Our home galaxy, the Milky Way, grew to its current size in part by consuming smaller galaxies. Now, new data from the NASA/ESA Hubble Space Telescope show definitive evidence of a dwarf galaxy merging with the young Milky Way galaxy in the earliest phases of its evolution. This finding extends our knowledge of our galaxy’s history 1.8 billion years farther back in time than before. The results were published today in the journal Nature Astronomy . The Milky Way today is a massive spiral galaxy home to hundreds of billions of stars. However, our galaxy wasn’t always so large; it has grown by

A team from the Instituto de Astrofísica de Canarias (IAC) has quantified for the first time the impact that the motions of binary stars can have on estimates of dark matter in some of the smallest galaxies in the universe. The study proposes a new methodology that will make it possible to obtain more precise measurements of the amount of dark matter present in these systems. The Milky Way, our galaxy, contains hundreds of billions of stars. However, dozens of much smaller galaxies orbit around it, dwarf companions that host thousands of times fewer stars and live embedded within our galaxy