Isn't it scary how the Earth is going to ripped in pieces.

[Laminal Cockroach]

My physics teacher was teaching us about Red and Blue shifts the other day, and out came the topic that the Andromeda Galaxy is the only galaxy which i moving towards us. I am actually well confused if the galaxy is moving directly towards us, but the concern is that if it actually is soon the earth is just going to be ripped into pieces by the gravity of another strong planet or space object onthe edge of thet galaxy :shifty: :shifty: :shifty:

[Moose]

IIRC, we're talking a timeframe of a hundred million to a billion years or so before anything happens, so you'll have plenty of time to set your affairs in order.

In any case, the sun will have expanded and engulfed the Earth much sooner anyway (again, IIRC, around a million years from now.)

No worries.

[Donnie B.]

Don't worry, be happy.

First of all, the Andromeda galaxy won't get here for a very, very long time. We'll be lucky if our descendents are still alive to see it. We certainly won't be.

Second, a collision of galaxies isn't as horrible as you might think. Most stars in both galaxies pass by each other with little or no effect. There might be a rise in the number of supernovae, and a few stars may "switch loyalties" and end up in the other galaxy (or neither), but that's not a big deal.

Third... welcome to the BAUT forum! :D

[Donnie B.]

In any case, the sun will have expanded and engulfed the Earth much sooner anyway (again, IIRC, around a million years from now.) Er, make that five billion or so. If it were only a million I'd be building a spaceship in my basement right now! ;)

[farmerjumperdon]

I think the timeframe for the Sun expanding to the point of harming Earth is more like a billion years+. Even if the models are off, or there are unknowns in how the changes in the Sun will effect the Earth - I think it is still on the order of hundreds of millions.

But what's a few 0's amongst friends?

[weatherc]

I am actually well confused if the galaxy is moving directly towards us, but the concern is that if it actually is soon the earth is just going to be ripped into pieces by the gravity of another strong planet or space object onthe edge of thet galaxy :shifty: :shifty: :shifty:
Don't know if this will make you feel any better, but:

Imagine the Grand Canyon.

Next, imagine a couple of gnats flying around in the Grand Canyon.

Now, try to imagine what the chances would be of those gnats hitting each other.

That's the kind of scale we're talking about here; stars (on average) are as far apart from each other as those gnats in the Grand Canyon. Even if Andromeda were colliding with the Milky Way right now, you probably wouldn't even know it, unless an astronomer told you it was happening.

[Moose]

Er, make that five billion or so. If it were only a million I'd be building a spaceship in my basement right now! ;)

[mad megalomaniacal sort]

"Curses! This changes everything!"

*erases chalkboard with secret doomsday plans and starts afresh*

"Muahahahaha!"

[/mms]

Ah well, I knew I should have actually looked up my figures rather than relying on memory. :)

[Wolverine]

Second, a collision of galaxies isn't as horrible as you might think. Most stars in both galaxies pass by each other with little or no effect. There might be a rise in the number of supernovae, and a few stars may "switch loyalties" and end up in the other galaxy (or neither), but that's not a big deal.

Precisely. Laminal Cockroach, you might find this neat presentation (http://hubblesite.org/discoveries/cosmic_collision/) informative. :)

[farmerjumperdon]

OK, so seriously: It appears to be well established that the Sun is about half-way thru an 8 to 10 billion year life. Also, that once the Sun reaches a certain age and expands accordingly, the Earth will boil away or vaporize or turn into a piece of cinder like a chimney clinker; but - what are the estimates for how long life as we know it, especially humans, will cease to exist on Earth? How subtle of a change in the Sun would render Earth uninhabitable? Seems safe to say it will be well before the red giant phase. Will it happen in 2 billion years, or 1 billion, or could it happen in as little as a couple hundred million? Given the uncertainties, and the incredible voyages involved, I'd say if we ever expect to colonize outside our soalr system, it is something we should never stop working on.

[Lianachan]

OK, so seriously: It appears to be well established that the Sun is about half-way thru an 8 to 10 billion year life. Also, that once the Sun reaches a certain age and expands accordingly, the Earth will boil away or vaporize or turn into a piece of cinder like a chimney clinker; but - what are the estimates for how long life as we know it, especially humans, will cease to exist on Earth? How subtle of a change in the Sun would render Earth uninhabitable? Seems safe to say it will be well before the red giant phase. Will it happen in 2 billion years, or 1 billion, or could it happen in as little as a couple hundred million? Given the uncertainties, and the incredible voyages involved, I'd say if we ever expect to colonize outside our soalr system, it is something we should never stop working on.

Isn't it supposed to happen in about 2012?

:whistle:

[Nicolas]

It's more like 3 years from now, but I don't think I was allowed to see into that information :).

Looking at human evolution, even a few hundred million years is still an incredible amount of time. Enough to develop some solid outer-solar-system colonisation techniques :). And last time I checked, the models predicted a few billion years, taking leap years into account ;). Anyway, it won't be my problem I guess :).

[weatherc]

OK, so seriously: It appears to be well established that the Sun is about half-way thru an 8 to 10 billion year life. Also, that once the Sun reaches a certain age and expands accordingly, the Earth will boil away or vaporize or turn into a piece of cinder like a chimney clinker; but - what are the estimates for how long life as we know it, especially humans, will cease to exist on Earth?
From what I've read, the Sun is putting out more energy as it gets older, and that within about a billion years, it will be putting out enough energy to make life (as we know it) on Earth nearly impossible. After a certain point, the atmosphere will evaporate, and the oceans will come to a boil. This is all well before the Sun actually hits its red giant phase (which should be about 4 or 5 billion years from now, give or take a few hundred million years).

[antoniseb]

the concern is that if it actually is soon the earth is just going to be ripped into pieces by the gravity of another strong planet or space object onthe edge of thet galaxy

The planet Earth will not get ripped apart by the differential gravity of M31 any more than it is being ripped apart now by the cental part of the Milky Way (that is to say it will not be).

[farmerjumperdon]

My fears are confirmed. There are only a few hundred million years left, . . . at best.

[Donnie B.]

*sigh*


It was nice while it lasted.

[Ilya]

OK, so seriously: It appears to be well established that the Sun is about half-way thru an 8 to 10 billion year life. Also, that once the Sun reaches a certain age and expands accordingly, the Earth will boil away or vaporize or turn into a piece of cinder like a chimney clinker; but - what are the estimates for how long life as we know it, especially humans, will cease to exist on Earth?
Weatherc already explained it -- Sun slowly gets hotter, and will eventually make Earth uninhabitable. The figures I saw range from 200 million to 1 billion years -- in any case, much less than Sun's remaining lifespan.

[Krevel]

Am I the only one who thinks that having a neighbor galaxy would be really cool? The Andromeda galaxy is pretty damn neat looking now, but imagine how awesome it would be if it were just a third or even half of its current distance from us. That will be spectacular, sorry I'm going to miss it!

[weatherc]

My fears are confirmed. There are only a few hundred million years left, . . . at best.
Cheer up! The good news is that with technology just barely more advanced than we currently have available and a little engineering, we can put off the Earth becoming toast until the Sun reaches red giant stage.

If we just put a big mesh filter (or a number of smaller ones) between ourselves and the Sun, it would block a certain percentage of the light hitting Earth. Just use whatever density mesh is needed to keep things at the status quo, and Earth is saved until the sun becomes a red giant, or as long as the mesh is maintained.

[fossilnut2]

"That's the kind of scale we're talking about here; stars (on average) are as far apart from each other as those gnats in the Grand Canyon"

Actually stars are MUCH farther apart than that. Multiples farther apart.

[weatherc]

"That's the kind of scale we're talking about here; stars (on average) are as far apart from each other as those gnats in the Grand Canyon"

Actually stars are MUCH farther apart than that. Multiples farther apart.
I think the scale holds up pretty well.

Let's assume that a standard gnat is 1.3 mm wide, and represents the Sun (which is 1.3 million km wide, give or take). This gives us the following scale:

1 mm=1 million km
1 m=1 billion km
1 km=1 trillion km
5.9 km=~1 light year
25.96 km=~distance to Alpha Centauri (4.4 ly, give or take)

Since the Grand Canyon is about 277 miles long (http://en.wikipedia.org/wiki/Grand_Canyon) (thanks, Wikipedia!), that actually means that you could put a lot of our local group of stars inside at that scale.

And stars at the center of the Milky Way are a lot closer together than they are out here where the Sun is, so you could cram a lot more stars in at the scale that we're discussing.

Even if you double the size of our "standard gnat" to 2.6 mm wide, that still puts Alpha Centauri about 52 km away from the Sun, which would still fit in the Grand Canyon with room to spare.

[antoniseb]

If we just put a big mesh filter (or a number of smaller ones) between ourselves and the Sun, it would block a certain percentage of the light hitting Earth.

So many people get confused by the idea that if we do nothing, the Sun will evaporate the oceans in 500 million years, and forget that we can do something, and that 500 million years is a very long time.

[Enzp]

Are we sure we are using standard gnats? WHo calibrated the gnats?

[weatherc]

Are we sure we are using standard gnats? WHo calibrated the gnats?
:D

Yup. We're using nothing but ISO-certified gnats.

[ASEI]

1 standard gnat = 1.3 mm. I'll remember it for future reference :lol:

[Musashi]

An African gnat?

[Maksutov]

Or a European gnat?

[ZaphodBeeblebrox]

"I DON'T Know!!!!"

AHHHHHHHHHHHHHHHHHHHHHHHH

[dakini]

My physics teacher was teaching us about Red and Blue shifts the other day, and out came the topic that the Andromeda Galaxy is the only galaxy which i moving towards us. I am actually well confused if the galaxy is moving directly towards us, but the concern is that if it actually is soon the earth is just going to be ripped into pieces by the gravity of another strong planet or space object onthe edge of thet galaxy :shifty: :shifty: :shifty:
Andromeda isn't the only one moving towards us.

It's just the first of the same size of our galaxy.

Our beloved milky way has been eating galaxies for some time. By the time we encounter andromeda, our sun will have burnt out and we will be long dead. Not to forget that usually when galaxies collide, stars end up fine after, there's enough space that they don't collide with one another and they go on their merry way.

It's the virgo cluster that we have to worry about in terms of tearing our galaxy (which will by then be combined with andromeda) to shreads.

[Champion_Munch]

"I DON'T Know!!!!"

AHHHHHHHHHHHHHHHHHHHHHHHH

"How do you know so much about gnats?"

"Got to know these things when your an astronomer, you know." :D

with regards

[weatherc]

"How do you know so much about gnats?"

"Got to know these things when your an astronomer, you know." :D

with regards
I thought we were an autonomous collective.

[Champion_Munch]

YOU'RE FOOLING YOURSELF! We live in a dictatorship, ruled by the working classes -

Anyway...back on topic... :D

with regards

[weatherc]

It's the virgo cluster that we have to worry about in terms of tearing our galaxy (which will by then be combined with andromeda) to shreads.
But that will be many billions of years in the future, so I don't think anyone should lose any sleep over it. Plus, even if our galaxy gets torn apart, most of the stars remain pretty much unharmed, and as you said, just go on their merry way.

I guess the biggest danger to individual stars would be if they wound up close to the center of the incoming galaxy; the density of stars is much higher in galactic centers, so that could cause trouble for a star that gets in the way. Even then, we're still talking about light years between objects, so it probably wouldn't be a big deal for most stars.

[Champion_Munch]

Am I the only one who thinks that having a neighbor galaxy would be really cool? The Andromeda galaxy is pretty damn neat looking now, but imagine how awesome it would be if it were just a third or even half of its current distance from us. That will be spectacular, sorry I'm going to miss it!

Me too, a nice big Andromeda in the summer sky would be a nice excuse for a random trip out-bush. :)

BTW, weatherc, I just noticed your avatar. :D

with regards

[weatherc]

BTW, weatherc, I just noticed your avatar. :D

with regards
None shall pass!

[farmerjumperdon]

None shall pass!

Not even if we present you with a shrubbery?

[weatherc]

Not even if we present you with a shrubbery?
None shall pass!

[Champion_Munch]

None shall pass!

Would you do it for Randolph Scott?

Oops...wrong movie... :P

with regards

[Donnie B.]

[Whips off hat, holds it over heart, and sings...]

Raaan... dolllph... Scott!

[Swift]

I'm sorry, this thread has become entirely too silly. We'll have none of that round here.
The penguin on top of your computer monitor will now explode.

[crosscountry]

Even if Andromeda were colliding with the Milky Way right now, you probably wouldn't even know it, unless an astronomer told you it was happening.


That is a very interesting point. Aren't we actually colliding with some Dwarf Galaxies currently?



That is a very interesting point. I'm glad you brought it up.

What if humand came into consienceness about the same time as our galaxy was meeting another just as large. Things would be very different.

[crosscountry]

I guess the biggest danger to individual stars would be if they wound up close to the center of the incoming galaxy; the density of stars is much higher in galactic centers, so that could cause trouble for a star that gets in the way. Even then, we're still talking about light years between objects, so it probably wouldn't be a big deal for most stars.


I'd be more worried about insteller happenings. Nova and such emitting harmful rays for life.

[worzel]

So if I understand the Grand Canyon analogy correctly, if gnat repellent improves at the same rate as computer technology then we should have a sufficiently strong galaxy repellent in plenty of time.

[Ara Pacis]

IIRC, the Saggitarius Dwarf Galaxy is slamming into the far side of our galaxy right now, as we are typing. Brace yourself!