# The Starless Galaxy That Shouldn’t Exist - But Does

An episode of [Space Nuts: Astronomy Insights & Cosmic Discoveries](https://invisiblenetwork.ai/podcast/1080090608), 3 Sep 2026, 38 min.

Audio: https://dts.podtrac.com/redirect.mp3/pscrb.fm/rss/p/op3.dev/e/api.spreaker.com/download/episode/74853287/utf_8_q_venus_e2_80_99s_clouds_may_be_dark_tar_not_signs_of_life_mp3.mp3

Space Nuts: Spanish Eclipse, Nancy Grace Roman Launch, Cloud Nine, and Venus's Mysterious Clouds Andrew Dunkley and Professor Fred Watson cover four big astronomy stories in this episode, from Fred’s trip to view a sunset eclipse in Spain to the launch of the Nancy Grace Roman Space Telescope. They also unpack a starless dwarf galaxy called Cloud Nine and a new way of thinking about the strange dark material in Venus’s clouds. Guests and speakers Andrew Dunkley - Host, frames the news, asks listener questions, and guides the discussion. Professor Fred Watson - Astronomer at large, explains the eclipse, the Roman telescope, Cloud Nine, and Venus’s clouds. Key topics In this episode, Fred recounts the Spanish eclipse expedition The eclipse was only 9 degrees above the western horizon at totality, making the viewing conditions unusually challenging. He and Marnie led a 16-person tour through France, Spain, and Switzerland before settling near Santander in northern Spain. They staked out a viewing site 2 kilometers from the hotel, set up a gazebo, and had to tie it down to a car to keep it from blowing away. The weather looked threatening, but a hole opened in the cloud just before totality, giving them a clear view of the corona. Fred described the yellowish corona, pink hydrogen clouds, and the crowd of around 2,000 people. We discuss the Nancy Grace Roman Space Telescope launch Andrew watched the launch live after being nudged by his own brain at the right moment. Fred noted the launch was flawless, with 27 Merlin motors firing. The telescope is headed for the L2 Lagrange point, about 1.5 million kilometers away. Roman is a 2.4-meter Hubble-class telescope but with 100 times the field of view. Its wide-angle infrared design should enable major surveys of dark matter, dark energy, and exoplanets via its coronagraph. Fred explains why Cloud Nine matters Cloud Nine is described as a starless dwarf galaxy about 14 million light years away. It lies near Messier 94 and was studied using the Gran Telescopio Canarias and its Hypercam instrument. The deep exposure was 2.36 hours, yet the team found no convincing stellar population. Fred says theory suggests the gas may be too hot to cool and collapse into stars because of the ultraviolet background radiation after reionization. He says Cloud Nine may be the first strong example of a galaxy predicted by standard cosmology but never before clearly identified. Venus’s clouds are still puzzling astronomers Fred explains that Venus appears yellowish because we see the top of its cloud layer, especially in visible light. In ultraviolet, Venus shows dramatic global cloud patterns caused by an as-yet unidentified absorber. The new study uses radiative transfer modeling to constrain what the unknown absorber could be. The team compares Venus’s cloud droplets to cigarette smoke, tiny particles that look light-colored when dispersed but could become dark sludge in bulk. The result suggests the absorber must be very efficient, very concentrated, or both, but it is not being claimed as evidence of life. Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support.

## Transcript

[0:00] Andrew Dunkley: Hi there. Thanks for joining us. This is
[0:02] Space Nuts. My name is Andrew Dunkley, your
[0:04] host, and it is good to have your company as
[0:06] always. Uh, coming up on this
[0:09] episode, uh, we're going to revisit the
[0:12] Spanish eclipse. Because the man of the
[0:14] moment, the man who went there and pointed it
[0:16] out to everyone and said, that's what an
[0:18] eclipse looks like, he couldn't join us, but
[0:20] Fred Watson Watson will talk about it. Uh,
[0:23] we'll also be, uh, discussing the Nancy,
[0:26] um, Roman, uh,
[0:28] observatory launch, which I watched online
[0:31] the other. The other night, which was
[0:33] spectacular. Uh, and there's a
[0:36] galaxy that they're looking at with, um,
[0:39] a bit of a frown and a scratch of the neck
[0:41] because, uh, it does not appear to have
[0:44] many stars. Uh, it's not emitting starlight.
[0:46] How could that be? And we'll finish
[0:49] up with the Mystery Clouds of Venus. That's
[0:52] all coming up on this episode of space nuts.
[0:55] Professor Fred Watson: 15 seconds. Guidance is internal.
[0:58] 10, 9. Ignition
[1:00] sequence start.
[1:02] Professor Fred Watson: Space nuts.
[1:02] Professor Fred Watson: 5, 4, 3. 2. 1. 2, 3, 4,
[1:05] 5, 5, 4, 3, 2, 1.
[1:07] Andrew Dunkley: Space nuts.
[1:09] Professor Fred Watson: Astronauts report it feels good.
[1:12] Andrew Dunkley: And he's back. After travelling halfway
[1:14] around the world and, uh, returning and then
[1:16] getting his leg amputated. Um, well, not
[1:19] quite, but, uh, he got it rebuilt. $6
[1:22] million. It was, I think the price of that
[1:24] it. Professor Fred Watson Watson, astronomer
[1:26] at large.
[1:27] Professor Fred Watson: Hello, Fred Watson. Hi, Andrew. Thank you for
[1:29] that great intro. Yes, $6 million.
[1:32] Um, and, um, my health fund, um, provided
[1:34] $42.5, so.
[1:36] Andrew Dunkley: Yes, that's, uh, usually how it goes in
[1:38] Australia. That's the going rate. No matter
[1:40] what it costs you to go and see a doctor, you
[1:42] get 40 bucks back. Yeah, it's a
[1:45] great system. Um, yeah. Anyway, we
[1:48] won't go there. That's politics.
[1:50] Professor Fred Watson: That's right.
[1:51] But as you alluded, uh, I have indeed
[1:53] received a new knee. So I had a.
[1:56] My second TKR total knee
[1:59] replacement. Wow. Um, which is, uh, it was a
[2:02] week ago. Yesterday was the surgery. So I'm
[2:05] still on painkillers, so. Will not make any
[2:07] sense whatsoever. Um, I might go to sleep
[2:09] halfway through the show. That's been one of
[2:11] the symptoms.
[2:13] Andrew Dunkley: Well, between you falling asleep and me
[2:16] sneezing, it should be an interesting show.
[2:18] Hay fever is running right.
[2:21] And I cannot control it. Um,
[2:25] I know there's medications out there, but I'm
[2:26] gonna let some. I'm not allowed to take
[2:28] anymore because of my eyes. So, uh, it's made
[2:31] it more complicated. So, um, I'm, I'm. I'm
[2:34] well armed. Look, I've got.
[2:36] Professor Fred Watson: Oh, yes.
[2:37] Andrew Dunkley: The mandatory box of tissues within arm's
[2:39] length. So hopefully we'll get through it.
[2:42] Fred Watson. And, um, I'm glad the knee
[2:43] operation went well. You're the second person
[2:45] in a week that I've met who's had a total
[2:48] knee replacement. A friend of mine,
[2:51] um, literally stepped into a hole that he
[2:53] didn't know was there because it was full of
[2:54] grass and buckled his knee and the damage
[2:57] was too severe and they had to do a knee
[2:59] replacement. It's a bit of a shocker, that
[3:01] one. Yes, but he's still on
[3:04] crutches.
[3:06] Professor Fred Watson: Okay, well, I've parked my crutches, although
[3:08] I did resort to one in the middle of the
[3:11] night. Uh, when I had to get up. I, uh,
[3:13] thought, no, I'm just going to use the
[3:14] crotch. But, yeah, um, it doesn't take
[3:17] long. But, um, you know, your
[3:20] colleague, uh, uh, there, he
[3:23] had much more than just a knee replacement
[3:25] with that accident damage. Mine was just a
[3:28] quick one out, one in. Uh, and
[3:31] so I think it's a lot more predictable and
[3:33] probably a lot easier for me to recover. Um,
[3:36] I'm sorry, he's still on crutches and hoopi.
[3:38] I wish him well. Yes, we used to speak on the
[3:41] radio a long time ago.
[3:42] Andrew Dunkley: That's right. One of my old radio mates.
[3:45] Uh, Fred Watson, let's talk about the Spanish
[3:47] eclipse. I saw a lot of pictures and footage
[3:49] online. People getting very artistic with
[3:52] their photography at times. These
[3:55] things have become very popular. And,
[3:58] uh, from what I could tell, it was. It was a
[4:00] little bit different because it wasn't sort
[4:02] of up there, it was over there. Is that how
[4:05] it went? It was more on the horizon than
[4:08] you'd normally expect.
[4:09] Professor Fred Watson: That's right. And that was always the
[4:12] issue for us, uh, because at the time of
[4:15] totality it was only 9 degrees above
[4:18] the western horizon, and that's very low
[4:21] down. Um, but we
[4:23] figured that we would take that risk.
[4:27] The storey actually goes back a long way.
[4:30] So we were leading a tour group. We had,
[4:33] uh, uh, 16 of us through France and
[4:36] Spain and Switzerland. We went to the Large
[4:38] Hadron Collider. We went to two observatories
[4:40] in France, uh, Haute Provence and Pic du
[4:42] Midi, both of which were sensational. We
[4:44] really enjoyed those visits and wound up at
[4:47] Santander in northern Spain. Uh,
[4:50] we got there, I think, three days before
[4:53] the eclipse. Um, and the first thing
[4:56] Marnie and I did was to basically
[5:00] stake out where we were going to watch it
[5:02] from. Um, because, um, in those
[5:04] resorts in northern Spain on the coast, uh,
[5:07] they're all built facing eastwards because
[5:10] they get the morning sun and often there is
[5:12] high ground behind them. And so we,
[5:15] um, found a spot about two kilometres from
[5:18] our hotel. We had a couple of vehicles so we
[5:20] could, and manipulate everything. Um,
[5:23] Marnie, um, bought a gazebo,
[5:26] uh, which we erected on our chosen
[5:29] spot. There was nobody there at that time,
[5:31] but we knew it was going to fill up. Uh, so
[5:34] we had this gazebo. Um, we, the first night
[5:37] I said, this is going to blow away if we just
[5:40] leave it here. So, so we parked one
[5:42] of our vehicles under the gazebo and tied the
[5:45] gazebo down onto the roof of the car.
[5:47] Andrew Dunkley: Oh, great idea.
[5:48] Professor Fred Watson: It's still there the next day. Yeah, yeah,
[5:50] until the next time, we said.
[5:51] Andrew Dunkley: But the gazebo was.
[5:54] Professor Fred Watson: So, yeah, it turned into, uh, quite a big
[5:56] event. There were, there were very big crowds
[5:59] there. We'd obviously chosen exactly the
[6:01] right spot. Lots, um, of people, an ice
[6:04] cream van was there. That turned up on day
[6:06] two.
[6:07] Andrew Dunkley: Oh, wow.
[6:08] Professor Fred Watson: Uh, day T minus one, Um, a whole lot
[6:11] of cops came on horseback and in vehicles and
[6:13] in helicopters. They were obviously all taken
[6:16] completely by surprise by this event.
[6:18] What's going on up there? Um, but
[6:21] yes, on the afternoon. So it was an evening
[6:23] eclipse, the afternoon, uh, the sky was
[6:26] completely clear. But, uh, towards the end of
[6:29] the afternoon, this bank of cloud appeared in
[6:31] the west. Uh, and you could see that it
[6:34] was sort of spreading upwards as it
[6:37] approached. So the sun was effectively
[6:40] setting into that. The partial phase started
[6:41] at half past seven. I spotted that
[6:44] with the binoculars. It was a magical moment
[6:47] when I first saw the mountains of the moon
[6:48] just encroaching into the sun's disc. This
[6:51] was with, uh, binoculars, with filters. Uh,
[6:53] and then we. You know, eclipses are an
[6:56] amazing spectacle. You've got this buildup
[6:59] over an hour or so as the moon's disc
[7:01] gradually covers the sun, and then that time
[7:03] of perfection when the two are exactly
[7:06] aligned. So what happened? We all got
[7:07] steadily more and more depressed as the sun
[7:09] was sinking into this bank of cloud. But
[7:13] about two minutes before totality, a hole
[7:16] opened up, uh, right where the sun was.
[7:18] And when the total eclipse happened, we got a
[7:21] perfect view of the corona. It was just
[7:23] magical. It was clear. Um,
[7:25] so we could see the outer atmosphere of the
[7:28] sun, the corona. It looked slightly yellowish
[7:30] and that's because the sun was so low.
[7:32] Normally pure white and
[7:35] pink clouds of hydrogen, which were bigger
[7:37] than I've seen before. They were spectacular.
[7:39] Lots of cheers from the crowd. There were
[7:41] about 2,000 people there by then. Uh, we, in
[7:44] our little uh, tent. There were 20 of us too,
[7:46] because two members of my UK family, or four
[7:48] members came out to watch. So, uh, a good
[7:51] time was had by all. Uh, and we were
[7:53] delighted to get a great eclipse. And I think
[7:56] everybody was very happy. Nani and I spent
[7:58] the next day.
[8:00] Andrew Dunkley: I was going to say, isn't that twice in a row
[8:01] that you've been to an eclipse that was
[8:03] cloudy and it cleared up at the last second?
[8:04] Professor Fred Watson: Cleared up, that's right. Um, not nearly
[8:07] twice in a row. It was the one before last, I
[8:09] think was.
[8:10] Professor Fred Watson: Uh.
[8:11] Professor Fred Watson: Nor was it the last one. Yes, it was the last
[8:13] one. It was in Texas. That's right. And it
[8:16] was cloudy. Uh, and then the holes
[8:19] appeared and we saw the eclipse. So,
[8:22] yeah, somebody's looking after us. I don't
[8:24] know who it is. Indeed. It was great.
[8:27] Um, yeah. And that sort of wrapped up the
[8:29] tour.
[8:29] Then we had a couple of days. Uh, we had.
[8:32] Bore you with the details. We had a nightmare
[8:34] journey home which involved
[8:37] rebooking flights, uh, two hours before they
[8:40] left through to Sydney from Barcelona. But
[8:43] anyway, that's another storey. Travellers
[8:45] tales. You've got plenty of them as well.
[8:47] Andrew Dunkley: Yeah, yeah, yeah. Um,
[8:50] I guess the difference with that eclipse in
[8:52] Spain was it was happening at sunset.
[8:55] And normally when you watch one of these
[8:57] eclipses, it turns, uh, day into night
[9:00] and then it comes back to day again, but at
[9:03] sunset, I guess you sort of missed out on
[9:05] that kind of effect to a certain degree.
[9:07] Professor Fred Watson: Yeah. Excuse me. To a certain extent.
[9:10] But it got dark very quickly, as it does.
[9:13] It's only when something like 80 or
[9:15] 90% of the sun's disc is covered. That's the
[9:18] only time when you notice that things are
[9:20] dimming. Um, I think birds did go to
[9:23] sleep. We didn't really take much notice. It
[9:25] was 1 minute and 3 seconds was the time m of
[9:28] totality that we had. Uh, um.
[9:30] But yes, it did get light again. Uh. Uh,
[9:33] light enough for us to take lots of
[9:35] photographs of each other and all the rest of
[9:37] it. Uh, we demolished the gazebo, gave it
[9:39] to a guy, a French guy, who thought it was
[9:42] the bee's knees. He. He had a camper van next
[9:44] door. We also gave him the inflatable
[9:47] fridge that we bought.
[9:48] Andrew Dunkley: Oh, my goodness.
[9:49] Professor Fred Watson: Did you know there was such a thing?
[9:51] Andrew Dunkley: I'd never heard of it.
[9:52] Professor Fred Watson: My wife does. Uh, we had an inflatable fridge
[9:55] and we gave him some chairs as well, because
[9:57] we couldn't take all this stuff back to
[9:59] Australia.
[9:59] Andrew Dunkley: Yeah, of course.
[10:00] Professor Fred Watson: Yeah.
[10:01] Andrew Dunkley: Fantastic.
[10:02] Professor Fred Watson: Yeah.
[10:03] Andrew Dunkley: Well, you know, I'm all set for, uh,
[10:05] Dubbo 2028.
[10:07] Professor Fred Watson: Yeah, 2028, that's right.
[10:09] Andrew Dunkley: So less than two years now, not far.
[10:12] We've just been sitting on this one for 20
[10:14] years when we first found out about it. But,
[10:16] uh, yeah, looking forward to that. In fact,
[10:18] uh, I think that year, um, there's going to
[10:21] be three or four eclipses in our part of the
[10:23] world or over those next couple years.
[10:25] Professor Fred Watson: Over the next few years, yeah, I think till
[10:28] 20, 30 something. I can't
[10:31] remember what it is. Yeah, I don't know.
[10:34] There are another three that'.
[10:36] Andrew Dunkley: Yeah, okay, uh, well, that sounds like fun.
[10:39] Let's talk about something else
[10:40] extraordinary. Uh, the other night I was
[10:42] sitting, uh, in my lounge, just about to pop
[10:45] off to sleep and my brain said, you know,
[10:47] they should be launching the Nancy Roman
[10:49] telescope sometime soon, Andrew.
[10:51] Professor Fred Watson: So I thought, oh, yeah, yeah.
[10:52] Andrew Dunkley: So I grabbed my iPad and I logged on and sure
[10:55] enough, the countdown was five minutes from
[10:58] launch.
[10:58] Professor Fred Watson: And I thought, brilliant.
[10:59] Andrew Dunkley: Isn't the brain an amazing thing? Yeah,
[11:02] that it, that it reminded me of that five
[11:04] minutes before the launch and I, uh,
[11:07] I was oblivious to it at that moment,
[11:10] so I watched the whole thing. It was
[11:12] fantastic.
[11:13] Professor Fred Watson: Yeah, I watched the replay the next day. I
[11:16] wasn't, um, switched on as you were. I was
[11:18] probably asleep actually with
[11:21] the painkillers. But yes, I did,
[11:24] um, realise that, uh, it was taking place
[11:26] then, uh, and yeah, flawless launch. It
[11:28] looked fantastic.
[11:29] Andrew Dunkley: Oh, it was, wasn't it?
[11:30] Professor Fred Watson: Um, all 27 of those Merlin motors
[11:32] firing away there
[11:35] Andrew Dunkley: and it now makes the 1 million,
[11:39] is it kilometres or
[11:40] Professor Fred Watson: miles journey to, uh, Yes, a million
[11:43] miles. A million and a half kilometres. Uh,
[11:45] yeah, and I think it's well on the way, this
[11:47] is to the L2 point, that point
[11:49] on the far side of the Earth, uh, from the
[11:52] sun where there's this stable gravitational
[11:55] thing which we call a Lagrange point. Um,
[11:57] several spacecraft there already, including
[11:59] the James Webb and Gaia, Um, that
[12:02] European, fantastic European project, that's
[12:04] there a few other ones.
[12:05] Andrew Dunkley: I'll be running out of room up there. They'll
[12:07] have to put in traffic lights.
[12:09] Professor Fred Watson: So it's interesting, um, you kind of think of
[12:11] that. Oh, if this is a stable point, they
[12:13] must always trying to get to the same point.
[12:14] But actually what they are, they're all in
[12:17] orbit around a stable point. So you're in
[12:19] orbit around nothing. Um, but the
[12:22] gravitational forces work to sort of keep you
[12:25] in orbit there. Um, yep.
[12:27] So it's, um. Yes. So
[12:30] I don't know, I haven't really looked at the
[12:33] commissioning schedule for the Nancy Grace
[12:36] Roman. Uh, but, um, it's probably already
[12:39] started because, uh, they don't waste much
[12:41] time with these things to get as much data as
[12:44] they can just in case something catastrophic
[12:46] goes wrong early on. Um, what
[12:49] we've got here is a Hubble class telescope.
[12:52] Um, same sort of size as The Hubble,
[12:55] uh, 2.4 metres, with,
[12:58] uh, the big difference that
[13:01] even though it's got the fine detail, the
[13:03] resolving power of the Hubble, it's got a
[13:06] hundred times the field of view of the
[13:08] Hubble, which means it sees 100
[13:11] times more sky. And so, you know, the
[13:13] Hubble's always been giving us these,
[13:16] what you might call pinhole images, just, um,
[13:19] almost looking through a straw at the sky.
[13:22] Uh, the Nancy Grace Roman is a wide angle
[13:24] telescope. It's also infrared. Uh, so, um,
[13:27] it is actually seeing redder than red
[13:30] light. And we've got high hopes for what it
[13:32] might achieve with huge galaxy
[13:35] surveys which hopefully will show light on,
[13:38] which shed light on dark matter and dark
[13:41] energy. And, um, also
[13:44] it's got a very sophisticated
[13:46] coronagraph on board. And a coronagraph
[13:49] is a thing that blots out the light of a star
[13:51] so you can look for other objects nearby.
[13:54] And so we should start seeing images of
[13:57] exoplanets coming from Nancy Grace Roman as
[14:00] well. So it is lots to talk about down the
[14:02] track, Andrew.
[14:02] Andrew Dunkley: Yeah, very exciting. When do they expect it
[14:05] to actually be ready to roll? It's a bit
[14:08] of a process, isn't it?
[14:10] Professor Fred Watson: It is, that's right. I'm not sure what the
[14:11] schedule is, as I was saying, but, um, we'll
[14:14] keep, um, we'll keep space notes listeners
[14:16] posted at the moment. The news is all good
[14:18] and.
[14:19] Andrew Dunkley: Yeah, it is, it is. In fact,
[14:22] um, I'm just looking,
[14:25] yeah, first observations, maybe early
[14:28] next year sometime.
[14:29] Professor Fred Watson: Yeah, they haven't got it in mind. It was
[14:32] 2027.
[14:33] Andrew Dunkley: Yeah.
[14:33] Professor Fred Watson: Um, and I mean I, I remember because
[14:36] we lived it in real time. The commissioning
[14:39] for the Hubble telescope back in
[14:41] 1990. I was an astronomer at the UK Schmidt
[14:44] telescope then and we were getting direct
[14:46] reports from NASA actually about the
[14:48] commissioning before the Interweb. Um,
[14:52] and we very quickly realised that
[14:55] something was wrong because we got, um,
[14:57] reports of the image diameter as they went
[15:01] and the image diameter never got small. So it
[15:03] was quite obvious very early on that there
[15:06] was a problem with the Hubble and of course
[15:09] took them three years to build a, a
[15:11] little device to correct for that. And, uh,
[15:14] then it was flown on a space shuttle mission
[15:16] and the rest is History. Yeah.
[15:19] Andrew Dunkley: A PUFU valve, I think it was, they needed to
[15:22] put on it. Yeah.
[15:24] Professor Fred Watson: M. Anyway, it did have a cost bar. Was it
[15:26] something like that?
[15:27] Andrew Dunkley: Something like that, yeah. It was lucky that
[15:30] it was close enough to get to, um.
[15:32] Professor Fred Watson: Yes, that's right.
[15:33] Andrew Dunkley: Can't do that with the L2.
[15:35] Professor Fred Watson: You can't. That's exactly right. Um,
[15:38] yes, things have moved on a bit since then.
[15:41] Andrew Dunkley: They have, uh, exciting times. And we will
[15:44] watch with interest. And of course, uh, when
[15:46] they achieve first light and we start to see
[15:49] some other images, we will share them with
[15:51] you here on Space Nuts. And you are
[15:54] listening to the latest edition with Andrew
[15:56] Dunkley and Professor Fred Watson Watson.
[16:00] Professor Fred Watson: I think we need to do a little more all
[16:02] weather testing.
[16:04] Professor Fred Watson: Amen, Space Nuts.
[16:06] Andrew Dunkley: Okay, Fred Watson, let's talk about this
[16:09] strange galaxy. Um, some
[16:12] are saying it's a failed galaxy. Uh, it's
[16:14] been described as a starless galaxy. And it's
[16:16] got a name. It's called Cloud 9. What is this
[16:19] thing?
[16:21] Professor Fred Watson: Uh, it's, um. Yes, it's
[16:25] not a mystery galaxy in the sense that people
[16:28] have speculated that there
[16:31] may be galaxies without stars. And,
[16:34] you know, we tend to think of galaxies as
[16:37] being made of stars. Yes, ours is.
[16:40] Milky Way is a gigantic spiral of stars
[16:43] and gas and dust. Very beautiful. If
[16:46] we could see it from the outside, which sadly
[16:47] we, we never can. Uh, but,
[16:50] um, it has always been
[16:53] speculated that there may be,
[16:56] uh, galaxies which
[16:58] contain clouds of hydrogen, the raw material
[17:01] of stars, which
[17:04] basically is too hot for
[17:07] the clouds to collapse into individual stars.
[17:10] I think I've got the logic the right way
[17:12] there. Yeah. So you've got the raw
[17:15] material of stars, but,
[17:18] um, it doesn't form a stellar
[17:20] population. Um, and
[17:24] maybe, um, it's because there's,
[17:27] you know, as I said, the gas is too hot.
[17:29] So this particular object, Cloud 9,
[17:32] it's not very far away. Uh, it
[17:35] is about 14 million light years away,
[17:39] which puts it really on our galactic
[17:41] doorstep. Uh, it's not far from a, uh,
[17:44] spiral galaxy called Messier 94,
[17:47] which is a lovely spiral, uh,
[17:50] if I remember rightly, in the Northern
[17:51] Hemisphere sky. Uh, well, it must be because
[17:54] it's being observed by a telescope that, um,
[17:56] I never really had anything to do with. But I
[17:59] knew its sight well because it was built on a
[18:01] place where I used to observe a lot. Uh, this
[18:03] is the Gran Telescopio Canarias,
[18:06] uh, which is the Big Canarian
[18:09] Telescope. It's actually the biggest optical
[18:11] telescope in the world. It has a 10 metre
[18:12] mirror, um, and it's
[18:15] located, uh, In La Palma
[18:18] in the Canary Islands. And I used to observe
[18:20] there on a telescope called the William
[18:21] Herschel Telescope. So uh, gtc as
[18:24] it's called, Grand Telescopio Canarias has
[18:27] a camera, um, ah, called
[18:30] Hypercam, ah, which is the
[18:32] one that I think has
[18:35] really given us this research on Cloud nine
[18:38] because uh, the colleagues who
[18:41] observed uh, this object, what they did
[18:44] was they used that big telescope with its um,
[18:47] wide angle camera in order
[18:50] to get very, very deep
[18:53] images. And by deep images we mean ones that
[18:55] penetrate to the, at really faint levels.
[18:58] Uh, they got 2.36 hours of
[19:00] integration, uh, which is um,
[19:04] quite, quite a long time, uh, and
[19:06] didn't see any stars. I think they, they
[19:09] think they might have seen a small number of
[19:12] stars but not uh,
[19:15] what we expect in a galaxy. Um,
[19:19] so the uh, one of the authors of
[19:22] this paper, um,
[19:24] basically in offering an explanation as to
[19:27] how you could have a galaxy with no stars,
[19:30] uh, I'll quote. The leading theoretical
[19:32] explanation involves the ultraviolet
[19:35] background radiation that permeates the
[19:37] universe after the epoch of
[19:39] reionization. Uh, that's right at the
[19:42] beginning, this radiation field heats the gas
[19:44] in low mass dark matter halos to
[19:46] temperatures high enough that the gas cannot
[19:49] cool efficiency and collapse to form stars. I
[19:52] think that might be what I said earlier,
[19:53] which is good. Um, when they do
[19:56] simulations um, of
[19:59] uh, you know, basically what this galaxy,
[20:02] how it might have evolved, sure enough it
[20:04] remains starless. They don't have any stars.
[20:06] So this looks like uh,
[20:09] look like, looks uh, like ah, the first real
[20:12] example of something that people have
[20:15] thought must exist. Um, and
[20:18] again quoting from. It's Dr.
[20:20] Trujillo, who I think I might have worked
[20:23] with in La Palma many, many years ago.
[20:26] Uh, says Cloud 9 has a halo mass
[20:29] consistent with this regime. In this picture,
[20:31] starless galaxies are not
[20:34] exotic anomalies, but a natural and
[20:37] abundant prediction of standard
[20:39] cosmological models. The challenge has simply
[20:41] been finding them. So uh, maybe it's
[20:44] not such an unusual thing after all, uh,
[20:47] but uh, something that uh, has been
[20:50] predicted. But yes, the first, I think the
[20:53] first one that we can really be sure, uh, is
[20:56] a starless galaxy.
[20:58] Andrew Dunkley: Yeah, very, very unusual. Um, I'd
[21:01] suppose the description failed galaxy would
[21:03] be probably accurate given
[21:06] the circumstances.
[21:07] Professor Fred Watson: Yes, if you think of a normal galaxy as
[21:10] being populated by stars, it is.
[21:13] Um, but you can see that there's good reason
[21:16] for it to fail if the temperature of the
[21:18] background gas and the dark matter that's in
[21:20] it are too high for stars to form.
[21:24] Um, and you might consider It a success
[21:26] because it's a purely gaseous
[21:29] galaxy.
[21:30] Andrew Dunkley: Yeah, yeah. Uh, I suppose one
[21:33] day it might merge with another galaxy and
[21:35] then, you know, all hell will break loose.
[21:39] Professor Fred Watson: No, you're right, that's a good point because
[21:41] it's not that far from M94, which is a big
[21:43] galaxy. Uh, this is a, it
[21:46] counts as a dwarf galaxy. I didn't really
[21:48] make that clear. And of course our
[21:51] own galaxy has dwarf galaxies in orbit around
[21:54] it, most of which contain stars. Uh,
[21:56] and so, and the fate of those dwarf galaxies
[21:59] is basically to become part of the, of the
[22:02] bigger galaxy. So it may be that Cloud nine
[22:05] eventually does that and maybe the conditions
[22:08] will change so that the, the gas becomes,
[22:11] um, uh, cool enough or
[22:13] otherwise relaxed enough, uh, in order to
[22:16] start and form stars.
[22:18] Andrew Dunkley: Okay. If you want to, uh, read all about the
[22:20] Starless Galaxy Cloud 9, there's a great
[22:23] article on Space dot com.
[22:26] Um, Fred Watson, we've got a live viewer
[22:29] who has, is from Dubbo, actually. Hi,
[22:31] Lynette. Um, she says, uh,
[22:34] hello from Dubbo. How long did you stay. I
[22:36] assume she means Spain. Um,
[22:40] from her earlier conversations.
[22:41] Professor Fred Watson: Yes, we were in Spain for, uh, roughly
[22:44] a week actually. Uh, I didn't tell you, but
[22:47] I, I got, um, I got,
[22:50] um, thieved from by a pickpocket.
[22:54] Professor Fred Watson: Oh.
[22:55] Professor Fred Watson: Yeah.
[22:56] Andrew Dunkley: Um, but very, very common thing over there.
[22:59] Professor Fred Watson: It was in Bilberryo and. Oh, we went
[23:01] there. Lovely place. Did you get your
[23:04] binoculars nicked as well?
[23:05] Andrew Dunkley: No, no, I, I'm very, very,
[23:09] um. We'll
[23:12] use the word anal about holding on to my
[23:15] stuff, quite literally.
[23:16] Professor Fred Watson: Yep.
[23:16] Andrew Dunkley: I put stuff in my pockets and I'll shove my
[23:18] hands in my pockets and I will not take them
[23:20] out. Yeah, I must look weird.
[23:24] Professor Fred Watson: Well, you look weird anyway, Andrew, but
[23:25] that's, you know, not good. Not bad news
[23:28] anyway. Uh, but, but no, you're right. Um,
[23:31] so I'm like that too. But, um, I, I
[23:34] had a sort of man bag. Um,
[23:37] and um, I was walking back
[23:40] from the Guggenheim exhibition, which you
[23:43] probably went to see as well, in Bilberry, to
[23:45] our hotel, and I thought
[23:48] I noticed a bit of a disturbance
[23:51] behind me. I had headphones on. Um, noise
[23:53] cancelling headphones because I was walking.
[23:55] Andrew Dunkley: Yeah.
[23:56] Professor Fred Watson: And um, when I got into the hotel, I looked
[23:58] in my man bag and the zip was open
[24:01] and I know I, I shut it up and my
[24:04] binoculars were missing. So Marnie said
[24:07] go outside and have a look. They might have
[24:09] thrown them away. So went outside.
[24:13] Here's four policemen bailing up these two
[24:15] guys
[24:18] and they've Been. They've been following them
[24:20] because they'd created some sort of problems
[24:22] in a bar. Um, and I approached
[24:25] one of the policemen and said,
[24:27] um, I've, uh, lost a pair of binoculars.
[24:30] And he just said, yeah, we've got your
[24:31] binoculars. Wow. So I got lucky.
[24:35] Fantastic.
[24:38] Yeah, these guys had tried to throw them away
[24:40] when they saw the police were on them and the
[24:43] cops had seen it. The cop who dealt
[24:46] with me spoke great English. He was an
[24:49] absolute gentleman. It was, uh, such a good
[24:51] experience that Marnie insisted on taking
[24:53] our, uh, photographs together and things like
[24:55] that afterwards.
[24:56] Andrew Dunkley: Well, you got very lucky, Fred Watson. Very
[24:58] lucky.
[24:59] Professor Fred Watson: Very, very lucky indeed. Yeah, absolutely
[25:01] lucky. Uh, I couldn't believe it. And
[25:03] actually, those, uh. You know, I can go on
[25:06] about binoculars ad. Uh, infinitum. M. Having
[25:08] written the first book in English on the
[25:10] history of binoculars. Uh, but they were a
[25:13] special pair as well. Quite new. They're new
[25:15] to me. They're, um. Basically, they
[25:18] were made in the 60s. Sorry, the. The 70s.
[25:21] But they're very, very good ones. And, um,
[25:23] yeah, they're worth a lot of money.
[25:25] Andrew Dunkley: So Starchild says, um, we've got a few live,
[25:28] uh, viewers at the moment. And Starchild
[25:30] says, quite a few thieves in the Milky Way.
[25:34] Professor Fred Watson: Yes, that's right, yeah.
[25:36] Andrew Dunkley: Um, and there was another
[25:38] question. Uh, uh, good. Uh, says, good to see
[25:41] you two together again. Moose says, how much
[25:43] did I miss? Uh, about that much.
[25:47] I think we're a bit past halfway, Moose. And,
[25:49] um, another question. Um, how
[25:52] many light years across is a dwarf galaxy? I
[25:55] guess they're all different sizes.
[25:57] Professor Fred Watson: They are, but it's a good question. I mean,
[25:59] um, so think of our galaxy, which is
[26:02] kind of 100,000 light years across.
[26:05] Um, and that's typical of
[26:07] a. Of a major spiral galaxy.
[26:10] Dwarf galaxy would probably be
[26:13] less than a tenth of that. Um, 10,000
[26:16] light years. That sort of size. You know,
[26:18] just on. On average. Uh, that kind of.
[26:21] That kind of size.
[26:23] Andrew Dunkley: Okay. Thanks for the question. It doesn't
[26:25] happen like this very often, but today
[26:28] we've got an active audience. That's good.
[26:32] Yeah. All right. Uh, you're listening to
[26:34] Space Nuts, by the way, uh, with Andrew
[26:36] Dunkley and Professor Fred Watson Watson.
[26:40] Professor Fred Watson: Okay, we checked all four systems.
[26:43] Andrew Dunkley: Space Nuts, our final topic. Fred Watson
[26:46] takes us to Venus. Sunny Venus.
[26:49] Ah, yes. What a place. Go outside, take a
[26:51] deep breath, drop dead. Um, but
[26:54] there's some news about Venus which involves
[26:56] its clouds again. Now, the last time this was
[26:59] big news was when they thought they might
[27:00] have found, um, signs of life in the
[27:03] clouds. That's still under a lot of
[27:05] speculation and debate. But, uh, what's the
[27:08] latest with these clouds? These aren't the
[27:11] ones we were talking about last time. These
[27:13] are a little bit different again.
[27:15] Professor Fred Watson: Yes, they are, yeah. So I think that was
[27:17] sulphur. Was it sulphur dioxide? I can't
[27:19] remember. Um, the detection, uh, which
[27:22] people got excited because it might mean
[27:24] living organisms in the upper atmosphere of
[27:26] Venus. But I think that's gone away now.
[27:29] Um, it's great to talk about Venus,
[27:31] especially just now, because you would know,
[27:33] Andrew, it's absolutely lighting up the
[27:35] evening sky. Uh, over there in the west. It
[27:38] is very bright, very high in the sky,
[27:41] beautiful object. And when we look at it,
[27:44] it's kind of got a yellowish colour, uh,
[27:47] which is because we're seeing reflections
[27:49] from the top of its cloud layer.
[27:52] Um, but, uh, it's been known
[27:55] for a long time that
[27:58] if you photograph Venus in with
[28:00] ultraviolet light, you. You
[28:03] see patterns, really
[28:06] dramatic patterns. And I've, uh, got one in
[28:08] front of me now. But I do remember
[28:10] photographs of this, that these are sort of
[28:12] global size patterns that actually
[28:15] move, uh, with the. The
[28:17] clouds of Venus. Uh, we
[28:20] know. I think most space notes, uh,
[28:23] listeners and viewers would know that we
[28:24] don't actually see the surface of Venus
[28:26] directly. We can with radar, uh, certain
[28:29] infrared observations that let you penetrate
[28:31] to the surface. But basically all we see, uh,
[28:34] and certainly in ultraviolet is the upper
[28:36] parts of the cloud belts, cloud
[28:39] layers. So the markings themselves,
[28:42] uh, are a puzzle. And,
[28:45] and this is where it sort of gets
[28:47] interesting. Although it's not one of these
[28:49] storeys that's got a neat and tidy answer,
[28:51] I'm afraid. Um, there's a
[28:53] chemical that is thought to be in
[28:56] Venus's upper atmosphere, which is
[28:59] called the unknown absorber.
[29:02] Uh, and because, uh, it absorbs
[29:05] light in the ultraviolet and you get dark
[29:08] patches from. From this, this stuff.
[29:11] Um, I was talking to somebody about this the
[29:14] other day and they said it sounds like a
[29:15] superhero, the Unknown absorber. Uh,
[29:18] which, uh, I think probably would work well.
[29:20] Andrew Dunkley: Yeah, his superhero name would
[29:23] be the Sponge.
[29:25] Professor Fred Watson: The Sponge, that's right.
[29:28] So what's happened is that,
[29:31] um, a team, an international team
[29:34] actually, of basically astrobiologists,
[29:36] people who were looking at,
[29:39] uh, the origin of life in the universe
[29:42] and what we need for life to form and all of
[29:44] those other good things, not necessarily
[29:46] trying to find life, but trying to understand
[29:48] life. Um, what they've done, uh,
[29:51] they've essentially this
[29:53] research team, I think they've done very
[29:57] cluey kind of modelling, um,
[29:59] of the droplets within the
[30:02] clouds of Venus to try and
[30:06] not identify what this unknown absorber
[30:09] is, but sort of, um,
[30:12] place limits on its properties. You
[30:15] know, it does this but it doesn't do that.
[30:17] Uh, and it does this to this extent, but it
[30:19] doesn't do that to this extent. So, uh,
[30:22] it's all about trying to model what
[30:25] cloud droplets would look like to
[30:27] actually reproduce what we see when we
[30:30] observe the planet. Um,
[30:34] so, uh, uh, one of the
[30:37] authors of the paper basically
[30:40] poses a question, uh, if
[30:43] we were to collect Venus's cloud
[30:45] droplets, and I'm paraphrasing here,
[30:48] into a bucket, how would the
[30:50] reformed bulk liquid appear? Uh,
[30:54] the scientist actually said a spectrometric
[30:56] cuvette. Uh, but a bucket's as good an
[30:58] allergy for that as you need. If you could
[31:01] collect the droplets, what would it look
[31:03] like? Um, and that
[31:06] is the sort of key
[31:09] to the modelling that's been done.
[31:12] Um, they, there's a comment, um,
[31:15] I think it might come from the original
[31:17] paper, but um, phys.org has got a very
[31:20] nice article on this and I
[31:22] think it may even come from their press
[31:25] release. Uh, but basically it's
[31:29] likening the droplets in
[31:32] the clouds of Venus to cigarette smoke.
[31:35] Um, because, um, cigarette smoke is
[31:37] tiny particles, tarry. Tiny tarry
[31:40] particles, um, which
[31:43] look sort of white or bluish because of the
[31:46] scattering of light. Because these things are
[31:47] so small they scatter light very effectively.
[31:50] But if you collected it into a flask, you
[31:53] got this horrible sludge, uh, tar,
[31:56] like sludge. Of course that was what ends up
[31:58] in your lungs if you're a smoker. Um,
[32:02] yeah. So what they're suggesting is that
[32:06] there's a similar phenomenon happening in
[32:08] Venus's clouds, uh, because the particle
[32:11] size of the droplets in Venus's upper
[32:13] atmosphere are comparable to the particle
[32:16] size of cigarette smokes, smoke.
[32:18] So even though, um, you know, even though
[32:21] the clouds with the visible light
[32:25] look that sort of yellowish colour that we've
[32:28] mentioned already, the actual
[32:31] droplets themselves could be really,
[32:33] really dark and it's only because they
[32:36] scatter the light in a certain way that they
[32:37] look that they look yellowish. Um,
[32:41] so this, um, basically this uh, research
[32:43] is asking that question. What happened? What
[32:46] would happen if you could collect a cloud of
[32:48] material from the atmosphere of Venus and put
[32:50] it into a, um. Basically, you
[32:53] know, a flask or
[32:57] um, a beaker or something like that. Um,
[33:00] and that's where this analysis has
[33:03] gone and they've used something, it's words
[33:06] that used to strike terror into me when I was
[33:08] a student in astronomy. Andrew And I don't
[33:10] know whether I've uttered them ever since.
[33:12] Radiative transfer. Uh, radiative
[33:15] transfer is the way radiation moves around
[33:18] uh, among atoms. Uh
[33:21] and it's very, very intense
[33:23] mathematics. So these scientists
[33:26] obviously like that kind of thing. I'm afraid
[33:28] I didn't. Uh, and they've built a radiat
[33:31] transfer model that uh, actually lets
[33:33] you um, account for not just
[33:36] single scattering but multiple scattering
[33:39] because you've got to um, take into account
[33:41] that light might scatter from one of those
[33:43] droplets and then hit another one and scatter
[33:45] from that. So you've got multiple scattering
[33:48] phenomena. Um and so
[33:52] they uh, have basically done that
[33:54] and produced what is called the
[33:57] absorption coefficient of the bulk cloud
[34:00] liquid. That's the, how it would absorb um,
[34:03] if you just had a flask of this stuff.
[34:06] Now what they're saying is that they don't
[34:08] really know what this, these droplets are
[34:11] but they're not suggesting it's life.
[34:14] Um, they've put limits on the
[34:17] absorption coefficient
[34:19] um, and uh,
[34:22] essentially again paraphrasing the
[34:25] uh, Press release from phys.org uh the
[34:28] result implies that the unknown absorber
[34:31] must either absorb light very
[34:33] efficiently, occur at a very
[34:36] high concentration or both. Um,
[34:39] my guess is it's going to be both. Um, so uh,
[34:43] it's some sort of, probably some sort of
[34:45] organic compound and by that I mean one that
[34:48] contains carbon rather than one that contains
[34:50] living organisms. Um and
[34:53] they've basically you know, they've suggested
[34:56] some chemicals that might actually
[34:59] be, be uh, responsible for this.
[35:01] Uh, excluding they say chlorophyll.
[35:04] Chlorophyll of course very important in life
[35:06] processes. Uh but they're excluding, they're
[35:09] saying they're not proposing chlorophyll as
[35:11] ah an example. So uh,
[35:14] as I said it's a storey that doesn't have a
[35:16] conclusion. But it's
[35:19] interesting to think of the clouds of
[35:21] Venus that if you could collect them in a
[35:23] bucket or a container they could be very very
[35:26] dark mixtures like tar, a sort of
[35:29] sludge, um,
[35:32] would be interesting.
[35:35] Andrew Dunkley: Yeah, um, it's a
[35:38] classic example of a failed Earth like world.
[35:42] Professor Fred Watson: Yes, that's right. Yes indeed. We don't have
[35:45] things like this in our planet thankfully.
[35:49] Yeah, I think there's more um, sorry Andrew,
[35:52] just to finish the storey, I think there's
[35:53] more research being
[35:56] designed possibly looking
[35:58] uh, uh, with a
[36:01] future mission to Venus, uh, perhaps
[36:04] looking for fluorescence
[36:07] uh, in the clouds because that would give
[36:09] them another angle on what this stuff is.
[36:12] Andrew Dunkley: Okay, we watch with interest. Uh,
[36:16] Venus Keeps throwing up curveballs.
[36:20] The potential for life in the clouds because
[36:22] of the discovery of phosphine. And now this.
[36:25] Um, a bucket of tar.
[36:26] Yay. What a place. Next
[36:29] holiday, I think.
[36:31] Professor Fred Watson: Well, yeah, plus you've got the sulfuric acid
[36:33] as well.
[36:34] Andrew Dunkley: Oh, that's true. Yes, yes. And. And the, um,
[36:36] undeniable level of heat. Uh, I think
[36:38] Australians could handle it and a few other
[36:40] places in the world, but most, no, most
[36:42] people couldn't. It's horrible. It's an
[36:44] horrible place. But very pretty in the sky at
[36:47] the moment. It is. You can read all about
[36:50] it@fizz.org as Fred Watson said, or you can
[36:52] read the entire paper, which was published in
[36:55] Astrobiology. And that brings us to
[36:58] the end. Fred Watson, thank you very much.
[37:01] Professor Fred Watson: Uh, it's a pleasure, Andrew. Um, it's always
[37:03] good to chat and, um, even better to chat
[37:05] when you're half asleep. You did
[37:08] well.
[37:09] Andrew Dunkley: You did well. For those who joined us late,
[37:12] um, you'll have to listen to the episode, get
[37:14] the full explanation of Fred Watson's
[37:16] sleepiness. Um, it's got something to do
[37:19] with, um, painkillers. Anyway,
[37:22] we'll get on. Hopefully he'll
[37:25] brighten up for the next episode.
[37:26] Professor Fred Watson: I suspect not.
[37:27] Andrew Dunkley: Um, thank you, Fred Watson. We'll catch you
[37:29] soon, dude.
[37:30] Professor Fred Watson: Sounds great. Thanks, Andrew.
[37:32] Andrew Dunkley: Professor Fred Watson Watson, astronomer at
[37:34] large. And don't forget to visit us at our
[37:36] website between episodes, which you can
[37:38] do@spacenutspodcast.com or
[37:40] spacenuts IO have a look around
[37:43] and, um, see what's there. The shop.
[37:46] You can send us messages, you can sign up for
[37:49] Astronomy AstroDailyPod. Plenty of things to
[37:50] see and do. And don't forget to leave reviews
[37:52] about our, uh, podcast wherever you listen to
[37:54] us. And thanks to Huw in the studio, who
[37:57] couldn't be with us today because he
[37:58] discovered that, um, he's more at home in a
[38:01] starless galaxy. And from me, Andrew Dunkley,
[38:04] thanks for your company. See you on the next
[38:05] episode of Space Nuts.
[38:07] Professor Fred Watson: Bye.
[38:07] Andrew Dunkley: Bye. You've been listening to
[38:10] the Space Nuts podcast,
[38:13] available at Apple Podcasts, Spotify,
[38:16] iHeartRadio or your favourite podcast
[38:19] player. You can also stream on
[38:20] demand@bytes.comm this has been another
[38:23] quality podcast production from
[38:25] bytes.com.

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