Scientists suspect that the Milky Way may have dwarf galaxies all around it. One of these galaxies is known as "Segue 2."
Segue 2 is an abnormally small galaxy located right outside of our galaxy, the Milky Way. This dwarf galaxy only has 1,000 stars; they are held together by a clump of dark matter. First discovered in 2009, Segue 2 is primarily known for its unique size.
In comparison to Segue 2, the Milky Way has 100 billion stars. For 15 years, scientists have believed that galaxies like the Milky Way “which are surrounded by thousands and thousands of low mass clumps of dark matter,” like the one in the center of Segue 2, must exist, according to Dr. James Bullock, a cosmologist at the University of California, Irvine.
However, the mass of Segue 2 is no greater than 100,000 times the mass of the sun. This dwarf galaxy may be the first of the clumps that scientists have identified and predicted to exist.
It’s a small galaxy, but its little size doesn’t trump how important and relevant this discovery is.
The New York Times