The study of how galaxies within the Local Group interact through gravity, influencing their motions, future evolution, and structure. The Local Group contains over 80 galaxies, including three large ones: the Milky Way, Andromeda (M31), and the Triangulum Galaxy (M33), along with many dwarf galaxies.
Local Group dynamics examines:
- Gravitational interactions between the Milky Way and Andromeda, which are moving toward each other and are expected to collide in about 4–5 billion years.
- The motion of satellite galaxies, such as the Large and Small Magellanic Clouds, which orbit the Milky Way and are affected by its gravity.
- Tidal forces, which can stretch galaxies and strip away gas and stars, forming stellar streams like the Sagittarius Stream around the Milky Way.
- Dark matter distribution, which plays a major role in binding the Local Group together through its gravitational effects.
- Galaxy mergers and evolution, which shape the structure and future of the Local Group.
Overall, Local Group dynamics helps astronomers understand galaxy interactions on a small cosmic scale, providing insight into how galaxies evolve through gravity, mergers, and dark matter influence.