Hubble Shows MilkyWay unavoidable Collision with Andromeda Galaxy

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NASA astronomers announced Thursday they can now predict with certainty the next major cosmic event to affect our galaxy, Sun, and solar system: the titanic collision of our Milky Way galaxy with the neighboring Andromeda galaxy.

The Milky Way is destined to get a major makeover during the encounter, which is predicted to happen four billion years from now. 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.

"Our findings are statistically consistent with a head-on collision between the Andromeda galaxy and our Milky Way galaxy," said Roeland van der Marel of the Space Telescope Science Institute (STScI) in Baltimore.

The solution came through painstaking NASA Hubble Space Telescope measurements of the motion of Andromeda, which also is known as M31. The galaxy is now 2.5 million light-years away, but it is inexorably falling toward the Milky Way under the mutual pull of gravity between the two galaxies and the invisible dark matter that surrounds them both.

"After nearly a century of speculation about the future destiny of Andromeda and our Milky Way, we at last have a clear picture of how events will unfold over the coming billions of years," said Sangmo Tony Sohn of STScI.

The scenario is like a baseball batter watching an oncoming fastball. Although Andromeda is approaching us more than two thousand times faster, it will take four billion years before the strike.

Computer simulations derived from Hubble's data show that it will take an additional two billion years after the encounter for the interacting galaxies to completely merge under the tug of gravity and reshape into a single elliptical galaxy similar to the kind commonly seen in the local universe.

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. However, the stars will be thrown into different orbits around the new galactic center. Simulations show that our solar system will probably be tossed much farther from the galactic core than it is today.

To make matters more complicated, M31's small companion, the Triangulum galaxy, M33, will join in the collision and perhaps later merge with the M31/Milky Way pair. There is a small chance that M33 will hit the Milky Way first.

The universe is expanding and accelerating, and collisions between galaxies in close proximity to each other still happen because they are bound by the gravity of the dark matter surrounding them. The Hubble Space Telescope's deep views of the universe show such encounters between galaxies were more common in the past when the universe was smaller.

A century ago astronomers did not realize that M31 was a separate galaxy far beyond the stars of the Milky Way. Edwin Hubble measured its vast distance by uncovering a variable star that served as a "milepost marker."

Edwin Hubble went on to discover the expanding universe where galaxies are rushing away from us, but it has long been known that M31 is moving toward the Milky Way at about 250,000 miles per hour. That is fast enough to travel from here to the Moon in one hour. The measurement was made using the Doppler Effect, which is a change in frequency and wavelength of waves produced by a moving source relative to an observer, to measure how starlight in the galaxy has been compressed by Andromeda's motion toward us.

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 have not been able to measure M31's sideways motion in the sky, despite attempts dating back more than a century. 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," said Jay Anderson of STScI.

"In the 'worst-case-scenario' simulation, M31 slams into the Milky Way head-on and the stars are all scattered into different orbits," said team member Gurtina Besla of Columbia University in New York, N.Y. "The stellar populations of both galaxies are jostled, and the Milky Way loses its flattened pancake shape with most of the stars on nearly circular orbits. The galaxies' cores merge, and the stars settle into randomized orbits to create an elliptical-shaped galaxy."

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 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 science team that did the investigation is led by Principal Investigator R.P. van der Marel (Space Telescope Science Institute [sTScI], Baltimore, Md.), and further consists of S.T. Sohn and J. Anderson (STScI), G. Besla (Columbia University, New York, N.Y.), M. Fardal (University of Massachusetts, Amherst, Mass.), R.L. Beaton (University of Virginia, Charlottesville, Va.), Thomas M. Brown (STScI), P. Guhathakurta (UCO/Lick Observatory, University of California, Santa Cruz, Calif.), and T.J. Cox (Carnegie Observatories, Pasadena, Calif).

http://hubblesite.org/newscenter/archive/releases/2012/20/full/

[Mosqutus]

Can't wait!!!

[Hum]

Cool -- bye bye, primitive humans. :shifty:

[vron247]

250,000 miles per hour. That is fast enough to travel from here to the Moon in one hour.

And still take 4 billion years to merge :s

[xbamaris]

Lol, 4 biillion years? The Sun will have expanded and become way to hot for the Earth to sustain life xD So its not that anyone will be around Earth to see it.

[Noir Angel]

It's a shame I'm not going to be alive to witness any of this because by all accounts it's going to be spectacular.

And really, some people seem to be under the impression that it's going to mean certain doom for organic life, which isn't necessarily true. Apart from the fact that the stars in galaxies are so widely spaced apart making a collision unlikely, the general consensus is that the position of the sun and solar system may shift compared to the rest of the galaxy the chances are the actual impact on the solar system won't be that big.

Estimates of the sun's remaining lifespan range from 5-7 billion years so it's still possible there may be some life left on earth when this event starts to occur but whether humans will still be here remains to be seen. Nonetheless still pretty cool and interesting

[devBrian]

Doesn't matter, the Reapers will wipe us out before then.

[Hum]

It's a shame I'm not going to be alive to witness any of this because by all accounts it's going to be spectacular.

^ Why are you not planning to be alive ? ;)

[Noir Angel]

Doesn't matter, the Reapers will wipe us out before then.

:laugh:

^ Why are you not planning to be alive ? ;)

Unfortunately, death isn't something I can mitigate with planning. I could extend my life by eating healthy and exercising but I still think 4 billion years is a bit of a stretch :p

[Phouchg]

Doesn't matter, the Reapers will wipe us out before then.

We should immediately go back to caves, licking our own eyes (trying to, whatsoever) and eating flies, so perhaps the reaptards won't trouble us until we quit doing so.

Stupid telomeres, though... safeguard against cancer that leads to cell death, anyway. Dumbass circular logic! Living forever isn't quite what it used to be, but human lifetime indeed seems too short to me.

[zeta_immersion]

Well ... that or a Stargate ... quick, lets move to Egypt ... clearly if we get the pyramyids to work, we'll travel the stars in a Destiny like ship (hell the Enterprise will be build before that, so i think we'll be safe no matter what)

[.Neo]

Damn it Apple! iCal won't let me make a new appointment for June 1, 4.000.002.012? :crazy:

[threetonesun]

Pfft, in 4 billion years spoiled teenagers will crash the galaxies their parents bought them just for fun.

[wahoospa]

I'm not going to wait around for it to happen, I've got better things to do. Like install Windows 180,756,465,5764,465,576, service pack 75,648,493. Hey look, they finnaly brought Aero back!

[psionicinversion]

I wonder if when our planet gets thrown around if vo5's latest hair gel keeps us looking cool!

[vraev]

Doesn't matter, the Reapers will wipe us out before then.

LMAO! And people will still complain about the ending.

[Phouchg]

Damn it Apple! iCal won't let me make a new appointment for June 1, 4.000.002.012? :crazy:

Be wary, even if it one day lets you do so, you could just oversleep it :shiftyninja:

https://www.neowin.net/news/alarm-clock-bug-hits-iphones-ipads-and-ipods (etc.)

[yowanvista]

And Earth won't probably be habitable by the time this event occurs.

[Dotdot]

Its cool well of blown ourselfs and the planet to a crispy blackened hollow shell by then and either be extinct and or colonizing the universe.

[Somnus]

Well, that's that. Time to start building my army of soldiers with lethal hand to spork combat training.

Sporks FTW!

[Noir Angel]

LMAO! And people will still complain about the ending.

You fools are all indoctrinated!

[spacer]

uh...didn't we already know this? I'm pretty sure I read a long, long time ago that scientists already extrapolated the two galaxy's trajectories and found out they will collide eventually. Did I miss something?

[Noir Angel]

uh...didn't we already know this? I'm pretty sure I read a long, long time ago that scientists already extrapolated the two galaxy's trajectories and found out they will collide eventually. Did I miss something?

From what I'm gathering, whilst it's been suggested for a while that the 2 had a chance of colliding, I think this is the first time that scientists have managed to get a clearer extrapolation of the dynamics of what will happen when they do. I like Hubble simply because it takes some stunning pictures but things like this always hold an interest for me.

[Hum]

And Earth won't probably be habitable by the time this event occurs.

Don't worry -- in a future life, I perfect Planetary Engineering, and we will build our own, new Earth. ;)

[sc302 Veteran]

bah...I have my minions I am ready for what this brings.