what is the distance across a galaxy
Though this galaxy is quite big (about 10,000 light years across), it will likely be disrupted by the tidal forces from the Milky Way Galaxy. (For comparison, our galaxy is 100,000 light years across.) The SagDEG is on the other side of the Milky Way from the Sun, about 70,000 light years away.
The Milky Way is the second-largest galaxy in the Local Group, with its stellar disk approximately 100,000 ly (30 kpc) in diameter, and, on average, approximately 1,000 ly (0.3 kpc) thick.