Galaxy was headed at us at like 100 times faster than a bullet

[Daark Nova]

so i heard that a galaxy was headed at us at like 100 times faster than a bullet. so what happens when it gets to us. Earth would be dead by then. mankind with it probably. but what happens to the galaxy?

 

[saltydog]

It appears that galaxies are always interracting with each other. They "feed" on one another, merging, tearing-apart, evolving. There's some good Hubble pictures of galaxies in collision. We only see a snap-shot in the sky. We'll just merge with Andromeda. The time is great, millions of years. We'll probably have changed a bit by then, maybe moved (from earth).

Salty

 

[Phobos]

Welcome to PF!

Colliding galaxies generally pass right through each other with very few direct collisions of the stars therein (galaxies are mostly empty space). However, there will be 2 very significant effects: (1) the shapes of both galaxies will be changed dramatically (no more neat spiral) and (2) there will be a burst of new star formations (as nebulae are gravitationally jolted). The 2 galaxies could merge or go into some kind of orbit around each other.

 

[Andromeda321]

When the Andromeda galaxy collides with our own there will be a lot of gravity interactions that will mess up the spiral shape of the two galaxies and throw many hundreds of stars out into space. Now I believe the sun will be gone by the time Andromeda and the Milky Way collide (don't remember how far into the future this is going to happen) but should our star and planet still be around to be flung out of the galaxy it won't be apparent on Earth. The Earth will continue to circle the Sun as it does normally and the only apparent difference will be no stars in the night sky because all the stars we currently see are from our own galaxy.

 

[Xare]

By the time this happens we will either be long dead from nuclear war or we will have the power to leave.

 

[Phobos]

Now I believe the sun will be gone by the time Andromeda and the Milky Way collide (don't remember how far into the future this is going to happen)

The 2 galaxies will "collide" approx. 6 billion years from now, which is about the same time our sun will be in its red giant phase, possibly engulfing the Earth.

 

[Ravine]

The 2 galaxies will "collide" approx. 6 billion years from now, which is about the same time our sun will be in its red giant phase, possibly engulfing the Earth.

I do believe that six billion is only when it expands to engulf venus's orbit, not earth's. Although the Earth will be destroyed by the close proximity It will fully engulf Earth's orbit in around 7-8 billion years.

 

[Chronos]

The sun will become a red giant rather quickly after it leaves the main sequence - a mere 680 million years.

 

[kirovman]

You can think of the galaxies as a low density gas in terms of collisions - the density of the galaxies are very low, I'm not sure how low, but I'd imagine a lot less dense than our atmosphere on average, considering the vast empty space. Just imagine a couple of gases being mixed (not thinking too much about their expansion from diffusion.)

Although the gravitational effects may cause a lot of orbits to be messed up.

In my astronomy class last year, I seem to remember that the Andromeda galaxy is apparently 5 times larger than the moon in the sky (angular size), but it is very dim so not easily observable. So that may give you some kind of scale of it, but it's hard to imagine.

 

[Phobos]

I do believe that six billion is only when it expands to engulf venus's orbit, not earth's. Although the Earth will be destroyed by the close proximity It will fully engulf Earth's orbit in around 7-8 billion years.

Well, I said "possibly".
My impression is that the exact radius of the red giant phase is not definitively predicted. Earth's radius is within the area of uncertainty.

 

[turbo]

In my astronomy class last year, I seem to remember that the Andromeda galaxy is apparently 5 times larger than the moon in the sky (angular size), but it is very dim so not easily observable. So that may give you some kind of scale of it, but it's hard to imagine.

If you go to a decent dark-sky site (getting VERY hard to find in some areas, but Maine has a lot of dark spaces), Andromeda will jump out at you. Very easy to see naked-eye, and a stunner in good binoculars. Our dark skies are a precious resource, and they are being lost to development, greed, and fear of the dark. It's very disheartening to hear Andromeda characterized as a dim or difficult naked-eye object, because it is a measure of how badly we are degrading our environment with light pollution and combustion-product pollution (causing haze).

 

[Andromeda321]

What kirovman might have been referring to is the overall surface density of the Andromeda galaxy. All told the galaxy itself is very bright to the naked eye as turbo-1 said but it's not very impressive at all in a telescope (binoculars are actually better for it). The reason is because of the huge size of the galaxy in our sky, which makes it have a low surface brightness overall when viewed through a telescope.

 

[Gold Barz]

It will merge into one giant galaxy, I also read that it will kill most of the life that is in the two galaxies, not saying life will be "banned" from this new galaxy, new life forms could arise after the collision...sort of like a fresh start

 

[Chronos]

Galaxies are predatory. Big ones eat little ones. When the big bully andromeda passes through our galaxy, it will trigger furious star formation. There will be few actual collisions between stars, but massive interactions between gas clouds. The end result may be a fairly large elliptical galaxy with many young stars.

 

[turbo]

...overall surface density of the Andromeda galaxy. All told the galaxy itself is very bright to the naked eye as turbo-1 said but it's not very impressive at all in a telescope...

It really depends on your telescope. Andromeda can be beautiful through a "light bucket" like the typical dobsonian. Again, though, you need dark, clear skies to get high-contrast views. If there is a Wal-Mart or some other big-box store moving to your town, a business that is expanding or renovating their parking areas or planning site "improvements" that involve lighting, etc, please attend the public hearings and try to focus some of the debate toward efficient, properly-directed lighting, timers, etc. Dark skies are disappearing.