We Found a Giant Structure In Space and We Don’t Know What It Is

0:00 Our planet is haunted.

0:06 Now, you might think that is an odd thing to claim for an astronomy channel,

0:14 but there have been whispers among astronomers that something is out there.

0:22 Ghostly specters lurking in our orbital path.

0:28 Entities that have eluded scientific detection for decades,

0:38 drifting in perfect balance between cosmic forces.

0:46 Some claim to have captured faint images of these ethereal

0:50 silhouettes looming up to nine times wider than Earth itself.

0:55 Yet others have searched the same regions of space and found nothing at all.

1:02 For over six decades, astronomers have debated their existence.

1:07 Are these mysterious entities merely elaborate optical illusions?

1:12 Or something truly extraordinary hiding in plain sight?

1:18 What celestial phenomenon could simultaneously be

1:21 so large yet remain so elusive?

1:26 Is the moon truly Earth's only companion in our journey around the sun?

1:32 I'm Alex Mccoan and you're watching Astramm.

1:36 Today, we're investigating one of astronomy's most enduring mysteries,

1:41 the controversial ghost moons that may be

1:44 silently accompanying our planet through the cosmos.

1:52 This ghost story begins in 1961 when Polish astronomer Kazmir Cordfki

1:59 first spotted two diffuse patches of sky that kind of looked

2:04 like clouds through a telescope which were located suspiciously near

2:09 the stable L4 and L5 Lrangee points of our Earth moon system.

2:15 In case you aren't familiar with Lrangee points, let me quickly explain.

2:21 Lrangee points are positions in space where

2:24 the gravitational forces of two large bodies

2:27 are balanced by the centropedal force required

2:30 for a smaller object to move with them.

2:33 This creates a sort of gravitational equilibrium that allows the smaller

2:37 objects to maintain a position relative to the two larger bodies.

2:42 Lrangee points were named after

2:43 the Italian French astronomer and mathematician Ysef

2:46 Louie Lrange after he published a prize-winning

2:51 paper about this phenomenon in 1772.

2:55 While we're going to be talking about the Lrangee

2:58 points present in our Earth Moon system in this video,

3:01 similar points exist for other two body systems such as between

3:05 the Earth and the Sun or Jupiter and the Sun.

3:10 In any two body system,

3:12 there are five spots where gravitational forces and orbital motion

3:16 create these lrangee points and they're labeled L1 through L5.

3:21 Three of these L1, L2, and L3 are considered unstable.

3:27 Small objects may be temporarily captured near these points like the NASA

3:32 issa satellite SOHO at L1 or the James Web Space Telescope at L2.

3:38 But they have to make corrections to their altitude

3:40 and course every 23 days to avoid drifting out of position.

3:45 Objects in these unstable equilibrium points are balancing on a metaphorical

3:50 knife's edge and any slight push from the solar wind,

3:54 radiation or the moon's gravity will tip the balance.

3:58 But L4 and L5, these positions are stable.

4:03 Unlike the other Lrange points,

4:05 these each make equilateral triangles with the Earth

4:09 and Moon and are resistant to gravitational pertubations.

4:13 Because of this, objects like asteroids

4:16 and dust tend to accumulate in these areas.

4:19 And that's where our story picks up.

4:23 Cordelpski's observation of these ghostly faint clouds in the [music] L4

4:27 and L5 Lrange points originally named liberation clouds but later known

4:32 as Cordeli dust clouds ignited a scientific debate that has lasted

4:37 for decades one that is still going on to this day.

4:43 Immediately following his observation, other astronomers,

4:46 both professional and amateur, attempted to locate these supposed clouds.

4:50 [music] But for years, nobody else could find them.

4:54 At the time, observational techniques were far less advanced than today.

4:59 Many astronomers questioned whether these dust

5:01 clouds were real or merely optical illusions.

5:04 After all, detecting such faint structures against

5:08 the darkness of space was a challenging proposition.

5:12 That skepticism persisted for years.

5:15 Every now and then, an astronomer would catch a glimpse

5:18 of a dust cloud in one lrangee point or the other,

5:21 and sometimes clouds would be visible in both locations.

5:25 A few astronomers, including Cordowski himself,

5:28 captured photographs of the clouds, but for years,

5:32 the dust clouds appeared so faint in the photos

5:34 that they could not be reproduced in newspapers.

5:38 These photos aren't like photos we're used to either.

5:42 Images of these dust clouds have to be taken using photometric techniques,

5:47 which involves glass photographic plates with long exposure times

5:51 to capture the faint lights of distant celestial objects.

5:56 They aren't of Hubble telescope quality.

5:59 They serve more to identify changes in light [music] intensity.

6:03 And this is what astronomers would use as evidence of the cloud's existence.

6:09 In 1966, NASA organized an airborne observation mission from its Converair 9990

6:15 jet laboratory operating far from city lights at an altitude of 12,000 m.

6:22 The astronomers on those four NASA flights were able to identify

6:26 Cordelia dust clouds in both the L4 and L5 Lrange points,

6:31 even managing to photograph the dust cloud at L5.

6:34 The orbiting solar observatory OSO6 also observed the clouds in 1966

6:41 and subsequent work was published measuring their brightness and size.

6:45 However, in 1976, another astronomer named Sigfrieded Aruza at the Max

6:52 Plank Institute for Astronomy used numerical simulations to show

6:56 that conditions were unfavorable for dust to accumulate in the L4

7:00 area and questioned whether or not these clouds actually existed.

7:06 Most of the KDC skeptics believe

7:09 that the gravitational pertubation of the sun, solar wind,

7:12 and other planets have too strong of a destabilizing effect

7:16 on the L4 and L5 Lrange points for KDC's to be maintained.

7:21 Additionally, radar studies of the clouds

7:24 around this time had produced negative results,

7:27 leading many to believe there was

7:29 nothing of circumstance at Little Grange points.

7:33 These doubts were further reinforced in 1983 when

7:37 observers using a 61 cm telescope near Tucson,

7:41 Arizona found no such clouds in either L4 or L5.

7:47 Yet just a few years later in 1989,

7:50 [music] the clouds were photographed again by astronomer Vinyoski

7:56 from an astronomical observatory in the Bastardada mountains in Poland.

8:00 Vinyoski observed the KDC's to be a few degrees in apparent diameter.

8:06 These were also the first three color phototric observations

8:10 of the clouds and they revealed that the clouds appeared

8:12 much redder than the counterglow which is the sunlight

8:16 that gets scattered by the general dust particles in space.

8:19 This observation suggested that the dust in the KDC's is

8:23 significantly different in composition to the other local space dust.

8:28 Which begs the question, where are these apparations coming from?

8:34 But then once again, the existence of KDC's was brought into question

8:39 when in 1991 the Japanese heightened space probe

8:43 did one loop around the L4 and L5

8:46 forrange points in an attempt to detect dust particles,

8:49 but didn't manage to find any.

8:52 However, astronomers say that this should not

8:55 be taken as evidence against the dust clouds,

8:57 as he highen was only able to do one loop around each Lrangee point.

9:02 And if the clouds do exist, the dust was likely moving too slowly for it

9:07 to be picked up by Heiten's dust detectors.

9:10 So, as you can see, the scientific debate that begun in 1961

9:15 after Cordel's initial observation is one

9:18 that has continued through the decades.

9:23 But now scientists seem to have made a breakthrough.

9:27 In 2018 and 2019, astronomer Udit Slisbalo and physicists

9:33 Gabbor Hvath and Andreas Bart were able to present

9:37 clear evidence of the L5 KDC by examining

9:41 how the dust creates patterns of scattered polarized light.

9:45 To do this, they use a type of photography called polarized imaging,

9:50 which uses a series of filters that can show light bouncing at specific angles.

9:55 When light hits these dust particles,

9:57 it scatters differently depending on the specific

10:00 composition and arrangement of the particles,

10:02 offering clues to the nature of the clouds.

10:05 After collecting a series of images through various polarized filters,

10:09 the scientists found that the patterns of polarized

10:12 light in the images matched theoretical predictions

10:15 for what we would expect to see

10:16 from sunlight that were scattered by dust clouds.

10:19 What's more, in their 2018 paper on the observations,

10:23 they said that in fact these results meant

10:26 that the scatters cannot be anything other than dust particles.

10:31 To back up these observations,

10:32 they were able to further understand the formation

10:35 of the clouds at L5 through the use of computer simulations.

10:39 They calculated the motion of 1.86 million dust particles to see how dust

10:44 in that region of space might behave and found that under the right conditions,

10:49 that dust could get trapped at the L5 point and remain there for a long time.

10:55 The result of these simulations were dust clouds that mirrored the shape

10:59 and size of what had been observed by the polarized imaging.

11:03 Very small particles spread over a large area.

11:08 So what is going on here?

11:11 Why could some astronomers see these dust clouds and photograph

11:14 them while others claimed they didn't exist at all?

11:18 The answer may lie in the structures themselves.

11:24 Despite spanning roughly 100,000 km by 70,000 km,

11:29 which is almost nine times wider than the Earth,

11:32 the total mass of the dust clouds is supposedly extremely small.

11:37 Not to mention, the particles themselves are likely micron or submicron sized,

11:43 a similar size to many bacterial cells.

11:46 According to observations from the polarized imaging of L5,

11:50 a micron is already a very tiny measurement at 1 millionth of a meter.

11:56 Individual particles of this size are

11:58 only visible through a powerful microscope.

12:03 Not only are the KDCs composed of these micron or submicron dust particles

12:08 sparsely spread across a wide area and nearly invisible to the naked eye,

12:13 but the recent models made by Slbalo and Horvath in 2018 suggest

12:18 that the shape of the L5 dust cloud also appears to be [music] dynamic.

12:23 The models point to the structure

12:25 being nonuniform with dust particle density varying

12:30 across the KDC and changing over time

12:33 in synchrony with the moon's orbital period.

12:37 This could also support the idea that KDC's

12:40 are not a stagnant accumulation of dust,

12:43 but rather that they may be continuously losing and refreshing their contents.

12:49 kind of like an ever evolving dust storm rather than a fixed stable cloud.

12:55 Things like solar wind or gravitational pull from the sun or other

12:59 planets may disrupt the delicate equilibrium

13:02 that holds together these dust clouds,

13:04 causing them to disperse before reforming again.

13:09 This combination of extremely tiny particles that are dispersed over

13:13 a large area and the possibility that these clouds may form,

13:17 disperse, and reform again and again over time could

13:22 help to explain the discrepancy in observations over three decades.

13:27 However, the tentative confirmation of the L5 KDC

13:31 in 2018 still leaves open scientific debate as to whether

13:35 these clouds exist continuously or whether they appear and disappear

13:40 depending on the influence of the sun and other planets.

13:44 Plenty of questions remain about cordfki dust clouds, but one thing is certain,

13:50 these observations are not just a mirage,

13:52 but a real phenomenon within our Earth moon system.

13:56 Even though aspects of their structure,

13:59 evolution, and composition remain under investigation,

14:02 there is broad acceptance that KDC's are worthy of further study.

14:11 While these so-called ghost moons that orbit

14:14 the Earth moon lrange points may seem otherworldly,

14:18 our planet is no stranger to additional moons.

14:21 In fact, Earth has had several mini moons and quasi moons before,

14:25 albeit very different from the KDC's.

14:28 For one thing, mini moons typically come and go within a year,

14:31 while the gravitational traps or lrange points,

14:34 which are theorized to cause these cordleski dust clouds,

14:37 have existed since our Earth moon system formed,

14:40 making the KDC phenomenon potentially billions of years old.

14:45 Another distinct difference is that mini moons and quasimoons are solid

14:49 objects whereas dust clouds are of course clouds of loose dust.

14:55 Quasimoons get their name because from one vantage point they

14:59 look as if they are true moons orbiting the earth.

15:02 However, with a wider view, these turn out to be asteroids orbiting the sun.

15:07 Mini moons, on the other hand, are objects that rarely orbit a planet.

15:12 They tend to be quite small and difficult to detect,

15:14 which is probably why we've only ever managed to identify four mini moons,

15:19 none of which are orbiting Earth anymore.

15:22 Take for example the mini moon called 2020 CD3,

15:26 which I discussed in a previous video.

15:28 This small natural satellite was captured in Earth's

15:31 orbit between January 2019 and May 2020,

15:35 temporarily giving our planet a second moon.

15:38 Well, mini moon.

15:40 In my opinion, our planet's possible ghost moons are perhaps the most

15:44 exciting of these obscure types of moons because of how unique they are.

15:53 Despite being dynamic structures,

15:55 these dust clouds are a long-term feature of our Earth Moon system,

16:00 and we still have so much to learn about them.

16:02 Observing these dust clouds has tested

16:05 the limits of our observational abilities.

16:08 And as our technology and science improves, so can our understanding of KDC's.

16:14 We should aim to build up more observation data of the L4 KDC.

16:18 as this feature is historically under represented compared to the cloud at L5.

16:24 We could also reservey the clouds using methods like radar to see

16:28 if technological improvements can yield

16:30 different results compared to the negative

16:32 detections of the past as this would further establish the presence

16:36 of these elusive features and fend off any lingering skeptics.

16:40 But now that they've been broadly accepted by the scientific community,

16:45 future research can begin to explore how KDC's are replenished over time,

16:50 their potential impact on space weather,

16:52 and their influence on satellite operations.

16:56 Whether KDC's exist continuously or appear and disappear over time,

17:01 at least now we know that something really is out

17:04 there and we can study them with the right focus.

17:08 These ghostly dust clouds continue to haunt our skies,

17:12 reminding us that even the faintest spooky traces of cosmic

17:16 apparitions can hint at something palpable and is worth investigating.

17:24 When 15 supernova go off close together,

17:27 both in time and proximity, it makes quite a bang.

17:31 It should be of no surprise that such a violent event

17:35 should fundamentally transform the region of space around where it occurred.

17:40 Interstellar dust was swept aside from the forces of those concurrent blasts,

17:45 creating a monumental void of low density matter and a shock wave that continues

17:51 to hurtle across the galaxy to this day at a rate of 6 km a second.

17:58 In its wake, plasma reaching 1 million degrees C in temperature.

18:04 This simultaneous Swiss cheesing and heating up

18:08 of the interstellar medium is what is now called a hot bubble and represents

18:13 both the end of stars and their beginning.

18:17 But this is not some distant structure that lurks

18:20 in a far away corner of the universe.

18:23 Our solar system isn't even heading right towards it.

18:27 We are in it charging for its point of origin head first.

18:34 Welcome to our local hot bubble.

18:38 What scientists now realize is the local

18:41 environment that exists around our solar system.

18:45 It is a neighborhood we are still exploring,

18:48 but its nature is becoming clearer and clearer.

18:52 So, what do we know about the local hot bubble?

18:56 How did it form?

18:57 And what more is there to be discovered?

19:01 I'm Alex Mccoan and you're watching Astramm.

19:04 Join me today as we walk in the aftermath of exploding stars and discuss

19:09 how scientists even determined we were

19:12 in the heart of a cataclysm to begin with.

19:18 The local hot bubble was not always something we knew about.

19:22 First identified in the 1970s from observations of low

19:27 energy X-ray emissions that were detected over the entire sky,

19:31 the local hot bubble was hypothesized to be a large cavity in the interstellar

19:36 medium called a superbubble filled with tenuous

19:41 million degree low density [music] gas.

19:45 In the 1990s, scientists found that X-ray emissions could

19:48 happen anywhere neutral atoms interacted with the solar wind,

19:52 challenging the idea that the emissions must point to a large hot bubble.

19:57 But soon, evidence would reveal that the hypothesis

20:01 from decades earlier was indeed correct.

20:05 In 2014, NASA confirmed the existence of the LHB through

20:10 the diffuse X-ray emission from the local galaxy mission known as DXL.

20:17 While soft background radiation can come from other sources,

20:21 like from comets, for example, the mission found that only 40% of the fog

20:26 of low energy X-rays came from within our solar [music] system.

20:31 This affirmed that the dominant source was diffuse X-ray emissions emanating

20:36 from the millionderee region of interstellar plasma known as the [music] LHB.

20:43 Although this confirmed the bubble,

20:45 questions remained about what could create such a massive void

20:49 and what might explain the thousands of surrounding young stars.

20:54 The prevailing answer proved to be both violent and [music] fascinating.

21:00 Recent research suggests that the local hot bubble was the aftermath of around

21:05 15 supernova explosions that occurred sequentially within

21:09 a span of a few million years,

21:12 erupting in relatively close proximity to one another.

21:15 Scientists estimated that the first of these massive

21:18 stellar explosions went off roughly 14 million years ago,

21:23 each expelling enormous amounts of energy,

21:26 pushing out the surrounding interstellar material and heating

21:30 the remaining gas [music] to extreme temperatures.

21:34 Evidence of these ancient explosions has been

21:36 preserved in our Earth's geological record in deep

21:40 sea [music] sediment deposits in the form of a special isotope called iron 60.

21:46 This radioactive isotope can come from a few different sources,

21:50 but the most common source of iron 60 is believed to be supernova explosions.

21:56 [music] We know that the source of the isotope

21:59 is extraterrestrial because the earth itself has no way

22:02 of producing iron 60 on its own and [music]

22:06 matching deposits have been found on the moon as well.

22:10 The reason that this radioactive isotope is special is

22:13 because [music] we know how long its half-life is.

22:17 We know that it decays into cobalt 60, another radioactive isotope,

22:21 [music] before it finally decays into nickel 60, a stable element.

22:26 Iron 60 has a halflife of 2.6 million years and cobalt

22:31 60 has a fairly short halflife of just 5.3 years.

22:37 Because of this, when we find a deposit that [music] contains these elements,

22:41 scientists can compare the amounts of iron 60,

22:44 cobalt 60, and nickel 60 like an elemental clock

22:48 to reveal when that material was deposited [music] on our planet.

22:53 And luckily for us, international research teams have found

22:56 several such deposits over the last couple of decades.

23:02 In 2016, iron 60 deposits were found

23:05 in deep sea crust samples taken from the Pacific, Indian, and Atlantic oceans,

23:11 indicating two distinct spikes in the radioactive debris that [music]

23:15 pointed to several supernova events in the notsodistant past.

23:19 And not too far from our solar system, just 326 lighty years away,

23:27 the sample showed a spike of iron 60 between 3.2 and 1.7 million years ago,

23:33 and another spike between 6.5 [music] and 8.7 million years ago.

23:39 Nuclear physicist Anton Walner,

23:41 who led one of these research teams studying the deposits,

23:44 said that the fact that the more

23:46 recent debris was spread across 1.5 million years,

23:50 suggests that there were a series of supernova

23:52 that occurred one after another in close succession.

23:57 Astrophysicist Dieter Breitvert who led a second

24:00 team of scientists [music] identified a likely source

24:03 of these supernova explosions which would have occurred

24:07 196 to 423 lighty years from the sun.

24:12 These supernova that created our local hot bubble may have been part of an aging

24:18 star cluster whose surviving members are now

24:21 associated with the Scorpius Centura stellar group.

24:25 Using the iron 60 deposits,

24:27 the team was able to trace the signals of two supernova,

24:31 one that happened 1.5 million years ago

24:33 and the other 2.3 million years ago as the result

24:36 of the deaths of stars that were 8.8 times

24:40 and 9.2 times the mass of our sun, respectively.

24:44 In fact, our LHB is still growing today,

24:48 albeit much more slowly than when the supernova exploded millions of years ago.

24:53 The speed of expansion has plateaued at about 6 km/s now,

24:58 according to astrophysicist [music] Katherine Zucker.

25:01 In 2022, Zucker authored a groundbreaking paper

25:05 that reconstructed the evolution of our galactic neighborhood,

25:08 tracing the chain of events that created our local hot bubble and led

25:13 to the formation of all the young stars we see nearby today.

25:17 From there, they made an incredible discovery.

25:21 Using data from the European Space Ay's Gaia telescope,

25:25 Zucker and her team were able to construct a 3D space-time map,

25:30 showing that within 500 lighty years of our planet,

25:34 all of the young stars and star forming regions

25:36 reside on the surface of our local hot bubble.

25:40 With these 3D positions and the 3D motions of the stellar clusters,

25:46 they traced back 20 million years of star

25:48 formation history near our local hot bubble.

25:51 The implications were clear that all of the well-known

25:55 star forming regions near our solar system had

25:58 formed along the outer edge of the local

26:01 bubble as it swept up gas during its expansion.

26:06 Stella nurseries are a field we are learning more about all the time.

26:10 particularly as new images are taken by our telescopes.

26:14 Here's a spectacular image of the Chameleon 1 dark cloud,

26:18 one of our nearest stellar nurseries taken

26:21 by a dark energy camera on the Victor M.

26:24 Blanco 4 m telescope [music] at Cherro Talo Interamerican Observatory.

26:29 By studying the propagation of starlight from within it,

26:33 scientists can tease out details about how stars form,

26:36 which might help us better understand the local

26:38 hot bubbles impact on our galaxy today.

26:41 You might not have seen this particular image before

26:44 as new space news is coming out all the time,

26:47 but I've talked about it in my newsletter,

26:50 which I've recently launched to help you keep up with all

26:52 the breathtaking photos released by our many telescopes on Earth and in orbit,

26:57 or new breakthroughs that reshape how we understand the cosmos.

27:02 You should sign up to never miss the most exciting news,

27:05 even if the headlines do, by following the link in the description below.

27:09 There are new editions that come out every Thursday.

27:13 From the local hot bubbles birth 14 million years ago,

27:17 Zucker and her colleagues identified four epochs

27:20 of star formation on the bubble shell.

27:25 Starting about 16 million years ago,

27:27 we see the birth of the upper centurus lupus or the UCL star cluster,

27:33 followed by the lower centurus crux or LCC star cluster.

27:39 These formed about 49 light years apart

27:41 from one another and about 14 million years ago.

27:45 These stellar populations were the source of the stars

27:48 that went supernova to create our local bubble.

27:54 About 10 million years ago,

27:55 we see the first of the four star forming epochs after the formation of the LHB.

28:01 The upper scorpius association and older afucuca

28:05 stella populations are born in the first epoch.

28:09 6 million years ago the second star forming epoch

28:12 formed Corona Arralis and the older stars of Taurus.

28:18 Then around 2 million years ago the stars in Lupus and Chameleon as well

28:24 as younger stellar populations of Taurus and ofucus

28:28 came to be in the third epoch.

28:31 And finally, our present time falls within the fourth star forming epoch.

28:37 We can observe the dense star forming molecular gas that surrounds the LHB,

28:42 which will eventually lead to more star

28:45 clusters being born along the bubble's outer edge.

28:49 With all of this stellar creation,

28:52 you might be surprised to learn that we are interlopers.

28:56 Our sun did not form inside the local bubble.

29:01 In fact, the sun was about 978 light years away

29:05 when the first supernova went off in UCL and LCC,

29:10 only joining up with the LHB about 5 million years ago

29:14 as its path through the galaxy took it into the bubble.

29:18 With the trajectory shown in yellow dots,

29:20 you can see our sun's location just before it entered the bubble.

29:25 And now, just by coincidence,

29:27 our sun happens to be located near the [music] center of the LHB.

29:33 Drifting into the heart of what was once a [music] raging furnace,

29:37 scientists became interested in mapping out

29:39 the ongoing temperature within the local bubble.

29:43 You might wonder why we're so calm if

29:45 temperatures of plasma here can reach 1 million° C.

29:50 The key lies in that plasma's density.

29:54 Look, this 3D map from Zucker's 2022 publication

29:59 shows our local hot bubble in dark blue.

30:03 The density inside our bubble is extraordinarily low,

30:06 containing about 100 times less hydrogen than the typical interstellar medium.

30:12 So while the temperature of this gas soarses to around 1 million° Kelvin,

30:17 giving rise to the diffuse X-ray emissions

30:19 we have observed around the whole sky, we don't have much to worry about.

30:25 Tracking temperatures within the local bubble

30:27 has provided more evidence of its existence.

30:30 The extended renen survey with an imaging telescope array,

30:35 better known as the e-roisa x-ray telescope,

30:38 has been able to gather the most detailed all sky survey of soft x-rays to date.

30:44 And that data has been used to map the LHB

30:47 and our solar neighborhood in much more detail than before.

30:51 launched aboard the joint Russian and German mission

30:55 Spectrum Renen Gamma or Spectre RG in 2019.

31:00 Data from the E Rosita X-ray telescope has allowed a team

31:04 of scientists led by the Maxplank

31:06 Institute for Extraterrestrial Physics to create

31:09 a 3D map of the LHB and identify a temperature gradient

31:14 where the galactic south was slightly hotter than the galactic north.

31:19 This temperature dichotomy could be explained by supernova

31:23 explosions in the past few million years.

31:26 And by creating this bubble map, the team also found that the LHB is

31:30 stretched out towards the poles of the galactic hemisphere.

31:34 This is because the hot gas in the bubble

31:36 expands out in the direction with the least resistance,

31:39 which happens to be away from the Milky Way's galactic disc.

31:44 Along with identifying temperature variations and the shape of the bubble,

31:48 the team compiled this and other data to create

31:51 an even more detailed map of our galactic neighborhood.

31:56 In the new 3D map, our local hot bubble looks like

32:00 a three-dimensional splatter surrounded

32:03 by and even overlapping other galactic structures.

32:07 These other structures represent known supernova remnants like the Gum Nebula

32:12 shown here in red and dense molecular clouds shown here in orange.

32:19 With the new data and 3D maps,

32:22 these super bubbles seem likely to be common in our galaxy,

32:26 creating a Milky Way that's sort of like Swiss cheese.

32:31 The cavities of our Swiss cheese galaxy

32:34 are blasted out by gigantic supernova explosions

32:38 with new stars forming along the edges of the holes created by dying stars.

32:43 And like Swiss cheese, it appears that some of these super bubbles may

32:48 have tunnels connecting them to other bubbles or other structures,

32:52 suggesting our local hot bubble could be part

32:56 of an intricate network of similar features throughout our galaxy.

33:01 For example, we have the Canis Majorus Tunnel,

33:05 which lies on the Milky Way's galactic disc and is believed

33:08 to connect [music] our local hot bubble to the Gum Nebula,

33:11 or another larger nearby superb bubble.

33:14 But the 3D map also revealed another previously

33:18 unknown interstellar tunnel stretching towards the constellation Centurus,

33:24 possibly connecting our local bubble to the neighboring Loop One super bubble.

33:31 While these interstellar tunnels are tantalizing,

33:34 our current understanding of them is limited.

33:38 Nevertheless, these tunnels of hot gas and bubbles of star

33:42 formation shaped [music] by the death of gigantic older

33:45 stars has me in awe of how powerful and interconnected

33:50 the evolution of our local galactic neighborhood really is.

33:55 It suggests that stars are not just born and die in isolation,

33:59 but that their energetic output continues to mold

34:02 the environment for millions of years after their demise.

34:06 And as our observational tools become more sophisticated,

34:10 we are beginning to uncover the extent of these hidden structures.

34:16 So next time you look up at the night sky,

34:19 you might remind yourself that we are surrounded by crazy patterns.

34:24 just like our local bubble in the Milky

34:26 Way that was carved out by ancient cataclysms.

34:30 And that some of those stars that you see are actually plastered along the walls

34:35 of a supernova blasted cavity which connects

34:39 to other parts of the galaxy through interstellar tunnels.

34:44 Wow.

34:49 In 2022, this astonishing image was published.

34:53 [music] What makes it so astonishing?

34:57 Well, this is one of the most detailed radio images

35:01 of the center of our galaxy that's ever been produced.

35:06 Assembled from the first survey using the full array

35:10 at the [music] MCAT radio observatory in South Africa.

35:13 This image took three years of data analysis

35:16 to complete and it is revealing something thoroughly bizarre.

35:21 Deep within the turbulent chaos at the center of the Milky Way are hundreds

35:26 of highly ordered one-dimensional filament-like structures dangling

35:32 [music] inexplicably above and below the galactic center.

35:37 These enigmatic filaments [music] stretch for up to 150

35:41 lightyear yet are only one to three lightyears across.

35:47 The big question [music] is what are these strange superersized strands?

35:53 Now scientists are trying to unpick this mircat image to work [music] it out.

35:59 I'm Alex Mccoan and you're watching Astramm.

36:02 Join me today as we uncover the mysteries

36:04 around one of the Milky Way's weirdest phenomena.

36:08 We'll explore the happy accident that led to their discovery

36:11 and the extreme characteristics that are leaving scientists baffled.

36:18 The center of the Milky Way,

36:21 27,000 light-years from Earth, is a [music] place of violence.

36:26 This innermost region, the central molecular zone,

36:30 spans 1,600 light-year and is by all accounts

36:34 [music] the most extreme part of our galaxy.

36:38 Density, temperature, and turbulent velocity, a measure of chaotic fluid motion,

36:44 are around 1 to two orders of magnitude

36:48 higher here than anywhere else in the galaxy.

36:52 The cosmic ray energy density, a proxy for [music] energetic activity,

36:57 is 2 to three orders of magnitude higher.

37:01 This region is home to vast complexes of molecular gas,

37:06 about 20 million solar masses worth,

37:09 dense cosmic clouds, ionized plasmas, extreme cosmic ray energy,

37:16 ultraviolet and x-ray radiation, and turbulent magnetic fields.

37:22 It is a hotbed of [music] cosmic activity

37:24 from the formation of stars to exploding supernova.

37:28 And let's not forget Sagittarius [music] a star,

37:31 the super massive black hole 4 million times the mass

37:34 of our sun at the very center of it all.

37:39 These conditions are hugely exciting for astronomers,

37:43 but they make the galactic center notoriously hard to image.

37:48 Visible light can't penetrate the dense clouds of dust and [music] gas.

37:52 So researchers turned to other parts of the electromagnetic spectrum to lift

37:57 the veil and reveal the secrets at the heart of the galaxy.

38:02 Radio waves have the longest wavelengths of the electromagnetic

38:06 spectrum from a few millime to hundreds of kilome

38:10 and the wavelengths in the range of millime

38:13 to [music] tens of meters are ideal for radio astronomy.

38:18 They pass through the obscuring clouds of gas and dust,

38:21 giving us a clear view of what lies beneath.

38:25 In the early 1980s, Furhad Ysef Zade studying

38:29 for his PhD was using the very large

38:32 array telescope in New Mexico to produce a radio

38:36 map of a section of the galactic center.

38:39 He was planning to study star forming regions,

38:42 [music] but narrow strips of radio emission were streaking across

38:46 the entire survey area right through the parts he was interested in.

38:51 He thought they must be artifacts in the data or imaging errors,

38:56 which any scientist will tell you is highly annoying.

39:00 So after much frustration and no luck resolving the problematic artifacts,

39:05 he returned to the VA to image again at another frequency.

39:10 And that was when his Eureka moment struck.

39:14 At 400 a.m.

39:15 one morning, he was comparing the two

39:17 samples taken at different times using different wavelengths,

39:21 and he saw the same structures in both images.

39:26 This was no artifact.

39:28 This was a very real finding, something unlike anything he or anyone else

39:35 for that matter had come across before.

39:39 Zade was seeing highly ordered structures where previously only chaos

39:45 was thought to exist and they had some very unusual features.

39:50 Most striking was their vast scale.

39:54 These were continuous narrow strips of radio

39:56 emission 50 to 100 light-years long, but only 1 to three light-years wide,

40:03 dangling vertically above and below the central molecular zone,

40:08 the most extreme part of the Milky Way.

40:11 Some appeared in pairs or clusters running parallel

40:14 to each other like strings on a harp,

40:17 each separated [music] by a standard distance of around one astronomical unit,

40:22 the distance between Earth and the Sun.

40:25 When he cross-cheed them with the infrared data from that area,

40:28 Zarde also discovered they had no counterpart in that area of the spectrum.

40:35 This told him they were non-therrmal emissions.

40:38 That is to say they were not produced by heated gases.

40:42 This was corroborated by other measurements

40:45 such as spectral index and polarization which showed that [music] the filaments

40:49 were highly magnetic and emitting synretron radiation.

40:55 Synretron radiation occurs when electrons moving near the speed

40:59 of light interact with a strong magnetic field.

41:02 which begged the question, what on Earth,

41:04 or should I say not on Earth, was accelerating the electrons to such speeds.

41:11 The emissions along the length of the structures were continuous,

41:15 ruling out localized events like star formation or supernova remnants.

41:20 So, Zade dubbed them non-therrmal filaments and suggested

41:25 they were likely related to galactic scale phenomena.

41:29 His observations didn't correspond to anything else in the known galaxy.

41:33 And Zarde had many more questions.

41:36 Where did the non-thermal filaments come from?

41:40 What was maintaining their linear structures over

41:43 such vast distances of space and time?

41:47 Why, when clustered, were they so evenly spaced?

41:52 But almost as soon as this startling discovery was made,

41:55 the trail started to go cold.

41:58 The available telescopes at the time simply

42:00 didn't have the sensitivity needed to provide answers.

42:05 Over the next 35 years, only a handful of other vertical

42:10 non-therrmal filaments were revealed and categorized.

42:14 Some were even given inigmatic names like the snake, pelican, and bent harp.

42:21 Sadly, there wasn't enough data to make

42:23 any great leaps forward in understanding.

42:26 Well, not until 2022.

42:29 [music] And Miaat's mindblowing image.

42:34 The Miaat radio telescope at the South Africa

42:36 Radio Astronomy Observatory or SARo is comprised of 64

42:41 interlin antennas each with a 13.5 m diameter parabolic

42:47 dish spread over 8 km of radio silent zone.

42:52 Built over four years, the full array was inaugurated in 2018.

42:58 Its location in the southern hemisphere is [music]

43:00 perfect for imaging the center of the Milky

43:02 Way thanks to our sun's axle tilt relative to its own position in the galaxy.

43:08 So, Miaat has a direct line of [music]

43:11 sight into the CMZ and the galactic center.

43:15 Over the course of 3 years, an international team led by Dr.

43:19 Ian Haywood and including Zarde, now professor at Northwestern University,

43:25 directed Mia Cat to a 6.5 square degree portion of the galaxy,

43:31 a section of the sky around 30 full moons wide with Sagittarius A star

43:37 right in the middle using Lband radio frequencies of 856 to [music] 1,712 MHz,

43:46 equivalent to wavelengths of 18 to 35 cm.

43:51 They split this area into a 20part mosaic,

43:56 directing the telescope to survey each tile in turn

43:59 over a total of 144 hours on target.

44:04 This was the first time Mircat's full array was used

44:09 with 60 to 62 dishes sampling the sky at any one time.

44:14 After generating 70 terabytes of raw data,

44:18 the equivalent to 700 hours of 4K YouTube content,

44:23 the team then had to process it.

44:26 That was no mean feat.

44:28 Given the complexity of the environment,

44:30 they needed to put the data through a highpass

44:32 filter using a method called difference of Gaussians.

44:37 This is a commonly used edge smoothing technique to remove

44:40 background noise and enhance the [music] visibility of fine structures,

44:44 especially important for visualizing non-therrmal filaments.

44:48 And this is the result.

44:52 More like a work of art than a scientific study,

44:56 it captures a wealth of features.

44:59 Some are wellnown like Sagittarius A star seen in the central saturated area

45:04 here and clearer views of previously

45:06 known supernova remnants and star forming regions.

45:10 This here is a supernova remnant.

45:13 To its left is a runaway pulsar, the mouse and up on the right one

45:19 of the longest and most famous non-therrmal filaments, the snake.

45:25 As noted by the team, one of the most startling discoveries was

45:29 the sheer number of filaments apparent in the image,

45:33 an order of magnitude greater than all previously known,

45:37 most of which had never [music] been seen before.

45:41 This was game-changing for Zard and his colleagues.

45:45 Now we finally see the big picture.

45:48 A panoramic view filled with an abundance of filaments.

45:51 He said this is a watershed in furthering our understanding of these structures.

45:57 There was finally enough data to carry out meaningful population studies.

46:01 They set to work carrying out statistical analysis of the filaments.

46:07 This work published in the astrophysical journal letters not only

46:11 further categorizes the filaments but gives tantalizing clues to their origin.

46:17 The new data confirmed that all of them are magnetized.

46:21 In fact, the team found that the magnetic

46:23 field was significantly greater in some

46:26 cases up to 10 to 100 times stronger than typical galactic magnetic fields.

46:32 The new analysis also confirmed

46:34 that synretron radiation is a defining characteristic.

46:39 Interestingly, the MICAT data revealed that there

46:42 is a steepening with galactic latitude.

46:46 In other words, the filaments appear to cool

46:49 as they stretch away from the galactic plane.

46:52 This gives us a clue as to their possible origin.

46:56 The electrons further away from the galactic plane could be older,

47:00 implying that the filaments are related to past activity of Sagittarius a star.

47:07 And there was another clue that suggested this too.

47:10 Enormous structures known as radio bubbles.

47:14 First discovered by Haywood Zade and the Miacat team in 2019,

47:20 these huge radio emmitting structures stretch

47:23 symmetrically above and below the galactic plane,

47:27 forming an hourglass shape thousands of light years across.

47:32 They are thought to have been created by a phenomenal outburst

47:36 from Sagittarius a star about 100,000 to a million years ago.

47:41 An event powerful enough to leave such a scar

47:45 on the galaxy could have been vast quantities of gas

47:48 and dust falling into the black hole or a huge

47:53 and sudden burst in star formation close by.

47:56 An incident like this would have triggered an intense

47:59 outburst of energy and whipped up galactic winds,

48:02 driving gas and cosmic rays violently away from the galactic center,

48:07 stretching and amplifying magnetic field lines in its wake,

48:10 creating those bubbles and non-therrmal filaments.

48:14 What's more, strong magnetic fields,

48:17 which as we now know are a confirmed characteristic of all filaments,

48:21 capture cosmic rays.

48:23 And the great thing is we can date [music] them.

48:26 Those detected in the filaments by a mircat match the proposed period

48:31 of the Sagittarius A star outburst considered responsible for the radio bubbles.

48:37 In other words, they are the same age.

48:41 The position and capabilities of Mircat alongside the same

48:45 highpass filtering used to resolve the non-therrmal radio filaments

48:49 not only revealed these bubbles in astonishing detail but showed

48:53 almost all of the filaments are confined within them.

48:56 This close physical association adds even more weight

49:00 to the argument that the same energetic event created them.

49:04 Something powerful enough to create the bubbles would certainly

49:08 be able to accelerate electrons to near the speed

49:10 of light with the stretch magnetic field lines

49:13 channeling them to produce the filament's signature synretron emission.

49:17 With this hypothesis in mind,

49:19 Zard and the team described the formation of non-therrmofilaments

49:23 as magnetized streamers in a cosmic raydriven [music] wind.

49:28 It certainly paints a compelling picture

49:30 for the possible origin of the filaments,

49:32 but it is by no means conclusive as even the authors themselves attest.

49:37 Other theories are being worked on.

49:40 With a mystery this tantalizing,

49:41 other astronomers have been studying the filaments, too.

49:45 But this single image is still the one that's told us the most.

49:49 Zard wasn't kidding when he said it was a watershed moment.

49:54 But with so many unanswered questions,

49:56 some going back 40 years, where does that leave us?

50:01 Are non-thermal radios merely a galactic curiosity?

50:07 Not by any means.

50:09 They are a riddle wrapped in a mystery inside an enigma

50:13 and could shed light on one of the biggest unanswered questions out there.

50:17 How super massive black holes regulate star formation within a galaxy.

50:23 Scientists know that the active centers of galaxies must transfer energy

50:26 and matter into interstellar [music] space

50:28 through a process called galactic feedback.

50:31 If they didn't, star formation would run away unchecked,

50:35 using up a galaxy's gas and dust faster than observations tell us.

50:39 But how this feedback happens is unknown.

50:42 Mircat's detailed imagery of non-therrmal filaments and the radio

50:46 bubbles provides us with compelling evidence that this outflow

50:50 of energy could happen in discrete but powerful outbursts

50:54 and this is something that has been seen before.

50:58 Fermy bubbles discovered by NASA's Fermy gammaray telescope in 2010 are

51:03 even bigger hourglass shaped configurations

51:06 spanning a total of 50,000 lightyear.

51:10 These mindbogglingly massive structures colored magenta in this image

51:15 are thought to be millions of years old.

51:18 Likely caused by a violent outburst from Sagittarius A star,

51:22 which calculation suggests had the energy of 100,000 supernova.

51:29 This is much more powerful and [music] ancient than

51:32 the event proposed to have made the filaments and radio bubbles.

51:36 But together they paint a picture of intermittent

51:38 outbursts from deep within the heart of our galaxy.

51:42 Both have the potential to regulate star formation,

51:45 ensuring that the Milky Way doesn't suffer from burnout.

51:49 As scientists continue to unravel the mysteries of non-therrmof filaments

51:53 and tackle the big questions about how the universe works,

51:57 the trail doesn't seem to be going cold again anytime [music] soon.

52:01 Since the first full array image,

52:03 Mircat has found more of these mystery strands in other galaxies

52:07 with very similar properties to the ones we see in the Milky Way.

52:11 Their very existence elsewhere suggests a common underlying mechanism

52:16 that alludes [music] to their role in fundamental galactic processes.

52:21 To conclusively piece together the whole picture

52:23 will require another step change in imaging resolution.

52:27 And hopefully that's not too far off as MICAT already awarded by the Royal

52:33 Astronomical Society for its spectacular observations in radioastronomy

52:37 was built with longerterm goals in mind,

52:40 namely to be incorporated into [music] the square kilometer array.

52:45 With a total collecting area of one square km,

52:49 it will be 50 times more sensitive than any other radio instrument in existence.

52:54 and it's expected to be fully constructed by 2028.

52:58 Keeping an eye on developments in other parts

53:00 of the electromagnetic spectrum will be important too.

53:03 Zard believes that the next breakthrough

53:05 will come from [music] gamma ray telescopes.

53:08 Imaging at higher frequencies results in higher resolution imagery

53:12 which [music] has potential to show us whether the filaments,

53:14 the radio bubbles that contain them, and the vast fermy bubbles are connected.

53:20 There's an elegance in order rising out of chaos [music] and observing

53:24 non-therrmal filaments streaming out through

53:26 the cosmic winds certainly fits that notion.

53:30 So, keep watching this space.

53:32 And with images and phenomena this spectacular,

53:36 I certainly have no problem doing that.

53:40 If you've been following the Astramm Answer series recently,

53:43 you'll notice that we've talked a lot about how the universe is structured.

53:48 filament structures of galaxies being pulled apart by the universe's

53:52 expansion with bubbles or voids forming in the gaps.

53:58 Because of the universe's expansion, everything is moving away from everything.

54:03 But of course, this isn't totally true

54:05 in practice due to a mysterious force called gravity.

54:10 Gravity is a pulling force or technically it is

54:13 the curvature of spaceime caused by uneven distribution of mass.

54:19 On very small scales, gravity is hardly relevant at all.

54:23 I don't feel any pull towards objects around me,

54:26 only towards the earth because it is so massive.

54:30 Celestial objects close enough to the sun are most influenced by its gravity.

54:35 And all stars in the galaxy orbit around

54:37 a super massive black hole at the galaxy's core.

54:41 But it doesn't stop there.

54:43 You've probably heard that the Andromeda galaxy is hurtling towards us.

54:47 How can that be when everything is moving apart?

54:51 Gravity.

54:53 Objects that are close enough together with a large enough mass are

54:56 pulled towards each other by gravity faster than the universe can expand.

55:01 This is why we have galaxy superclusters.

55:04 And in fact, we are part of one.

55:06 Gravity is keeping these galaxy clusters bound together,

55:10 meaning over extremely large time scales, collisions aren't totally unusual.

55:16 In fact, a new theory has recently been proposed that the Milky Way may

55:20 have recently experienced a collision with a large

55:23 melanic cloud-sized diffused galaxy called Antlia 2.

55:28 Scientists have discovered that the Milky Way has ripples

55:31 consistent with it having had a collision in the past,

55:35 but we couldn't pinpoint what it collided with until Gaia

55:38 discovered the Anier 2 galaxy hidden behind our galactic disc.

55:43 This makes it very hard to spot as although it is massive,

55:47 it is very spread out due to the collision and being behind our galactic

55:51 disc makes it hard to see due to the stars and dust in the way.

55:57 But that brings us on to the main topic of this episode, the great attractor.

56:02 In an opposite vein from the supervoids video,

56:04 where there are regions of space where there is an almost total

56:08 absence of mass for hundreds of millions of light years in any direction,

56:12 the great attractor is the biggest concentration

56:15 of mass for hundreds of millions of light years.

56:18 It is so massive that even though our galaxy

56:21 is between 150 to 250 million lighty years away,

56:26 we and all galaxies around it are currently moving towards it.

56:31 Estimates put its mass at roughly 1,000 trillion suns,

56:35 which is enough for many thousands of galaxies.

56:39 But what could possibly be there that is that massive?

56:42 Well, for the longest time it was a total mystery because like Adlia 2,

56:48 the region where the great attractor is

56:50 located is hidden behind our galaxy's disc.

56:53 However, X-ray telescopes can see through the disc.

56:57 And recent technological improvements and advances in X-ray

57:01 telescopes have meant that we have been able

57:03 to detect thousands of galaxies in the region

57:06 where the great attractor is supposed to be.

57:08 But the mass detected didn't add up.

57:12 There wasn't enough present to create such a pull.

57:15 Further analysis has revealed something very interesting that while

57:19 we are being pulled towards the great attractor,

57:22 there is something even more massive behind it.

57:26 Located 650 million lighty years away called

57:29 the Chappley attractor or the Shappley supercluster.

57:32 Located there are many thousands of galaxies densely packed together with a mass

57:37 of 10,000 trillion suns and everything within

57:41 1 billion lightyear is being pulled towards it.

57:45 On the other hand, looking

57:47 the opposite direction from the Shappley supercluster,

57:49 we see an underdent region where everything seems

57:52 to be moving away from it called the dipole repeller.

57:57 It isn't actually repelling mass, but due to all the mass around it

58:01 being pulled towards more dense regions by gravity,

58:04 it creates the illusion that it is repelling that mass.

58:07 Although there are some scientists that do claim

58:10 that an unknown repelling force is at work there.

58:14 Simply put, we are still in very early

58:17 days when it comes to understanding the universe.

58:21 We do observe certain things like the motion of galaxies,

58:25 dense galaxy groups and absences of galaxies

58:28 in large voids or repelling regions.

58:32 We observe the expansion of the universe and observe the filamentary structures.

58:37 But the universe is an impossibly large place.

58:40 We can only see so far, only live so long.

58:44 Plus, our technology is limited.

58:47 We have theories which try and explain what we see.

58:50 But I really wouldn't be surprised to see

58:52 these theories change as more data becomes accessible.

58:55 Some may ask what's the point then?

58:58 However, I for one am hugely grateful for the bright minds working

59:02 on this as discovering our place in the universe is so fascinating.

59:07 I'm glad humans have an insatiable need

59:09 to explore and understand everything around them.

59:12 This innate sense of wonder and curiosity

59:14 is what drives the evolution of mankind, and I am excited to witness it.

59:22 A massive thank you to our astronauts on Patreon.

59:26 This video had no sponsors,

59:28 but it was still made possible thanks to the hundreds of members we have there.

59:32 Link is in the description to join our growing community.

59:36 Patreon is where Astramm truly takes shape.

59:39 A place for people who love space,

59:41 who want to see these videos keep improving and reaching more curious minds.

59:46 Every new member keeps the channel focused on what really matters,

59:50 making the complexity of space available to everyone.

59:53 If you enjoy what we do, come join the Astramm community today.