 The irregular galaxy NGC4485 shows the signs of having been involved in a collision with another galaxy. The right side of the galaxy is a blaze with star formation, shown in the large number of young blue and pinkish star birth nebulas. The left side, however, looks intact. It contains hints of the galaxy's previous spiral structure, which at one time was undergoing normal galactic evolution. Here's the other colliding galaxy, NGC4490. The two galaxies side-swiped each other millions of years ago and are now 24,000 light-years apart. The gravitational tug-of-war between them created rippling patches of high-density gas and dust within both galaxies.