The Milky Way’s 2 biggest satellite galaxies are oddly lonely, study finds


The Milky Way’s system of small, orbiting satellite galaxies is quite unusual, a new 12-year study of other galaxies in the local universe has found. 

The Satellites Around Galactic Analogs (SAGA) survey is being conducted by a small group of astronomers to learn how the Milky Way and its little retinue of dwarf satellite galaxies compares to other galaxy systems.

“The Milky Way’s satellite population is a unique combination of small satellites containing only older stars, and its two largest satellites, which are actively forming new stars,” says Marla Geha, who is a professor of astronomy and physics at Yale University and co-founder of SAGA, in a statement.

A Milky Way-type galaxy, with its satellite galaxies highlighted. (Image credit: Yasmeen Asali (Yale)/DESI Legacy Surveys Sky Viewer)

Those two largest satellites are the Large and Small Magellanic Clouds, known as the LMC and SMC in shorthand. These two satellites are far and away the largest in the Milky Way’s family and are readily visible to the naked eye from the Southern Hemisphere. Most of the other 59 known satellite galaxies of the Milky Way are exceedingly faint, requiring the Hubble Space Telescope or large ground-based telescopes to detect them.



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