Podcast: Telescopes that changed astronomy

From Galileo's refractor, to the Hubble Space Telescope, to the JWST - there have been some telescopes that have changed how we look at the night sky.

Published: August 12, 2021 at 2:12 pm

Telescopes have come a long way since Galileo and Newton created their first astronomical telescopes back in the 17th century.


Today, the descendants of these two models can be found all over the world and even above it.

This month, we take a look at the telescopes that have changed astronomy - Galileo's, Newton's, Hubble, SOHO and the upcoming era of extremely large telescopes and the James Webb Space Telescope.

Listen to more episodes of the Radio Astronomy podcast.


Ezzy Pearson Greetings, listeners, it's time for the September 2021 episode. I'm News Editor Ezzy Pearson, and I'm joined on the podcast today by staff writer Ian Todd.

Iain Todd Hello.

Ezzy Coming up later, we'll be telling you how to observe the lunar X and V on the Moon, but for now we're going to be taking a look at what we learnt putting together the September twenty twenty one issue of the magazine. Now, when it comes to astronomy, there's really one instrument that defines the entire discipline, and that's the telescope. There are, of course, other ways of observing the night sky with your naked eyes and with binoculars. But certainly when it comes to the world of doing professional space science, it's telescopes that really do the lion's share of the work. And over the years, there have definitely been a couple of telescopes that have really made their impact in the field of astronomy and revolutionised how we look at the night sky.

Iain Yes, exactly. And sort of I suppose if you if you are thinking about the telescopes that have changed astronomy, you would go all the way back to the first telescope, wouldn't you? Which is which is sort of generally considered to be Galileo's refractor. I mean. I was thinking about this, and, you know, usually when something as something that's a really sort of ubiquitous invention that's everywhere, I think it's quite difficult to sort of actually pinpoint what the first incarnation of that was, you know, because who can say he was the first person to sort of create the, you know, the optics that would magnify light. But generally speaking, when we're talking about sort of European astronomy and the telescope as we know it, in terms of a celestial observing instrument, people go people go back to the Netherlands and 1608 and with the spectacle makers, Hans Lippershey, Zacharias Johnseen and Jacob Matteus. So they are sort of considered to be the first people who created the concept of a telescope. But as far as I understand it, those were mostly used for earthly matters, for observing things on Earth and for military purposes and things like that. But the story goes that it was Galileo. He was the first to create his own refracting telescope in 1609 and use it for the purposes of observing and bodies of the solar system for observing the stars.

Ezzy Refracting telescope is referring to ones that uses its lenses as opposed to any other kinds of things, just in case anybody listening at home wasn't sure.

Iain Cool. Cheers Ez. Now supposedly Galileo's first telescope could magnify objects by about three times, but he kept working on the instrument and it got up to like eight times magnification, eventually 30 times. And the really interesting thing about when you consider Galileo's telescope and its effect on astronomy, it's not just that he created the capability of observing distant objects like the moon and the planets. And it's also that is sort of. Almost single handedly changed the way humanity considered itself within the context of the universe. And so the first of the first objects Galileo sort of observed were like the Moon. We observed the Moon and he created sketches of the Moon and he found it had mountains and craters and all these features. And then, I suppose, most famously observed Jupiter, four of its moons, its largest moons, which now, of course, we knew as the Galilean moons, which are Europa, Calisto, Ganymede and Io and those I mean, you know, astronomically speaking. It's it's fantastic, of course, getting a closer look at these of these bodies. But it's also sort of noticing, first of all, that the moon is sort of imperfect and it's not this perfect sphere, the sort of almost like Godly otherworldly, perfect sphere. It does have sort of imperfections.

Ezzy Yeah, exactly. Because at the time, a lot of people's understanding of how the heavens and the solar system works was that it was a perfect system. Everything was based around perfect circles and everything orbited in perfect circles. And it was about this time that they were beginning to realise that actually the heavens weren't that perfect. And, you know, the Moon's got wibbly bits on it

Iain Yeah. Wibbly bits... I wonder if that was the term Galileo used to describe it when he was..

Ezzy whatever the word for wibbly is in Italian.

Iain Uh, yeah. Yeah, you're right. And also, of course, this idea that, you know, Earth is at the centre of the solar system or Earth is at the centre of the universe, which in a lot of sort of work on the on the heliocentric model had been done by Copernicus. You know, the idea that the Sun is actually at the centre of the solar system and everything revolves around the sun, orbits the sun and and observing Jupiter and its moons, Jupiter's a planet. Jupiter has moons. So maybe Earth is also dragging the moon across the solar system. Maybe maybe the moon is going round the earth and earth is going around the sun and the sun is actually at the centre of the solar system. And so, yeah, as as you said, it's sort of helped us understand maybe perhaps our own sort of insignificance, but also it made those celestial objects a bit more ordinary, which I think in a way makes them a bit more extraordinary because you sort of think, well, they're not sort of these like perfect spheres. There are imperfections and those imperfections are there to be studied and understood. And there must be other imperfections throughout the throughout the solar system, throughout the cosmos that are just waiting to be discovered and understood.

Ezzy If you actually the way the telescope was described in the early patents and people talking about it was an instrument to make things that are far away look as if they are close up. And that really kind of hit for me because it suddenly made me realise it is you know, we take for granted the fact that, you know, everything's got a zoom lens and you can look at stuff that's far away. But this was just like even the concept of being able to do that was completely new to these people. So it must have been quite a big shift at the time.

Iain Yeah, it always thinking with that sort of thing, it always brings me back to the late Patrick Moore's house, because he called his house Farthings, which was like a play on words, far things. And when you think about that, it's sort of like a humorous pun. But there's also something quite philosophical about that and something sort of it really gets to the heart of what astronomy is, isn't it? You're just basically trying to see far things and get clarity on it.

Ezzy And it's just as the telescopes get bigger, bigger things get further away. That's all that happens.

Iain As if there's a few other sort of Galileo's observations that are worth sort of touching on. And he did observe Saturn's rings, but he didn't realise that there were rings. He thought there were like perhaps moons or I think he called them arms. He wasn't sure what they were. And it wasn't until a Christian Huygens used even better telescopes. But 50 years later, he was the first to sort of say that there were rings and which is obviously why the where the Cassini-Huygens mission got its name from the Huygens lander that landed on Titan named after Huygens discovered Saturn's rings. And he was also Galileo was also one of the first Western astronomers.... There was a group of European astronomers who sort of independently of one another were observing sunspots at the time, which are these sort of dark spots that are cooler, cooler spots on the surface of the sun. So they appear darker than their surroundings. And there were some of the first Western astronomers to observe them. But apparently, apparently, we of the Chinese astronomers were observing sunspots just almost as long ago as like 165 B.C. Um, we've got records of that. But as I say and that was one of them, one of those big observations as well. But I think ultimately, you know, as we've said already, sort of getting beyond the actual practicalities of Galileo's telescope and what it enabled him to see. I think its its biggest achievement was just It's almost sort of kick starting the field of astronomy and also this idea that we're that the human race isn't at the centre of the universe and the Earth isn't at the centre of the universe, and there are mysteries yet to be solved. And everything can't be sort of explained away by perfect circles and perfect sort of symmetry. And but it brings us nicely under the next telescope, because I suppose Galileo's observations of moons and orbits was one of the sort of concepts and theories that was later developed by Isaac Newton. And he sort of, many would say, improved upon Galileo's telescope design, would you say?

Ezzy Well, he came up with a different design, whether or not it was better, I think it depends on who you talk to. What he designed was the reflecting telescope. So this is a telescope that used mirrors to focus the light instead of lenses. So exactly the same principle of using magnifying and focusing light to make the image bigger. And he wasn't the first person to try to do this. Lots of other astronomers have been trying in, such as Niccolò Zucchi and James Gregory, which are the people who also tried. But Newton was the first person to be successful. And this was in the mid 17th century, so only about 50 or 60 years after Galileo had made it the first telescope. And the reason why people were trying to find another way of making telescopes was because Galileo's telescope was affected by something called chromatic aberration. And what this meant was that the light... Sort of on the edges of various objects picked up these kind of like blue and orange fringes, and nobody was quite sure what they were. Newton worked out that what was happening was that light wasn't a single colour. It was made up of lots of colours and the lenses were actually splitting apart that light and creating this chromatic aberration. So he thought the best way to get around this was to just get rid of the lenses and use mirrors. Now, the problem was to make the best telescope that would produce the sharpest image you wanted to use. You wanted to use something called a parabolic mirror. So this is a parabola is basically if you can't be asked to explain that. Sorry, I might move where I am because I keep getting loads of straight noise. OK, I'll just keep going. Yeah. So he decided the best way to get around this was to just get rid of the lenses entirely and use mirrors. The problem was that they needed to use a very specific shape of mirror called a parabolic mirror. And these were very hard to produce. It was a very specific shape because bear in mind, at this time, everybody was trying to produce their mirrors by hand, you know, they were grinding them by hand and they didn't have all of the fancy instruments we have today to make sure that it was exactly the right place, exactly the right shape. What Newton did compared to the other people who'd been trying at the time was make a spherical mirror, which is a lot more of a kind of smooth shape. It's a lot easier to grind. It's a lot easier to sort of make sure you've got it correct. This did introduce a new type of problem. It got rid of that chromatic fringing aberration and introduced spherical aberration where different bits of the light hitting different places on the mirror don't quite focus in the same place. And it blurs out your image slightly. But a lot of people thought that problem was better than having these weird colour fringes on the side of your telescope. He first showed his telescope off to the Royal Society in 1671, where it was an absolute hit. Everybody loved it. He ended up demonstrating it to King Charles II. And it's become the basis of pretty much every mirror based reflecting telescope since has been based on Newton's design. Another 50 years after he made it. John Hadley, another astronomer, came along and worked out how to make parabolic mirrors, eliminating the spherical aberration. And then again, in 1930, somebody else came along, Mr. Schmidt, and created the Schmidt corrector plate, which was as it sounds, just a glass plate that went in front of the telescope, and that's adjusted all of the lights slightly so that you could make a spherical mirror focus and get rid of this aberration and that made telescope suddenly much cheaper and easier to make as well. So Newton came up with the original design, but it has been adjusted and perfected in the years since.

Iain Yeah, and it's incredible. And as you said, you know, it's Newton's design informs the still informs the reflecting telescope today, which be the Newtonian telescope, being a perfect example. And, you know, this is the same with the refractor. Both models are still being used today by amateur astronomers and professional astronomers. And, you know, I mean, you sort of think about the reflecting telescope built in Burr castle by Lord Ross, you know, the great leviathan in Ireland and so many other famous telescopes since then and huge observatories that have sort of adopted that sort of reflecting, reflecting telescope design. It's incredible, isn't it? You know, like you make something and it's a good design and it just it's like it's sort tweaked throughout the centuries. But, you know, it's a good design is a good design.

Ezzy Yeah, they just basically got bigger and you fixed the odd problem here, the odd problem there, and now it tends to be do you like to have... because mirrors are cheaper and easier to make than lenses. So do you want the nice cheap mirror so you can have a good lot of area? But mirrors are a bit hard to take a lot of finagling to reflecting telescope. So instead, do you go for the refracting telescopes, which you basically just plonk on a tripod and you good to go.

Iain You don't need to collimate it or anything like that.

Ezzy But yes, most of the professional telescopes out there in the world today are based on the reflecting on the Newtonian design. And there's one particular one which other people might have heard of, and that's the Hubble Space Telescope.

Iain You might just have heard of that one. I know. I mean, like when you think about, you know, Galileo and Newton and Telescope designs, if you could go back in in time and tell them one day there's going to be a telescope that's actually going to be in space orbiting Earth. I mean, they just blew their minds. They just wouldn't believe you. But yes, no, as you say, I mean, you know, you can't talk about telescopes, the change, the something without talking about the Hubble Space Telescope, which launched on the 24th of April, 1990, launched into Earth orbit. It's a telescope that orbits Earth. And the idea goes back to the 1940s. And it's sort of attributed to the US astrophysicist Lyman Spitzer Jr who spoke about launching a telescope into space so that it could observe beyond the distorting effects of Earth's atmosphere. And then in the 1970s, the US Congress approved funding for what would eventually become the Hubble Space Telescope. Hubble was named after Edwin Hubble, who was the famous U.S. astronomer in the 1920s, who made observations that proved it Andromeda Galaxy layer beyond our own galaxy, and therefore there are other galaxies beyond our own. And also his calculations led to evidence that the universe is expanding. So was sort of no wonder that the Hubble Space Telescope was named after such an influential astronomer who made some of the biggest discoveries of the 20th century. And I also think when you sort of go through the list of deep sky objects that the Hubble Space Telescope has observed over the decades loads of them are, for example, Messier objects or NGC objects that were maybe first discovered by astronomers like William Herschel. And again, it's the idea of going back, going back in time and seeing William Herschel, looking at a sort of distant galaxy or nebula as he might have known it, and just. Just imagining what he saw when he looked at a specific galaxy or deep sky object or globular cluster or something like that and what we can what we've now seen with the Hubble Space Telescope, and it's just completely changed the way we look at the universe. I suppose you can't really talk about Hubble without at least talking about the optical flaw that had to be corrected. Can you know, I mean, that's sort of like a it was a pretty big, pretty big failure at the time, I think, because I think they were pretty sort of NASA's pretty sort of lampooned in the press. The you know, this massive telescope was going up and using public funding. And it doesn't even work.

Ezzy Oh, yeah. No, it got I remember there was the film Naked Gun featured a joke. It was like a list of all of the biggest, most expensive failures throughout history. And the Hubble Space Telescope was one of them. And that was a film done in between that. So it was it was it was a big joke.

Iain I didn't know that. It's years since I've seen that film. I have to go back. But, you know, the great thing about Hubble was it was designed to be serviced. So once they came up with the idea, they sent astronauts up on the space shuttle and fixed the problem on them throughout the throughout the years and various space shuttle missions have repaired and upgraded Hubble. And, you know, with this new technology, as new technology has has become available and when you think of some of the most iconic images of space they have, probably they've probably come from Hubble Space Telescope. So it's that sort of direct effect on popular culture and sort of, I suppose, like astronomy and space and cosmology within the mind of the general public and sort of non astronomers. And so I thought we were just going through a list of some of the just a few of the many things that Hubble has done. And so it's helped astronomers determine the age of the universe. It's pretty good. It's not a bad one.

Ezzy Good stuff.

Iain And the first confirmed detection of a supermassive black hole at the centre of Galaxy M87. You think of the pillars of creation image in the Eagle Nebula, these cosmic clouds, and you can see sort of newborn stars shining. And the Hubble ultra deep field in 2004 revealed over ten thousand galaxies, some nearly as old as the universe. And it's been used to explore gravitational lensing, which is a phenomenon initially predicted by Einstein, where the light from distant galaxies is magnified by the mass of closer galaxy clusters. So it's sort of like a cosmic magnifying glass using the mass of galaxies as a sort of a magnifying glass, which is pretty cool. Closer to home, it's observed, you know, iconic features such as like Jupiter's great red spot, spotted fragments of Comet Shoemaker-Levy crashing into the planet and produced the first images of Saturn's moon Titan. And it's discovered moons around Pluto, around Uranus. It's made measurements of exoplanets, planets orbiting stars beyond our solar system. I mean, you know, you could do a podcast on just the Hubble Space Telescope alone, which I think we did do quite possibly in June when it was its anniversaries

Ezzy You could you could write that people have written books and all kinds of things. There's fifteen thousand scientific papers at least have... That's the last number I have. Numbers probably gone up by now... Have come out of data taken by the Hubble Space Telescope. And that's just going to go up and up.

Iain Yeah, exactly. And even after Hubble retires, when it eventually does that that data will be used by generation after generation of PhD students writing their papers and, you know, planetary scientists and cosmologists and astronomers. But, yeah, I mean, just speaking of US retirement, there were sort of fears relatively recently within the past few months that the Hubble is in a bit of trouble. But it seems to have pulled through, doesn't it?

Ezzy Yes, so Hubble is at this point, it's well over 30 years old, it's beginning to show signs of its age. So back in July, back in June, there was a. A computer fault basically that put it into safe mode and the team behind Hubble ended up taking a month to get it back online. Hubble had had problems previously with various things going off online. Stuff happens, but most of the time NASA could get it back online almost instantly, like just be down for a couple of days. But this time it was down for an entire month, which had a lot of people worried. And it's you know, it's basically Hubble has lots of backups on it. Every space mission does. But now the backups are beginning to. They're relying on a lot of the backups and the backups are beginning to fail as well. So there is concern that the days of Hubble might be coming to an end. We don't know when. And they are going to I'm sure that NASA is going to run Hubble until it dies. It's just way too useful not to. So we will have to wait and see. Hopefully it will be around for another couple of years, hopefully made it to its 35th anniversary in 2025.

Iain At least we'll get another podcast out of it.

Ezzy Exactly.

Iain And just before we move on from space telescopes, there is another one I wanted to talk about, which is SOHO, the Solar and Heliocentric Observatory, which is a joint NASA and European Space Agency project, mission and which launched in 1995. And rather than sort of looking outwards to the cosmos, it's looking inwards because it's looking at the sun. It was only supposed to operate from 1995 to 1998. But it's been so successful that its mission has been extended multiple times, which is pretty useful if you're observing the sun, because the sun goes through a period of peaks and troughs and its activity, quiet periods, and then really active periods of about 11 years called solar cycles. So SOHO has lasted longer than anticipated, which means it's the data can sort of analyse these peaks and troughs, these solar cycles. And when you think about it, if you're going to launch an amazing telescope that can look at cosmic objects without the distorting effects of Earth's atmosphere, you would launch to look at the sun. Wouldn't you? You know that the sun is the source of our life. A constant influence on the planets? Some of the bodies of the solar system shapes and affects them. So understanding the sun sort of helps us understand the processes of the solar system. And it's also observing the sun is also it's really our best chance that our best opportunity to observe a star up close. Is like there's a star just there that we can we can take a look at and analyse and work out what's going on. And yeah. So SOHO has looked at solar phenomena like coronal mass ejection and prominences, all of which sort of which do you think need to be better understood? So SOHO has really led the way in solar science, it's captured images of the Sun's convection zone, which is this upper layer of its interior and it's studied sunspots. And that's really cool. Thinking back to Galileo and all those other European astronomers observing sunspots or even going back to, you know,165 BCE and the Chinese astronomers were looking at sunspots and looking at what they are. And now we've got an orbiting telescope showing us some amazing images of the class and examining them different in different wavelengths and things like that. And it's also been measuring the solar wind, which is this stream of charged particles that emanates from the sun and it's Aurora and sort of affects the bodies of the solar system. But a prime minister who's apparently so, who was also discovered three thousand new comets didn't know, and new solar phenomena called coronal waves and solar tornadoes. And so it's had quite a quite a sort of... Lifespan so far. Yes. Well, if you go to the NASA website, there's amazing images and different wavelengths of the sun and you can see all these glorious videos and animations and things. It's fantastic. It's not really spoken about that much, but yeah.

Ezzy Yeah, it's the sun doesn't get the credit in astronomy. And it's like, yeah, you can go on the SOHO website and look at daily updates and see what's going on with the sun right now. And there have since SOHO there's been a couple of more solar probes that have gone out of particularly the solar orbiter and the Parker solar probes. But those are the ones that are going to be getting right in close to the sun or SOHO's kind of set back quite a lot. It's closer to Earth orbit. So it's looking with a very big telescope from a distance. But that gives us a great view and hopefully helps us predict things like solar weather, predict whether a solar storm is on the way, what we're likely to have an aurora tonight. All of these kinds of things come from SOHO.

Iain Fantastic object.

Ezzy Yes, but so those are some of the big telescopes that in so those are some of the big telescopes from the past, but obviously people are constantly building new ones and there's quite a few that are on the way, which whilst they haven't changed the way we look at astronomy yet, they're probably going to in the future. On Earth there's been a big boom lately in building what's called extremely large telescopes, because astronomers like to name things very simply sometimes. And this is the sort of collective name for any telescope that has a mirror over 30 metres. And the reason why we haven't built any mirrors this big before is because mainly for a long time there wasn't any point. one of the big advantages with Hubble is that it's above the Earth's atmosphere, which means it's not affected by something called seeing. That's where the Earth's atmosphere wavers, as it's different heat, as it's moving around. And that causes the light passing through it to waiver as well. And it blurs the image. So if you've got a mirror that's over a couple of metres wide, there's no point in getting any... because usually with the telescope, the bigger the mirror is, the finer resolution you can get. But over a few metres, the resolution is so fine that it's just blurred out at that point by this effect of seeing. That changed in 1990 with the invention of something called adaptive optics. And this is where underneath the mirror you have a bunch of little arms, a little fingers that basically just poke at the mirror and deform it slightly. These are, of course, robotic figures controlled by a computer, not like people standing there. But that's funny an images as that I just had in my brain. But, yeah, if you. But what that does is it deforms the mirror slightly and using various things like using a GuideStar to lock onto and some fancy computer work, the telescope can actually correct out this blurring effect from the motion of the atmosphere. And that's suddenly meant that you could build telescopes that, you know, 20, 30 metres across, and you'd get the benefit from them. Unfortunately, you then have to work out how to build a mirror that is 30 metres across. That is incredibly difficult. Like, for one thing, just the logistics of building something big, like how do you grind a telescope that big? How do you transport it? And also, there's a much bigger problem, which is glass is heavy, metal is heavy, and in fact to get so heavy that if you were to build the telescope that big, it would deform under its own weight. So instead, what they do with these big telescopes is they cut them up. And if you look at the sort of designs for these telescopes, they are made up of dozens and dozens, sometimes hundreds of hexagonal mirror segments that slot together, and that's how you come up with these absolutely huge – or We will in the future – come up with these absolutely huge mirrors. There are currently two over 30 metre telescopes being built. I should add that these are over 30 metre visible light telescopes. We've been building absolutely huge radio telescopes for years. There's one that's half a kilometre across in China. But when it comes to visible light, they tend to be much more. So there's two other things that are being built. There is the thirty metre telescope, again, very on the money name there, being built on top of Monica in Hawaii, and that's due to be finished by 2027. And then there is the European ELT - European extremely large telescope. That will be built in Chile and that's going to be ready in 2025. And both of those are currently under construction. So hopefully within those soon. And who knows, there might even be more

Iain Yeah. I mean not just not really hammers home what you were saying about moving a mirror of that size because they have to be in places like the Atacama Desert in Chile where. You know, like you, like just you....

Ezzy You can't put it on the back of a truck because there's not even like it's 30 metres long, it's also 30 metres wide, like. No. Yes, so you have to cut it up and put it on a truck.

Iain Or putting it on Mauna Kea or something like that is absolutely incredible, isn't it? Yeah, I mean, yeah, but because I suppose, you know, even harder would be launching that into space. So you get the adaptive optics enables you to build these huge telescopes and not have to worry about launching them into space because you can correct for the distorting effects of Earth's atmosphere through A.I. essentially.

Ezzy Yes, exactly. You can. Having said that, they are launching one into space. It's just that this one is going to be a little bit more modest. It's going to be 6.5m across. But again, with this kind of segmented mirror, and that is the long awaited James Webb Space Telescope, or JWST. And this is it's been billed as the kind of successor to Hubble in that it's going to be the next big space telescope. But it's actually very different. It doesn't look at visible light. It looks at Infra-Red light. And that's really useful because Infra-Red Light can get can go through things like dust, which obscures most of Hubble looks at. And also it's given off by things that are too cold to give off visible light will still give off Infra-Red light. So that lets you look for things like planets and stuff. But what's really cool about JWST is it's been made up of a whole bunch of... 18, in fact, hexagons, that are gold plated. It looks very shiny, very bling if you look up pictures of it. And these are all honeycombs together. Unfortunately, a 6.5m Mirror is still too big to go on a rocket. Most rockets are only about three metres across. That's why Hubble's mirror is only about two and a half metres. So what they've had to do is they've had to put these 18 sections together and then fold up the mirror so that it will fit in a rocket

Iain That's amazing.

Ezzy Which it's just the idea of folding up a mirror amuses me quite a lot. And then when it gets into space, it will unfold. But it was supposed to launch many, many years ago, but it has been beset by a lot of delays. The biggest one is to do with its sun shield. So the JWST is looking at Infra-Red light and that means you want your telescope to be very cold. If you don't have a cold telescope when you're looking at Infra-Red, you might as well have built a regular... It's like building a regular telescope out of light tubes or you're going to see is the telescope not what it's looking at. So they have to keep it very cold. And they do that through this thing called a sun shield, which is a tennis court sized umbrella, basically, which shields the entire telescope from the sun. And again, this needs to be folded up so that it can fit into the into the rocket to take into space. But it's made of this incredibly delicate foil, kapton foil, which is the same thing that they put on... if you ever see a picture of a satellite and it's covered in some kind of like shiny silver or gold foil, it's that. And it's incredibly delicate, incredibly difficult to work with and back in 2018, it tore while they try to put it together and they've had lots of problems with trying to get it completely... So that it won't, you know, so that they can guarantee that this incredibly expensive mission – it's ended up costing 10 million dollars, approximately – doesn't get into space. And then just tears the second they tried to get up.

Iain because unlike Hubble, it can't be serviced because it's just not in Earth orbit. This is far further along.

Ezzy It's not something called the second Lagrangian point, which is one point five million kilometres away from Earth as opposed to Hubble, which is five hundred kilometres away.

Iain So you're going to get it right.

Ezzy You've got to get it right. Also, there's no space shuttle anymore to go up there and look at it.

Iain And then obviously, they had lots of problems in 2020 with sort of covid and restrictions. I remember at the time, but this time last year, talking to JWST scientists and it was basically what they were saying was, you know, a lot of their problems this year have just been really just 2020 have been covid related.

Ezzy Yeah, it's I know that there's a lot of because the JWST because it's just going to go to the second Legrangian point, it doesn't matter too much when it launches. There are some times when it's better than others. But if you've got something like the Mars rovers like Perseverence back in February last year that has to go in February or it won't get there. So it did mean that the JWST was sometimes a bit pushed back in terms of priorities. But that said, the ddeadline... the launch window has only slipped by about a month from when they were hoping. So it's only a couple of months. And is aiming, hopefully they hope will launch in November this year. So in a couple of months, we could be finally seeing our first images from the JWST. it's kind of like a weird one for me, because pretty much throughout my entire career in astronomy, which has been going on for almost 15 years now, people have been talking about the JWST. It's one of those ones that has been being built and worked on and developed. And everybody's saying it's like, oh, well, when we get the JWST, we'll be able to look at this thing and be able to do anything. And so the fact that it is finally about to go up is quite strange to me.

Iain Definitely. I think that that will definitely warrant a podcast special before the end of the year.

Ezzy Absolutely. Hopefully you will be saying it's all brilliant and wonderful and working well, but that is certainly it looks like it is set to be the next big telescope. That's really going to change how we look at the the universe around us. Its goal is to investigate the early universe, to look at things like the formation of galaxies and stars and planetary systems, these things which tend to be surrounded and shrouded in this thick layer of dust. The other telescopes can't see through looking at possibly even the origins of life and how that came to be throughout the universe. And the Infra-Red is one of the most effective tools to do this with.

Iain Incredible. Yeah, it's really exciting thinking about what potentially lies ahead. And the other the other big project that I've been thinking about recently is the square kilometre array. As you were saying, you know, we've been building radio telescopes much, much bigger. And the square kilometre array, you know, we could we could do an entire podcast. And that's going to eventually connect with you telescopes around the world to have the world cover an area of a square kilometre of, you know, viewing capability.

Ezzy Now, we've been talking about how telescopes have been getting bigger, but it's sort of using arrays and things, talking to each other. The other one I think of is the event Horizon telescope, which was telescopes literally all over the world from the south, even the South Pole, to look at black holes. And it's really exciting. Another field which has been really advancing, of course, is not even looking at light, it's not looking at electromagnetic radiation, whether that's radio or visible light. And that's gravitational waves. You know, in the last decade, we've had these various gravitational wave observatories coming online and making their first detection of this thing that was predicted one hundred years ago back by Einstein, and that's opening an entire new avenue of astronomy. And there's another new one of those observatory coming up called the Einstein Telescope, which we have a feature on in the September issue of BBC Sky magazine. if you want to read about that or any of the other telescopes that we've talked about here, we have pictures on them in the September 2021 issue of the magazine.

Iain For this month's stargazing tip, we're going to be taking a closer look at our celestial neighbour, the moon, and in particular two examples of a type of feature known as a Clair obscure effect. Clair obscure effects on the moon or tricks of light and shadow where sunlight and shade produce familiar shapes on the lunar surface. And because the phases of the moon are cyclical and repetitive, over the years, some clear, obscure facts have become popular targets for lunar observers. And this month, see if you can spot the lunar X and the lunar V. These are an X shaped and a V shaped formation that appear along the line, dividing the lit and unlit portions of the moon as seen from Earth, which is known as the Terminator. Both letters are visible for just a few hours and you should be able to see both the X and the V at 9:30pm BST on the 13th of September and use a pair of binoculars or a small telescope and see if you can spot them. The Lunar X can be fined about one quarter of the way up the Terminator from the moon's southern edge and the Lunar V can be found slightly north of the halfway point. A full guide on how to see these two effects can be found by visiting www.skyatnightmagazine.com And searching for Lunar X in the search bar at the top of the page.


Ezzy So that's it from us this month. You can find out more about the telescopes that changed astronomy in the September issue with BBC Sky Night magazine, where we also take a tour through variable stars that will be visible in the late summer night sky. Tell you what you need to study if you want to prepare for a career in space science and will be previewing the upcoming Einstein Telescope Gravitational Wave Observatory. And that's not forgetting our regular sections that will help you unlock the wonders of the night sky. Find the right equipment to observe it with and discover the best things to see after dark this month. So for all of us here at BBC Sky Night Magazine, goodbye.


Ezzy Pearson is the News Editor of BBC Sky at Night Magazine. Her first book about the history of robotic planetary landers is out now from The History Press.


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