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andromeda versus the milky way

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astronomers predict a titanic collision

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presented by science at nasa

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imagine having a galaxy fall on your

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head and you survive the experience nasa

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astronomers say that's exactly what's

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going to happen to our milky way galaxy

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approximately 4 billion years from now

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new data from the hubble space telescope

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confirmed that the milky way is on a

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collision course with the great

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andromeda galaxy

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when the mash-up occurs say researchers

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it's likely the sun will be flung into a

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new region of our galaxy

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but earth and the solar system are in no

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danger of being destroyed

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after nearly a century of speculation

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about the future destiny of andromeda

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and our milky way we at last have a

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clear picture of how events will unfold

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over the coming billions of years says

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sangmo tony son of the space telescope

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science institute in baltimore maryland

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astronomers have long known that

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andromeda and the milky way were

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converging drawn together by their

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mutual pull of gravity and an invisible

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dark matter halo that surrounds them

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both but no one knew whether the far

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future encounter would be a near-miss a

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glancing blow or a head-on smash-up

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it all depends on the amount of

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andromeda's sideways motion

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a lot of sideways motion would allow

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andromeda to sail wide of the milky way

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missing our galaxy entirely

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less of it would bring the two galaxies

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directly together

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the hubble team led by roland van

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damerell of the space telescope science

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institute conducted extraordinarily

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precise observations of the sideways

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motion that removes any doubt andromeda

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is destined to collide directly and

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merge with the milky way

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although the two galaxies will plow into

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each other stars inside each galaxy are

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so far apart that they will not collide

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individually

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instead the stars will be thrown into

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different orbits around a new combined

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galactic center

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simulations show that our own sun will

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probably be tossed much farther from the

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galactic core than it is today

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team member gertina besla of columbia

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university in new york describes what a

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head-on collision will be like

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the stellar populations of both galaxies

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would be jostled and the milky way will

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lose its flattened pancake shape

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the two galaxies cores will merge and

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the stars will settle into randomized

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orbits to create a new elliptical shaped

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galaxy

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to make matters more complicated

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andromeda has a companion the triangulum

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galaxy also known as m33

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m33 is a relatively small galaxy not

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nearly as large as andromeda or the

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milky way nevertheless it could play a

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big role

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m-33 will join in the collision and

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perhaps later merge with the andromeda

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milky way pair

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there's even a small chance that m33

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might hit the milky way first

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amazingly earth and the solar system

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should emerge from the melee unscathed

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we'll just have a new galactic address

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and perhaps a night sky with a double

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helping of stars

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it turns out that a galaxy falling on

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your head isn't so bad after all

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for more news about cosmic collisions