Sagittarius Dwarf Elliptical Galaxy

Not all galaxies are solitary and least or all, this one. It is a satellite galaxy, which means it orbits around another galaxy, which I consider important to mention, is ours.

This small one revolves around our galaxy and slowly it is being absorbed by it due to the interaction between the galaxies.

With a diameter of about 10,000 light years , it is currently at 70,000 light years distance from Earth and moves in a polar orbit at about 50,000 light years from the center of our galaxy.

It is situated on an opposite emplacement to the solar system in relation to the galactic center, which makes it a very difficult object to observe, even though it covers a wide region of the sky. It will pierce the galactic disk of the Milky Way in the next 100 million years and will eventually be absorbed by our galaxy. It seems that this was a dwarf spheroidal galaxy in the beginning, but has been stretched considerably by the tidal forces of the Milky Way. Many of its stars and gas stream seem scattered along its orbit. Four globular clusters of the Milky Way have visibly originated from it: M54, Arp2, Terzan 7 and Terzan 8. In fact, it is thought that M54 is part of this galaxy and not the Milky Way, and it has even been suggested that it can be its core.

Yes, indeed our galaxy cannot escape things like galactic collisions, far from it actually, as it is devouring the Sagittarius dwarf.  

The Milky Way and The Sagittarious Dwarf Galaxy