
Our Dazzling Night Sky When the Milky Way Collides with Andromeda in 4B Years - mpweiher
https://kottke.org/19/10/behold-our-dazzling-night-sky-when-the-milky-way-collides-with-andromeda-in-4-billion-years
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kregasaurusrex
Time to reference my favorite Wikipedia page:
[https://en.wikipedia.org/wiki/Timeline_of_the_far_future](https://en.wikipedia.org/wiki/Timeline_of_the_far_future)

From a logarithmic standpoint, around 1 billion years is when geologically
interesting things happen to the earth as it's no longer to sustain life an
have the oceans boil over as well.

~~~
gradschool
My favorite datum from this page is that the days will be 1 hour longer in 180
million years. If the year lengths are constant, by linear interpolation some
time around 63 million years from now the years will be exactly 360 days, just
like the ancient Babylonian calendar. What a great time that will be to be
alive and to be a programmer, with exactly 30 days every month.

~~~
tzs
What makes you think that a 360 day year would be 12 months of 30 days each?
We'll probably do something weird, like take all 5 out of February.

~~~
n0rbwah
Just imagine the nightmare for the poor programmers who will have to maintain
backward compatibility for 63 million years of timekeeping.

~~~
gremlinsinc
This all assumes we survive the unix 2036 apocalypse.

/s I mean it apparently is so bad they sent time travelers back in time to try
and fix it. (Google: John Titor)

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ChuckMcM
Ok, that is the first thing I've read that makes it sound like fun to be
around in 4B years to watch it all happen.

It is also interesting to think about two galactic civilizations coming
together over a common need to survive in the post collision Milkdromeda
galaxy.

~~~
thatswrong0
I don't think they'd really have to worry about survival:

> it’s extremely unlikely that any individual stars will collide because of
> the sheer amount of empty space in galaxies.

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outworlder
Many stars will get ejected into intergalactic space as well. Hopefully they
are not the unlucky ones.

~~~
Mirioron
What kind of impact would that have on a star and its planets?

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Santosh83
This is almost as long as the Earth has existed since its formation. It is an
extremely long length of time. Suffice it to say humans will _not_ be around
anywhere close to that time. Nor will any currently recognisable life. All
current species and families would've drastically changed and evolved into
other forms, with the exception of simple, unicellular life. And of course
around this time our Sun will be on its way to a red giant so the Earth would
be becoming well nigh inhospitable for life (as it exists now). As for
intelligent life, I don't think intelligence can remain stable for such
lengths of time.

~~~
i_am_nomad
The Earth will be inhospitable for life (as we know it) within the next 800
million years, in fact. It’s a bit sobering to think that we’ve progressed
through about 75% of the time life has on this planet.

Source: my favorite Wikipedia page,
[https://en.m.wikipedia.org/wiki/Timeline_of_the_far_future](https://en.m.wikipedia.org/wiki/Timeline_of_the_far_future)

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8bitsrule
Ah well. That's 2.5 billion years after the collision with the Large
Magellenic Cloud. Which may turn 'our' galaxy into a quasar.

[https://www.space.com/42901-milky-way-galaxy-large-
magellani...](https://www.space.com/42901-milky-way-galaxy-large-magellanic-
cloud-crash.html)

[https://academic.oup.com/mnras/article/483/2/2185/5181341](https://academic.oup.com/mnras/article/483/2/2185/5181341)

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opless
Lest we forget, in around 5bn years the Sun will become a red giant. I doubt
humanity will make it that far.

Cool images though

~~~
SubiculumCode
I think the problems may happen as soon as 1B from now.

[https://www.google.com/url?q=https://www.universetoday.com/1...](https://www.google.com/url?q=https://www.universetoday.com/12648/will-
earth-survive-when-the-sun-becomes-a-red-
giant/&sa=U&ved=2ahUKEwjLqbXizbDlAhWDhJ4KHYRhAdYQFjADegQIChAB&usg=AOvVaw3AmzSGiWUATfsCIKeKUvjQ)

~~~
SamBam
On the off-chance that humans are around in a billion years, I would hope we'd
have learned to manage a planet-sized climate by then, so preventing Earth
from turning into Venus should be manageable. Certainly more manageable than
surviving another billion years, at least.

~~~
_Microft
If there are descendants of humans in a billion years, their capabilities
might only be limited by the laws of physics - and I would not even be
surprised if this time is off by quite a few orders or magnitude (up to like
... six? _Edit: that would mean as early as 1000 years from now. It 's a bold
guess, I know_).

~~~
coldtea
> _If there are descendants of humans in a billion years, their capabilities
> might only be limited by the laws of physics_

Or, something few consider, they might have plateaud way earlier, after most
low hanging fruits have been achieved (fire, steam engine, electricity,
nuclear power, computing, telecommunications) and the rest are diminishing
returns...

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marcosdumay
Isn't that what the "limited by the laws of physics" mean? Worldwide climate
engineering is within that envelope.

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coldtea
> _Isn 't that what the "limited by the laws of physics" mean? Worldwide
> climate engineering is within that envelope._

"Limited by the laws of physicals" implies only physical laws are the
limitation.

Whereas my response was more about being more limited (due to complexity, lack
of resources, etc). So response was about a possible way lower envelope. I.e.
not necessarily much more advanced than we are today, with diminishing
advances in various areas.

So no "worldwide climate engineering" (except the clumsy stuff we already
have), and no personal robot assistance of sci-fi style...

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crazydoggers
It should be noted that these views will require long time exposure
photographs.

The surface brightness of Andromeda and the Milky Way are both around 22
mag/arcsec2. As andromeda grows closer, the surface areas spreads out in our
sky, so even as it gets closer it’s not really going to get brighter.

[https://en.m.wikipedia.org/wiki/Surface_brightness](https://en.m.wikipedia.org/wiki/Surface_brightness)

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rman666
Note: That’s 4,000,000,000 years from now, not 48 years from now!

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netsharc
My eyesight is really failing me...

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java-man
In four billion years the Earth might be engulfed (or at least fried lifeless)
by the Sun.

[0]
[https://en.wikipedia.org/wiki/Future_of_Earth](https://en.wikipedia.org/wiki/Future_of_Earth)

~~~
beat
Out of curiosity, I looked it up, and it seems like there's less than a
billion years left for life as we know it on Earth before the Sun sterilizes
the planet. That doesn't mean some of our descendants won't figure out ways to
move farther out in the Solar System (or to other planetary systems), to
survive it.

~~~
jandrese
It seems like we might sterilize the Earth ourselves long before the Sun has a
chance to.

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beat
We are a long way from being able to sterilize the Earth. Heck, I don't think
we could even wipe out humanity - or even civilization - much less all the
myriad forms of life out there that thrive in conditions that would kill
humans instantly. (Go to Yellowstone, see the brightly colored pools of
boiling volcanic mud, realize those pools are brightly colored because they're
full of living beings...)

I think what we're looking at right now is making life a little more
uncomfortable and expensive for part of humanity. That's as bad as we can
manage right now. The fact that we treat it like the end of the world says
more about us than the damage itself does.

~~~
outworlder
> Heck, I don't think we could even wipe out humanity - or even civilization

You are talking about global warming and the like, right? There's another
possibility, and it involves nuclear weapons. THOSE can sterilize the planet
many times over.

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shkkmo
While we MIGHT be able to wipe humanity off the planet with nuclear weapons
[0] and would certainly create a mass extinction event, it is extremely
unlikely we would be able to sterilize the earth. Even if we somehow manage to
wipe out all multi-cellular life (which would, at a minimum, require
completely vaporizing our oceans to expose deep ocean vents), it would take
massively more destruction to wipe out all single celled life on the planet
(which would likely require removing the entire planet's crust.)

[0]
[https://en.wikipedia.org/wiki/Nuclear_holocaust#Likelihood_o...](https://en.wikipedia.org/wiki/Nuclear_holocaust#Likelihood_of_complete_human_extinction)

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Ididntdothis
I have marked my calendar so I won’t miss it!

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cardiffspaceman
I literally can't wait.

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lukifer
The vast majority of the stars will pass through each other; what I'm curious
about is what happens at the galactic cores, and how many solar systems will
end up being swallowed by the super-massive black holes at the center of each
galaxy. Also, what are the side effects of two black holes merging? Have we
ever observed such a thing?

[https://www.youtube.com/watch?v=fMNlt2FnHDg](https://www.youtube.com/watch?v=fMNlt2FnHDg)

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ses1984
>it’s extremely unlikely that any individual stars will collide

What do you mean they'll pass through each other.

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lukifer
The distances are so vast, that essentially, yes. Think about two sailors in
small boats, crossing an ocean in opposite directions, and how unlikely it
would be that their boats collide. Now multiply that by several orders of
magnitude.

One of my favorite factoids: if you fire a laser from the surface of the earth
(and the beam magically stayed perfectly straight), you have a small but
significant chance of hitting the sun or the moon, but anything beyond that,
the scale is so enormous, the odds that your laser would ever hit a celestial
body _anywhere_ in the universe are effectively zero.

~~~
ses1984
You're confusing me more. Stars passing through each other like you said
before to me implies collision. Would you say these sailors are going to pass
through each other?

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ajna91
They stars won't pass through each other. The "solar systems" will pass
through each other.

~~~
ses1984
I would have guessed that even that is highly unlikely.

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hi41
I was moved by the images. It reminded me about how selfish I am the way I
grab at things. At these time scales would it matter if I had more prestige or
material possessions. I want to become kinder but I don’t know how or if I
ever can. The more immediate instincts of anger and jealousy hold far more
sway.

~~~
hirundo
At these time scales does kindness matter any more or less than prestige or
possessions? The only behaviors that might matter are those that could lead to
our interstellar diaspora. It's not clear that kindness is or isn't a greater
motivator for that than pride.

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Camillo
Yeah, but this is astrophotography _and_ it's from Nasa, so it's what it would
look like with ultra-long exposure, lots of photoshop, and false color. If we
extrapolate the naked eye view, it'd be a grayish smudge at best.

~~~
HoveringOrb
The first couple of images show the milky way pretty much as it actually
appears from a suitably dark location. Maybe just a bit brighter and more
contrasty than I recall, but I'm sure there are many here who see it almost
nightly and can speak to that better. Just saying, it doesn't look grossly
exaggerated to me.

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notjustanymike
It makes me feel so small to know something so large will happen so far in the
future that any memory of the human race is so unlikely.

~~~
rwmurrayVT
I am really not a fan of the feeling reading a lot of this thread and linked
materials gives me.

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rkagerer
5B years eh? Perfect timing for some fresh matter; we'll probably have used up
most of the raw materials in this galaxy by then.

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withinrafael
This shows a (beautiful) theoretical point of view from Earth. I feel dumb
asking this but will this event affect our solar system?

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ChuckMcM
Looking at the video, yes. But not in the form of something colliding with the
Sun. I would guess the most likely interaction would be perturbations of
orbits as the solar system deals with these freight trains going by. That
could result in anything from planets changing orbits as they follow the
changes in the Sun's orbit around the galactic center, to having the entire
solar system ejected on its own path away from the galaxy (that first pass
"collision" is going to impart a lot of momentum on different systems. It
shows a 'spray' of things going out from the galaxy but those things are stars
with their nominally attached planetary bodies!)

~~~
jessriedel
The planetary orbits in the solar system are vastly smaller than the typical
distance between stars in the combined Milky-Way-Andromeda system. The only
difference will be a slightly higher typical speed for Andromeda stars
compared to the relative motion of stars in the Milky Way disk. But that's
only by like a factor of 10, and I don't have any reason to think that will
cause a perturbation that's noticeable above the normal uncertainty from chaos
in planetary orbits.

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russdill
Ah, but what will this look like from our light polluted cities?

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outworlder
You are very optimistic if you are talking about "cities" in that timeframe.

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russdill
Meh, the sun will grow warmer but won't enter it's red giant phase until about
5 billion years from now. Placing reflectors in a lagrange point to control
the amount of solar energy reaching Earth with be child's play. Even once it
enters the red giant phase, it'll be several hundred million years before it
consumes Earth.

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jason46
Mass Effect Andromeda anyone?

