Australia, Chile, Northern Hemisphere discussed on Space Nuts
Nuts Fred is well loved by the Amateur Astronomical Community but few know of his pioneering work on multi object spectroscopy Oris Fascination for optics and binoculars. He's around knowledge of all things. Light place him. Well my first guest on dark sky conversations. Thanks for joining us for it. Thank you for having made a pleasure to be here. Thank you question has to be asked. What does an astronomer at large actually do hopes? Nobody'll find find out so the job is essentially an outreach education and advocacy role role. It's all about trying to spread the word scientists good for people to let the wider public. Know just what an enormous contribution contribution Australia makes to the world of astronomy and to engage with with the wider community internationally so there is now a lot of international involvement in astronomy with things like the space agency and despite the fact that we Australia now has a strategic partnership with the European Southern Observatory which operates the biggest telescopes in the world on the finest observatory site in the world in northern Chile. Right and so why why is it is it is astronomy moving offshore to Chile for example. A really interesting story and depends on how long you've got. The story. Goes back to the nineteen sixties when astronomers realized that because of the advent of wide body jets and cheap F- F- flight relatively cheap air flights. They could put their telescopes where the conditions were best rather than where the strongest happen to be before that strong observatories we're always in cities. Because that's where I live. So there was a worldwide push to find the very best observing sites in the world In during the nineteen sixty s and that means sites that are dark without light pollution. That's of course a given start with which we might talk a bit more rebel against but also sites which have clear whether a particular sites which are very stable atmospheres a a a low level of atmospheric turbulence and so Sykes were identified. All over. The world. Australia siding Spring Mountain was discovered it to be probably one of the best places to do. Astronomy visible light astronomy Australia. But we now know that some of the other ascites in the world are even better and in particular it turns out that you need a place on a mountain top. Maybe three thousand five hundred meters is kind of twelve thirteen thousand feet on the western seaboard of a continent. That's what you need to get this spectacular atmospheric stability and and the problem is. We don't have that in Australia. We we don't have a mountain. That high on the Western seaboard. I mean we should pay somebody to build one if we could we do that so observatories elsewhere have better sites and that's what's happened. The astronomical infrastructure has concentrated concentrated on those sites principally in the southern hemisphere in northern Chile in Northern Hemisphere. It's principally begawan defer wire which has the best conditions in the world world. And so that's why we engage with with international. So you mentioned there are a couple of times light. The first being that light is moved away from light pollution. So what does that mean to stretch of what is like pollution. And why. Why did you have to move away from it? So many people don't realize that the night sky itself has its own luminosity which comes partly from a AH atoms in the upper atmosphere of the earth relaxing after a hard day in the Sunday. Get excited and they released that radiation after dark. There's also dust in the solar system mm-hmm which lights up the night sky and a very fame background of stars and galaxies. They all contribute to a natural sky brightness so astronomers are always battling thing against that an often what they're doing is studying faint objects whose light is only maybe one percent brighter the this natural background. So they're right down there up against what nature throws at you if you then put in artificial light you lose the signal together. It's as simple as that. So you simply cannot tolerate any artificial light pollution for this kind of groundbreaking research and AH AH. Are there technologies or anything that we can use to try and adapt conditions or is it just simply that we have to have no pollution. Yes it really is. It really is that you can't have light pollution. The problem the problem is astronomers. Look across cross what we call the whole visible wave band so there measurements are made in all colors of light from deep violet and beyond in what we call coli ultraviolet right up the wavelengths scale to red light and far infrared light and far infrared light. Those are. That's what you might say. Covers the the the visible light waves and light. Pollution tends to occupy much of that spectrum for a while there was an enthusiasm among astronomers for what it called low pressure sodium vapor lamps. Yeah street particularly the street lighting getting because they emit light effectively of one single wavelength are in. July's very familiar to people. See You could Aratu Kate so what that's what's doing. He's only polluting that one little bit of the spectrum and the rest of the spectrum is much much clearer but you never get a city or a community community that only has so every wondering outdoor housing lights normally incandescent lights mercury lights all the rest of it. Actually it turns out now so From the Vantage Point Twenty Nineteen that Sodium Vapor Street lights are almost obsolete. And that's for a number of reasons operationally operationally for for for councils and bodies like that that actually operate them. These sodium vapor lights have some disadvantages right. Yeah so I've heard you talk previously about a rainbow of light that you that you can study and you've just mentioned in the band of flight. Could you explain a little bit about the bar. Code of information that you get from from from this rainbow this spectrum of color that you're that astronomers use so. Yeah Ah I mean it's a really fascinating story. Goes back to Newton who a played around with a prison in the sixteen sixty s and discovered that you can shine wide wight light for example sunlight which effectively why even though it looks but yellowish he could pass that light through prison and break it up into this rainbow of colors. uh-huh Red Orange Yellow Green Blue and violet indigo. Isn't there people used to say those indigo as well but it's not really there so the spectrum colors which merge into one another so it's actually a continuum and it was Newton who coined the term spectrum in fact back a little bit later than that in the early eighteen hundreds around eighteen hundred to a scientist by the name of Williston noticed that if he put sunlight through a prism. Did it in a way that allowed you to look at specific wavelengths. Sorry look at specific color. Shouldn't use that. That came later. Williston notice that there were dark lines crossing the spectrum of the Sun and he thought Oh this must be just where these colors join together but ah later in the nineteenth century it was realized that those dark lines actually are the imprints of atoms in the atmosphere of the Sun. Who and the positioning of the lines actually depends on which elements elements are producing them? So what you've got is this array of lines and in the son's case it's it's tens of thousands of them The the early guys could only see a handful but now we recognize there. There are very many of them and each one is the signature of a particular a particular atom elements like Hydrogen Yup. Yep exactly the most. Common Element is hydrogen but we also find iron calcium sodium. All of those things are imprinted on the sun spectrum. So if you use a device vice to to form the spectrum then you can tell with absolute clarity what the sun is made of. So what is the device to ease. It's called a spectrum. Graph actually clean in early days. It was called a spectra scope which is just a something for looking at the word. Scopus Spectrum Spectroscopy. Lets you look at it and the early days when we started the first people who really put spectrum together. We're at the turn of the of the nineteenth nineteenth century so the likes of Williston. Yes that's right. It was actually two German scientists by the name of kickoff onto Bunsen pair of them. They were the guys who really built the first decent spectra scope and they were the people who worked out what was going on in the atmosphere appear the sun and it was actually an Englishman by the name of William Huggins later. Sir William Huggins who tried that technique on the stars ause realized that he could tell what the stars were made of was it. was there a comment that I remember some way that someone said that we would never know what all this that was. A Frenchman by the name of. Auguste comte was a philosopher and in eighteen. Thirty five he wrote in a book no we will never know what the stars are made of. We will never no the densities sizes. We just won't know that temperatures. He said we'll never know these things and actually in that same year. A demonstration took place in Dublin. In fact by a man called Charles Wheat Stone doing more or less the same as it was talking about with Williston but he it was using metal two pieces of metal with the spark passing between them and he realized that if you looked at the spectrum of the spark I told him what metal the electrodes who made of and that was once again building up to this idea kickoff Brunson were slightly later. They were around the eighteen sixties. So comp got it wrong we actually know a lot of stuff about this does go to complete. So what other information does like give us about the universe hard to overestimate what we can learn about the spectrum of objects coming from the universe so not only do you get for example exemplify looking at stars you not only get composition a starts composition. You can also tell whether it's moving towards or away from us and how Fast Austin moving what you did with the radio velocity. That's right that's something called. The radial velocity its its velocity along the line of sight and and so measuring the velocity of a star towards or away from you is pretty straightforward to do the spectrum of a look actually took until the eighteen ninety s before another German called the handle it better fogel time. He was the first guy to measure of raining. So yes you can tell the speeds also you can tell whether an object's rotating you can see that from the spectrum. E can even tell whether it has a magnetic connectic field because a magnetic field actually splits up the spectrum lines Z.. But wait there's because you can use and and this is technology that we really have only we've only had for the last twenty four twenty five years you can use a spectrum graph to see whether a star is moving slightly towards or away from you as it is pulled this way and that by a planet in orbit around. You can't see the planet is too far away to faint but you can see that. This research has allowed us to find exit planet. Exactly what we call exoplanets or extra solar planets and how many have we found. Now it's swell over three thousand the Yes. There is a different method. That's now used to detect them that. The the methods called the Doppler wobble technique the one I just mentioned because the doppler effect another German scientists. This is the effect of the of the wavelength of the light changing slightly by the towards or away from the motion of a star. And but the what happens is if you've got a planet going around to start pulls the star Dr this way and that and the the doppler effect is measurable for the Movement of the story itself. It's a matter of only meters per second for an object. The size is of Jupiter but something the size of the centimeters per second these tiny tiny houses. They're they're not even walking pace. They're very very slow. And yet you can muse light to measure those and so as you're saying I'm realizing how critical technologies with this and how how much information there is that we could about universe but we we're actually impairing these with pollution that's right yes that's correct Having said that all the world's leading observatories and you can these probably half a dozen of them that will be right at the top of the heat there in terms of the the excellence of the sites that they're on they're all protected with legislation to prevent there being undue light pollution and the legislation simply says that if you've got if you've got a development nearby within up to while in in the case of the siding uh-huh Otari in Australia it's up to a hundred kilometers with two hundred kilometers under certain conditions developments within area have to comply with Orwell's observatories all leading. Pretty well yeah. It varies The the major observatories in on the island of La Palma in the Canary Islands. This this grey observatory there in the Northern Hemisphere. The Hawaiian one's the Chilean ones..