Just some little facts that might help....
"...galaxies experience neutral attractions on one other. Due to relativity, the speed of the Milky Way varies when compared with different objects in space. For example... the Milky Way and Andromeda galaxy are approaching each other with a speed of about 130 km/s, however the collision of these two galaxies will not occur for about 5 billion years. Another result... was that our galaxy and neighbors are moving at 600 km/s in the direction of the constellation Hydra. Finally... the Milky Way moves through space within the cluster of galaxies it is a member of, and this cluster in turn moves through space towards yet another larger cluster of galaxies off in the direction of the constellation Virgo. This speed is approximately 300 km/s. Therefore, the speed of the Milky Way galaxy is not a single number, its value is relative to the speed of other objects" - Patricia Kong 1999
The motion of galaxies is determined from an apparent change in the color of light they emit. There are gaps within the spectra of the light emerging from every galaxy. These gaps, called absorption lines, are not located in the spectra at random. The patterns in the missing wavelengths tell us something about the elements present in the stars. In a sense, spectra are like fingerprints. Each element has its own specific set of absorption lines. When a star or group of stars (which is what a galaxy is) are moving relative to us on earth, these elemental fingerprints get shifted from their usual location in the spectra. When a galaxy is moving towards us, these fingerprints get shifted toward the blue end of the spectrum and when a galaxy is moving away from us, they get shifted toward the red end. The amount of shift can be used to determine speed. The greater the shift, the faster the galaxy is moving relative to us on earth.
In 1987, a group of seven astronomers uncovered this coordinated motion of the Milky Way and our several million nearest galactic neighbors -- Alan Dressler, Sandra Moore Faber, Donald Lynden-Bell, Roberto Terlevich, Roger Davies, Gary Wegner and David Burstein. Their results were so astounding they acquired the equally astounding nickname of "The Seven Samurai" (the name of a classic Japanese Samurai movie that spawned the classic American Western movie "The Magnificent Seven"). The place towards which we all appear headed was originally called the New Supergalactic Center or the Very Massive Object until one of the discoverers, Alan Dressler, decided they needed a catchier name and came up with "The Great Attractor".
The mass of the Great Attractor truly is great. Whereas our galaxy contains the equivalent of (10 to the 11th power) solar masses, the Great attractor is estimated to be on the scale of (10 to the 17th power) solar masses; a million times heavier than the Milky Way. If the Milky Way were a piece of gravel, the Great Attractor would be a truck. It's attraction is so strong that we are being sucked into it at the rate of 600 km/s. In comparison, the earth moves around the sun at the relatively pokey rate of 30 km/s and rockets escaping the earth's gravitational pull barely move at 11 km/s.
The Great Attractor is something on the order of 150 million light years from earth. One light year is the distance a ray of light would travel in the vacuum of space in one year -- about 1013 km. At the rate stated, we should arrive at the center of the Great Attractor in something like 15 billion years. Those of you who can't wait will be pleased to know that this is the upper limit on the estimated time of arrival. Since forces accelerate objects we will surely arrive there a few billion years earlier.
...alot of info.... but that hardly scratches the surface...
Arramon