July 15, 1999: Exciting Hubble telescope images of more than a dozen very distant colliding galaxies indicate that, at least in some cases, big massive galaxies form through collisions between smaller ones, in a "generation after generation" story.
Hubble studied 81 galaxies in the galaxy cluster MS1054-03 and found that 13 are remnants of recent collisions or pairs of colliding galaxies. The large picture on the left shows this galaxy cluster. The eight smaller images on the right are close-ups of some of the colliding galaxies. The snapshots show the paired galaxies very close together with streams of stars being pulled out of them. The colliding "parent" galaxies lose their shape and smoother galaxies are formed. The whole merging process can take less than a billion years.See the rest: