several trumers are one of these stars. Galaxies are much closer together relative to their own size than the stars are to one another. That's an interesting thing I never really thought about. It's a matter of perspective. If we adapt the Asperin analogy to galaxies, I think the other one was it would have been 40 kilometers away. what it's like between us and the nearest star.

So if the Milky Way is a single aspirin now, then the Andromeda Galaxy would just be 13 centimeters away. And then add just three meters or about, you know, 10 feet away from that, then you're going to find a huge collection of about 2,000 galaxies. spread over the volume of a basketball, representing a group of galaxies known as the Virgo cluster. On a scale where a single aspirin represents the Milky Way, the entire observable universe would then be only a kilometer across.

What? I mean, you know, an aspirin compared to a kilometer, that'd be a long way for it to travel, but I can at least imagine that. I never really considered like an analogy like that before. It gets me. Observable universe would only be a kilometer across. It would contain hundreds of billions of aspirin.

In terms of galaxies, the universe is definitely a crowded place. Much for watching guys. I appreciate all the continued love and support during a special. especially in the space, but of course history, psychology, philosophy, all that as well. Live it up for the 50th anniversary of the Apollo Mission. Hope you're looking forward to some content on that.