

NASA can now predict Andromeda collision with certainty - sytelus
http://science.nasa.gov/science-news/science-at-nasa/2012/31may_andromeda/

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bfe
Fascinating.

"It is likely the sun will be flung into a new region of our galaxy, but our
Earth and solar system are in no danger of being destroyed."

Pretty close, but not precisely zero danger -- and from a broader perspective,
this is a curious statement when by this point in time, four billion years
from now, the Sun will be nearing the end of its life and will already have
roasted the Earth into sterility (barring intelligent intervention).

"Simulations show that our solar system will probably be tossed much farther
from the galactic core than it is today."

This bodes well for the long-term safety of the Solar System; it should be
less likely to be broiled by supernovas or black hole accretion disk x-ray
emissions further out from the merged core.

"Previously, it was unknown whether the far-future encounter will be a miss,
glancing blow, or head-on smashup. This depends on M31’s tangential motion.
Until now, astronomers had not been able to measure M31's sideways motion in
the sky... The Hubble Space Telescope team, led by van der Marel, conducted
extraordinarily precise observations of the sideways motion of M31 that remove
any doubt that it is destined to collide and merge with the Milky Way. 'This
was accomplished by repeatedly observing select regions of the galaxy over a
five- to seven-year period,' says Jay Anderson of STScI. ... The space shuttle
servicing missions to Hubble upgraded it with ever more-powerful cameras,
which have given astronomers a long-enough time baseline to make the critical
measurements needed to nail down M31's motion."

The Space Shuttle really made major contributions to science by allowing
regular maintenance and upgrades to the Hubble Space Telescope.

"The Hubble observations and the consequences of the merger are reported in
three papers that will appear in an upcoming issue of the Astrophysical
Journal."

The articles don't appear to be listed yet in the Table of Contents for an
upcoming issue of ApJ. Stay tuned...

Edit to add:

[http://hubblesite.org/newscenter/archive/releases/2012/20/vi...](http://hubblesite.org/newscenter/archive/releases/2012/20/video/a/)

This computer model video of the next eight billion years in a minute and 16
seconds is mind-blowing.

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JonnieCache
I _highly_ reccommend watching the video simulation of the collision:
[http://hubblesite.org/newscenter/archive/releases/2012/20/vi...](http://hubblesite.org/newscenter/archive/releases/2012/20/video/a/)

Phil Plait also has some good commentary over at Bad Astronomy:
[http://blogs.discovermagazine.com/badastronomy/2012/05/31/ho...](http://blogs.discovermagazine.com/badastronomy/2012/05/31/hold-
on-tight-in-4-billion-years-were-due-for-a-galactic-collision/)

~~~
thwarted
Reminds me of the the galaxy xscreensaver hack.

------
albertzeyer
Note that already after 0.8 billion years, on Earth, "Carbon dioxide levels
fall to the point at which C4 photosynthesis is no longer possible. All plant
species die. Free oxygen eventually disappears from the atmosphere.[23]
Multicellular life dies out.[25]".

And after 3.5 billion years, "Surface conditions on Earth are comparable to
those on Venus today".

From: <http://en.wikipedia.org/wiki/Timeline_of_the_far_future>

So I guess it doesn't matter that much for humans what happens with the Earth
on the collision. Either we managed already to colonize other planets and then
the human race will like survive somewhere. Otherwise, we were probably doomed
earlier anyway already.

~~~
bfe
Even if we settle on a bunch of other planets, I imagine we will always remain
interested in preserving Earth as well. It will always be our original home.
And astrophysical engineering of the solar system should enable us to keep the
Earth in good shape well beyond the solar system's lifespan if left to its own
devices.

More thoughts on the far future prompted by this thread here:
<http://bfe242.com/the-stars-like-sea-froth>

~~~
ImprovedSilence
"I imagine we will always remain interested in preserving Earth as well."

Interesting thought, but after a few generations (or maybe 10+) of being born
on some other planet, or some combination of other planets, people will have
almost no relation to, or particular interest in earth. Let alone a million
years after the fact. Heck, I have no idea where my ancestors are even from if
I go back more than 5 generations. Does the entire human race currently have
some interest in preserving some place in Africa or Mesopotamia? Doubtful. I'm
not arguing here, I just think it's an interesting thought, about how quickly
(relatively) we lose track of where "we" are really from.

~~~
bfe
About 100,000 years ago, the entire subspecies of Homo sapiens sapiens -- all
of our ancestors -- consisted of about 2,000 to 5,000 individuals living
around the Rift Valley in Kenya. What if they had built museums of their art,
culture, and science, parks, gardens, temples, and libraries that had been
preserved ever since? What if all of life had also originated there and spread
out since then, and the ecosystem there was by far the oldest in existence?

I don't doubt there might be many of our descendants who think or know little
of the Earth, but I think there would also be various causes for enduring
interest among many.

------
brudgers
I'll admit it. I'm as skeptical of this as I am of religious claims.

 _'"Our findings are statistically consistent with a head-on collision between
the Andromeda galaxy and our Milky Way galaxy," adds Roeland van der Marel of
the STScI.'_

How the hell does one establish statistical consistency when predicting an
event four billion years in the future across 2.5 million light years? The
sample size which has been analyzed is zero.

 _"The Hubble Space Telescope team, led by van der Marel, conducted
extraordinarily precise observations of the sideways motion of M31 that remove
any doubt that it is destined to collide and merge with the Milky Way."_

Here is the fundamental fallacy at heart of the matter - the very one which
makes this certainty bad science: the degree of precision with which one makes
their measurements has absolutely no bearing on the accuracy of those
measurements. Instead it indicates that all the errors were repeatable.

Science does some wonderful things...when it uses its own original methods
rather than relying on faith that its high purpose makes its conclusions true.

~~~
bfe
At its heart, this is straightforward mechanics using precision measurements
of the tangential motion of a statistically large sample of bright stars in
Andromeda, as opposed to trying to track every single star in Andromeda
(impossible of course), combined with radial motion easily measured by the
Doppler shift on spectral lines. We know how to do this.

There are three separate papers that have been accepted for publication in The
Astrophysical Journal but haven't appeared yet. Let's see what they say.

~~~
brudgers
> _"There are three separate papers that have been accepted for publication in
> The Astrophysical Journal but haven't appeared yet. Let's see what they
> say."_

The metaphysical equivalent of an Encyclical. Swapping one group of experts
for a group of experts with different training doesn't get one anything
without the premise that the new experts espouse the one true view.

------
jberryman
> Although the galaxies will plow into each other, stars inside each galaxy
> are so far apart that they will not collide with other stars during the
> encounter.

Wow, that is just impossible to fathom.

~~~
dredmorbius
Not impossible.

It just takes a lot of fathoms.

The nearest star is 2.3796167e+16 fathoms from Earth.

The Andromeda Galaxy is presently about 1.3e+22 fathoms away.

It's approaching the Milky Way at roughly 5.8e+8 furlongs per fortnight.

------
dm8
Fabulous and fascinating. Question is whether earth can survice the onslaught
of existing human activity in next billion years rather than collision from
next 4 billion years.

~~~
Erunno
Earth will easily survive humanity, even if we carpet bomb the surface with
nuclear weapons. Even life is very likely to survive in its own niches as it
has done during past global catastrophes. So worrying about earth is
unwarranted in my opinion. Humans should be mostly concerned about their own
species surviving in the foreseeable future. And so far I do not see any
imminent danger of that happening, especially with our masterfully
understanding to adapt our environments to suit our needs. But developments
like global warming could lead to some drastic population swings in the future
(e.g. via wars, famine, etc.).

Oh, and live will be gone on earth anyway, AFAIK in about 1 billion years when
the sun has become so luminous that the oceans on earth will vaporize and
ultimately escape into space. And the collision between the galaxies will very
likely have no immediate effect on our solar system due to the vast space
between stars (and therefore planets).

------
Toenex
Good bases for next years Deep Impact/Armageddon movie head-to-head.

