Hubble Actually PEERED INSIDE Andromeda — What It Found Is Horrifying

A vast galactic mystery has recently

baffled astronomers. They've noticed

that all but one of Andromeda's 37

satellite galaxies point toward the

Milky Way. It's so extraordinary that it

challenges current cosmology and might

provide the answer to the dark matter

question. So, it happened like this. One

day, scientists looked at those other

satellite galaxies that go around

Andromeda and spotted a really weird

alignment. Now, we should keep in mind

that Andromeda is kind of like our Milky

Way's neighbor. It's huge, about twice

as wide as the Milky Way, stretching

200,000 light-years across. It also has

way more stars, around a trillion,

compared to our galaxies mere 250 to 400

billion.

Just like our galaxy, it has a bunch of

tiny galaxies called dwarf galaxies

spinning around it. There are 37 of

them. The strange thing is almost all of

those little galaxies are on the same

side of Andromeda. And it's getting even

creepier because it's the side that

faces the Milky Way. Only one galaxy is

hanging out on the other side. Imagine

tossing a bunch of marbles around a tree

with nearly every single marble landing

on just one side. That's weird, isn't

it? Scientists say that this discovery

doesn't match what they expected at all.

Their usual space models show that stuff

like this should be spread out more

evenly. But this isn't even close to

even. It's so lopsided that they can't

really explain it yet. Those models

follow the main space theory we use

today called the lambda cold dark matter

model. [music] According to this theory,

the little galaxy should be spread

around Andromeda pretty evenly. Maybe

just a bit lopsided. But in real life,

their distribution is way more uneven

than the model said it should be. The

scientists have run tons of simulations,

and only about 03% of them ended up

close to what we actually see. And

still, none of them match the real thing

exactly. So, does it show the lambda CDM

model has flaws? That would be a big

deal because we normally use this model

to explain how the universe works. If

the real sky doesn't match what our

model says, especially in a place as

close and well known as Andromeda, it

might mean that we're missing something

big.

Another strange thing, many of

Andromeda's satellites seem to lie in a

flat plane instead of being randomly

distributed in all directions. This kind

of flattened structure has been seen in

other big galaxies, too, including our

own, but it's still not well understood.

Maybe the satellite disc is connected to

the weird cosmic asymmetry, but no one

really knows how. In any case, the fact

that all the tiny galaxies on

Andromeda's side line up almost

perfectly in the direction of the Milky

Way is super weird. It makes you wonder,

could our galaxy be pulling or affecting

them? But the catch is that nothing like

this is happening to the Milky Way's own

satellites. Plus, the gravity between

our two galaxies doesn't seem strong

enough to do that kind of pulling.

The answer might lie in one of the most

mysterious things the universe has to

offer. Dark matter. Let's start from the

very beginning. We'll go all the way

back to the early universe [music] just

after the Big Bang. Now, back then, hey,

I wasn't around then, but I'll tell you

anyways. Matter in the universe was

spread out pretty evenly, but not

perfectly even. In a few spots, there

were just slightly higher amounts of

matter than in others, tiny clumps.

Those little differences were important

because gravity could latch onto them.

Over time, those denser regions started

pulling in more material, slowly growing

into the first structures in the

universe. Astronomers believe that dwarf

galaxies were the earliest and [music]

smallest building blocks of galaxy

formation. Think of them like Lego

bricks, tiny pieces that were later

pulled together by gravity to build

larger galaxies over billions of years.

Now, when we talk about matter, we mean

two different things. Normal matter, the

kind we can see and touch, including

atoms, gas, stars, planets, and

everything around us. And dark matter,

the invisible kind. It doesn't give off

any light, doesn't absorb it, and

doesn't interact with normal matter in

the usual ways. The only reason we know

it exists is because of its

gravitational pull. There's also a lot

more of it than normal matter.

Scientists think that roughly 85% of all

matter in the universe is dark matter.

At the same time, we've never directly

detected a dark matter particle, but we

know dark matter is there because it

bends light. It holds galaxies together.

They spin too fast to stay intact

otherwise. and it shapes the structure

of the universe, allowing us to map its

influence on larger scales. While normal

matter can clump together, crash, heat

up, cool down, and eventually form stars

and galaxies, dark matter can't do any

of that. It doesn't bump into itself or

radiate heat. But it can still form big

invisible clumps, which we call dark

matter halos. In the early stages of the

universe, the halos acted like gravity

wells. They pulled in normal matter

which sank into the centers of those

halos and formed the first galaxies. So

galaxies like the Milky Way or Andromeda

might be sitting inside enormous blobs

of dark matter that we just can't see.

So cosmic asymmetry explained not yet.

Scientists are sure that dwarf galaxies

are some of the most dark matter

dominated objects in the universe. In

many cases over 99% of their mass is

likely to be dark matter. That means

they give us a unique chance to study

dark matter without all the messy gas

and stars that exist in larger galaxies.

Researchers use dwarf galaxies to figure

out how dark matter clumps together or

whether there are alternative theories

of dark matter like warm or

self-interacting dark matter.

At the moment, the main theory is that

dark matter behaves like a cold, clumpy,

and slowmoving fluid. At the same time,

it might not be totally cold. Maybe it

has other properties. Maybe it interacts

with itself or with normal matter in

subtle ways we haven't discovered yet.

If that's true, it could help explain

why satellite galaxies form in strange

patterns like the ones around Andromeda.

In other words, the Lambda CDM model

might indeed have flaws. According to

it, thousands of dwarf galaxies should

be orbiting around larger galaxies like

the Milky Way and Andromeda, but we only

see a few dozen. This is known as the

missing satellites problem. There are

other puzzles too. For example, Lambda

CDM predicts that dark matter halos

should be the densest at the center, but

many dwarf galaxies seem to have cores

of their own. Plus, dwarf satellites

around galaxies like Andromeda and the

Milky Way seem to lie in thin

co-rotating planes, and it's something

extremely rare in lambda CDM

simulations. And finally, some simulated

dark matter halos are so massive that

they should form bright dwarf galaxies,

but we don't see them. No wonder

astronomers are so interested in dwarf

galaxies and the explanation of cosmic

asymmetry. For that, we need more

precise measurements of their motions

and structures and simulations that add

more realistic physics like stellar

feedback, turbulence, and so on. Plus,

we got to search for new dwarf galaxies

in the local group and beyond using

better telescopes and deeper surveys.

Now, getting back to Andromeda's weirdly

positioned satellites. If the dark

matter theory doesn't work out, there's

another possibility that involves

large-scale interactions between

galaxies. It could be an old collision

or a near miss that shape the current