When galaxies almost collide
A titanic near miss stirs up stars.
The image of a massive galaxy called NCG 4485, captured by the Hubble Space Telescope, shows remarkable asymmetry.
The reason, NASA scientists say, lies off-camera: another galaxy, called NGC 4490, which millions of years ago came very close to smacking into it.
The extraordinary gravitational force of the near-miss caused massive destruction and disruption, resulting in a compression of interstellar gas that triggered a flurry of new star formation. The process continues, visible as the blue and pink areas on the right-hand side of the image.
The two galaxies are now 24,000 light-years apart, but the effects of their close encounter will be visible for eons.