Planetary Radio: Space Exploration, Astronomy and Science - The Royal Observatory, Greenwich and the Quest for Longitude

Episode Date: July 28, 2015

Come with us on a visit to the home of the prime meridian for a conversation with the curator of the Royal Observatory, Greenwich about the race to create a practical means for determining longitude.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

The sound of H1, the timepiece that shook the naval world 280 years ago. We'll meet it this week on Planetary Radio. Welcome to the travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. Come with me today to the Zero Meridian, the line that begins and ends longitude on planet Earth. And the quest for longitude, or an accurate way to determine it, will be my topic with the curator of the Royal Observatory Greenwich, Dr. Louise Devoy.

Bill Nye is on vacation this week. Bruce Betts will join us later to solve a radioactive puzzle. Here and now is senior editor Emily Lakdawalla with yet more excitement delivered by the New Horizons spacecraft. Emily, how did you react to that image of really Pluto's atmosphere? I literally gasped. I just couldn't believe what I was seeing. I mean, I don't really know what I expected from the look back images, but I certainly didn't expect anything as dramatic as these layers of haze floating quite a long way away up above the surface of Pluto.

And I guess you weren't the only one who was surprised. I think it's safe to say that everybody was surprised by these pictures. I've heard of scientists crying, in fact, seeing this photo. It's really quite amazing. Do we know what we're looking at here? What is that haze? Well, haze is particles suspended in the atmosphere. They're very, very good at scattering light forward to

the viewer if you have them backlit by the sun, and that's the lighting situation here. They're probably created up there in the atmosphere when solar ultraviolet radiation knocks apart smaller molecules like methane and nitrogen in the atmosphere, and they recombine into longer and longer materials called tholins, which eventually settle down on the surface. This kind of stuff happens at Triton and at Titan, and it's quite likely that it's happening on other worlds in the Kuiper Belt. Speaking of Titan, talk about this comparison that you've put up. Yeah, so when I first saw the full disk look-back image, it's really quite striking because

you can see Pluto's atmosphere forming a complete circle, a ring around the disk. And it's not even in eclipse. The sun isn't behind the disk of Pluto. It's off to one side. It's just that the atmosphere is so tall that you can see it scattering sunlight all the way around. And you can see something very similar on Titan when Cassini has a similar point of view. In fact, both of them are the same phase angle, 165 degrees, meaning that the sun isn't directly in front of, just a little to the side of being in front of you. And it just lights up the whole atmosphere like a ring. People can take a look at this great blog entry by Emily. She posted it on the 25th at planetary.org, and it's

called Looking Back at Pluto. There is one term I want you to explain here that you use as you describe these images. You say they've been deconvolved. Do I have that right? Yes. What we're looking at, we're looking at these processed images from the Long Range Reconnaissance Imager or LORRI on New Horizons. And LORRI, like any other camera, has a point spread function where if you pointed at a light source, that's a point light source, you won't see just one pixel light up. You'll see a couple of pixels light up. Most of the light will be in one pixel, but then the surrounding pixels will get a little light too. It's a very slight blur and it's not a defect. It's actually done on purpose with some

cameras in order to make sure that you can more accurately target, you can determine precisely where a point source of light is. But in order to make the images look sharper, they process the pictures knowing what the shape of the point spread function is, trying to remove that effect from it, and it makes the images sharper. It takes some computing power, but it gives us a crisper view of Pluto. Got it. Thanks, Emily. And congratulations on the completion of your Pluto montage, which is also part of this blog entry.

Thank you, Matt. She is our senior editor, planetary evangelist for the Planetary Society, and a contributing editor to Sky and Telescope magazine. Enjoy your vacation, Emily. We'll talk to you again in a couple of weeks. I was on vacation in the United Kingdom not long ago. A highlight of that holiday was my pilgrimage to one of our planet's most intriguing and exciting science landmarks, the Royal Observatory Greenwich.

It sits atop a hill in the midst of a beautiful park not far from the Thames. I arrived early on that June morning, well before the public exhibition hours, with time to visit the lovely gardens just below the complex. Looking up, I saw atop a pole the famous bright red time ball that is still dropped at precisely 1 p.m. Greenwich Mean Time each day.

I was about to meet Louise Devoy, the enthusiastic curator of all that this wonderful facility contains. Our focus would be on one large room. Dr. Devoy, thank you so much for welcoming us to the Royal Observatory Greenwich. It is thrilling to be here. Well, thank you for coming over. It's a joy to share these amazing objects with you today. And we are standing in front of one of the most amazing objects, which heretofore I'd only seen in a book that I think we'll talk about a little bit, Ships, Clocks and Stars,

the Quest for Longitude, which actually the observatory and the Maritime Museums were responsible for. Could you tell the audience a little bit about this absolutely marvellous device? Yes. Well, before we look at the device in detail, I'd just like to say that we have these devices thanks to Rupert Gould, a former naval officer who worked as a hydrographer in the Aberdeen in the 1920s. And unfortunately, these magnificent devices at that time were languishing here at the observatory, and he rescued them and restored them and brought

them back to life. So it's thanks to him that we can enjoy them today. So John Harrison started working on these marine timekeepers in response partly to the 1714 Act of Longitude in which a reward fund of about £20,000 was set up by the British government to be awarded to anyone who could find a feasible way of determining longitude at sea. Not too different from prizes that are still being offered. I'm thinking of like the X Prize Foundation in the United States.

Exactly, yes, the Ansari X Prize and then also the Google Lunar X Prize. And then last year there was actually a new prize that was set up, the 2014 Longitude Prize, where teams are now trying to devise ways of combating global resistance to antibiotics because that really is the next big challenge of our generation. So I think that prize fund theme is still continuing very much today. This prize that was offered by the King in Parliament may not sound like that much nowadays,

but it would be worth millions in today's currency, right? Absolutely. It was an immense fortune. And like all prize funds or reward funds, it attracted lots of weird and wonderful ideas. It almost became a byword for madness or a crazy idea, something like perpetual motion. There are several satirical poems and different forms of literature that mock the idea. But some philosophers at the time and mathematicians and horologists were keen to resolve the problem in a feasible way. And eventually there were two sort of main strands of approach.

One was the astronomical method where you were trying to determine your longitude using the position of the moon against the background stars and comparing that against almanacs of data. against almanacs of data. Then you'd have the timekeeper method, where you're trying to compare your local time against a reference time, which is what your timekeeper would effectively hold for you. So you'd measure your local time and compare it against, say, Greenwich time compared to what your timekeeper was set to. Why was this such an important goal? Well, actually, the story starts much earlier, back in the 1670s,

when the observatory was set up. At that time, international trade between Europe, Africa, actually, the story starts much earlier, back in the 1670s, when the observatory was set up. At that time, international trade between Europe, Africa, Asia was really booming. Merchants were quite willing to send out their ships and crews to far-off destinations to bring back very luxurious products, such as tea, coffee, spices, ceramics. And the profits were really worth the risk. But obviously, once you're out in a featureless ocean it's very difficult to find out where you are you haven't got any particular landmarks to help you and it's much more likely that you'll veer off course now longer voyages

obviously mean that there's a much greater risk that your product will deteriorate and your precious commodities of tea and coffee and You might lose crews due to sickness, or you might even encounter bad weather and have shipwrecks. So there was a huge risk in taking those voyages, and anything that could be done to reduce the length of those voyages to make navigation easier and more accurate was really desirable, both from a commercial point of view, but also politically as well, in terms of reaching other countries.

So determining your latitude, north-south on the globe, not terribly difficult, that had been worked out, but mostly by position of the sun. But longitude, that was a real challenge. Yes, with latitude, you have the equator as a sort of natural reference point, so you're either north or south of the equator. But for longitude, your east-west position, there is no such natural equivalent. It's completely arbitrary, whether you choose Paris or Greenwich or wherever, as your zero points. So much more difficult.

And we should mention in passing, this is the zero point, almost where we're standing. Almost, yes. Just a few metres over to the east is the prime meridian, or zero degrees longitude. So 360 degrees around the globe. So you can measure your position relative to that one line. The problem is trying to get everyone to agree to use the same line. I read that a lot of folks in Paris, in France, decided or felt that really it deserved to be through Paris. Yes, and before the decision to use the meridian here at Greenwich, there were other countries that had their own meridians, whether it was through Rio or St. Petersburg. There was just a whole range of different values. Well, I'm glad we could all agree on something around the world. So the prize was offered,

and there were these two approaches that you began to talk about, one of them having very much to do with the observatory right from the start, the astronomical. Can you talk a little bit about why that presented such a challenge? When the observatory was set up in 1675, the first Astronomer Royal, John Flamsteed, was tasked with creating a very accurate star chart and catalogue that could be used by mariners. But Flamsteed took rather a long time to get going with his data. He worked for several decades without really publishing anything, so other ideas came about as well.

The idea with the astronomical method is that you need three key pieces of information. So the first is your local time, which, as we said, you can measure using the sun or stars. Then you need to measure the angular distance between the moon and a certain bright star. This gives us the name, the lunar distance method. And then finally, you need your reference. So you need an almanac that shows you the angular distance between the moon and the bright stars,

as seen from a particular known location. Because that would shift depending on where you were. Yes, so that comparison then gives you your measure of longitude. So the astronomical method had been devised over, gosh, even 150 years, even before Flamsteed. So it'd be an idea that had been brewing for a long time, but it was still very much a theory. Trying to get it work in practice, you still needed accurate instruments for measuring this angular distance between the moon and the stars, but also you needed accurate star charts, and that's where the observatory came in to really try and produce that data.

And Flamsteed, he had quite a work ethic, didn't he? Yes, he was known to be a perfectionist. He took over 50,000 observations that were eventually reduced down into about 3,000 catalogue star positions. He had a real battle on his hands. Although he was effectively appointed by the king when the observatory was founded, once the building was set up, he was pretty much on his own,

had little support other than from Sir Jonas Moore, his patron, who generously paid for many of the instruments that were set up here at the observatory. So it was a really difficult uphill battle. There are so many fascinating aspects to this story. Isaac Newton played a role and it wasn't an entirely genial one. No. Once the observatory had been set up, Flamsteed was collecting all this data.

By the 1690s, Newton was starting to get a little bit impatient. He'd already published the Principia but he really wanted Flamsteed's accurate data to develop his ideas even further particularly in relation to the motion of the moon. Newton managed to persuade Flamsteed to hand over some of the data and Flamsteed agreed thinking that it was just between friends and the correspondence is quite chatty, quite friendly

and then you can imagine Flamsteed's horror then in 1712 when he found that his work had been published by Newton and Halley as a sort of somewhat pirate copy. Halley of Halley's Comet fame. Exactly. Edmund Halley, who would later succeed Flamsteed as the next Astronomer Royal, ironically. So Flamsteed spent the next few years trying to recall many copies. I think about 400 copies of this pirate version had been published.

And with support from the king, Flamsteed managed to recall about 300 of them and legend is that he burnt them here in the park as a sacrifice to heavenly truth. So it wasn't particularly friendly relations and it took another 10 years or so before Flamsteed's work was eventually published, the official version, about five years after his death. Did he ever forgive Newton? Good question. I don't know. It's an interesting thought, isn't it? It certainly is.

He was just the first, as you said, of the Royal Astronomers, a tradition that continues today. Yes, very much. Today it's more of an honorary title. The Astronomer Royal is seen more as a figurehead for British astronomy in general, will represent British astronomy at an international level, but it's also very much involved in public outreach and engagement.

But there's no actual research done here today, unfortunately. One of the buildings here at the observatory property is Flamsteed House. Was that actually where he lived? Yes, so the room that we're standing in now is part of Flamsteed House. So it was designed by Christopher Wren, the same architect who designed St Paul's Cathedral. And Wren himself was an astronomer, so he had a keen interest in the subject. And the site was chosen essentially because, like all government projects, they were on a tight budget. And so they decided to use this former hunting lodge, or use the foundations, as the basis for this new observatory.

Wren designed this building as a dwelling house so you have four sort of living rooms downstairs, the bedroom and the supper room and so forth and then upstairs is the octagon room which is designed both as an observatory with its huge windows that give you a good view of the horizon but also as a room for pomp and ceremony. It's a good place to entertain guests as well. And it is a beautiful facility. I was here early enough that I was able to circumnavigate the entire property and saw the garden just below the building where the complex of buildings up here.

It really is a beautiful place to visit. Yes, it would have had kitchen gardens and stables and the necessary house, as it was then called, in the corner. And it really was a family home as well. Successive generations of astronomers royal lived here. They lived here with their wives, their assistants, their servants, their children. It's expanded over the years. So Neville Maskelyne built this extension here and then George Biddle Airy in the Victorian period added extra rooms

because he had quite a large family, had six children plus servants. So it's very much an evolving family home as well. Neville Maskelyne, that's a name I'll come back to in a moment. But let's pick up here with this parallel development by John Harrison, a contemporary of John Flamsteed's. At least their lives overlapped a little bit. Flamsteed, beginning with the full support of the government at that time, Harrison decides on his own, he'd already started building clocks,

to take on this challenge. It would take him years, wouldn't it, to reach this point with this device we're looking at? Yes. So Harrison came down to London in 1727 with some ideas. He wasn't quite sure how to approach the Board of Longitude, the people who assessed all the entries for the reward fund. And so he first came here to the observatory and met with Edmund Halley, who was by then Astronomer Royal.

Halley wasn't really comfortable with the ideas, he felt it was within his expertise and so he recommended that Harrison contacted George Graham who was London's foremost clockmaker at the time. Now Harrison presented his ideas to Graham. Graham recognised that actually that there could be a nugget of truth here, some really good ideas. And so he very generously funded Harrison and also crucially introduced him to the London clockmaking community. So Harrison could really draw on that advice and skills as well.

We'll talk more with Louise Devoy about the quest for longitude in a minute. This is Planetary Radio. Hey, hey, Bill Nye here. I'd like to introduce you to Merck Boyan. Hello. He's been making all those fabulous videos, which hundreds of thousands of you have been watching.

That's right. We're going to put all the videos in one place, Merk. Is that right? Planetary TV. So I can watch them on my television? No. So wait a minute. Planetary TV's not on TV?

That's the best thing about it. They're all going to be online. You can watch them any time you want. Where do I watch Planetary TV, then, Merc? Well, you can watch it all at planetary.org slash TV. Random Space Fact! Nothing new about that for you, Planetary Radio fans, right? Wrong! Random Space Fact is now a video series, too.

And it's brilliant, isn't it, Matt? I hate to say it, folks, but it really is, and hilarious. See, Matt would never lie to you, would he? I really wouldn't. A new random space fact video is released each Friday at youtube.com slash planetary society. You can subscribe to join our growing community and you'll never miss a fact. Can I go back to my radio now? Welcome back to Planetary Radio. I'm Matt Kaplan. More now from my conversation with Curator Louise Devoy of the Royal Observatory Greenwich. You can hear my complete and fascinating 30-minute conversation with Louise about the quest for longitude in the online version of today's show. That quest began in earnest with the work of the first Astronomer Royal, John Flamsteed. began in earnest with the work of the first astronomer royal, John Flamsteed.

Flamsteed's challenges were in the sky. The challenges for Harrison were down here at the surface, particularly at sea. And they were very substantial. I mean, why was it so difficult to make a clock that would run accurately, particularly on a ship? There are essentially three main problems for trying to run a pendulum-based timekeeper at sea. So the first problem is obviously motion. When you're on land and you've got your pendulum clock installed in your hallway,

it can run quite regularly, no problem. But imagine trying to be on a ship. Your ship is pitching and rolling all over the place. Trying to keep a nice, steady, regular beat is virtually impossible. The other problem then is temperature change. As you can imagine, we're here in the UK, so a fairly temperate climate. steady regular beat is virtually impossible. The other problem then is temperature change. As you can imagine, we're here in the UK, so a fairly temperate climate, but then if you head further south, you might get more tropical extremes, higher temperatures, which then may cause materials, especially metals, to expand. And then if you go further south to colder regions, then

obviously the metals contract. So there's a huge range of temperatures that can really affect the rate of the device. The third criteria really is oil as well and you can imagine these are made of several thousand parts you want to try and keep them all running smoothly. The oils that were used at this time were often quite problematic and usually caused more problems than they solved and that's one of the approaches where we can really see Harrison's skill as a carpenter come in. Because if you look closely at H1, you'll notice that some of the components are made of wood. And this is actually made of lignum vitae, which is a tropical hardwood that has these natural oils that keep it supple. So Harrison was able to draw on that knowledge and incorporate that into his design.

So no additional lubrication, nothing done from the outside? Not for those parts, yeah, very much. And that really, really does help the design. So many other innovations that I read about as I learned more about Harrison's work. It's just a marvelous device to look at with these springs and dual pendulums, vertical pendulums swinging back and forth behind there. He was a mechanical genius. Yes, and some of his ideas have made the transition from horology into other applications as well.

So, for example, in H3 we have the bimetallic strip, so a piece of brass and steel riveted together, which expand and contract at opposite rates so as to cancel out. You'll find this even today in your kettle or your toaster or your thermostat. The thermostat on my wall. Exactly, exactly. So that idea is still running through technology today. There's also some caged roller bearings on H3 as well that you'll often find in complex machinery as a way of making them more efficient and reducing friction. Some great concepts that have really endured and run through today's technology as well.

Let's walk down the hall here past, is this H2? So this is the second device, yes, H2. So H1 was actually trialled at sea because that was one of the conditions of the reward fund, was that it had to be trialled at sea. And it performed reasonably well. It was taken on a voyage to Lisbon, but it didn't quite satisfy the demands of the criteria,

and so Harrison started working on H2, or what we now call H2. This one took a lot of effort. It has different features. One particular feature is what's called a remontoir. If you look on the side, there's like a metal paddle-shaped vise. So this helps to sort of regulate the driving force. That was a new innovation that came in. And then eventually Harrison decided to abandon that and start work on H3. Yeah, he wasn't entirely happy with H2, right? He said, no, I can do better than this. Yeah, I guess a bit like Flamsteed's perfection with his starter.

He just wanted more, better running. And as you can see, H2 is still quite large. It's maybe two foot high. It's still quite bulky. You can imagine trying to take that on ship is no easy task. I particularly like this plate, made for His Majesty George II by order of a committee held the 30th of June 1737. Fascinating. So we move down to H3, which is the only one of these that's not running at the moment. Yes, sadly we're having a few technical problems. It's not working at the moment. This is the one that has the bimetallic strip and the cage roller bearings that I mentioned earlier.

Harrison spent, gosh, nearly 20 years working on this. It was a real mission to try and complete this. And then he realized that it wasn't going to work. And so he then took a completely different approach, which we'll then see in H4. And this is as marvelous as these devices are. This is completely revolutionary because he goes from these relatively huge devices to what we have in front of us now. Yes, and ironically, this is one that visitors often walk past because it looks just like a giant pocket watch.

But actually, this is the timekeeper that effectively won Harrison the reward. So it's now known as H4. The story is that Harrison was getting increasingly frustrated with H3. He was working on other projects, like all of us, working on several projects at once, and he realised that actually a watch might be a better solution rather than these big, clunky timekeepers that we've just seen so far. Now, conventional wisdom at the time

was that a watch wouldn't be able to cope with the demands of travel at sea, it was too lightweight. But Harrison realised actually one of the main things to do is to make sure it beats very quickly because the quicker it beats, the less susceptible it is to the effects of motion. So this actually beats five times a second and it also has these jewelled bearings to reduce friction and energy losses. So Harrison took many of the ideas that he developed in the earlier versions

and sort of condensed them down into this very compact version H4. As you said this is the one that really set the course for the chronometers that are still used on some ships today. Absolutely yes. So Harrison was awarded half of the prize fund, so £10,000. To try and get the remainder, he had to hand over his designs, which were then sent to other London clockmakers, and they had to prove that they could make something fairly easily, that it wasn't just a one-off fluke. Because this was a very expensive device.

Yes, very expensive, very complex. So Harrison had to demonstrate that this knowledge could be passed on to someone else to make a similar device and from that we have the emergence of what then became known as the chronometer which by the 1840s had become sort of standard issue on Royal Navy ships. He was not happy was he about only being given half the prize? No it was it took a lot of haggling and petitioning from the king to really get Harrison the final amount. His son was involved as well. He did finally receive a lump sum just a few years before he died. I think some calculations even suggest that he might have even earned slightly more than the total prize fund if you add up all the intervening amounts that are awarded to help him develop the timekeepers.

And through all of this, for people who've read the book Longitude by Davis Abel, past guest on this program, you might think that one of the other astronomers royal, Neville Maskelyne, that he was sort of the bad guy in this story, that he was holding Harrison back. It's not quite that simple though. No, I think like all historical stories, it's easy to have a good guy and a bad guy. but Maskelyne did a lot of work in developing the lunar distance method as well he did he was involved in testing some of the Harrison's so I think he remained open-minded in most senses with regard to the idea I think Maskelyne was driven by what's best for navigators how can we make this as easy and reliable as

possible and so for example when the lunar distance method was first developed, it took several hours, about four hours, to calculate your position. But with Neville Maskelyne's work, he was able to reduce this to just a half an hour calculation. So a significant improvement for navigators. And was that because of the tables that he developed with his assistants? Yes, so we have the nautical almanac. Oh, and here they are.

Yes. So first of all, Maskelyne produced the British Mariner's Guide, which is like a sort of textbook, explains how to do the lunar distance calculations. And then later on, using instruments here at the observatory, Maskelyne and his assistants developed the nautical almanac. So this is the tables of data that I mentioned earlier that you'd need as a comparison against your own values

that you've measured in the sky, and then these are the values as they would be seen at Greenwich. And it's the difference that gives you a measure of longitude. And these had to be updated every year. It was a big task. Yes, and they're still published this year as well. Every year they're published. Yeah, so it's a huge piece of work. And Maskelyne quite cleverly actually sent out a lot of the data

to mathematicians across the country who were known as computers who would actually number crunch all the data, refine it, then it would be sent to other mathematicians known as comparers who would then check the data, make sure it was all OK, and then send it all back here to the observatory. So it was a huge industrial process. Didn't one of those comparers find a couple of the calculators, the computers, cheating at one point? Oh, possibly. I don't know.

I read that in the book. Did one of these methods, the timepieces or the astronomical, did one win, or did they both come into use? I think they both came into use, yes, because you still need to use instruments for measuring your local time to then compare against your reference time, whether you're using a chronometer or the tables of data. And interestingly, in recent years, some navies have actually started to bring back some of these more traditional methods because they're worried about being over-reliant on global positioning systems in case there's any satellite failure or some sort of solar storm

that could knock out all these satellites. Or even some kind of hostile action against satellites. Exactly. We're all very vulnerable to that kind of attack. And so I think some places now they're actually bringing back some of these traditional methods using sextants and tables of data so that people can actually do it if they needed to. I actually got to talk to a retired navigator. He had been a navigator on an American aircraft carrier in the 1960s and 70s.

And I said, did you have chronometers? He said, oh, yes, we had three. Yes, yes, certainly many voyages have multiple ones. I think some of the voyage that Charles Darwin went on, the Beagle, I think they had about over 20, 22 kilometers, just in case. Any astronomer listening to this certainly knows right ascension declination. They are, to the universe, what latitude and longitude are for those of us stuck down here on the surface. I read that John Flamsteed may have been the first to use those, or at least right ascension? Yes, certainly. When he was compiling his star catalogue, he listed the stars in order of increasing right ascension.

This became sort of the foundations, if you like, for modern star atlases and star charts. Yeah, that's how we now find any object in the sky. You look up the right ascension and declination. Not being much of an astronomer, I just plug those into my telescope's computer. Exactly, exactly. And also, I mean, the great joy with the equatorially mounted telescopes as well is that they could be used for astrophotography. If you imagine with your

transit telescope or your altazimuth mount telescope, you can only look at certain parts of the sky and you have to constantly adjust the telescope, whereas with the equatorial mount, you can really track the movement of the stars, which is ideal if you want to take long exposure photographs. As I look at these timepieces, these clocks behind us here, when we first came into the room, I had the same feeling, the same thrill that I've had when I have stood in front of, for one example, Curiosity, the Mars Science Laboratory rover, before it left the Jet Propulsion Lab. or when I walked around an experimental fusion reactor, it's that same feeling of pushing the edge of human knowledge,

which is just incredibly exciting to me. I mean, does that seem to ring true for you? Yes, and I think these devices really give a sense of the work that's involved, and also I think they remind us of how much of it is a team effort as well. We think about Flamsteed and Harrison but both of them were supported by friends and family who made it all possible. To me it seems there may be a lesson in this. Here is something that a government decided this is worthy of our support because it will benefit the nation, it may benefit seafarers around the world. Do you see a message in that for us today? Possibly, yes. I think, I mean, certainly the

amount of money that was put up by the original Act in 1714 was immense. And I think perhaps maybe the modern prize that we have now are maybe not quite on the same scale, but certainly the impetus is still there. And certainly with modern communication now, we can do a lot more collaborative work and teamwork across the globe, which is a real asset that perhaps Harrison and Flamacy didn't have. I also think of government support for a project for research and development that might not otherwise take place because a corporation or an individual even today, like Harrison, might say, well,

that's years of work. I have to make a living. I can't take on something like that. Yes, I think certainly for Harrison, it was very much a personal passion as well. He was very driven to do the work as well as think about the financial rewards. So I think there's plenty of scope there that we can see in today's innovators as well. There's plenty of scope there that we can see in today's innovators as well. Let's talk for a moment before we finish about the observatory itself. I think it is absolutely wonderful that this facility is maintained and that the public is so welcome here. Can you tell us a little bit about what happens here and what you're trying to communicate?

Well, I think our most popular feature here at the observatory is, of course, our prime meridian line, zero degrees longitude, which was determined by the Airy Transit Circle telescope, which you can still see in our meridian observatory. So I think people like a sense of standing on that line and thinking of where they've come from, whether it's back home somewhere and thinking what time it is there and what time it is here. That's quite a powerful experience. We also have a range of public outreach and education activities. We have our Peter Harrison Planetarium, where you can either have a night sky show or more of a film cinematic experience.

One of our biggest projects is the Insight Astronomy Photographer of the Year competition, where we invite amateur astronomers to send in their images, and we get entries from all over the globe. It's absolutely incredible across a range of different categories and then the winners images are displayed in the autumn and that's a really great event. It's also simply a beautiful setting here on top of the hill. Yes we're certainly very privileged with the view and certainly that was one of the reasons for choosing this site in the first place is that it gives you a great view of the horizon, you've got easy access into London via the river,

but you're sufficiently out of town to keep away from the smoke, certainly in the 1670s. It's just a beautiful environment with the parkland, just a nice place to visit. And there is one unmistakable feature of the observatory, I believe it's the highest point on the observatory, which is that funny red ball up on top of one of the buildings. Yes, that's our time ball. It's set up in 1833. It's raised up at 1pm each day and then it's dropped precisely, so it just raises a few minutes before and then drops precisely at 1pm. And the idea is that mariners down the Thames, looking up the the hill could then check their kilometers before they head off across the ocean and we still do it today. It's a really nice icon, it's a link with our heritage as well. Maybe it's not used today for what it was originally intended

but it's a really nice part of our history. How did you end up in this job of curator? Oh gosh, a long journey. I started off in astrophysics and then I did an internship at the Smithsonian and I really enjoyed working at the Air and Space Museum and that really got me into the history bug and then I came back and studied history of science and museology and I've worked at various museums before coming here. And you've written about some of the devices we've seen here and some of the development of navigational devices,

which we won't get into, quadrants, sextants, things like that. You must be fascinated by these devices. Yes, I think we're so dependent on computers now, it's difficult to realise that actually people could do a lot of functions without computers using these amazing devices and some very complex mathematics, I have to say.

I don't envy them in that respect. But when you look at the skill and the craftsmanship both in terms of making the the instruments and actually using them as well it's so impressive. It has been so delightful to be able to spend a few minutes with you here at the Royal Observatory Greenwich and actually stand in front of these devices and I just want to thank you for giving us the opportunity. Oh, thank you. My pleasure.

And I hope you get to look around and enjoy it for slightly longer. I look forward to it. Time for What's Up on Planetary Radio, which means it's time to talk to the director of science and technology for the Planetary Society. But he has a new title now, Program Manager for... for... Chocolate. Yeah, well, but you had that title ages ago. No, for LightSail. This is, I just learned this last week.

Congratulations. Why, thank you. Tell us about this. What's your job? I have multiple components. So what happened was Doug Stetson, who was basically doing a program and project manager type role, has stepped aside because he's a busy guy. And Dave Spencer at Georgia Tech, who was mission manager on the first light sail, is the project manager. So handling all the technical management and stuff.

And as program manager, I'll be a prime interface with the Planetary Society and the rest of our staff, like you. And that's the sad part of my job. Thank you very much. I'll also be handling exciting things that'll be way better than talking to you, like contracts. Oh, yeah. It took a moment to register that you were being ironic. And budgets and, you know, the fun stuff.

You can admit it. This will be the best part of the job, talking to me, giving us updates. Maybe not weekly, but at least we'll have somebody handy that we can talk to about where the project is going. It's true. somebody handy that we can talk to about where where the project is going it's true i'll be handy and tracking what's going on directly in the the flow of information so yeah no you're you're right matt the best part of my job is talking to you oh no matter no matter how the titles change all right enough of that crap get on with it what's up golly well uh it's a it's a slow week in uh in planet land in the sky although you can try because they're really bright to still catch venus and jupiter soon after sunset low in the west but

they're getting very low saturn the easy target it's up in the south in the early evening a preview we've got the Perseid meteor shower peaking like August 12th, 13th, but actually increased shower counts starting even as early as now for the next two, three weeks. But I'll remind you next week. Man, it seems like it was only last year

we were talking about the Perseids. I know, it's weird. On to this week in space history. It was 1971 that Apollo 15 was landing on the moon and the first humans driving a car on the moon. Not just a car, a dune buggy. The lunar roving vehicle, please. Yeah, well, you can call it that. We'll see what other people think we should call it later in the show.

But first, on to random space okay apollo 15 was the first apollo to release a sub-satellite into lunar orbit shortly before leaving lunar orbit apollo 15 released pfs1 a small satellite to study plasma particle and magnetic field environment of the moon and do a little lunar gravity mapping. All right, we move on to the trivia contest. We asked you, what was the mass of plutonium flown on the New Horizons mission? How'd we do? How we did is an interesting question.

Big, big response, but something of a discrepancy in the answer, which I'll allow you to explain in a moment. But first, Random.org chose Brian Foster of Mililani, Hawaii. Aloha, Brian. He said 10.9 kilograms of plutonium-238, which is the answer we got from almost everyone, I think there may only be one exception. Is he correct? No. No, this is an interesting case where I believe everyone is wrong. And there's a second issue where I wasn't quite as precise as I should have been. But here's the deal.

There were 10.9 kilograms, the answer almost everyone gave. That was the design baseline for New Horizons. That is not what they flew because of various issues, including a shutdown at Los Alamos in 2004. There were delays in fuel processing. Anyway, nutshell, RTG was filled with only 9.75 kilograms of plutonium dioxide. 9.75 kilograms of plutonium dioxide. Now, we, in researching this, found that Wikipedia is what listed 10.9, and everyone bit into that. But Wikipedia cites a source from 2003, which was when they were still doing design baseline and had not reduced the amount.

Now, there is a separate issue. Did you want to bring that up? You know, we should bring that up because the one person, Ed Lupin, down in Sunnyvale, California, he said, you probably intend to accept the answer 10.9 kilograms. No. He said, but if you do, I must protest strongly. That's the mass, he says, of the plutonium dioxide. Please explain. So this is a separate issue. So again, he was using the 10.9. 10.9 and the 9.75 seem to be the mass of plutonium dioxide, which is the way you pack plutonium into a spacecraft. So technically, it would be slightly less than 9.75

since I, being imprecise, asked how much mass of plutonium there would be. However, the plutonium atoms are much, much like, you know, order of magnitude heavier than the oxygen atoms ballpark. So it's still close to the answer, but there's even that subtlety. But since, yeah, yeah. A very complex answer, but good work, Sherlock. Thank you for figuring this all out. We are going to send the Planetary Radio t-shirt to Brian Foster.

And I did say two weeks ago that we would have a little bonus here. It is a brand new... Plutonium. Or is it plutonium dioxide? I always forget. I think the dioxide because it's so much safer. No, we're going to send him a brand new light sail patch, and it is beautiful.

It is absolutely gorgeous. I've actually only seen pictures. I haven't seen one in person, but it looks really cool. Honorable mention, better than honorable mention, also to Ed Lupin for going into a bit more detail. Take us on into the new contest. All right, I've learned a lesson. Here's a question

that has no right answer. If you were a car company trying to market the lunar roving vehicle for whatever purpose, what would you name it? And what would your slogan be for it? We will judge on humor and or effectiveness or however the mood strikes us. Go to planetary.org slash radio contest. Get us your entry. Got that right. However the mood strikes us. That is the way we roll as did the car on the moon. Is that your slogan?

No, no, no. I'm not submitting. You have until the 4th. That would be August 4th, Tuesday at 8 a.m. Pacific time to get us this answer and Planetary Radio t-shirt and a cool light sail patch will be the prize. All right, everybody, go out there, look up at the night sky and think about radioactive rice. Thank you and good night.

It's so good for you. He's Bruce Betts, the director of projects for the Planetary Society and now the light sail program manager. He will continue to join us in spite of that every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California and is made possible by the timely members of the Society. Daniel Gunn is our associate producer. Josh Doyle created the theme. I'm Matt Kaplan. Clear skies.