Speaker 1: Welcome to Tech Stuff, a production from I Heart Radio.
Speaker 1: Hey there, and welcome to tech Stuff. I'm your host,
Speaker 1: job and Strickland. I'm an executive producer with iHeart Radio
Speaker 1: and a love of all things tech. It is time
Speaker 1: for a classic episode, my friends. This episode originally published
Speaker 1: on May nineteen, twenty fourteen, back when we had three
Speaker 1: pieces of tech. How far we've come. So this particular
Speaker 1: episode is about how planetariums work. So I would say
Speaker 1: it's out of this world. Let's take a listen. So
Speaker 1: there are a lot of different types of planetariums that
Speaker 1: all use a very similar approach, but you know, the
Speaker 1: actual implementation can differ between one and the other. But
Speaker 1: we wanted to talk more about all of the kind
Speaker 1: of history that built into coming up to the planetariums
Speaker 1: as well as how they actually work. Right. We didn't
Speaker 1: I just explain it's a projector and then go in
Speaker 1: from there. I mean, because because y'all basically it's a projector. Yea,
Speaker 1: So we could just say it's a projector, and if
Speaker 1: you know how a projector, it's a Friday, so we're
Speaker 1: ready to go home. But no, we wanted to actually
Speaker 1: talk about the history of planetariums because it's a fascinating story.
Speaker 1: I mean, obviously, as as a species, humans have been
Speaker 1: fascinated with the heavens since before recorded history. I mean,
Speaker 1: this is something that we've obviously been really amazed by
Speaker 1: over thousands of years. It's pretty amazing. And what's interesting
Speaker 1: is that there have been lots of different attempts to
Speaker 1: create a an indoor version of this experience, because it's
Speaker 1: not always convenient to go outside and do all your
Speaker 1: your work. And based upon thousands of years of observations,
Speaker 1: we've got pretty good at figuring out how to represent
Speaker 1: the night sky in a way that was accurate even
Speaker 1: the movement of things like planets in the moon and
Speaker 1: the sun and Earth itself. Yeah, I mean it took
Speaker 1: us a while to figure that part out, that the
Speaker 1: Earth itself was moving and not say everything else was
Speaker 1: moving around the Earth. And depending upon whom you are,
Speaker 1: you might still argue that thinking of a specific documentary
Speaker 1: that Jane Way was the voice for anyway, So assuming
Speaker 1: you're not having this geocentric view, even even that would
Speaker 1: allow you to see that the the heavens move in
Speaker 1: a very predictable way. It may take a long time
Speaker 1: for a particular cycle to happen. But once you know
Speaker 1: what those cycles are, you could predict make observations that
Speaker 1: would end up either verifying or or negating the previous
Speaker 1: guesswork and eventually make it into a science. So why
Speaker 1: our planetariums themselves awesome? Well, for one, you get to
Speaker 1: look at the stars, even if again you are in
Speaker 1: a place where you can't normally see them, like here
Speaker 1: in Atlanta, we get a lot of what's called light pollution.
Speaker 1: So that's just you know, any major city tends to
Speaker 1: have this where you've got lots of lights that are
Speaker 1: on at night, and that tends to drown out some
Speaker 1: of the stars. You can't see the fainter ones. You
Speaker 1: really only see the brightest ones that are in the sky. Uh.
Speaker 1: You know, you might be able to see things like Venus,
Speaker 1: which are that's that's extremely bright, and you might see
Speaker 1: some of the major stars and some of the major constellations,
Speaker 1: but you're missing out on a lot. Oh certainly, so
Speaker 1: unless you go way out into the middle of nowhere
Speaker 1: where there aren't so many lights, or you have to
Speaker 1: live someplace that has really strict rules about the lights
Speaker 1: at night. Because there are a few of those places
Speaker 1: you probably can't see that many and even in those
Speaker 1: places it sometimes rains or gets cloudy. That turns out
Speaker 1: clouds really inhibit the stargazing activities. Also, the sky over
Speaker 1: the Southern Hemisphere is different than that over the Northern Hemisphere.
Speaker 1: So um, if if you don't travel back and forth
Speaker 1: pretty frequently between the two, yeah, you don't know. If
Speaker 1: don't cross the line over at the equator and shout
Speaker 1: out to all my navy buddies who do. Um, if
Speaker 1: you don't do that frequently, yeah, you don't. You miss
Speaker 1: out on the way the sky looks and in the
Speaker 1: Southern Hemisphere or if you live in the Southern Hemisphere
Speaker 1: the Northern hemisphere. So to our new deal and listeners,
Speaker 1: there's a lot of you. There's actually quite a few
Speaker 1: of you. Um, I will not confuse you with the
Speaker 1: Australian listeners. We love all of you equally. So if
Speaker 1: you've never been there, but you want to see what
Speaker 1: the sky looks like, a planetarium, some of them anyway
Speaker 1: can accommodate you. A lot of them have the capability
Speaker 1: of showing the stars over any particular point on Earth
Speaker 1: like that's how sophisticated they've become so. Not only that,
Speaker 1: but they many of them can also show you what
Speaker 1: the sky would look like on any given date, So
Speaker 1: you might say, well, what did the sky look like yesterday,
Speaker 1: What will it look like tomorrow? What will it look
Speaker 1: like in a century? What will it look like a
Speaker 1: hundred centuries from now? What did it look like back
Speaker 1: in the day that Shakespeare wrote his plays? Like, you
Speaker 1: could do any of those things, and by plugging in
Speaker 1: some some numbers. The computers that handle the calculations for
Speaker 1: most of these uh devices, not all of them, some
Speaker 1: of them are a little older, but most of them
Speaker 1: can take that into consideration and actually determine what the
Speaker 1: position of the planets would be on any given date,
Speaker 1: the stars, etcetera. Which is pretty awesome. Yeah. Um. They
Speaker 1: can also be used to teach celestial navigation, and they
Speaker 1: certainly were used for that purpose during World War Two.
Speaker 1: Very useful, especially if you can't always depend upon instruments
Speaker 1: to be able to get around. Also, uh, hey, uh
Speaker 1: it teaches astronomy, which you know, I always almost left
Speaker 1: that out of the notes, and I was like, yeah,
Speaker 1: that's uh, that's a big deal. I guess that's a thing. Yeah,
Speaker 1: so obviously the astronomers out there if you want to
Speaker 1: be able to identify various star clusters things like that.
Speaker 1: And a lot of these have special um projectors that
Speaker 1: show things like the Milky Way galaxy or other nebula
Speaker 1: or things like that. And that's important. Oh sure, sure,
Speaker 1: but we will get into that later on. Um, let's
Speaker 1: talk for right now about the history of these devices,
Speaker 1: because people have been painting the sky on ceilings, I mean,
Speaker 1: for for basically ever. Yeah, I mean, like I got
Speaker 1: a cousin who has the Glow in the Dark ones
Speaker 1: that's been on her her bedroom ceiling like since she
Speaker 1: was like four. So yeah. Also, there's a star map
Speaker 1: on the ceiling of the tomb of the Egyptian official
Speaker 1: Sentement that dates from like that does predate my cousin,
Speaker 1: so a little bit. Your your argument is valid. Yeah,
Speaker 1: I mean this is something, like I said, humans have
Speaker 1: been fascinated with the stars for as long as we've
Speaker 1: been looking around and being able to express our thoughts.
Speaker 1: So it's no surprise that we're seeing evidence of that
Speaker 1: in in prehistoric and and uh, you know, just post historic,
Speaker 1: fairly historic uh you know, drawings and and uh and
Speaker 1: depictions on things like this tomb. And then we have
Speaker 1: some early examples of what could be something like a
Speaker 1: planetarium from the Arabic world. Right right there, there were
Speaker 1: Arabic tents made with holes in the fabric to let
Speaker 1: outside lights shine through, representing each star or each star
Speaker 1: as they knew them in in that time. UM described
Speaker 1: in European History Circle that twelve hundreds or so, and
Speaker 1: so that's that's you know, that's a good while back,
Speaker 1: right and then we had, uh, let's let's switch up
Speaker 1: to say, oh, I don't know, let's let's go to
Speaker 1: the idea of using globes and sky maps. This is
Speaker 1: really cool too, So starting a couple of thousand years ago,
Speaker 1: it became really popular in the West to draw sky
Speaker 1: maps on globes and um the first planetariums known to
Speaker 1: history were huge versions of these, like big enough for
Speaker 1: people to sit in. A really famous example is the
Speaker 1: gor Top globe, supposedly based on plans found among Tico
Speaker 1: Brahe's papers. Okay, so wait, wait, wait, Tico Brian, I've
Speaker 1: always heard Tycho Bray. Where did you hear Tico Brian?
Speaker 1: I'm one of my astronomy professors in college called him Tico.
Speaker 1: That's good enough for me. So, I know, I know
Speaker 1: that the Penny Arcade dude calls himself tycho, but hey,
Speaker 1: we're going with an astronomy professor's approach. I'm I'm all
Speaker 1: right with bowing to authority on this one. He had
Speaker 1: a really impressive beard. So that also, I mean, that's
Speaker 1: like credentials in the astronomy world. So that's totally cool.
Speaker 1: So that that was that was built in the mid
Speaker 1: sixteen hundreds and what's now Germany, and it was large
Speaker 1: enough for like twelve people to sit in on these
Speaker 1: circular benches that were around a table um where refreshments
Speaker 1: could be served. Obviously, yeah, um so so the so
Speaker 1: the object, this globe was about ten feet or three
Speaker 1: meters in diameter, and the stars in it were these gilded,
Speaker 1: spangled fixtures in the inside surface of the globe that
Speaker 1: we're eliminated by a lamp that would sit on the
Speaker 1: table along with your you know, snacky cakes. Interesting. So
Speaker 1: it's like it's like if you look at a regular globe,
Speaker 1: you know, that's something that we look at on the
Speaker 1: outside service obviously that's you know, representing the Earth. But
Speaker 1: this is one where we would go on the inside
Speaker 1: and we're looking at the inner wall, which is representing
Speaker 1: the heavens, the heavens right right, and the outside of
Speaker 1: it was actually painted like like the Earth. It had
Speaker 1: all of the continents and everything on it. Pretty cool
Speaker 1: that whole globe shell could could rotate around the viewers
Speaker 1: thanks to some water powered machinery. And it took some
Speaker 1: ten years to build and weighs like three tons, despite
Speaker 1: which it was moved to St. Petersburg as a gift
Speaker 1: to Peter the Great in seventeen seventeen. Shortly after that
Speaker 1: it was partially destroyed in a fire, then restored, then
Speaker 1: stolen by the Germans in World War Two, found by
Speaker 1: US troops, and restored again to St. Petersburg. Pretty sure,
Speaker 1: that should be an Indiana Jones plot, right, it's great,
Speaker 1: And this thing weighs three tons. It takes some determination
Speaker 1: to steal anything that weighs three tons. That's pretty incredible.
Speaker 1: But so the practice of making these these enterable sky
Speaker 1: globes like this unwieldy as they were persisted into the
Speaker 1: nineteen hundreds, and the Museum of the Chicago Academy of
Speaker 1: Sciences built their atwood globe as late as nineteen um
Speaker 1: and that's that's about the same size a little bigger
Speaker 1: at measure sixteen feet that's about five meters in diameter
Speaker 1: um and shows six stars plus the planets in our
Speaker 1: Solar system as as holes through which outside light can shine.
Speaker 1: It's electric and the shell can spin once every eight
Speaker 1: minutes around viewers. Interesting, and so this is kind of
Speaker 1: it's it's like it's taking a note back from those
Speaker 1: old Arabic tents, right, the lights coming from outside shining
Speaker 1: through holes, and that's what represents the stars, very much
Speaker 1: like those tents that had the holes pin break through
Speaker 1: the tent canvas right right. You know, of course this
Speaker 1: depends on either in this case probably electric lights outside
Speaker 1: or in the case of those tents, having a good
Speaker 1: source of sun light in order to see what's going on. Um.
Speaker 1: By the way, a couple of distinctions that I wanted
Speaker 1: to make here. If you've ever heard of an order
Speaker 1: e um, that's that's a physical model of the planets
Speaker 1: in our Solar system and sometimes also called a planetarium,
Speaker 1: and they're also sometimes included in planetariums. So that's nice
Speaker 1: and confusing, right, So orris are if you've ever seen
Speaker 1: one of those physical models where you've got the Sun
Speaker 1: in the center, and then you have all the different
Speaker 1: planets that can spin around the Sun. Sometimes they are
Speaker 1: actually mounted on gears or motors so that it represents
Speaker 1: the accurate movement of each of these bodies as they
Speaker 1: would move in relation to one another. So for example,
Speaker 1: the Earth's uh, the Earth's movement around the Sun is
Speaker 1: different from Saint Mars, which is different from Neptune or Saturn. Anyway,
Speaker 1: you would be able to watch these and see how
Speaker 1: they move in relation to each other, see the times
Speaker 1: when they happen to align, when they get out of alignment,
Speaker 1: and it's really fascinating to see an or but it's
Speaker 1: from an outside perspective. You're not looking from the inside out.
Speaker 1: You're looking as if you were able to distance yourself
Speaker 1: all the way out of the Solar system and look
Speaker 1: in on it, right and and being that especially early ones,
Speaker 1: where we're you know, the planets were all on their
Speaker 1: little rods and would all be going on a on
Speaker 1: a single plane around the Sun, rather than in the
Speaker 1: truth three dimensions in which right right, it would be
Speaker 1: it would be as if we had a completely flat
Speaker 1: solar system, which is not exactly true. Yeah, it's like
Speaker 1: Star Trek world. Everything just comes right knows up to
Speaker 1: each other. Yeah. And also they would move in and
Speaker 1: essentially perfect circles. They wouldn't have these kind of elliptical
Speaker 1: orbitals because that's really hard to do with physical rods.
Speaker 1: But you know, my favorite or y of all time
Speaker 1: is from the movie The Dark Crystal, and it's what
Speaker 1: Augra had. Now that of course was an or y
Speaker 1: for a fictional solar system, but was amazing that an
Speaker 1: enormous things spinning around all over the place. That that
Speaker 1: lady still creeps me out as an incredible movie that
Speaker 1: everyone should go see. Uh oh, absolutely, yes, very much so.
Speaker 1: Plexis I can't okay science besides planetariums and uh and
Speaker 1: or planetaria if we want to talk about or reason
Speaker 1: in that sense, and these globes, we also have the
Speaker 1: concept of keeping track of astronomical phenomena in other ways
Speaker 1: that aren't again all immersive. All right, Well, part of
Speaker 1: the function of a planetarium is as an astronomical clock, right,
Speaker 1: like you were saying earlier, being able to to go
Speaker 1: into the future, into the past and see what the
Speaker 1: stars looked like at any given point. Um, and you
Speaker 1: and Joe talked about a really famous one Antiquathera device
Speaker 1: or Antiquithera mechanism, which is a some people would call
Speaker 1: the oldest computer and analog computer. And yeah, on Forward
Speaker 1: Thinking we did a podcast. No I think I think
Speaker 1: you did it on tech Stuff. It was well days,
Speaker 1: that's right, that's right. See here's the things that I do.
Speaker 1: Too many shows for too many different different versions. Yes,
Speaker 1: we did do the tech Stuff one so as a
Speaker 1: re minder, because obviously I need one. Uh. The Anticathera
Speaker 1: device was this, uh, this gadget that had been lost
Speaker 1: in a shipwreck and recovered by sponge divers, and it
Speaker 1: was recovered in very poor repair. It was all these
Speaker 1: different pieces and some of them were big chunks and
Speaker 1: some were smaller pieces. Uh. And eventually it took decades
Speaker 1: to do this, but eventually we figured out that this
Speaker 1: was an astronomical computer. It was able to show where
Speaker 1: the position of the planets were in relation to the
Speaker 1: Earth on any given date, including the position and phase
Speaker 1: of the Moon and the position of the Sun. And
Speaker 1: you would turn a crank in order to adjust the
Speaker 1: dials so that you could change it to any date
Speaker 1: and see what what the that actual alignment happened to
Speaker 1: be on that given date. It was also very useful
Speaker 1: for things like planning out specific events, because you could
Speaker 1: do this and find out when there was going to
Speaker 1: be an eclipse, for example, and an eclipse tended to
Speaker 1: be considered a bad men, so you might think, hey,
Speaker 1: this big festival, we want to have what happened to
Speaker 1: fall on in the eclipse, So we're going to have
Speaker 1: a special a special festival that's going to be three
Speaker 1: weeks earlier so that we don't have to worry about that,
Speaker 1: or an Olympics event that there would be another example,
Speaker 1: So it's really super cool. However, again this was something
Speaker 1: that was relatively small. We're talking about like the size
Speaker 1: of a large book, and so you're looking at at
Speaker 1: these dials rather than again being immersed in the experience.
Speaker 1: But it was really useful for checking out, you know,
Speaker 1: what a a a planetary alignment would be on any
Speaker 1: given date, because again they understood that the movements of
Speaker 1: the planets were regular and cyclical. Yeah, and so they
Speaker 1: were able to do this, and I don't want to
Speaker 1: minimize how difficult this was. They had to build exact
Speaker 1: gear ratios to represent the movement of all these planets
Speaker 1: and sometimes hand machining those yeah, yeah, yeah, and dorble
Speaker 1: amount of precision is required and sometimes you know, you
Speaker 1: would have to have things move backwards a little bit
Speaker 1: and then move forwards because from our perspective, that's the
Speaker 1: way things seem to be moving. So really really complicated stuff.
Speaker 1: Uh but still again, that's that's not quite an astronomical clock.
Speaker 1: It's very similar to one. Once we looked at actual
Speaker 1: astronomical clocks. Those look like clocks, but they happen to
Speaker 1: have either a dial or sometimes it's a uh, you know,
Speaker 1: a little physical representation of what the planetary alignments are
Speaker 1: going to be or those phase of the moon or whatever.
Speaker 1: These have been popular since the Middle Ages. There were
Speaker 1: also some of those posh sky globes that could hypothetically
Speaker 1: predict the movement of celestial bodies, and Archimedes is said
Speaker 1: to have had one background two right, so uh, probably
Speaker 1: true lost stuff about that time period. Difficult for us
Speaker 1: to verify, but but I'm willing to believe it because
Speaker 1: they are wicked smart. So uh yeah, yeah, again, we're
Speaker 1: still talking about stuff that lets you look at it.
Speaker 1: It doesn't surround you like the crazy um the globes
Speaker 1: where you would walk inside and take a seat. But
Speaker 1: that's what leads us to the more modern day planetarium
Speaker 1: that would require projection and not not like standing in
Speaker 1: the middle and projecting out by speaking more loudly. We're
Speaker 1: talking about light projection here. Okay, we've got some some
Speaker 1: planetarium talk ahead of us, but uh says here on
Speaker 1: my clock that it's time for us to take a
Speaker 1: quick break and we'll be right back. Okay, So projectors planetarium,
Speaker 1: all right. The first one was installed in a roof
Speaker 1: on a rooftop in Jenna, Germany. And I apologize, I
Speaker 1: suppose it would it be Jenna, Germany? The j is
Speaker 1: generally pronounced like a y. I did well, Jacob would
Speaker 1: be a cub Johan. I, I see where you're going,
Speaker 1: and I approve. I'm guessing it's Jenna. Any of our
Speaker 1: German listeners who would like to to reprimand me on
Speaker 1: my pronunciation feel free, because um, I should know better
Speaker 1: at this point. But it was an optical projector, so
Speaker 1: it actually used light and lenses to project images of
Speaker 1: stars on a curved surface the inside of a dome. Yeah,
Speaker 1: so this dates all the way back to nineteen thirteen
Speaker 1: for the earliest of the plans. That's when a man
Speaker 1: named Oscar von Miller commissioned the device for the Deutschet
Speaker 1: Museum in Mind. So the idea to actually use projection
Speaker 1: was agreed upon in nineteen fourteen. There was this big
Speaker 1: meeting and generally speaking, most people credit and engineer by
Speaker 1: the name of Walter Bausfeld who came up with this
Speaker 1: idea to use a projector. He was working with the company,
Speaker 1: a company called Carl Zeiss, which was an optics company
Speaker 1: still is in fact, is that that's very true? Uh,
Speaker 1: And they decided that they would use this kind of approach.
Speaker 1: They decided that they wanted to use something that was
Speaker 1: fairly new, the idea of a new source of light
Speaker 1: for people at that time. Well, their their original idea
Speaker 1: here was was to use those fancy newfangled light bulbs
Speaker 1: as instead of a pin prick, instead of having a
Speaker 1: pin hole for for each light source, they wanted to
Speaker 1: use a light bulb for each star. And they very
Speaker 1: quickly realized how complex and expensive and terrifying that would be,
Speaker 1: especially if you want to be able to move your
Speaker 1: field of vision right right. So if you had all
Speaker 1: these stars in fixed positions on the dome. How do
Speaker 1: you move them if you want to if you want
Speaker 1: to move the entire ceiling and that's oh, that's not good.
Speaker 1: Can you imagine the heat generated from those old bulbs
Speaker 1: to all of those things. So this this one engineer,
Speaker 1: Vaulter Uh supposedly said, hey, why don't we put the
Speaker 1: light in the middle and then shine it out on
Speaker 1: the on the on the inside, as opposed to poking
Speaker 1: holes on the inside and putting these light bulbs through.
Speaker 1: And people said, you're crazy, except for another engineer, and
Speaker 1: this one. This is a very interesting and tragic story.
Speaker 1: There's actually a really good documentary that we'll talk about.
Speaker 1: But there's an engineer, a scientist, an engineer named Rudolph
Speaker 1: Straubel who expanded upon Bauersfeld's suggestion. He actually said, wait,
Speaker 1: this is a great idea. We can use a projector,
Speaker 1: and not only can the projector show things like the
Speaker 1: the position of planets, which was that that was kind
Speaker 1: of the initial approach was, well, we can show the
Speaker 1: planets this way, So no, we can actually show the
Speaker 1: stars this way too. We don't have to just rely
Speaker 1: on this as being a way of showing the planets,
Speaker 1: and they all began to work on this. Now, Strawble
Speaker 1: would eventually leave the museum and this his position working
Speaker 1: on this project because he refused to divorce his Jewish wife.
Speaker 1: So this was the rise of the Nazis in Germany
Speaker 1: at the time. And UM there's a documentary called Planetarium
Speaker 1: that really follows this, and the the general perspective on
Speaker 1: Planetarium is that straw was actually a major contributor to UH,
Speaker 1: to this first planetarium, but his work was all but
Speaker 1: erased by the Nazis, and then the Nazis attempts to
Speaker 1: erase it were then subsequently erased, partly because the the company,
Speaker 1: the Zeiss Company, got split into two companies after World
Speaker 1: War Two. Half of it was in the East Germany,
Speaker 1: the other half in West Germany, and too for the
Speaker 1: West Germany side to UH to talk about Strawble would
Speaker 1: have also been to admit that they had bowed to
Speaker 1: the Nazis UH demands, and so it was not politically UH,
Speaker 1: let's see, what's the rightway prudent. It was not prudent
Speaker 1: at that at that juncture, so to speak, to make
Speaker 1: that admission. So if you're really interested to hear more
Speaker 1: about the uh, the drama behind that and also the
Speaker 1: truly the tragedy behind that story. Check out the documentary
Speaker 1: Planetarium at Anyway, getting back to the planetarium itself, it
Speaker 1: took year of research and development before construction could begin, right.
Speaker 1: Also they were there was a war from from uh, yeah,
Speaker 1: there was World War one, yeah, and then and then
Speaker 1: the nineteen fourteen nine eighteen yeah, so that we had
Speaker 1: World War one going, so that that puts things on hold.
Speaker 1: Construction will begin in nineteen nineteen. It wouldn't be completed
Speaker 1: until nineteen twenty three and was first shown on a
Speaker 1: rooftop in Jena, Germany, and then would eventually move to
Speaker 1: its permanent home in the Deutsche Museum in nine and
Speaker 1: this had what was called a star ball. A star
Speaker 1: ball this is this is a perforated sphere that that
Speaker 1: powerful light can be shown through up onto the dome
Speaker 1: like like we've been talking about um by By around
Speaker 1: a decade later, domes like this would be installed in
Speaker 1: museums around the world, especially after affordability improvements were made
Speaker 1: to the Zeis device by Armand's fits in nineteen six.
Speaker 1: He was then the director of the Franklin Institute in Philadelphi.
Speaker 1: You and he His innovation was to um to scale
Speaker 1: it down from from a starball to a star dottecahedron.
Speaker 1: Ah yeah, okay, that makes sense. You get a lot
Speaker 1: more flat surfaces. Flat surfaces, it's easier to machine in
Speaker 1: those days. The machining a sphere is not easy. No, no, Um.
Speaker 1: It was actually suggested to him by Einstein. The story
Speaker 1: goes way to go Einstein. All right, So yeah, Um,
Speaker 1: circ of the nineteen sixties, lenses would come and to
Speaker 1: use to amplify the appearance of brighter stars to make
Speaker 1: a more realistic starfield, and more expensive machines around the
Speaker 1: same time, multiple projectors, each with their own star plates.
Speaker 1: Um would let you use lights of different brightnesses to
Speaker 1: project different magnitudes of stars. Gotcha. So yeah, it gets
Speaker 1: a little tricky, like how do you represent the stars
Speaker 1: accurately because some, of course when you look up in
Speaker 1: the sky, are much brighter than others. And there's only
Speaker 1: so much you can do with with machining different different
Speaker 1: apertures of pin pricks, right right, So yeah, it was
Speaker 1: pretty complicated stuff. So how do they work today? Well,
Speaker 1: if you were to go to the one in the
Speaker 1: Deutsche museum. It's been updated several times over the course
Speaker 1: of its history, so it's not the same device that
Speaker 1: was installed back. It's had some eight million visitors or
Speaker 1: more over the intervening years. And now they use a
Speaker 1: projector that has thirty two different slides to create the
Speaker 1: images of stars and planets on the curved surface of
Speaker 1: the walls and ceiling. Now these slides have a fine
Speaker 1: pattern of holes that correspond to the actual position of
Speaker 1: stars in the night sky above Germany. It's specific to that. Yeah,
Speaker 1: I mean it would be weird for them to have
Speaker 1: a representation of the sky above somewhere else. I mean,
Speaker 1: this is this is, you know, above where the facility is.
Speaker 1: Each slide is a pair of glass panes, you know,
Speaker 1: like a slide you know, the jubilender a microscope or something.
Speaker 1: Between these pines there's a thin layer of copper and
Speaker 1: they punch holes in the copper. Now, the size of
Speaker 1: the whole determines how bright the star is going to be, right,
Speaker 1: So if you make a tiny hole, it's going to
Speaker 1: be a relatively faint star. If you make a larger hole,
Speaker 1: it's gonna be a brighter star. The lenses you used
Speaker 1: to help focus that light so that it's the right size,
Speaker 1: so you've got the right brightness and size. Yep. Yeah,
Speaker 1: you don't want to have just this kind of fuzzy
Speaker 1: blurry effect. Uh. So generally speaking, you got a lamp
Speaker 1: that's what's providing the back light, and you have special
Speaker 1: projectors for the sun, Moon, the planets, and the Milky
Speaker 1: Way to complete the picture. So this is a multi
Speaker 1: projector set up. Now, the original structure relied on gears
Speaker 1: to turn the projectors precisely to mimic celestial movements, so
Speaker 1: you would actually have someone manually turning something. We have
Speaker 1: sense upgraded now it's electric motors that do this. Uh.
Speaker 1: And again you have the gear ratios worked out so
Speaker 1: that they mimic the actual movements. So uh, you know,
Speaker 1: you could just have everything turning, but of course that
Speaker 1: wouldn't be accurate to what we actually see in nature.
Speaker 1: You have to be a little more specific so that
Speaker 1: you know when Mars is going past your vision, it's
Speaker 1: doing so at the right speed relative to the other
Speaker 1: other sites in the sky. So the neat thing about
Speaker 1: this is that you can actually obviously speed things up
Speaker 1: or slow things down. So you could sit there and say,
Speaker 1: all right, here's what the path of Mars looks like
Speaker 1: over the course of a month, and you could show
Speaker 1: it in in uh sped up time, so you don't
Speaker 1: actually have to sit there for a month to see
Speaker 1: it happen, right, Or you can reverse it so that
Speaker 1: you can say, here's what Mars did last month, right,
Speaker 1: And then of course that sets time backward. And then,
Speaker 1: because we learned that from Superman, right, if you spend
Speaker 1: the world backwards, then obviously time reverses. It's okay, they
Speaker 1: all have way back machines in turns, right, so they
Speaker 1: all everything works out in the end. By the time
Speaker 1: you leave, everything's right back to where was, so you
Speaker 1: don't have to mess with your watch. That's that's really smart.
Speaker 1: Now about six of all planetariums still use projectors like this.
Speaker 1: I get this particular figure from the planetarium in Hilo,
Speaker 1: white E, a lovely place to visit, by the way,
Speaker 1: So they use standard video special mechanical projectors to create
Speaker 1: those images of the night sky. But beginning in the
Speaker 1: nineteen eighties, some planetariums began to experiment with going digital
Speaker 1: rather than analog. It wouldn't be until the nineteen nineties
Speaker 1: that planetariums could actually experiment with full dome animated content.
Speaker 1: Uh now, full dome animated content. This is used for
Speaker 1: lots of stuff. It's not just used for planetariums. For example,
Speaker 1: there are virtual environments that use domes to represent things
Speaker 1: like say the sky for a a jet simulator. So
Speaker 1: these domes allow you to have this amazing field of
Speaker 1: view that you can then project some sort of virtual
Speaker 1: environment on, and that's more effective than say being in
Speaker 1: a flat room with corners and flat surfaces. That doesn't
Speaker 1: usually convey as realistic and experience. So for planetariums it's
Speaker 1: great because it can mimic the night sky very well.
Speaker 1: Uh Now, this this full dome approach meant that you
Speaker 1: could have some really cool effects, but it also comes
Speaker 1: with some challenges. It's not uh always easy to do.
Speaker 1: If you're using a multiprojector approach, for example, you have
Speaker 1: to make sure that all of the edges are going
Speaker 1: to line up with each other so that you don't
Speaker 1: have any kind of wackiness in between, right exactly. Let's so,
Speaker 1: let's say that you have a projector that is a
Speaker 1: certain like if you look at the dome as kind
Speaker 1: of a a pie. So you think of a slice
Speaker 1: of that pie. One projector is responsible for that slice,
Speaker 1: the next projector is responsible for the slice next to that.
Speaker 1: If those two projectors are out of alignment, then you're
Speaker 1: gonna have some stars that are overlapping each other. And
Speaker 1: then you have this additive property of light. You know,
Speaker 1: you have light from two different sources hitting the same
Speaker 1: physical space, and it's gonna be blurry, it's gonna be
Speaker 1: too bright, it's not going to represent the actual stars.
Speaker 1: So this is something that has to be very carefully
Speaker 1: calibrated every single time any maintenance is done on it.
Speaker 1: So this is true for all planetariums. It's not just
Speaker 1: for the ones that are multiprojector, but multi projector in particular.
Speaker 1: You have to make these considerations. Yeah, they generally still
Speaker 1: call it a star ball. By the way, this kind
Speaker 1: of a spherical construction into which all of these projectors
Speaker 1: are are sat is still called a star ball. I
Speaker 1: think starball is a really great word. Starball just I mean,
Speaker 1: it sounds like something out of Cartamari Domonty to me,
Speaker 1: which I think is why I'm so fond of it.
Speaker 1: I was I was thinking it sounds like a like
Speaker 1: like a John Carpenter movie, but maybe I'm thinking Starman.
Speaker 1: We've got more about how planetariums work, but before we
Speaker 1: get to that, let's take another quick break. So if
Speaker 1: you wanna have a planetarium, one of the concerns you
Speaker 1: have is that you wanted to be really dark. You
Speaker 1: don't want to have any kind of other light bleeding
Speaker 1: into it because that's going to interrupt the actual view
Speaker 1: that you want. Um Also, you know, you could go
Speaker 1: with a single projector, which would be at the center
Speaker 1: of the planetarium, so you've got a injector that's right
Speaker 1: in the very middle. Now, one thing that you have
Speaker 1: to keep in mind, there's a drawback there. You can't
Speaker 1: stand in the middle because that's where the actual projector is.
Speaker 1: These things, by the way, cost lots of money, you know,
Speaker 1: sometimes hundreds of thousands of dollars. So generally speaking, if
Speaker 1: you're in a planetarium that has a single projector, there
Speaker 1: tends to be like railings and things like that so
Speaker 1: that you can't get too close and mess with it.
Speaker 1: I remember standing right next to one for a commercial
Speaker 1: for a science fiction convention back when I was thirteen
Speaker 1: years old, and I would never been more terrified in
Speaker 1: my life that I was going to end up bankrupting
Speaker 1: my parents by by accidentally falling against this planetarium projector.
Speaker 1: But yeah, it's it's uh, it's it's usually blocked off.
Speaker 1: It takes up that center space. So one thing you've
Speaker 1: got to keep in mind is that takes up potential
Speaker 1: place for people to sit. However, sitting in the center
Speaker 1: of a planetarium is rarely the best seat, so usually
Speaker 1: you just you just make use of the outer edge
Speaker 1: as much as you possibly can. But with that center
Speaker 1: single projector, you also don't have to worry about bleeding
Speaker 1: into other projectors. Assuming you've got one that's the master
Speaker 1: projector that handles everything including the planets, the Sun, the moon,
Speaker 1: all that stuff, you're good to go. You don't have
Speaker 1: to worry about that those other issues of are these
Speaker 1: things perfectly aligned, because everything should be fine assuming that
Speaker 1: the projector itself is in good working order. The multi
Speaker 1: projector set ups that that that I was talking about
Speaker 1: a second ago are are in those starballs. But I
Speaker 1: but it sounds like Jonathan, you're talking about a a
Speaker 1: different kind of projector set up. Yeah, there's actually there
Speaker 1: are different ways you can do this. You can have
Speaker 1: the multiprojector all in the center, which is similar to
Speaker 1: that single projector I was just talking about, which may
Speaker 1: or may not have multiple lenses on it. In fact,
Speaker 1: it usually does have multiple lenses on it, so it
Speaker 1: can look a lot like the multi projector set up.
Speaker 1: But there are other multi projector setups where it leaves
Speaker 1: the center completely clear. And the way they do that
Speaker 1: is they set the projectors up along the inside perimeter
Speaker 1: of this dome and they use mirrors to reflect the
Speaker 1: lie from the projectors so that it hits the precise
Speaker 1: spots on the inside of the dome, so you get
Speaker 1: that starry night appearance. So yeah, you know, they're multiple.
Speaker 1: The nice thing is is that once you know the
Speaker 1: actual movement of the celestial bodies and you're able to
Speaker 1: represent them accurately, there are multiple ways to actually achieve that.
Speaker 1: And that's the cool thing is that we've seen lots
Speaker 1: of different approaches to this particular problem and all of
Speaker 1: them work. They just work in different ways, which is
Speaker 1: pretty awesome. It just shows the ingenuity of people when
Speaker 1: it comes to I want to represent this thing that's
Speaker 1: in nature, how do I do that? And people come
Speaker 1: up with completely different ideas that all work the uh
Speaker 1: you know, equally well, just in different ways. So we
Speaker 1: actually have we have a couple of planetariums here in
Speaker 1: Atlanta that uh you know. I think fern Bank has one,
Speaker 1: but Emory also has one, and uh, Emory's is interesting
Speaker 1: for a couple of different reasons. One is that it
Speaker 1: h it's a classroom as well as a planetarium, so
Speaker 1: it can actually double up, and in fact, the planetarium
Speaker 1: stuff can fade off into the background so that it
Speaker 1: can just be a regular schoolroom. By by by fade off,
Speaker 1: you mean you mean sink into the floor like a
Speaker 1: super villain layer. Apparently in Atlanta we have this thing
Speaker 1: about incredible equipment sinking into the floor. It's it's the
Speaker 1: planetarium at Emory. It's the Mighty mo Oregan over at
Speaker 1: the Fox Theater. Why don't why don't we have this
Speaker 1: in the office anywhere? Yeah, you know, I think Ben
Speaker 1: sunk into the floor once, but I'm not sure that
Speaker 1: anyone besides me saw it, so I could just be crazy,
Speaker 1: but I don't know. Sometimes he likes to make me
Speaker 1: think that. The other reason why I wanted to bring
Speaker 1: it up is because the planetarium itself has a projector
Speaker 1: called the Zeiss Skymaster z KP three, which is cool
Speaker 1: because it's it's Yeah, it's from the same company that
Speaker 1: made the very first planetarium projector, so again they're still
Speaker 1: in business. They're still making that. This one was installed,
Speaker 1: I believe in two thousand two, so it wasn't wasn't
Speaker 1: that long ago. Now, the one at Emory is computer controlled.
Speaker 1: It's got a key board for manual input and has
Speaker 1: thirty nine different projecting lenses of different sizes that create
Speaker 1: the stars, planets, and other celestial bodies on the inner
Speaker 1: surface of the dome, and can project more than seven
Speaker 1: thousand individual stars, plus star clusters, nebula galaxies, the Milky Way,
Speaker 1: the planet's sun, the Moon, and it can superimpose lines
Speaker 1: between stars to illustrate constellations. So if you hear about
Speaker 1: these constellations and you think I just just looks like
Speaker 1: a cluster of stars. I don't, I don't get it,
Speaker 1: then they can actually show the connections that U The
Speaker 1: inspired the imaginations of people thousands of years ago to
Speaker 1: call the stars wacky things like O Ryan. Yeah, I
Speaker 1: always had trouble with those. The only one I could
Speaker 1: ever pick out was a Ryan because I could pick
Speaker 1: out a Ryan's belt. But otherwise I was I was hopeless.
Speaker 1: I was. I was a whiz at it when I
Speaker 1: was a kid. I've had a really big astronomy phase. Yeah,
Speaker 1: I wish I had taken a course in astronomy. I
Speaker 1: never did. Uh. The one at Emory also usually shows
Speaker 1: the sky over Atlanta. Again, no big surprise, but because
Speaker 1: it is a computer system, it's one of those that
Speaker 1: can show you the sky over any given point on
Speaker 1: the art at any given time, so you can set
Speaker 1: it for whenever now. Um. The other cool thing about
Speaker 1: is that it's connected to a telescope that's on the
Speaker 1: building's rooftop, and they have a direct video feed from
Speaker 1: the telescope to the planetarium, So for astronomical events you
Speaker 1: can go and you know, yeah, just watch it, and
Speaker 1: just watch it from on the ceiling of this planetarium,
Speaker 1: which is you know, you could see a live event.
Speaker 1: They they've hosted several live events there, not all of
Speaker 1: them were some that you could watch through the telescope. Like, uh,
Speaker 1: I'm pretty sure that the Mars rover landing you probably
Speaker 1: couldn't see thither the telescope. I cannot imagine that would
Speaker 1: be possible. Now, but but they do show some interesting
Speaker 1: feeds from various sources. So these days, I mean, as
Speaker 1: impressive as that planetarium is and as proud as I
Speaker 1: am as a as a native at Lantin, that's here.
Speaker 1: Uh there are others that are even more sophisticated. We're
Speaker 1: talking four K or eight K projectors. So you know,
Speaker 1: think of the general rule of thumb, and granted it's
Speaker 1: a rough rule of thumb is four K means four
Speaker 1: times the the resolution of say a ten eight high
Speaker 1: definition television. That that's when you get into ultra high definition. Yeah,
Speaker 1: this is this is way more high def than your
Speaker 1: local cinema. Yeah, eight K even more so. Uh yeah,
Speaker 1: even if you have a four K cinema near you,
Speaker 1: eight K twice as good relations when you get down
Speaker 1: to it. Again, that's very rough. I mean, anyone who's
Speaker 1: a a true video file is cringing when I say this.
Speaker 1: But yeah, you can go and see planetariums use eight
Speaker 1: K projectors. Some of them have full three D effects
Speaker 1: at six D frames per second, so you can actually
Speaker 1: feel like you're floating through space. They can take you
Speaker 1: on on journeys all the way around the the Solar
Speaker 1: System and the galaxy. You've got data feeds from all over,
Speaker 1: like including space probes. It's pretty incredible. So yeah, yeah,
Speaker 1: some of these things can show over nine and stars
Speaker 1: that ago, go backward and forward ten thousand years into
Speaker 1: the past and future, um and and right take you
Speaker 1: so far beyond Earth to to show any kind of
Speaker 1: any kind of data that we have anywhere in the universe.
Speaker 1: Um and you can you can composite the astronomer's data
Speaker 1: and and artists composits. Yeah, it's fantastic. I love the
Speaker 1: idea of also being able to see things like here's
Speaker 1: what the Knights Sky would look like if you were
Speaker 1: on Mars. I mean, that's incredible stuff that we clearly
Speaker 1: most of us are not going to ever have the
Speaker 1: chance of looking at the stars from the surface of
Speaker 1: another planet, or to go into the center of our
Speaker 1: galaxy and check out the black hole there. Yeah. I
Speaker 1: had plans and they got canceled. The other couple that
Speaker 1: was gonna go with us something came up, and when
Speaker 1: that happened. Yeah, So that's the nice thing about the
Speaker 1: planetariums is they give us this opportunity to journey to
Speaker 1: places we physically could not get to and really understand
Speaker 1: more about our galaxy and the way everything seems to
Speaker 1: work in relation to each other based upon our knowledge now.
Speaker 1: And the other nice thing about planetariums is that these
Speaker 1: facilities update as our understanding grows, So there are times
Speaker 1: when we might learn something that ends up affecting the
Speaker 1: way a planetarium is displaying the night sky, and it's
Speaker 1: pretty easy with digital projection to fix it and relatively yeah,
Speaker 1: and so you might even be able to watch something
Speaker 1: like here's what a supernova looks like. And you know,
Speaker 1: there there have been events in the past where they've
Speaker 1: been amazing astronomical events, but many of them happened before
Speaker 1: most of us were alive, so it'd be really cool
Speaker 1: to be able to see those kind of representations things
Speaker 1: like uh Hallie's comment as another good example, or maybe
Speaker 1: if you wanted to see what it would look like
Speaker 1: with some of the other famous comments that have gone by,
Speaker 1: but you never got a chance when they actually happened,
Speaker 1: maybe it was clowney that day, or maybe you weren't
Speaker 1: born yet. It would give you the opportunity. So super
Speaker 1: cool stuff. Um really interesting again to look into it,
Speaker 1: and the fact that so many different people have created
Speaker 1: similar but different approaches for this same purpose is really cool.
Speaker 1: I mean it's it's it's rare when we talk about
Speaker 1: a technology where there are all these multiple pathways that
Speaker 1: get to the same destination. Usually we talk about convergence,
Speaker 1: where you know, competing technologies start to fall away until
Speaker 1: you have a clear front runner or maybe two possible ones.
Speaker 1: But with this there are lots of different ways. Oh yeah,
Speaker 1: and all of these interactions with multiple disciplines of of
Speaker 1: bringing together the knowledge that we have been gathering over
Speaker 1: the centuries about the universe around us, along with the
Speaker 1: optics fields that have let us use these technologies to
Speaker 1: to project stuff onto a ceiling. That wraps up this
Speaker 1: classic episode of tech Stuff How planetariums work. Hope you
Speaker 1: enjoyed it. If you have any suggestions for topics I
Speaker 1: should cover in future episodes of tech Stuff, or perhaps
Speaker 1: a topic that needs an update, maybe you just want
Speaker 1: to say hi, the best way to reach me is
Speaker 1: over on Twitter. The handle we use is tech stuff
Speaker 1: H s W and I'll tell it to you again
Speaker 1: really soon. Yeah. Tech Stuff is an I Heart Radio production.
Speaker 1: For more podcasts from my Heart Radio, visit the i
Speaker 1: Heart Radio app Apple Podcasts or wherever you listen to
Speaker 1: your favorite shows,