View Full Version : When Our Galaxy Smashes Into Andromeda, What Happens to the Sun?

2007-May-10, 06:33 PM
When astronomers look into the night sky, almost every single galaxy is speeding away from us, carried by the expansion of the Universe. There's one notable exception; though, the massive Andromeda galaxy (aka M31), which is speeding towards us at a rate of 120 km/s. ...

Read the full blog entry (http://www.universetoday.com/2007/05/10/when-our-galaxy-smashes-into-andromeda-what-happens-to-the-sun/)

2007-May-11, 04:59 PM
Part of the above story was what happens in 100 billion years, and I think you forgot that our local group, along with many others, is being pulled towards the great attractor:

The Great Attractor is one such structure, a diffuse concentration of matter some 400 million light-years in size located around 250 million light-years (ly) away in the direction of the southern Constellation Centaurus, about seven degrees off the plane of the Milky Way -- at a redshift-distance of 4,350 kilometers (or around 2,700 miles) per second. It lies in the so-called Zone of Avoidance, where the dust and stars of the Milky Way's disk obscures as much as a quarter of the Earth's visible sky

The Great Attractor is apparently pulling in millions of galaxies in a region of the universe that includes the Milky Way, the surrounding Local Group of 15 to 16 nearby galaxies and larger Virgo Supercluster, and the nearby Hydra-Centaurus Supercluster, at velocities of around 600 (in the Local Group) to thousands of kilometers (or miles) per second (Lynden-Bell et al, 1988; and Dressler et al, 1987). Based on the observed galactic velocities, the unseen mass inhabiting the voids between the galaxies and clusters of galaxies is estimated to total around 10 times more than the visible matter in this region of the universe and so must be composed of mostly dark matter. Calculations indicate that the Great Attractor has perhaps around 5.4 times 1016 Solar-masses. Galaxies located on the other side of the Great Attractor are also being pulled in its direction, so that they were being held back very slightly from expanding as fast as rest of the universe, by the gravitational pull of the Great Attractor (Renée C. Kraan-Korteweg, 2000).

From the link:


So how long will it take for us to get there (how long will it take for our group to travel the 250 million light years at 600km/s)?

It would take about 100 billion years to get there ... what will happen then? Our sky might actually be full of nearby galaxies that have also been pulled in ...

2007-May-11, 05:50 PM
You wrote:

"...Milkomeda will account for the entire visible Universe."

Please correct me if I am wrong: but the local group - and the supercluster (Virgo) - should still be visible...they are not going anywhere

2007-May-11, 09:53 PM
Astronomers have run new simulations to see what could happen when an expected collision takes place between our galaxy and another big one - possibly within our descendants’ lifetimes.
The surprising results: little of the celestial fireworks that were widely expected to occur as great gas clouds crunch together to form new stars. In*stead, a more outlandish possibility arose.
The computer simulations indicated there is a one in 37 chance we’ll end up living in that other galaxy - majestic Andromeda, said the researchers, T. J. Cox and Abraham Loeb of the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Mass.

Source (http://www.world-science.net/exclusives/070510_galactic-collision.htm)

If Homo sapiens can stick it out on Earth for another two billion years, our descendants may witness quite a show in the night sky. Researchers estimate that the Milky Way will collide with its nearest neighbour, the Andromeda galaxy, at around that time—well before the sun collapses into a white dwarf.
This close encounter of the galactic kind could easily kick our solar system to the farthest reaches of the galaxy, and there is a small chance we might even take up residence in Andromeda, according to astronomers T. J. Cox and Abraham Loeb of the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Mass.

Read more (http://www.sciam.com/article.cfm?chanID=sa003&articleID=7C641AD7E7F299DF354A34FEAE2CAB1A)

One Skunk Todd
2007-May-15, 06:39 PM
I think they should call the combined galaxy Amway. :)

2007-Jun-07, 01:26 AM
This might not even be a problem...If the andromada hits by us then its a huge problem but if it hits the other side of the galaxy then i dont see what we are worying about...sure it might be able to through our solar system out of the galaxy but i thing we might still be able to survive with just our sun wondering aimlesly through the heavens.