Enjoy the Milky Way while you can. Our home galaxy and the Andromeda Galaxy are the main members of the Local Group of galaxies; you can think of them as the anchor stores of the Local Group mall. Unlike Sears and JCPenney, however, our galaxy and Andromeda are moving closer all the time. In a couple of billion years, they’ll begin to interact gravitationally, then they’ll collide. Now they’re classic spiral galaxies; five billion years from now, they’ll merge into a single big elliptical galaxy.
Five billion years is a very long time, but our Sun and Earth will still exist. The Sun will be in its red giant phase, and Earth will be a scorched cinder packed full of fossils.
T. J. Cox and Avi Loeb of the Harvard-Smithsonian Center for Astrophysics have calculated what will happen to our Sun when Andromeda and the Milky Way collide. They found that the Sun will move outward until it orbits about 100,000 light-years from the heart of the new elliptical galaxy. We orbit about 30,000 light-years from the center of the Milky Way today.
The dreadful thing about this not that we’ll be moving to a new neighborhood. Rather, it’s that the silvery band of the Milky Way that we see in dark night skies will not survive. We see that hazy band because the Milky Way is a flat spiral and we’re within it. When you look up at the Milky Way’s hazy band, you are looking through the dense plane of our galaxy. Starting two billion years from now, that lovely band will blur and vanish as Andromeda’s gravity stirs up the Milky Way’s 100 billion stars.
So get out under a dark sky and view the Milky Way while you still have the chance.
Closure at last!
This is a very interesting study …
what a wonderful view it would be to look up in the night sky and view andromeda filling the heavens even if it were on a collision course. i have read that even when galaxies with billions of stars collide they rarely have a collision of stars or planets due to the sheer distances involved. but there would be problems with the attraction of gravity.still its a breathtaking thought.i have a question.would the gravity of,and speed of both bodies speed up the merger? i have seen some slides that show galaxies shooting through, and others pulling apart.but if we know the speeds are we sure of an elliptical galaxy being formed?
Scorched earth…if that’s correct, hopefully we’ll have found a new and safe planet to call home before that happens so we don’t end up being the fossils.