: S.E.T. Smith et al., Astrophysical Journal, 2024)

When it comes to the galaxies in the Universe, most of us think about the Milky Way and galaxies similar to it. After all, it is our galactic home, and spanning more than 100,000 light-years across. It’s an interesting fact that galaxies comparable in size to the Milky Way (as well as larger ones) , but that they only represent , overall. The majority of galaxies present in the Universe are:

• small,
• low in mass,
• contain very few numbers of stars, overall,
• but are dominated largely by dark matter.

Most of the galaxies in the Universe, because they’re small and contain very few stars within them, are also exceedingly difficult to detect: they’re also ultra-faint galaxies. It takes wide, deep surveys to reveal them at all, and even once they’re imaged, the stars within them need to be measured individually to determine that they’re all at the same distance, and that they’re all…