Welcome back to Cosmos in a Pod Space and Astronomy series.
You know, every time I look up at the night sky
and see all those stars,
I can't help but wonder what lies beyond our own Milky Way.
It's like, are we alone out here?
Well, let me tell you, we're definitely not alone.
In fact, there's a whole other galaxy out there,
a massive spiral galaxy, twice the size of our own,
packed with a trillion stars,
and it's on a collision course with us.
Whoa, whoa, whoa, wait a minute, a collision course?
Are you serious?
You're talking about the Andromeda Galaxy, right?
That's the one.
So this isn't some sci-fi movie plot,
this is really gonna happen.
Oh, it's as real as it gets, but don't worry,
it's not gonna be some catastrophic explosive crash
like you see in the movies.
Okay, that's a little reassuring,
but you've gotta explain this to me.
What is the Andromeda Galaxy exactly?
We can see it with the naked eye,
but what do we actually know about it?
Well, imagine a vast island of stars, gas, and dust.
It's a spiral galaxy, just like our own Milky Way.
Okay, I can picture that.
But get this, Andromeda is more than twice the diameter
of the Milky Way.
It stretches over 220,000 light years across
and contains a trillion stars.
A trillion?
That's mind-blowing.
Our Milky Way only has a few hundred billion.
It's like comparing a tiny village to a meganacity.
Exactly, and like the Milky Way,
Andromeda has a super massive black hole at its core,
just like we do.
It's also shrouded in a halo
of this mysterious stuff called dark matter.
Dark matter, that's a whole other deep dive right there.
But I gotta ask, how do we even know all this
about a galaxy that's millions of light years away?
Is this all just speculation,
or is there actual science behind it?
Oh, there's definitely real science involved.
Astronomers use all sorts of amazing techniques
to study Andromeda.
We analyze the light coming from it.
We break that light down into its spectrum
to reveal its composition, how far away it is,
and even how fast it's moving.
So by studying the light, we can learn so much
about this distant galaxy.
That's incredible.
It is.
We also study Andromeda's structure.
We compare it to other galaxies to figure out
how it's classified and how it's evolved over time.
And by observing the movements of its stars and gas,
we can map its gravitational field
and understand how this invisible dark matter
is influencing its destiny.
Wow, it's like we're piecing together
a giant cosmic puzzle.
But let's get back to the main event, this collision.
I mean, it's billions of years away,
but I'm already getting nervous just thinking about it.
OK, so picture this.
Two vast swarms of bees, each with its own intricate dance,
slowly merging together.
OK, I'm visualizing it.
That's what this galactic collision will be like.
You have about four to five billion years.
Two.
So we have some time.
Yes, thankfully.
But in about four to five billion years,
the Milky Way and Andromeda will have
their first close encounter, passing through each other
like, well, like ghostly apparitions.
Their gravitational forces will start to tug and pull
at each other, distorting their shapes.
We'll see these incredible tails of stars and gas
streaming out into space.
So it's not like a head-on crash,
more like a cosmic tango.
You got it, a slow, graceful tango.
And the dance doesn't end there.
Over billions of years, they'll swing back towards each other,
passing through multiple times.
Each time, things get a little more chaotic.
Stars get flung into new orbits.
New stars are born.
And eventually, over a very long time,
they merge into a single, larger elliptical galaxy.
A whole new galaxy.
Do they have a name for this mega galaxy?
They do.
It's often called Milkomeda.
Milkomeda, catchy.
But I have to ask, what happens to our sun and solar system
during all this?
I mean, are we going to get flung out into the void?
It's a natural question to ask.
And it might sound scary.
But direct collisions between individual stars
are extremely unlikely.
Think about it.
Stars are incredibly far apart, even within a galaxy.
The chances of our sun colliding with another star
during this whole process are astronomically small.
So no cosmic billiards?
Not quite.
But while our solar system will probably survive,
things won't be exactly the same.
The sun's orbit will likely be significantly altered.
We might end up further out from the galactic center
or on a completely different trajectory altogether.
And what about the night sky?
Will we still see the Milky Way?
Oh, the night sky will be completely transformed.
Just imagine the Milky Way's familiar band of light
merging with the glow of Andromeda.
It'll be a breathtaking tapestry of stars,
unlike anything we can imagine today.
Wow, that's both terrifying and awe-inspiring
at the same time.
It is, isn't it?
It really makes you realize the vastness of the universe
and the incredible forces at play.
OK, I need a minute to process all this.
We've covered a lot.
Andromeda size, how we study it, the timeline of the collision,
and the fate of our solar system.
But I'm sure our listeners have a million more questions,
just like me.
Welcome back to Cosmos in a Pod.
Remember we were talking about this galactic collision
between the Milky Way and Andromeda.
Let's get into some of the finer details of what will actually
happen during this cosmic dance.
OK, yeah, last time we left off with the idea
that these two galaxies will sort of pass through each other.
Right, it's not so much a head-on crash, but more like,
well, imagine two ships passing in the night.
But these ships are absolutely massive,
like colossal islands of stars.
And their wakes are literally ripples
in the fabric of space time.
OK, I like that analogy.
So as they get closer, what's going to happen first?
Well, those beautiful spiral arms
that we see in pictures of galaxies,
those will be the first to feel the effects.
Oh, right, because those arms extend out pretty far, right?
Exactly.
And the gravitational pull between the two galaxies
will stretch and distort them, creating
these incredible streams of stars and gas
extending out into the void.
They're like luminous arcs, almost like cosmic brushstrokes
across the canvas of space.
That's a beautiful way to put it.
But is that kind of a destructive process?
I mean, are those stars getting ripped away from their galaxies?
It is destructive in a way, yeah.
But it's also a process of creation.
You see, these streams, which astronomers call title tails,
can actually lead to the birth of new stars.
Wait, really?
How does that work?
Well, as the gas and dust in those tails get compressed,
it can trigger the formation of new stars,
lighting up those regions with their brilliance.
It's like even in this seemingly destructive event,
new life can emerge.
Wow, that's incredible.
So we've got these spiral arms getting stretched
and distorted, new stars being born in these title tails.
What happens next in this cosmic tango?
Well, eventually, those two galaxies,
they'll have their first close encounter.
Oh, OK.
So this is the moment we've been building up to.
What happens during this first cosmic meet and greet?
It's not a head-on collision, as you might imagine.
Think of it more like two schools of fish
swimming through each other.
Their paths intertwine, but they don't directly collide.
So no stars smashing into each other.
Right, the distances between individual stars
are just too vast for that to happen.
But even though there are no direct collisions,
the gravitational forces will be immense.
Stars will get flung into new orbits.
The whole galactic structures will be disrupted.
And these vast clouds of gas and dust
will collide, which, as we said, can trigger even more star
formation.
So it's like a cosmic fireworks show.
You could say that.
And this first encounter, it's a pivotal moment
in the merger process.
You see, once they pass through each other,
those galaxies won't just go their separate ways.
Oh, right.
They're locked in by gravity.
Exactly.
Their gravitational dance continues.
They'll slow down.
They'll be drawn back towards each other.
And eventually, they'll have a second close encounter,
and then another, and another, each time they get closer,
more entangled, until.
Until they finally merge into one,
into that milcomita galaxy we talked about.
You got it.
It's a slow process, taking billions of years.
But each time they pass through each other,
the galaxies get more and more mixed.
Their stars and gas swirl together,
well, like ingredients in a cosmic blender.
So all this gas and dust and stars swirling around,
what happens to those supermassive black holes
we talked about, the ones at the center of each galaxy?
Ah, yes.
That's where things get really mind blowing.
You see, we're talking about two objects, each millions,
maybe even billions of times the mass of our sun
on a collision course.
As they get closer, they'll start to orbit each other,
a dance of unimaginable power.
OK, now I'm really trying to picture this.
Two supermassive black holes in a cosmic waltz,
that can't be good, right?
Well, it's certainly a dramatic event.
As those black holes orbit each other,
they actually create these powerful waves of energy,
ripples in the very fabric of space time.
Wait, you're talking about gravitational waves?
Exactly.
Those gravitational waves travel at the speed of light,
carrying with them information about these cataclysmic events.
Wow, that's a whole other deep dive we could do.
But what happens when those black holes finally meet?
Is it like an explosion?
It's more of a merging, a slow and powerful embrace.
As they spiral closer and closer,
they lose energy through those gravitational waves.
And eventually, they become one, a single, even more massive
black hole right at the heart of that newly formed
Milcomeda galaxy.
So after all that drama, all those close encounters,
all that stellar tango, we end up
with one giant elliptical galaxy with a supersized black hole
in the middle.
Precisely.
But that's not the end of the story.
Milcomeda will continue to evolve.
It might even merge with other galaxies.
And in this way, it will continue
to shape the cosmic landscape for billions of years to come.
It's just incredible to think about this whole journey
from two distinct spiral galaxies
to this single elliptical giant.
It's more incredible than any sci-fi movie I've ever seen.
It really shows you just how dynamic the universe is.
But we're not done yet.
In our final part, we need to zoom out even further,
explore the implications of this galactic merger
for our local group of galaxies and for the fate
of the universe as a whole.
Welcome back to Cosmos in a Pod.
We've been talking about this incredible collision
between the Milky Way and Andromeda,
the birth of new stars, these supermassive black holes
merging.
It's just mind-blowing stuff.
It really is.
But now I think it's time we zoom out a bit.
Look at the bigger picture.
What does this galactic dance actually tell us
about the universe as a whole?
Zoom out for me.
We've been focused on these two galaxies.
But are these kinds of events common?
I mean, is this like a freak occurrence?
Or is the universe just this giant mosh pit
of colliding galaxies?
You know, it's probably more of a mosh pit
than you might think.
Astronomers, they believe that these galaxy mergers
have been happening since, well, since basically
the beginning of the universe, since the Big Bang.
Early galaxies, they were much smaller and way more numerous.
So they were constantly bumping into each other,
merging, growing larger.
This process has been going on for billions of years.
So those amazing, majestic galaxies that we see today,
those pictures of grand spirals and ellipticals,
they're all a result of this cosmic demolition derby.
Exactly.
And this Andromeda-Milky Way collision,
it's just one example of this process that's
happening right now, right in our own cosmic neighborhood.
And astronomers, they've observed tons of other mergers
at different stages, which actually gives us
this incredible glimpse into both the universe's history
and its future.
It's like we have a time machine.
We can look back and see how these giant galaxies were
built.
But if these mergers are so common,
what does that actually mean for the future of Milkomeda,
this new galaxy that we've been talking about?
Well, Milkomeda, it won't be immune to the pull of gravity
from other galaxies.
It's probably going to attract smaller galaxies,
absorb them, grow even more massive.
It's this never-ending cycle of, well,
cosmic growth and evolution.
So even though the Milky Way and Andromeda are merging,
it's not like the whole universe is
going to become just this one giant blob of stars.
It just keeps going, this merging and growing.
Well, yeah, that's the thing about the universe.
It's constantly changing, always evolving.
But there is kind of a twist.
As the universe expands, the distances between galaxies
are also increasing.
Oh, right, the expanding universe.
Yeah, so that expansion, it could eventually actually
overpower the force of gravity, meaning that future mergers
might be less likely.
So even though they're happening all the time now,
someday galaxy mergers might become a rare sight,
kind of a lonely thought with galaxies drifting farther
and farther apart.
Yeah, it is kind of a lonely thought.
But remember, the universe is a pretty vast and surprising
place.
And even if these mergers become less frequent,
other processes, like the formation of new stars
and the evolution of existing galaxies,
that will all keep going.
The universe is dynamic.
It's always changing.
And who knows what incredible wonders are waiting for us
out there billions of years from now?
It's just amazing to think about.
We've gone from this intimate dance of two galaxies
to the grand expanse of the entire universe.
And this collision, it's just one small chapter
in this much larger story.
It is.
And the Andromeda-Milky Way collision,
it reminds us that we live in a universe that's
in constant motion, full of beauty and mystery
and endless possibilities for exploration and discovery.
It's been a truly incredible deep dive.
We've explored the science, the drama,
all these mind blowing implications
of this cosmic event.
And it shows us that our place in the universe,
it's not static.
It's dynamic.
It's evolving.
And it's interconnected in ways that we're just
beginning to understand.
And as we continue to explore and learn more,
I'm sure we'll uncover even more wonders out there,
which just fuels our curiosity and our awe.
Who knows what other cosmic dances are
waiting for us to discover?
It's exciting to think about.
Listeners, thank you so much for joining us
on this incredible journey.
We hope you enjoyed this deep dive into the Andromeda-Milky
Way collision.
Don't forget to follow and subscribe to the podcast
and our YouTube channel for more deep dives
into the wonders of the universe.
Until next time, keep looking up.