According to Einstein’s general theory of relativity, matter tells space how to curve, and space tells matter how to move. Gravity shapes the universe.
These three galaxies are located about 35 million light years from Earth and bear multiple scars from their mutual gravitational interactions. Seen edge-on at left, NGC 3628, known as the Hamburger Galaxy, is bisected by a dark dust lane and has prominent tidal distortions visible on both sides of its disk. M66, the barred spiral galaxy at lower right, has asymmetric spiral arms, a noticeable bar structure, active star-forming regions, and tidal streams of stars extending outward, all signs of gravitational dances with its neighbors.
Over the next few billion years, gravity will gradually cause the orbits of NGC 3628 and M66 to decay, pulling their gas, stars, and dark matter together until they merge. M65, at top right, will eventually contribute its stars, gas, and dark matter as well, resulting in a single large elliptical galaxy.
