
A smaller galaxy that orbits a larger galaxy, bound by its gravitational pull.A satellite galaxy is a smaller galaxy that orbits a larger one, held by the larger galaxy's gravitational pull. The most familiar example is the Milky Way's own companions, such as the Large and Small Magellanic Clouds, which are visible to the naked eye from the Southern Hemisphere. These systems are not just cosmic curiosities — they are natural laboratories for studying how galaxies form, evolve, and interact.
The concept of satellite galaxies became clear in the early 20th century as astronomers realized that some nebulae were actually separate galaxies. The Magellanic Clouds were known to ancient navigators, but their true nature as galaxies was established in the 1910s–1920s.
The larger galaxy's gravity dominates the region, pulling the smaller galaxy into an orbit. Over time, tidal forces can distort the satellite's shape, stripping away stars and gas, and sometimes triggering bursts of star formation. The satellite's motion and internal dynamics reveal the mass distribution of the larger galaxy, including its dark matter halo.
Studying satellite galaxies helps astronomers map dark matter, test models of galaxy formation, and understand how small galaxies are disrupted and absorbed by larger ones.
The Milky Way has more than 50 known satellite galaxies, and many of them are so faint that they were only discovered in the last two decades with sensitive digital surveys.








