Yeah.

And that's, um, something we've talked about.

It's well known, well established, uh, one of those phenomena that we recognize as being scientific facts.

But, uh, what they, what they found, what these researchers found when they put the same sort of analysis into Venus and a moon, uh, the moon would go the other way.

Uh, it would basically eventually, um, it would start to drift inwards towards Venus and spiral into- towards the planet, eventually passing within the Roche limit, which is where you can't have something, uh, staying together because of the com- competing gravitational pull on one side and the other, what we call the tidal effect.

Um, so it would break up.

Um, and, uh, the f- y- you know, even a, even a big moon, uh, would not necessarily survive.

Mm-hmm.

Yeah.

And that's, um, something we've talked about.

It's well known, well established, uh, one of those phenomena that we recognize as being scientific fact.

But, uh, what they, what they found, what these researchers found when they put the same sort of analysis into Venus and a moon, uh, the moon would go the other way.

Uh, it would basically eventually, um, it would start to drift inwards towards Venus and spiral into, towards the planet, eventually passing within the Roche limit, which is where you can't have something, uh, staying together because of the com- competing gravitational pull on one side and the other, what we call the tidal effect.

Um, so it would break up.

Um, and, uh, the f- y- you know, even a, even a big moon, uh, would not necessarily survive.

Mm-hmm.

Mm.

Why isn't there a, a hexagon or something like it near the, the southern polar region? And so that is something Trevor has long kept an eye on working with his colleagues, um, one of whom is actually in Spain.

In fact, we, uh, we were very close to where his colleague Agustín works.

Uh, we were very close to where it is, um, about th- a, a month ago when we were there for the eclipse.

Um, the, the bottom line is that within the last three years, they've started seeing evidence of something fishy going on, which has now been followed up by the Hubble telescope.

And what has been revealed is not a hexagon, but a decagon, a 10-sided, uh, figure around the South Pole of Saturn.

And the big difference between that and the hexagon, we don't know how old the hexagon is.

... it's getting ever closer, and they're, um, they're really getting to the pointy end by the sound of it.

Yeah.

Why isn't there a, a hexagon or something like it near the, the southern polar region? And so that is something Trevor has long kept an eye on, working with his colleagues, um, one of whom is actually in Spain.

In fact, we, uh, we were very close to where his colleague Agustín works.

Uh, we were very close to where it is, um, about th- a, a month ago when we were there for the eclipse.

Um, the, the bottom line is that within the last three years, they've started seeing evidence of something fishy going on, which has now been followed up by the Hubble telescope, and what has been revealed is not a hexagon but a decagon, a 10-sided, uh, figure around the south pole of Saturn.

And the big difference between that and the hexagon, we don't know how old the hexagon is.

We don't know how long it's been there.

... it's getting ever closer, and they're, um, they're really getting to the pointy end, by the sound of it.

Haven't we, Fred? [laughs]

Yeah, so it's, it's, uh, it is, it's really sad because, um, this project has been a bit of a poster child for NASA because normally their projects take decades to come into fruition.

But they've, they tasked a company, uh, uh, something like a, with a year's notice or something, uh, to, uh, develop a spacecraft, uh, and actually, um, basically work out how you could rescue the Swift spacecraft.

So the story is Swift is, uh, an, an elderly spacecraft, uh, launched in 2004 to study gamma ray bursts, but it's been so successful, uh, that there was a, a real, uh, I guess desire to, uh, to save it because its orbit is decaying.

And as of later this year, we expect it, its orbit will actually get so much atmospheric drag that it will decay very quickly, and the spacecraft, the, the Swift spacecraft will burn up in the atmosphere.

So, um, the Link mission, uh, was a joint, uh, project between NASA and a company called Catalyst, Catalyst Space.

Uh, and indeed the Link spacecraft was launched on July the 3rd, um, uh, with every intention of rendezvousing with the Swift spacecraft and, and lifting its orbit, and I'll get onto that in a minute 'cause that's basically, uh, James's question.

Bye now.

What is this thing?

Yes, it's not a mystery galaxy in the sense that people have speculated that there may be galaxies without stars.

And we tend to think of galaxies as being made of stars because ours is.

The Milky Way is a gigantic spiral of stars and gas and dust.

Very beautiful if we could see it from the outside, which sadly we never can.

But it has always been speculated that there may be galaxies which contain clouds of hydrogen, the raw material of stars, which basically is too hot for the clouds to collapse into individual stars i think i've got the logic the right way there yeah so you've got the raw material of stars but it doesn't form a stellar population and maybe it's because there's, you know, as I said, the gas is too hot.

So this particular object, Cloud 9, it's not very far away.

These are a little bit different again.

Wow.

Um, and it's located, uh, in La Palma, in the Canary Islands, and I used to observe there on a telescope called the William Herschel Telescope.

So, uh, GTC, as it's called, Gran Telescopio Canarias, has a, a camera, um, uh, called HiPERCAM, uh, which is the one that I think has really given us this research on Cloud Nine because the, uh, the colleagues who observed, uh, this object, what they did was they used that big telescope with its, um, wide-angle camera, uh, i- in order to get very, very deep images.

And by deep images, we mean ones that penetrate to really faint levels.

Uh, they got 2.36 hours of integration, uh, which is, um, quite, quite a long time, uh, and didn't see any stars.

I think they, they think they might have seen a small number of stars, but not, uh, a, a... what we expect in a galaxy.

Um, so the, uh, one of the authors of this paper, um, basically in offering an explanation as, as to how you could have a galaxy with no stars, uh, I'll quote, "The leading theoretical explanation involves the ultraviolet background radiation that permeates the universe.

Yeah.

Yeah.

Something orbiting around a common center of gravity.

Uh, so you've got that, uh, unusual situation to start with, but, um, it, it appears that because of that geometry, the, the atmosphere of Pluto, which is very, very thin, but it is there.

I was once helping a project that measured the atmosphere of Pluto, not from space, but by Pluto passing in front of a star, as observed from, with the Anglo-Australian Telescope.

We could see it dimmed gradually, the light of the star, rather than just switching off as it would've been if there'd be no atmosphere.

So that atmosphere is mostly nitrogen gas, uh, or the part that's escaping, uh, and apparently it is basically captured by Charon.

There's this flow of the nitr- nitrogen from Pluto to its dwarf planet companion.

Mm

Mm.

Something orbiting around a common center of gravity.

Uh, so you've got that, uh, unusual situation to start with.

But, um, it, it appears that because of that geometry, the, the atmosphere of Pluto, which is very, very thin, but it is there-- I was once helping a project that measured the atmosphere of Pluto, not from space, but by Pluto passing in front of a star, as observed from with the Anglo-Australian telescope.

We could see it dimmed gradually, the light of the star, rather than just switching off as it would've been if there'd been no atmosphere.

So that atmosphere is mostly nitrogen gas, uh, or the part that's escaping, uh, and apparently it is basically captured by Charon.

There's this flow of the nitr- nitrogen from Pluto to its dwarf planet companion.

Alpha.

Ah.

Uh, and what set the cat among the pigeons and made it a hot topic is the James Webb Space Telescope.

Because, um, until that came along, the idea was that as, basically as Dan suggests, black holes were formed i- in the early universe by exploding stars that, um, collapsed at the end of their lives into, to form a black hole.

The, the core would collapse to a black hole.

And that then over, over billions of years, that black hole would grow, and eventually, in our own epoch today, thirteen point eight billion years after the, after the Big Bang, uh, you have supermassive black holes at the center of every galaxy.

That was the old wisdom, but the James Webb telescope has turned that completely on its head because we have serious evidence of supermassive black holes within the first five hundred million years of the universe's existence, and that's too quick for or too short a time for this, um, you know, the, this slow accretion of, of stuff, uh, as being the, or, um, the, the, the growth mechanism for black holes.

Uh, it's too, too short a time for that to be the case.

Mm-hmm.

Mm.

Uh, and what set the cat among the pigeons and made it a hot topic is the James Webb Space Telescope.

Because, um, until that came along, the idea was that as, basically as Dan suggests, black holes were formed i- in the early universe by exploding stars that, um, collapsed at the end of their lives into, to form a black hole.

The, the core would collapse to a black hole.

And that then over, over billions of years, that black hole would grow, and eventually, in our own epoch today, 13.8 billion years after the, after the Big Bang, uh, you have supermassive black holes at the center of every galaxy.

That was the old wisdom, but the James Webb telescope has turned that completely on its head because we have serious evidence of supermassive black holes within the first 500 million years of the universe's existence, and that's too quick for or too short a time for this, um, you know, the, this slow accretion of, of stuff, uh, as being the, or, um, the, the, the growth mechanism for black holes.

Uh, it's too, too short a time for that to be the case.

Mm.

Yeah

... every nine minutes.

It was extraordinary.

And, and that's how it was picked up by the world's seismologists.

[clears throat] So a changing climate can increase landslides.

Now, we're not saying that's what's happening on Pluto, uh, but, uh, there are landslides on Pluto.

And of course, pretty well everything we know about Pluto now comes from that flyby of the New Horizons spacecraft.

And I'd, I'd put it in that basket myself.

Is the universe expanding, contracting, and at what rate?

It's definitely expanding.

That's one of the easiest measurements to make with the technology that we have today.

But the second part of your question, what rate is it expanding? This is a big puzzle because we get two answers depending on how we measure it.

There are two ways of doing it.

One is to look at the flash of the Big Bang, which we can still see.

A lot of people are surprised at that, but we can look so far back in time that we can see the flash of the Big Bang, which occurred about 13.8 billion years ago.

So, Professor, who's the panel or the judge who decides whether it is 61 or 70? Who's it go before and says, no, it is 61?

Uh, would they achieve, uh, zero angular momentum under those special circumstances?

Uh, and the answer is yes, yes they could.

Um, so there are two things at play here.

Uh, one is the individual spin of each black hole.Uh, most black holes are spinning.

Uh, and so those two, um, the angular momentum of those two, of each black hole when they collide, uh, it could be that they'll cancel out if they're rotating at the same rate in the opposite direction.

Now, normally, um, that's unlikely to happen because, uh, you, you know, it will be very, very un- unusual to have two black holes with exactly the same rotation rate, but one, the, the negative of the other one rotating in the opposite direction.

But it could happen.

There's a one-word answer for this, and it could be one or the other.

But it's a, it's a thing, or will be.

It is a thing.

It's, it's a thing, and it's all about understanding how fires burn on the Moon.

Um, it's something called the flamma- flammability of materials on the Moon experiment, uh, otherwise abbreviated to FM2, uh, developed by NASA, uh, in a number of their research centers, the Glenn Research Center, Johnson Space Center, East, uh, sorry, Case Western Reserve University.

What they're doing is they're sending, uh, what's called a self-contained combustion chamber to the Moon, and it's going on one of these commercial lunar payload services flights, uh, that we sort of know about from, uh, from discussions we've had before, where the, you know, uh, basically private companies provide hardware, uh, to, uh, send on robotic missions to the Moon to set up things for when humans are exploring the Moon, um, a few years down the track.

So it's all about, um, safety actually, Andrew.

Uh, that's the bottom line for this.

Mm-hmm.

But it's a, it's a thing, or will be.

It is a thing.

It's, it's a thing, and it's all about understanding how fires burn on the moon.

Um, it's something called the flamma- flammability of materials on the moon experiment, uh, otherwise abbreviated to FM2, uh, developed by NASA, uh, in a number of their research centers, the Glenn Research Center, Johnson Space Center, East, uh, sorry, Case Western Reserve University.

What they're doing is they're sending, uh, what's called a self-contained combustion chamber to the moon, and it's going on one of these commercial lunar payload services flights, uh, that we sort of know about from, uh, from discussions we've had before, where the, you know, uh, basically private companies provide hardware, uh, to, uh, send on robotic missions to the moon to set up things for when humans are exploring the moon, um, a few years down the track.

So it's all about, um, safety actually, Andrew.

Uh, that's the bottom line for this.

Mm.

Mm

... by natural processes.

And you, you've gotta, gotta think back to Jocelyn Bell Burnell and her- Discovery of the first pulsar, because that's what she saw.

Um, narrowband, um, sorry, uh, narrow band in time signatures, uh, or bursts of radiation, which we now know as the pulsar, the kind of lighthouse beam of radiation from the pulsar sweeping round and passing the Earth.

Um, she didn't know that then, so she wrote, "Little green men" in her, uh, in, uh, on her, uh, chart record are very, very famous words.

Um, so that's what basically, uh, the, uh, Chang'e, um, F- low frequency radio spectrometer has been looking for.

Uh, and it's things that, um, you know, that speak of an artificially generated source.

Mm.

Mm

... by natural processes.

And y- you've kinda gotta think back to Jocelyn Bell Burnell and her discovery of the first pulsar because that's what she saw.

Um, narrow band, um...

Sorry, uh, n- narrow band in time signatures, uh, or bursts of radiation, which we now know as the pulsar, the kind of lighthouse beam of radiation from the pulsar sweeping round and passing the Earth.

Um, she didn't know that then, so she wrote, "Little green men" in her, uh, in, uh, on her, uh, chart recorder.

Very, very famous words.

Mm.

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Yes

We might have had it before, but, uh, what keeps them keeping on, Fred?

[laughs] Well, they do.

They just keep on keeping on.

Uh, so Justin, Justin's right in that, uh, yes, the thing that sends the, the marble down to the bowling ball on the rubber sheet is the friction, uh, of the, of the, the, the rolling phenomenon.

Um, all sorts of frictions come in.

There's a bit of air breaking as well with that.

Not much, but, um...

Mm

Now, that's the big mystery, but they're starting to think that it might have been a slow release system rather than one big event.

Yes, exactly.

That's right.

It's two stories here that have got separate media releases and they're telling the same story, but they're also conflicting with a different nuance.

Yeah.

So the first one comes from the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder.

And it's about, as you've said, it's about how the water that we do believe exists as ice in the deepest, darkest craters near the Moon's South Pole.

Same concept but different materials, I think.

computer.

Yeah, we're getting updates all the time.

And, you know, this is kind of NASA at its best, isn't it, really? It's just such a fantastic achievement for us to see.

this mission going so profoundly well.

You said the trans-traverse behind the moon has taken place now.

There was a 40-minute loss of signal, which you'd expect for exactly the reason that you mentioned.

The moon is a big rock and gets in the way of radio signals.

It's all over Red Rover by the sound of it.

Yeah, Bennu, it's funny that the question should turn up when it does because I think Bennu's just got back into the news, has it not?

Yes, that's right.

There's a really interesting story which came out this week in the proceedings of the National Academy of Science in the United States.

And because this is a press release, it means I can read from it with impunity.

And so it introduces the issue very well.

Scientists studying samples from the asteroid Bennu have uncovered a surprisingly complex chemical landscape at the tiniest scales.

A new study shows that at an extremely small scale, organic material and minerals inside the asteroid Bennu are organized into three clearly different chemical groupings.

splice? Can they splice a black hole? That's the question.

It's a better degree in mathematics than mine.

Well, anyway, yes, it nearly wasn't a degree at all.

Only the generosity of the Scottish education system let me fail an exam five times and pass it on the sixth attempt.

Yes.

Sounds like my driver's license.

All right, okay.

Don't remind me never to come driving with you.

what's the solution?

That's

a lot, isn't it? That's old, yeah.

But you've got to balance that against the fact that it does have a chemical composition.

in terms of the elements that are present, the abundances of the elements that's not too different from ours.

But that's clearly something that the pundits are working on.

I think the nub of Shane's question is, I think his estimate of 99% of its time being in deep space is, and 1% being passing through a solar system.

I suspect that's probably wildly wrong, because I suspect that it's more like 99.999999999% in deep space, and a tiny fraction that would be passing through solar systems.

Fred?