In this episode of SpaceTime, we explore thrilling recent discoveries and events in the cosmos, including close encounters with asteroids, a newly discovered moon around Uranus, and the cosmic dance of dwarf galaxies.
Earth Dodges Two Asteroid Near Misses
Planet Earth has narrowly avoided two asteroid near misses within days of each other. The first, asteroid 2025 PF2, zipped past at an altitude of just 22,000 kilometers, while the second, 2025 PU1, came even closer at 29,000 kilometers. Both asteroids, small yet significant, highlight the ongoing risks posed by near-Earth objects, with 2025 PU1 being particularly alarming as it was only detected hours after its closest approach.
A New Moon for Uranus
Astronomers have identified a new moon orbiting Uranus, bringing the total number of known satellites to 26. Detected using NASA's Webb Space Telescope, this moon, estimated to be about 10 kilometers in diameter, eluded previous observations, including those from the Voyager 2 mission. Its discovery adds to the complexity of Uranus's moon system and raises questions about the chaotic history of its rings and satellites.
Dancing Dwarf Galaxies and the Milky Way's Fate
A new study suggests that the fate of our Milky Way galaxy is intricately tied to the gravitational interactions with smaller dwarf galaxies as it approaches a merger with the Andromeda galaxy. By studying similar galactic systems, researchers aim to predict how these cosmic dances will influence the evolution of our galaxy over the next few billion years, providing insights into dark matter and cosmic structure.
www.spacetimewithstuartgary.com
✍️ Episode References
Monthly Notices of the Royal Astronomical Society
https://academic.oup.com/mnras
NASA's Webb Space Telescope
https://www.nasa.gov/mission_pages/webb/main/index.html
Become a supporter of this podcast: https://www.spreaker.com/podcast/spacetime-space-astronomy--2458531/support.
00:00:00 --> 00:00:02 Stuart Gary: This is space Time Series 28 Episode
00:00:02 --> 00:00:04 102 for broadcast on 25
00:00:04 --> 00:00:07 August 2025. Coming up on space
00:00:08 --> 00:00:10 time, planet Earth dodges two asteroid
00:00:10 --> 00:00:13 near misses within days of each other. A new
00:00:13 --> 00:00:16 moon discovered orbiting around the planet Uranus
00:00:17 --> 00:00:19 and dancing dwarf galaxies may help predict the
00:00:19 --> 00:00:22 Milky Way's ultimate fate. All that and more
00:00:22 --> 00:00:24 coming up on, uh, Space Time.
00:00:26 --> 00:00:28 Voice Over Guy: Welcome to Space Time with Stuart
00:00:28 --> 00:00:29 Gary
00:00:45 --> 00:00:48 Stuart Gary: Planet Earth has just dodged two asteroid near misses
00:00:48 --> 00:00:51 within days of each other, both swooping past the Earth
00:00:51 --> 00:00:53 lower than the orbits of many satellites.
00:00:53 --> 00:00:56 Asteroid 2025 PF2 sped
00:00:56 --> 00:00:59 past the Earth at an altitude of just 22
00:00:59 --> 00:01:02 kilometers, traveling at around 13 kilometers per
00:01:02 --> 00:01:05 second. Estimated to be somewhere between 2 and
00:01:05 --> 00:01:08 6 meters in size, the space rock was flying in
00:01:08 --> 00:01:10 the constellation Aquila ah as it passed. Then
00:01:10 --> 00:01:13 there's asteroid 2025 PU1. It missed
00:01:13 --> 00:01:16 the Earth by just 29 kilometers, traveling at
00:01:16 --> 00:01:19 around 10 kilometers per second. It's
00:01:19 --> 00:01:22 estimated to have been somewhere between 2 and 3 meters in
00:01:22 --> 00:01:24 diameter and is currently in the direction of the constellation
00:01:24 --> 00:01:27 Pegasus. The frightening thing about
00:01:27 --> 00:01:29 2025 PU1 is that it was only
00:01:29 --> 00:01:32 observed 4 hours after it met its closest approach.
00:01:33 --> 00:01:36 It belongs to the Apollo class of near Earth asteroids
00:01:36 --> 00:01:39 and will make its next close approach to the Earth on, um, April
00:01:39 --> 00:01:42 3, 2036. It was the 10th
00:01:42 --> 00:01:45 closest asteroid flyby of Earth in just 12 months,
00:01:45 --> 00:01:48 the 85th known flyby of the planet within
00:01:48 --> 00:01:50 one lunar distance since the start of the year and the
00:01:50 --> 00:01:53 third so far this month. This is
00:01:53 --> 00:01:56 space time. Still to come, a new
00:01:56 --> 00:01:59 moon discovered orbiting the planet Uranus and
00:01:59 --> 00:02:02 dancing dwarf galaxies could help predict the ultimate
00:02:02 --> 00:02:05 fate of our own Milky Way. All that and more
00:02:05 --> 00:02:07 still to come on space time.
00:02:23 --> 00:02:25 Astronomers m have discovered another moon orbiting around the
00:02:25 --> 00:02:28 ice giant planet Uranus. The new
00:02:28 --> 00:02:30 observations were made using NASA's Webb Space
00:02:30 --> 00:02:33 Telescope. The previously unknown moon brings
00:02:33 --> 00:02:36 the total number of satellites orbiting Uranus to 26.
00:02:37 --> 00:02:40 The object was detected in a series of ten 40
00:02:40 --> 00:02:43 minute long exposure images captured by Webb's near
00:02:43 --> 00:02:45 infrared Camera. One of the study's authors,
00:02:45 --> 00:02:48 Maryam Al Mutamid from the Southwest Research
00:02:48 --> 00:02:51 Institute in Boulder, Colorado, says it's a small
00:02:51 --> 00:02:54 but significant discovery, which is something that even
00:02:54 --> 00:02:56 NASA's Voyager 2 spacecraft didn't see during its
00:02:56 --> 00:02:59 flyby of Uranus 40 years ago. The
00:02:59 --> 00:03:02 newly discovered moon is estimated to be around 10 kilometers
00:03:02 --> 00:03:05 in diameter. That's assuming it has a similar reflectivity
00:03:05 --> 00:03:08 or albedo to Uranus. Other small satellites
00:03:08 --> 00:03:11 it was its tiny size, which likely rendered it
00:03:11 --> 00:03:14 invisible to Voyager 2 and earlier telescope
00:03:14 --> 00:03:17 observations. No, uh, other planet has as many
00:03:17 --> 00:03:20 small inner moons as Uranus. And their complex
00:03:20 --> 00:03:22 interrelationships with the planet's rings hint at a
00:03:22 --> 00:03:25 chaotic history that blurs the boundary between what
00:03:25 --> 00:03:27 a ring system is and what's really a
00:03:27 --> 00:03:30 constellation of moons. Also, this New
00:03:30 --> 00:03:33 Moon discovery is a lot smaller and fainter than the smallest
00:03:33 --> 00:03:36 of the previously known inner moons, making it likely
00:03:36 --> 00:03:39 that even more complexity remains to be discovered in the
00:03:39 --> 00:03:42 system. The New moon is the 14th member
00:03:42 --> 00:03:45 of the intricate constellation of small moons orbiting
00:03:45 --> 00:03:47 inwards of the largest moons, Miranda, Ariel,
00:03:47 --> 00:03:50 Umberal, Titania, and Oberon, all of which
00:03:50 --> 00:03:53 were named after characters from Shakespeare and Alexander
00:03:53 --> 00:03:56 Pope. It's located about 56
00:03:56 --> 00:03:59 kilometers from the center of Uranus. And it's orbiting the ice
00:03:59 --> 00:04:01 giant's equatorial plane between the orbits of
00:04:01 --> 00:04:04 Ophelia, which is just outside the planet's main ring system.
00:04:04 --> 00:04:07 And Bianca. The authors believe its nearly
00:04:07 --> 00:04:10 circular orbit suggests that it may have formed near its
00:04:10 --> 00:04:12 current location. As for a name for the
00:04:12 --> 00:04:15 newly found moon, well, that'll wait until one is approved by the
00:04:15 --> 00:04:18 International Astronomical Union, the leading authority in
00:04:18 --> 00:04:21 assigning official names and designations to astronomical
00:04:21 --> 00:04:24 objects. The discovery continues to build upon a
00:04:24 --> 00:04:27 legacy of missions like Voyager 2, which flew past
00:04:27 --> 00:04:30 Uranus back in January 1986, giving
00:04:30 --> 00:04:33 humanity its first close up look at this mysterious
00:04:33 --> 00:04:36 world. Now, nearly four decades later, the
00:04:36 --> 00:04:38 Webb Space Telescope is pushing that frontier
00:04:39 --> 00:04:42 even further. This is space time.
00:04:42 --> 00:04:45 Still to come, a new study trying to determine the
00:04:45 --> 00:04:48 ultimate fate of our Milky Way galaxy. And later
00:04:48 --> 00:04:51 in the science report, the first almost
00:04:51 --> 00:04:53 100% effective prevention drug for HIV
00:04:53 --> 00:04:56 AIDS. All that and more still to come,
00:04:56 --> 00:04:57 um, on space time.
00:05:02 --> 00:05:05 Okay, let's take a break from our show for a word from our sponsor, uh,
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00:06:58 --> 00:07:01 A new study is trying to determine the ultimate
00:07:01 --> 00:07:04 fate of our Milky Way galaxy as it hurtles towards
00:07:04 --> 00:07:07 a merger with our big galactic neighbor, M M31
00:07:07 --> 00:07:09 Andromeda. As the two galaxies come
00:07:09 --> 00:07:12 closer together, the gravitational tidal forces
00:07:12 --> 00:07:15 interacting between them will cause both to undergo
00:07:15 --> 00:07:17 massive changes. Now, a new study
00:07:17 --> 00:07:20 reported in the Journal of the Monthly Notices of the Royal
00:07:20 --> 00:07:23 Astronomical Society suggests that the cosmic dance
00:07:23 --> 00:07:25 of small, smaller satellite galaxies orbiting around the two
00:07:25 --> 00:07:28 giants will also play a significant role in
00:07:28 --> 00:07:31 that ultimate cosmic collision. One of the
00:07:31 --> 00:07:34 study's authors, Sarah Sweet from the University of Queensland,
00:07:34 --> 00:07:37 says the Milky Way will merge with Andromeda and with their
00:07:37 --> 00:07:40 respective smaller dwarf galaxies in the next two and a half
00:07:40 --> 00:07:43 to seven billion years. And while there's been a
00:07:43 --> 00:07:45 lot of research into what's happening in our local galactic group,
00:07:45 --> 00:07:48 astronomers really don't know how typical that will be.
00:07:49 --> 00:07:52 So to better understand how representative such a galactic collision
00:07:52 --> 00:07:55 will be, Sweet and colleagues studied NGC
00:07:55 --> 00:07:57 5713 and NGC
00:07:57 --> 00:08:00 5719, which are two very similar
00:08:00 --> 00:08:03 spiral galaxies which are about 3 billion years ahead
00:08:03 --> 00:08:05 of where the Milky Way and Andromeda now are in their
00:08:05 --> 00:08:08 merging. The authors are showing that these
00:08:08 --> 00:08:10 galaxies are combining as if they were dancing with
00:08:10 --> 00:08:13 closely located dwarf satellites rotating around them.
00:08:14 --> 00:08:17 It may provide our clearest look yet at how
00:08:17 --> 00:08:20 structures like the Milky Way satellite Galaxy System
00:08:21 --> 00:08:23 and how over the next few billion years, it'll evolve.
00:08:24 --> 00:08:27 Understanding our galaxy's likely future helps
00:08:27 --> 00:08:29 astronomers refine models of galactic evolution,
00:08:30 --> 00:08:32 models of dark matter, and models of the cosmic
00:08:32 --> 00:08:35 structure of the universe. Sweet says.
00:08:35 --> 00:08:38 We're all part of a much larger cosmic story,
00:08:38 --> 00:08:40 one that unfolds over billions of years,
00:08:41 --> 00:08:44 involving dances of galaxies and the shaping of
00:08:44 --> 00:08:47 the universe itself. She says. By comparing our
00:08:47 --> 00:08:49 Local Galaxy Group with other systems like it,
00:08:49 --> 00:08:52 astronomers can determine whether the Milky Way and Andromeda
00:08:53 --> 00:08:55 Group are a poster child for this sort of event or a
00:08:55 --> 00:08:58 cosmic outlier. Until astronomers know
00:08:58 --> 00:09:01 this, their ability to generalize findings from the Local
00:09:01 --> 00:09:04 Group of galaxies to understand galaxy evolution in a
00:09:04 --> 00:09:06 broader cosmological context remains hampered.
00:09:06 --> 00:09:09 For example, there's a persisting tension between the
00:09:09 --> 00:09:12 Local Galaxy Group observations and the world's most
00:09:12 --> 00:09:15 sophisticated cosmological computer models, such
00:09:15 --> 00:09:18 as the observed placement of dwarf galaxies preferentially
00:09:18 --> 00:09:20 in satellite planes around their hosts.
00:09:21 --> 00:09:24 And these observations therefore suggest that scientists will need
00:09:24 --> 00:09:27 to, uh, overhaul their current computer simulations.
00:09:27 --> 00:09:30 Sweet wants to know the Milky Way will begin its own
00:09:30 --> 00:09:32 dance with Andromeda, with the smaller dwarf galaxies
00:09:32 --> 00:09:33 rotating around them.
00:09:34 --> 00:09:37 Dr Sarah Sweet : Well, just like in our own Local Group, that's what
00:09:37 --> 00:09:39 you've been describing. Our, uh, Milky Way, Andromeda, our
00:09:39 --> 00:09:42 satellite galaxies, our dwarfs, including the Large and Small
00:09:42 --> 00:09:45 Magellanic Cloud, Sagittarius as well, and
00:09:45 --> 00:09:48 dozens of other satellites. We've been studying other
00:09:48 --> 00:09:51 systems that are quite like our Local Group. One in particular
00:09:51 --> 00:09:54 is this pair of gal, NGC 5713 and
00:09:54 --> 00:09:57 NGC 5719. They're quite like our
00:09:57 --> 00:10:00 Milky Way and Andromeda in that they're both massive spiral
00:10:00 --> 00:10:03 galaxies and they're approaching each other just like our
00:10:03 --> 00:10:06 Milky Way and Andromeda are approaching as well. And they
00:10:06 --> 00:10:08 both have associated dwarf galaxies with them. What's
00:10:08 --> 00:10:11 unusual about this system is that their dwarf
00:10:11 --> 00:10:14 galaxies are rotating around the center of mass
00:10:14 --> 00:10:17 of both of the galaxies rather than being
00:10:17 --> 00:10:19 associated with either one. They're not in a
00:10:19 --> 00:10:22 random cloud, but they're actually showing this rotation
00:10:23 --> 00:10:26 and what we think this system is quite
00:10:26 --> 00:10:28 like, what our Local Group will be like. In about 2 to
00:10:28 --> 00:10:30 3 billion years.
00:10:30 --> 00:10:32 Stuart Gary: Some degree of organization will come together. The
00:10:32 --> 00:10:35 gravitational tidal forces won't just simply cause
00:10:35 --> 00:10:38 things to plunge through each other. They'll arrange them in a, in
00:10:38 --> 00:10:39 a different way.
00:10:39 --> 00:10:42 Dr Sarah Sweet : Yes, that's right, because as you've described, there's, there's a
00:10:42 --> 00:10:45 lot going on just around our, ah, Milky Way galaxy that
00:10:45 --> 00:10:48 our dwarfs are interacting. They're also interacting
00:10:48 --> 00:10:50 with our Milky Way galaxy. And on a
00:10:50 --> 00:10:53 slightly larger scale, we see These dwarfs rotating in a
00:10:53 --> 00:10:56 disk around their Milky Way. We also see dwarf galaxies is
00:10:56 --> 00:10:59 rotating in a disk around Andromeda. And
00:10:59 --> 00:11:02 the same thing we see happening around a lot of other galaxies as
00:11:02 --> 00:11:05 well. But what we expect is that as
00:11:05 --> 00:11:08 our Milky Way and Andromeda continue to approach each
00:11:08 --> 00:11:11 other, the dwarfs won't be just orbiting each massive
00:11:11 --> 00:11:13 galaxy, they'll actually be orbiting the whole system.
00:11:13 --> 00:11:16 And we think this is a way that these flat
00:11:16 --> 00:11:19 rotating disks of dwarf satellite galaxies can
00:11:19 --> 00:11:20 actually form.
00:11:20 --> 00:11:22 Stuart Gary: Are, uh, globular clusters the cause of merged
00:11:22 --> 00:11:25 dwarf galaxies, or are they individual
00:11:26 --> 00:11:28 nurseries of stars that are formed together and
00:11:28 --> 00:11:29 stayed together?
00:11:29 --> 00:11:32 Dr Sarah Sweet : Yeah, well, there are differences between dwarf
00:11:32 --> 00:11:35 galaxies and globular clusters. Globular clusters
00:11:35 --> 00:11:38 tend to have slightly or sometimes much
00:11:38 --> 00:11:40 more simple stellar populations. So they've had,
00:11:40 --> 00:11:42 usually had fewer generations.
00:11:43 --> 00:11:45 Stuart Gary: Of star formation, similar composition, and close,
00:11:46 --> 00:11:47 very close, gravitationally.
00:11:47 --> 00:11:50 Dr Sarah Sweet : Yes, that's right. So we think just a single epoch of
00:11:50 --> 00:11:53 star formation in globular clusters. Some are larger, like
00:11:53 --> 00:11:55 Omega Cen, um, you might have heard of
00:11:55 --> 00:11:58 47P. These are, um, a bit larger, like
00:11:58 --> 00:12:01 they're the largest ones. And they have had probably a
00:12:01 --> 00:12:04 few generations of star formations and stellar evolution. But
00:12:04 --> 00:12:07 dwarf galaxies tend to have a lot more of this. And
00:12:07 --> 00:12:10 so even if you're seeing just the cores, you still see
00:12:10 --> 00:12:13 a, uh, larger spread in their stellar population
00:12:13 --> 00:12:16 characteristics. Also. Another difference is that when
00:12:16 --> 00:12:19 there's a cores of dwarf galaxies, they still have a
00:12:19 --> 00:12:21 massive intermediate, massive or black
00:12:21 --> 00:12:24 hole at the, at the center, whereas globular
00:12:24 --> 00:12:27 clusters don't. And we also have a halo of dark
00:12:27 --> 00:12:29 matter still surrounding these stripped dwarf galax.
00:12:30 --> 00:12:33 There's a few ways that we can distinguish them.
00:12:33 --> 00:12:35 Stuart Gary: Uh, you just mentioned the key phrase halos of
00:12:35 --> 00:12:38 dark matter. These provide what we consider
00:12:38 --> 00:12:41 the scaffold of the universe, don't they?
00:12:41 --> 00:12:43 Dr Sarah Sweet : Yes, yes, that's right. Uh,
00:12:44 --> 00:12:47 in fact, our simulations trace these building blocks.
00:12:47 --> 00:12:49 We have simulations of dark matter halos, and they
00:12:49 --> 00:12:52 come together, they gravitationally interact and form
00:12:52 --> 00:12:55 larger and larger halos, and so too the
00:12:55 --> 00:12:58 galaxies inside them. So in our, uh, cosmological
00:12:58 --> 00:13:01 simulations, we inject the baryons or so, you
00:13:01 --> 00:13:03 know, the uh, luminous matter into these dark matter
00:13:03 --> 00:13:06 halos and retrace the evolution of the galaxies and their
00:13:06 --> 00:13:08 halos over cosmic time.
00:13:08 --> 00:13:10 Stuart Gary: And as you look at these computer models, these
00:13:10 --> 00:13:13 simulations, how do they compare with what you see in the real
00:13:13 --> 00:13:13 world?
00:13:14 --> 00:13:17 Dr Sarah Sweet : M. Well, for the most part, uh, very good they
00:13:17 --> 00:13:19 are. Our cutting edge simulations
00:13:19 --> 00:13:22 describe a lot about what we see really quite well.
00:13:23 --> 00:13:25 One key difference and something that
00:13:25 --> 00:13:28 I'm and my colleagues are interested in is that
00:13:28 --> 00:13:31 it extremely rare to see a flat rotating
00:13:31 --> 00:13:34 disk or satellite around a galaxy. But
00:13:34 --> 00:13:37 we see this, as I've mentioned, around our Milky Way,
00:13:37 --> 00:13:40 around Andromeda, and half a dozen or so other,
00:13:40 --> 00:13:43 um, systems nearby to us that we can study in great
00:13:43 --> 00:13:45 detail. So it's a bit of a puzzle to know
00:13:45 --> 00:13:48 just how this happens when our, uh, simulations don't
00:13:48 --> 00:13:51 capture it. But they do so well on, um, so many other
00:13:51 --> 00:13:53 characteristics. And so that's why what we've found
00:13:53 --> 00:13:56 with this rotating system is quite interesting, because we think
00:13:56 --> 00:13:58 that's one way that these can form.
00:13:58 --> 00:14:01 Stuart Gary: As you've carried out your obs and you looked at
00:14:01 --> 00:14:04 5713 and 5719,
00:14:04 --> 00:14:05 what are you seeing there?
00:14:05 --> 00:14:08 Dr Sarah Sweet : Well, what we're seeing is that the
00:14:08 --> 00:14:11 dwarf galaxies around these two massive
00:14:11 --> 00:14:14 spirals are, uh, in this sort of like this cosmic dance
00:14:14 --> 00:14:17 around these other two. So they've been falling, they've been
00:14:17 --> 00:14:20 approaching the center of mass, but trailing
00:14:20 --> 00:14:22 behind their massive, their host galaxy.
00:14:22 --> 00:14:25 So whereas they might have been isotropically
00:14:25 --> 00:14:28 distributed so randomly around the two
00:14:28 --> 00:14:31 massive galaxies as they were more separated as they're
00:14:31 --> 00:14:34 approaching each other, trailing along behind.
00:14:34 --> 00:14:37 And because the conservation of angular momentum as
00:14:37 --> 00:14:39 these two galaxies approach, it's like they're, they're pulling their
00:14:39 --> 00:14:42 arms in as like a figure skater, spinning
00:14:42 --> 00:14:45 faster. And so these dwarf galaxies, as they're approaching
00:14:45 --> 00:14:48 too, they feel this gravitational pull, and that's why they're
00:14:48 --> 00:14:51 coming in, in this rotating structure, we think.
00:14:51 --> 00:14:54 And, um. Yeah, so you get these. Yeah, they
00:14:54 --> 00:14:56 get, they do get into line. It's not a disc shape yet.
00:14:56 --> 00:14:59 It's still puffy. And it's like they're in these two wedge shapes,
00:14:59 --> 00:15:02 one either side. When you look at an image, you
00:15:02 --> 00:15:05 see these two massive galaxies in the middle, and
00:15:05 --> 00:15:08 all the galaxies on the left wedge are there
00:15:08 --> 00:15:11 approaching us. All the galaxies on the right hand wedge, they're
00:15:11 --> 00:15:13 moving away from us. So it's this really dramatic
00:15:13 --> 00:15:15 rotation that we can see.
00:15:15 --> 00:15:18 Stuart Gary: It sounds like as the merger continues
00:15:18 --> 00:15:21 over the next few billion years, these two galaxies won't
00:15:21 --> 00:15:23 be forming an elliptical galaxy, but probably a bigger
00:15:23 --> 00:15:25 spiral. Am I getting that right?
00:15:25 --> 00:15:28 Dr Sarah Sweet : Yeah, it's possible. It does depend,
00:15:28 --> 00:15:31 um, just on the angle of inclination
00:15:31 --> 00:15:34 that's the biggest one. It's a little bit hard to tell from
00:15:34 --> 00:15:37 the projected angle that we see, but one we can see edge on and
00:15:37 --> 00:15:40 one we can see face on, and we can actually see
00:15:40 --> 00:15:43 in the one that's edge on a little bit of a warp in the disk
00:15:43 --> 00:15:46 already. And in fact, the hydrogen gas, the neutral
00:15:46 --> 00:15:48 hydrogen that surrounds these galaxies, it's actually already
00:15:48 --> 00:15:51 forming a bridge between them. They are already interacting,
00:15:51 --> 00:15:54 uh, even though they don't look much like they are
00:15:54 --> 00:15:56 in the optical sense already.
00:15:56 --> 00:15:59 Stuart Gary: Now, when we look at our own Milky Way galaxy, not all that
00:15:59 --> 00:16:02 long ago, we discovered a warp in the disk of our galaxy as
00:16:02 --> 00:16:02 well.
00:16:02 --> 00:16:05 Dr Sarah Sweet : Yes. And that could be also because, you know, we have this neighbour,
00:16:05 --> 00:16:08 Andromeda, we are approaching each other, but that
00:16:08 --> 00:16:11 interaction is a lot. We've got another.
00:16:11 --> 00:16:14 Yes, it is a lot more subtle and a lot earlier on as well. So
00:16:14 --> 00:16:17 we've got, like I said, 2 or 3 billion years before we get
00:16:17 --> 00:16:20 as close and as interacting as this pair
00:16:20 --> 00:16:23 NGC 5713 and 19 is, they're.
00:16:23 --> 00:16:26 Stuart Gary: A lot more at advanced stage now when galaxies
00:16:26 --> 00:16:29 collide. It sounds spectacular, but it's not
00:16:29 --> 00:16:32 like two billiard balls hitting each other on the table,
00:16:32 --> 00:16:32 is it?
00:16:32 --> 00:16:35 Dr Sarah Sweet : That's right. There's a lot of empty space between the
00:16:35 --> 00:16:37 stars. When our Milky Way and
00:16:37 --> 00:16:40 Andromeda merge, the biggest difference
00:16:40 --> 00:16:43 for people on Earth, if Earth was still to be
00:16:43 --> 00:16:46 around then, um, then would be that we would just
00:16:46 --> 00:16:49 see the night sky becoming filled with stars.
00:16:49 --> 00:16:52 We see Andromeda approaching and there's. But
00:16:52 --> 00:16:55 the, the stars in Andromeda would be, uh, moving past the
00:16:55 --> 00:16:58 stars in our galaxy. And so, yeah, we'd see
00:16:58 --> 00:17:01 a much more full night guy.
00:17:01 --> 00:17:03 Stuart Gary: We see those computer simulations of the two
00:17:03 --> 00:17:06 galaxies merging. Do you think they're fairly representative
00:17:06 --> 00:17:09 or is your data showing it's going to be a little different to that?
00:17:09 --> 00:17:12 Dr Sarah Sweet : Well, that's one thing that we want to find out. We know a
00:17:12 --> 00:17:14 lot about our Milky Way and Andromeda and
00:17:14 --> 00:17:17 our dwarf galaxies. Because they're so close to us.
00:17:17 --> 00:17:20 We can resolve individual stars and we
00:17:20 --> 00:17:23 studied them in such great detail, but we don't know how
00:17:23 --> 00:17:26 well we can apply this knowledge to the rest of the
00:17:26 --> 00:17:29 universe in particular because we don't see all of the
00:17:29 --> 00:17:31 characteristics in our simulations. So, uh, something
00:17:32 --> 00:17:34 maybe, like you said, maybe it is just by random jump that we see these
00:17:34 --> 00:17:37 planes of satellites, for example. So that's what we're doing
00:17:37 --> 00:17:40 with this Local Group analog study is looking at
00:17:40 --> 00:17:43 these other systems that are as close to
00:17:43 --> 00:17:46 our Local Group as we can find and
00:17:46 --> 00:17:49 looking at them in, um, as much detail as
00:17:49 --> 00:17:52 we can and working out how far down in detail
00:17:52 --> 00:17:55 we need to go before we start seeing differences to our
00:17:55 --> 00:17:58 Milky Way and Andromeda and therefore
00:17:58 --> 00:18:01 what the limit of that extrapol might be. This pair
00:18:01 --> 00:18:04 of galaxies is one of our
00:18:04 --> 00:18:07 samples from our survey delegate, which is
00:18:07 --> 00:18:10 so called because the dwarf galaxies, ah, are delegates of
00:18:10 --> 00:18:13 their environment, so that they represent their host
00:18:13 --> 00:18:16 galaxies and their neighbours. We have handpicked
00:18:16 --> 00:18:19 these various local group analogues and
00:18:19 --> 00:18:21 this one in particular, my colleague at
00:18:21 --> 00:18:24 anu, Helmet, Jurgen, was looking in detail
00:18:24 --> 00:18:27 at this existing imaging of this system
00:18:27 --> 00:18:30 and he was looking at the velocity field, the
00:18:30 --> 00:18:32 velocity field of the hydrogen between the
00:18:32 --> 00:18:35 galaxies, piecing together existing observations that
00:18:35 --> 00:18:38 hadn't been combined before. And he had some deep
00:18:38 --> 00:18:40 imaging as well, looked at the
00:18:41 --> 00:18:44 velocities from existing catalogues of
00:18:44 --> 00:18:46 the different dwarf galaxies around
00:18:46 --> 00:18:49 the system and discovered that there was this
00:18:49 --> 00:18:52 striking difference between the dwarf galaxies on the
00:18:52 --> 00:18:55 left side of the figure and on the right side of the figure. And
00:18:55 --> 00:18:58 that's where he got the clue that the dwarf galaxy galaxies were
00:18:58 --> 00:19:01 actually rotating in this coherent
00:19:01 --> 00:19:03 motion around the two massive hosts.
00:19:03 --> 00:19:06 Stuart Gary: That's Dr. Sarah Sweet from the University of
00:19:06 --> 00:19:09 Queensland. And this is space,
00:19:09 --> 00:19:09 time
00:19:25 --> 00:19:26 and time.
00:19:26 --> 00:19:28 Now to take a brief look at some of the other stories making news in Science
00:19:28 --> 00:19:30 this week with a science report.
00:19:31 --> 00:19:34 Researchers in the United States believe they may have finally
00:19:34 --> 00:19:37 developed the first almost 100% effective prevention
00:19:37 --> 00:19:40 drug for HIV AIDS. America's
00:19:40 --> 00:19:42 food and Drug Administration has now approved the Lena
00:19:42 --> 00:19:45 Kappavir vaccine which is being sold under the brand name
00:19:45 --> 00:19:48 Yestoogo. It belongs to a class of
00:19:48 --> 00:19:51 antiretroviral medications known as capsid
00:19:51 --> 00:19:53 inhibitors. See, in the HIV type 1
00:19:53 --> 00:19:56 virus, the capsid is the protein shell that houses
00:19:56 --> 00:19:59 and protects the viral genetic material and it's crucial
00:19:59 --> 00:20:02 for transporting the virus into a host cell.
00:20:02 --> 00:20:05 Once inside the host cell, the capsids shed
00:20:05 --> 00:20:07 and the virus begins copying itself.
00:20:07 --> 00:20:10 Lenacapavir stops that from happening.
00:20:10 --> 00:20:13 In 2022, it was approved under the brand name
00:20:13 --> 00:20:16 Sunlinka to treat HIV in those already infected.
00:20:16 --> 00:20:19 But a long acting prevention medication has been much
00:20:19 --> 00:20:22 more difficult to realize. Last year,
00:20:22 --> 00:20:25 Lencapavir was named as the breakthrough invention of the year
00:20:25 --> 00:20:27 in the journal Science. The drug is now
00:20:27 --> 00:20:30 available across the European Union and the United States and
00:20:30 --> 00:20:32 it's awaiting regulatory approval in Australia,
00:20:33 --> 00:20:35 Brazil, Canada, South Africa, Switzerland,
00:20:35 --> 00:20:38 Argentina, Mexico and Peru. The
00:20:38 --> 00:20:40 human immunodeficiency virus
00:20:41 --> 00:20:44 attacks the immune system, causing Acquired Immune
00:20:44 --> 00:20:46 Deficiency Syndrome, or aids, which allows opportunistic
00:20:46 --> 00:20:49 diseases to normally easily combated by the body to
00:20:49 --> 00:20:52 take hold and eventually kill the patient.
00:20:52 --> 00:20:55 The World Health Organization says that since first being
00:20:55 --> 00:20:58 identified back in 1981, AIDS has
00:20:58 --> 00:21:00 killed over 43 million people globally and
00:21:00 --> 00:21:03 infected up to 113 million. With
00:21:03 --> 00:21:05 1.3 million new infections annually.
00:21:06 --> 00:21:09 HIV is transmitted through body fluids. Right
00:21:09 --> 00:21:12 now, there's no cure, although it can be controlled
00:21:12 --> 00:21:15 using a combination of complex drug cocktails. Australopithecus
00:21:16 --> 00:21:18 paleoanthropologists have discovered a new species of
00:21:18 --> 00:21:21 Australopithecus hominid, the earliest known member of
00:21:21 --> 00:21:24 the human family. The new fossil finds,
00:21:24 --> 00:21:27 reported in the journal Nature date back to between 2.6
00:21:27 --> 00:21:30 and 2.8 million years and coexisted with
00:21:30 --> 00:21:33 Australopithecus afarensis at the same place in
00:21:33 --> 00:21:35 Ethiopia at the same time. The
00:21:35 --> 00:21:38 oldest evidence of Australopithecus afarensis dates
00:21:38 --> 00:21:41 back some 2.95 million years years. The
00:21:41 --> 00:21:44 new Lady Garou Australopithecus species are based on
00:21:44 --> 00:21:47 just 13 teeth discoveries and demonstrate how
00:21:47 --> 00:21:50 human evolution was not linear, but a bushy
00:21:50 --> 00:21:53 tree with many branches going extinct. The
00:21:53 --> 00:21:56 authors are now examining the newly discovered species tooth
00:21:56 --> 00:21:59 enamel to try and find out what they can about what these
00:21:59 --> 00:22:01 species were eating. A
00:22:01 --> 00:22:04 new study has shown that some seabirds prefer to
00:22:04 --> 00:22:07 defecate in the air, so much so they'll actually
00:22:07 --> 00:22:10 take flight just to take a damp. Scientists
00:22:10 --> 00:22:12 strapped cameras to the bellies of 15 streaked
00:22:12 --> 00:22:15 shearwaters, migratory birds that travel from Japan as
00:22:15 --> 00:22:18 far as Australia. And they found that all but one
00:22:18 --> 00:22:21 of the 195 video bombardments were
00:22:21 --> 00:22:23 airborne. A report in the journal Current
00:22:23 --> 00:22:26 Biology claims in flight evacuations, for
00:22:26 --> 00:22:29 want of a better term, may have benefits outweighing the
00:22:29 --> 00:22:32 efforts to take off from the water, like avoiding germs,
00:22:32 --> 00:22:35 protecting the birds, delicate bits from seawater and a
00:22:35 --> 00:22:38 comfier position than simply floating. The
00:22:38 --> 00:22:41 authors say the findings could also help studies in how seabird
00:22:41 --> 00:22:44 excrement contributes to ocean ecosystems and
00:22:44 --> 00:22:47 whether bird flu can be transmitted between birds out at
00:22:47 --> 00:22:50 sea. Then again, as far as the bird's concerned,
00:22:50 --> 00:22:52 it may just be easier to target people from the air.
00:22:54 --> 00:22:57 A bunch of academics from the National Autonomous University
00:22:57 --> 00:23:00 of Mexico are giving credibility to a UFO
00:23:00 --> 00:23:03 report from Columbia. The UFO was first
00:23:03 --> 00:23:05 spotted flying over the town of Buga, reportedly
00:23:05 --> 00:23:08 zigzagging through the sky in a way that witnesses claim
00:23:08 --> 00:23:11 defies the movement of conventional aircraft.
00:23:11 --> 00:23:14 The ball shaped object was allegedly later seen sitting on
00:23:14 --> 00:23:17 the ground, where it was quickly recovered and taken away for
00:23:17 --> 00:23:19 testing. That led to claims there was a strong m
00:23:19 --> 00:23:22 decaying ionized field coming from the sphere.
00:23:22 --> 00:23:25 Others claimed it could be radiating anions.
00:23:25 --> 00:23:28 These are negatively charged ions that have gained an
00:23:28 --> 00:23:31 electron or another negatively charged subatomic particle in
00:23:31 --> 00:23:34 order to fill their outer shells. Those behind the
00:23:34 --> 00:23:37 story claim that since the investigation began, this
00:23:37 --> 00:23:40 UFO is now five times heavier than what it was when it
00:23:40 --> 00:23:42 landed and they say that proves that it's
00:23:42 --> 00:23:45 manipulating gravity to make itself lighter in order
00:23:45 --> 00:23:48 to fly. Tim Mendham, um, from Australian Skeptics
00:23:48 --> 00:23:51 says it's worth pointing out the guy pushing the story has
00:23:51 --> 00:23:53 a long history of making elaborate fake space
00:23:53 --> 00:23:55 alien claims.
00:23:55 --> 00:23:57 Tim Mendham: This is a sphere that was supposedly floating in the
00:23:57 --> 00:24:00 sky, performing sort of weird movements and things and then
00:24:00 --> 00:24:03 found on the ground. Originally seen in Colombia,
00:24:03 --> 00:24:06 South America, but there's now researchers in
00:24:06 --> 00:24:08 Mexico having a look at it from a place called the National
00:24:08 --> 00:24:11 Autonomous University of Mexico. People there
00:24:11 --> 00:24:13 promoting some sort of invisible energy emanating
00:24:13 --> 00:24:16 from this machine that when it landed, uh, it was
00:24:16 --> 00:24:19 a burnt out area or something. They're saying it sucked all the
00:24:19 --> 00:24:22 water out of the grass and the soil and that there's all sorts
00:24:22 --> 00:24:25 of strange things going on emanating from it. There's engravings all the way
00:24:25 --> 00:24:28 around it and the engravings look pretty sloppy quite frankly. And they do.
00:24:28 --> 00:24:31 They're hardly the sort of work of advanced species
00:24:31 --> 00:24:32 sending these things across.
00:24:33 --> 00:24:35 Stuart Gary: How do we know we wouldn't know what an alien
00:24:35 --> 00:24:37 script looks like? Like would we or would we?
00:24:37 --> 00:24:40 Tim Mendham: No, we don't of course. No, there's not a lot of it around. But anything they
00:24:40 --> 00:24:43 can't understand naturally becomes alien 51 anyway.
00:24:43 --> 00:24:46 Yeah, I mean the, it was suggested that this is an art project
00:24:46 --> 00:24:49 and in any case there's no actual link between a thing that was
00:24:49 --> 00:24:52 seen in the sky, whatever it was, you know, unidentified. I'm not going to say flying
00:24:52 --> 00:24:55 saucer or alien technology, just something that was seen in
00:24:55 --> 00:24:58 the sky and then this was found that there's no necessarily
00:24:58 --> 00:25:01 connection apart from correlation that these two things are
00:25:01 --> 00:25:04 associated with each other. A thing in the sky, ball found on the
00:25:04 --> 00:25:07 ground, bit bigger than a soccer ball with these strange sort of little
00:25:07 --> 00:25:08 carvings on it.
00:25:08 --> 00:25:09 Stuart Gary: They're very small people.
00:25:09 --> 00:25:12 Tim Mendham: I don't know if it was a craft with people inside. There's supposed to be a lot of
00:25:12 --> 00:25:14 wires and things inside. I don't know how X raying this.
00:25:14 --> 00:25:17 Stuart Gary: Thing or something but advanced civilization is still using
00:25:17 --> 00:25:18 copper wires, are they?
00:25:20 --> 00:25:23 Tim Mendham: Um, this craft apparently bumped up against some power lines and
00:25:23 --> 00:25:26 that took all the energy out of it. So not a particularly good craft for
00:25:26 --> 00:25:29 bringing across the great depths of space. But it's just one
00:25:29 --> 00:25:32 of those things that you think is just one of those silly things that
00:25:32 --> 00:25:34 people are getting carried away with. And there's some academics within this
00:25:34 --> 00:25:37 university who are endorsing it. And it's also being
00:25:37 --> 00:25:40 heavily promoted by a quote UFO
00:25:40 --> 00:25:43 researcher who is known for faking and
00:25:43 --> 00:25:46 promoting fake products you know, mummified bodies that
00:25:46 --> 00:25:49 turn out not to be sort of, uh, mummified alien bodies at all,
00:25:49 --> 00:25:51 or all sorts of evidence of UFO sightings that have been
00:25:51 --> 00:25:54 seriously debunked. So one of the main proponents of this thing is someone
00:25:54 --> 00:25:57 he really had trouble trusting or certainly
00:25:57 --> 00:26:00 believing. And others are some academics who are making some really
00:26:00 --> 00:26:03 quite outlandish statements. The things that sort of just don't comply with
00:26:03 --> 00:26:06 the laws of physics at all. But they're using these as the
00:26:06 --> 00:26:09 explanation of why this is a real, um, alien technology.
00:26:09 --> 00:26:12 Doesn't look particularly impressive from my point of view, especially the
00:26:12 --> 00:26:15 carvings, the engravings on the side of it. They just look sort of
00:26:15 --> 00:26:15 amateurish.
00:26:15 --> 00:26:18 Stuart Gary: That's Tim Mendham from Australian Skeptics.
00:26:34 --> 00:26:37 And that's the show for now. Space Time is
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